CN113484116A - Method for nondestructively preparing artificial core with fracture-cavity/fracture structure and artificial core - Google Patents
Method for nondestructively preparing artificial core with fracture-cavity/fracture structure and artificial core Download PDFInfo
- Publication number
- CN113484116A CN113484116A CN202110805218.4A CN202110805218A CN113484116A CN 113484116 A CN113484116 A CN 113484116A CN 202110805218 A CN202110805218 A CN 202110805218A CN 113484116 A CN113484116 A CN 113484116A
- Authority
- CN
- China
- Prior art keywords
- fracture
- core
- artificial
- rock
- artificial core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention relates to the field of oil and gas field development and discloses a method for preparing an artificial core with a fracture hole/fracture structure in a nondestructive mode and the artificial core. The method comprises the following steps: (1) filling the first rock forming mixture into a core mould; (2) pressing an ellipsoidal capsule body and/or a strip body corresponding to a karst cave and/or fracture structure of an actual oil-gas reservoir into the first rock-forming mixture, and performing pressing treatment after arranging an injection-production well; (3) taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slit hole/slit structure; (4) filling 2-camphene powder into a slot/crack structure, and filling the second rock forming mixture into a core mould; (5) and pressing, curing, detecting and pouring the diagenetic mixture to obtain the artificial core. The artificial core prepared by the method can simultaneously meet the requirements of fine simulation of complex fracture-cave/fracture networks of oil and gas reservoirs and nondestructive preparation of the artificial core.
Description
Technical Field
The invention relates to the field of oil and gas field development, in particular to a method for preparing an artificial core with a fracture hole/fracture structure in a nondestructive mode and the artificial core.
Background
At present, the exploration and development of global unconventional oil and gas are in a high-speed development stage, the unconventional oil and gas resources have huge potential and great strategic significance, and the global unconventional oil and gas exploration and development is gradually becoming the take-over resources of the conventional oil and gas. Among them, fracture-cavity carbonate reservoirs and fracture-cavity tight sandstone reservoirs play more and more important roles in the development process of oil and gas fields.
The reservoir seepage space of the fracture-cavity carbonate rock oil-gas reservoir mainly comprises karst caves and cracks, the three-dimensional space is irregularly distributed, the fracture-cavity communication relationship is various, the oil-water relationship is complex, and the heterogeneity is strong; the fracture-type compact sandstone oil and gas reservoir generally has the characteristics of low porosity and high permeability, and for the reservoir, due to the development of fractures, the core is fragile, the drilling probability in the coring process is low, and the acquisition quantity of natural cores is limited. For the two types of oil and gas reservoirs, the difficulty of describing the actual oil and gas reservoir structure by using the conventional artificial rock core is high, the underground seepage space communication condition cannot be truly simulated, the research progress of related physical simulation experiments is restricted, and the difficulty of fluid seepage characteristic research is increased. Therefore, the preparation of complex artificial rock cores (including fracture-cavity carbonate rock artificial rock cores and fracture-type tight sandstone artificial rock cores) is of great significance.
At the present stage, common complex oil and gas reservoir physical simulation models comprise a one-dimensional physical model, a two-dimensional physical model and a three-dimensional physical model, and key technologies for realizing successful preparation of the models are seam making technologies in a rock core. At present, the seam making process in the preparation process of the complex core mainly comprises the following steps: (1) the method for cutting the cracks is characterized in that the cutting device is utilized to make the cracks in the rock core, so that the crack forms and the distribution of the cracks can be effectively controlled, but the cut parts of the non-cracks still need to be cemented or filled again, the cemented material used by the method and the rock core substrate have larger difference, and the cutting process has higher technical requirements on operators and certain dangers; (2) the fracture pressing method is characterized in that a triaxial stress loading machine and other devices are utilized to apply external force to enable cracks to be generated in a rock core, but the process mainly simulates the fracturing process, and the generated cracks are random in distribution, form and other parameters, difficult to control and incapable of ensuring the fracture forming effect; (3) the splitting method is that a cutter or a pricking pin is used for applying normal stress to the core to generate micro cracks, but the opening degree and the trend of the cracks are difficult to control, and the core can be broken; (4) filling method, namely filling materials such as a base plate, a metal net, a zinc sheet, paraffin or salt particles and the like in the core, and realizing seam making by physical or chemical means, wherein: firstly, materials such as a filling base plate, a metal net, a zinc sheet and the like need to be soaked in acid or alkali solution to the artificial rock core, but the physicochemical properties of the surface of the rock can be changed, and the cementing structure of the rock core is damaged to a certain extent, secondly, paraffin is filled, and the paraffin is melted at high temperature, but the paraffin cannot completely flow out of the rock core after being melted, a large amount of paraffin remains in the rock core, thirdly, salt particles are filled and washed to the rock core continuously to ensure that the salt particles are completely dissolved, and partial rock particles can be transported and blocked in the rock core under the condition of large-amount fluid washing, and the rock core can be damaged once by the above existing methods; (5) the photoetching method is that a photoetching glass model is utilized to research the flow rule of crude oil in a karst cave and a crack, but the surface characteristics, wettability and the like of a glass medium have great difference from an actual reservoir, and the temperature resistance and pressure resistance are poor, so that the seepage characteristics of underground oil reservoir fluid cannot be described really.
CN104089806A discloses an artificial rock core with a multiple pore structure and a preparation method thereof, wherein inorganic salt particles and/or metal sheets are randomly embedded during preparation of the rock core, and after solidification, the rock core is soaked in distilled water, acid or alkali liquor in sequence, so that the inorganic salt particles and the metal sheets are dissolved to form dissolved pores and cracks. However, in the method, the core is only treated by a soaking method, so that the dissolution or the reaction is difficult to ensure to be completely carried out, and the core is damaged once when the core is pretreated by distilled water, acid or alkali liquor, so that the experimental effect of physical simulation is greatly influenced.
CN103712843A discloses a method for preparing fracture-cavity carbonate rock core, which comprises using rosin particles and rosin powder as fracture-cavity and crack fillers, and dissolving rosin with organic solvents such as absolute ethyl alcohol to form effective fracture-cavity and crack in the rock core. However, the method is difficult to ensure that the rosin is completely dissolved, the residual rosin can cause damage to the core at one time, and the physical and chemical properties of the core are greatly influenced by using the rosin and the organic solvent to treat the core.
CN107831057A discloses an indoor manual seam making method for a compact sandstone core, which is characterized in that a notch is formed in the end face of the compact sandstone core fixed on a protective sleeve, a seam making needle is inserted into the notch, and a seam is made by pressurizing, so that the structural integrity of the seam making core can be ensured. However, the method only considers the guarantee of the structural integrity of the rock core, the number of formed cracks is small, and the length and the opening degree of the cracks are difficult to guarantee.
In conclusion, the preparation method of the complex artificial core is difficult to simultaneously meet the technical requirements of fine simulation of complex fracture-cave/fracture networks of oil and gas reservoirs and nondestructive preparation of the artificial core, so that the experimental result cannot objectively reflect the actual seepage process of fluid in an underground reservoir.
Therefore, the artificial core with the fracture-cavity/fracture structure and the preparation method thereof, which can simultaneously realize the fine simulation of the complex fracture-cavity/fracture network of the oil-gas reservoir and the nondestructive preparation of the artificial core, have important significance.
Disclosure of Invention
The invention aims to overcome the defects that the existing complex artificial core preparation technology is difficult to simultaneously satisfy the fine simulation of a complex fracture-cave/fracture network and the nondestructive preparation of an artificial core, and provides a method for preparing an artificial core with a fracture-cave/fracture structure in a nondestructive mode and an artificial core.
In order to achieve the above object, a first aspect of the present invention provides a method for nondestructively preparing an artificial core having a fracture-cavity/fracture structure, the artificial core comprising a fracture-cavity carbonate artificial core and/or a fracture-cavity tight sandstone artificial core, wherein the method comprises:
(1) filling the first rock forming mixture into a core mould;
(2) pressing an ellipsoidal capsule body and/or a strip body corresponding to a karst cave and/or fracture structure of an actual oil-gas reservoir into the first rock-forming mixture, and performing pressing treatment after arranging an injection well and a production well;
(3) taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slit hole/slit structure;
(4) filling 2-camphene powder into the slot/crack structure, and filling a second rock forming mixture into the core mould;
(5) and carrying out pressing, curing, detecting and pouring treatment on the diagenetic mixture to obtain the artificial core with a fracture-cave/fracture structure.
In a second aspect, the invention provides an artificial core with a fracture-cavity/fracture structure prepared by the method.
Through the technical scheme, the invention has the following beneficial effects:
(1) the filler 2-camphene powder of the complex fracture hole/fracture network in the artificial core provided by the invention can be rapidly sublimated under a high-temperature condition, and the core can be gasified and discharged in the constant-temperature solidification process of the core, so that the core is not damaged;
(2) the invention can meet the requirements of various and controllable fracture-cave/fracture combinations, accurately adjust the quantity, size, coordination number and spatial distribution of karst caves and fractures, quantitatively design parameters such as porosity, permeability and the like of the rock core containing the karst caves and the fractures, and further realize effective and fine simulation of complex oil and gas reservoirs;
(3) the invention can flexibly arrange related injection and production wells, and effectively realize physical simulation of various development modes of different types of complex oil and gas reservoirs;
(4) the artificial core with the fracture-cavity/fracture structure provided by the invention is simple and convenient in manufacturing process and has good repeatability.
Drawings
Fig. 1 is an exploded view of a synthetic core mold according to the present invention;
FIG. 2 is a typical layered drawing of an actual fracture-cavity carbonate hydrocarbon reservoir geological slice;
FIG. 3 is a three-dimensional schematic longitudinal cross-sectional view of a fracture-cave carbonate rock artificial core prepared in example 1 of the present invention;
FIG. 4 is a schematic longitudinal cross-sectional view of a fracture-cave carbonate rock artificial core prepared in example 1 of the present invention;
FIG. 5 is a schematic three-dimensional view of an artificial core of fracture-cavity carbonate rock prepared in example 1 of the present invention;
FIG. 6 shows the low-field NMR T of a representative region of a fracture-cavity carbonate rock core prepared in example 1 of the present invention2A spectrogram;
FIG. 7 is a low field MRI of a representative region of a fracture-cave carbonate synthetic core prepared in example 1 of the present invention;
FIG. 8 is a typical layered drawing of a geological section of an actual fracture-type tight sandstone reservoir;
fig. 9 is a three-dimensional schematic plan cross-sectional view of a fractured tight sandstone artificial core prepared in example 2 of the present invention;
fig. 10 is a schematic plan sectional view of a fractured tight sandstone artificial core prepared in example 2 of the present invention;
fig. 11 is a three-dimensional schematic view of a fractured tight sandstone artificial core prepared in example 2 of the present invention;
FIG. 12 shows the low-field NMR T of a representative region of a fractured compact sandstone artificial core prepared in example 2 of the present invention2A spectrogram;
fig. 13 is a low field nmr image of a representative region of a fractured tight sandstone artificial core prepared in example 2 of the present invention;
FIG. 14 is a low field NMR T of a representative region of a fracture-cavity carbonate synthetic core prepared according to comparative example 1 of the present invention2A spectrogram;
FIG. 15 is a low field MRI image of a representative region of a fracture-cave carbonate synthetic core made according to comparative example 1 of the present invention.
Description of the reference numerals
1-a bottom plate; 2-a main side plate; 3-auxiliary side plate; 4-cover plate; 5-long bolt; 6-a nut; 7-artificial core; 8-core matrix; 9-ellipsoidal capsule body; 10-coarse bars; 11-thin strip; and 12-injection and production wells.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides a method for nondestructively preparing an artificial core with a fracture-cavity/fracture structure, wherein the artificial core with the fracture-cavity/fracture structure comprises a fracture-cavity carbonate artificial core and/or a fracture-cavity tight sandstone artificial core, and the method comprises the following steps:
(1) filling the first rock forming mixture into a core mould;
(2) pressing an ellipsoidal capsule body and/or a strip body corresponding to a karst cave and/or fracture structure of an actual oil-gas reservoir into the first rock-forming mixture, and performing pressing treatment after arranging an injection well and a production well;
(3) taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slit hole/slit structure;
(4) filling 2-camphene powder into the slot/crack structure, and filling a second rock forming mixture into the core mould;
(5) and carrying out pressing, curing, detecting and pouring treatment on the diagenetic mixture to obtain the artificial core with a fracture-cave/fracture structure.
The inventors of the present invention have surprisingly found that: the 2-camphene powder is filled into a complex slot/crack structure in an artificial core, the 2-camphene powder can be rapidly sublimated under a high-temperature condition, the core can be gasified and discharged in the constant-temperature solidification process of the core, and the core is not damaged; the invention can provide various complex fracture-cave/fracture combinations and is controllable, thereby realizing effective and fine simulation of complex oil and gas reservoirs; in the process of preparing the artificial core, related injection and production wells can be flexibly arranged at different positions, and the physical simulation of various development modes of different types of complex oil and gas reservoirs can be effectively realized; in addition, the artificial core with the slot/crack structure provided by the invention has simple and convenient manufacturing process and good repeatability.
In the present invention, it should be noted that: "fracture and cavern" refers to a fracture and a cavern, wherein the shape of the fracture is closer to a strip shape, and the shape of the cavern is closer to a capsule shape.
In addition, the injection and production well is a professional term and can be understood as an inlet channel and an outlet channel of the artificial rock core, and the injection and production well is adopted in the invention because the artificial rock core is used for simulating an oil and gas reservoir and is combined, so that the practical engineering significance is realized.
According to the invention, before the first rock-forming mixture is filled into the core mould in the step (1), the core mould and the fracture hole/fracture structure characterization step are prepared.
Preparing a core mould:
in the invention, the core mould can be made of hastelloy; fig. 1 is an exploded view of a synthetic core mold according to the present invention; as shown in fig. 1, mainly by 1 bottom plate 1, 2 main curb plate 2, 2 vice curb plate 3 and 1 apron 4 constitution, the bottom plate is equipped with the first positioning groove of fixed 4 curb plates, and the main curb plate side is equipped with the second positioning groove and the fixed round hole of fixed vice curb plate, during the equipment earlier arrange 2 main curb plates in corresponding first positioning groove, arrange 2 vice curb plates in corresponding first positioning groove and second positioning groove again. After preliminary fixed the completion, utilize 4 long bolts 5 and 4 pairs of nuts 6 that pass fixed round hole to further fasten whole rock core mould, the rock core mould equipment is preliminary accomplished.
According to the invention, the design size of the core mould is as follows:
length, width and height of 300mm, 100mm and 9000cm3。
According to the invention, preferably, butter grease is uniformly coated on the inner wall of the space of the core mould, so that the cementing effect of the artificial core on the core mould is prevented from being too strong.
And (3) carving the structure of the seam holes/cracks:
according to the invention, a geological prototype diagram of a target layer position of the fracture-cavity carbonate rock oil and gas reservoir is selected by combining geological model data of an actual research block, and a representative fracture-cavity structure is carved, so that the complex artificial rock core is close to the actual oil and gas reservoir in aspects of fracture-cavity ratio, fracture-cavity density and the like.
According to the invention, a geological prototype diagram of a target layer of the fracture type tight sandstone oil and gas reservoir is selected by combining geological model data of an actual research block, and a representative fracture structure is carved, so that the complex artificial rock core is close to the actual oil and gas reservoir in aspects of fracture distribution, number of fractures and the like.
According to the invention, in step (1), a core material, i.e. a diagenetic mixture, is prepared and the first diagenetic mixture is filled into a core mould.
In the present invention, the permeability of the core matrix of the target block is 0.5 × 10-3μm2To 6.0X 10-3μm2And determining a rock core matrix material to form a rock mixture formula according to an experimental result for determining the mineral composition of the natural rock core and the permeability requirement of the rock core.
According to the invention, the first and second diagenetic mixtures are identical, each comprising diagenetic mineral powder and/or a cementing agent.
According to the invention, the diagenetic mixture comprises diagenetic mineral powder and/or a cementing agent; preferably, the diagenetic mixture is diagenetic mineral powder and cementing agent; more preferably, the diagenetic mineral powder is selected from one or more of carbonate minerals (calcite and dolomite) and/or non-carbonate minerals (quartz, feldspar and clay); even more preferably, the diagenetic mineral powder is selected from carbonate minerals (calcite and dolomite) and non-carbonate minerals (quartz, feldspar and clay).
More preferably, according to the present invention, the cement includes a bisphenol a type epoxy resin, a curing agent, and a diluent. In the invention, based on the total weight of the cementing agent, the content of the bisphenol A type epoxy resin is 65-87 wt%, the content of the curing agent is 10-25 wt%, and the content of the diluent is 3-10 wt%; preferably, the content of the bisphenol A type epoxy resin is 72-80 wt%, the content of the curing agent is 15-20 wt%, and the content of the diluent is 5-8 wt% based on the total weight of the cementing agent.
According to the invention, the diagenetic mineral powder is contained in an amount of 75-85 wt% and the cementing agent is contained in an amount of 15-25 wt%, based on the weight of the first diagenetic mixture or the second diagenetic mixture; preferably, the diagenetic mineral powder is present in an amount of 82 to 85 wt% and the consolidating agent is present in an amount of 15 to 18 wt%, based on the weight of the first diagenetic mixture or the second diagenetic mixture.
According to the invention, based on the total volume of the core mould, the volume consumption of the first rock-forming mixture is 30-70 vol%, and the volume consumption of the second rock-forming mixture is 30-70 vol%; preferably, the volume usage of the first rock-forming mixture is 45-55 vol% and the volume usage of the second rock-forming mixture is 45-55 vol% based on the total volume of the core mold; more preferably, the volume usage of the first diagenetic mixture is 50 vol% and the volume usage of the second diagenetic mixture is 50 vol% based on the total volume of the core mould.
According to the invention, the diagenetic mixture is stirred uniformly and is screened by a 20-mesh screen for later use. Preferably, the diagenetic mixture consisting of diagenetic mineral powder and cementing agent is equally divided into 6 to 8 parts, and 3 to 4 parts of diagenetic mixture is uniformly filled into the core mould, namely the first diagenetic mixture is 1/2 design height.
According to the invention, in the step (2), the ellipsoidal capsule body comprises a middle part and an end part connected with the middle part, wherein the middle part is a cylinder, and the end part is a hemisphere.
According to the invention, the radius of the hemisphere is 15-20 mm; preferably, the radius of the hemisphere has two specifications of 15mm and 20mm, and the length of the capsule body is self-processed according to the physical simulation requirement.
According to the invention, the radius of the strip is 1-2 mm; preferably, the radius of the strip body has two specifications of 1mm and 2mm, the two conditions of a fine crack and a coarse crack are simulated respectively, and the length of the strip body is processed automatically according to the physical simulation requirement.
According to the invention, in order to simulate the development modes of different types of complex oil and gas reservoirs, the invention is realized by arranging injection and production wells at different positions of an artificial rock core with a fracture-cave/fracture structure, wherein the inner radius of the injection and production wells is 1-4mm, and the outer radius of the injection and production wells is 1.5-4.5 mm; preferably, the injection and production wells are steel thin tubes, the inner radius is 2-2.5mm, the outer radius is 2.5-3mm, and the length of the injection and production wells is automatically processed according to the arrangement position.
According to the invention, the ellipsoidal capsule body, the strip body and the injection and production well are all made of metal materials; preferably, the ellipsoidal capsule body and the strip body are made of steel materials, and the capsule body and the strip body can be processed by customizing the size.
According to the present invention, in the step (2), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5 h; preferably, the temperature is 25-30 ℃, the pressure is 10-20MPa, and the time is 1-2 h.
According to the invention, in the step (3), after the diagenetic mixture in the core mould has certain strength, all ellipsoidal capsule bodies and strip bodies are taken out to form a complex slot/crack structure.
According to the invention, in the step (4), sufficient 2-camphene powder is filled into the slot/crack, the mass of the added 2-camphene powder is recorded, and the rest diagenetic mixture, namely the second diagenetic mixture, is continuously and uniformly filled into the core mould to the designed height. In addition, in the present invention, the inventors of the present invention unexpectedly found that: the 2-camphor powder is relatively stable at room temperature and has certain strength (during core pressing treatment), can be completely sublimated at high temperature (during core curing treatment), and sublimation of the 2-camphor powder at high temperature is physical change. In the present invention, 2-borneol powder is purchased from Shanghai Aladdin Biotechnology GmbH, purity is 96%, melting point is 176-.
According to the present invention, in the step (5), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5 h; preferably, the temperature is 25-30 ℃, the pressure is 10-20MPa, and the time is 1-2 h.
According to the invention, in the step (5), after the solidification treatment, the 2-camphene powder is sublimated, and a complex cave/crack structure corresponding to the cave and/or crack structure of the actual hydrocarbon reservoir is formed inside the artificial core.
According to the invention, the conditions of the curing treatment include: the temperature is 60-120 ℃, and the time is 24-60 h; preferably, the temperature is 80-90 ℃ and the time is 30-36 h.
According to the invention, in step (5), the method of detection comprises a mass difference detection method and/or a nuclear magnetic detection method.
In the present invention, the quality difference detection method includes formula (a), formula (b), formula (c), and formula (d):
N＝(m1-m2)/m0formula (a);
wherein, in the formula (a), m0The mass of 2-camphor powder for filling the complex slot/crack structure; m is1The total mass of the artificial core with the structure of the fracture hole/fracture before the solidification treatment; m is2The total mass of the artificial core with the fracture-cavity/fracture structure after the solidification treatment is obtained;
Vr＝V-Vwformula (b);
wherein in the formula (b), the formula (c) and the formula (d), V is the total volume of the artificial core with the fracture-cave/fracture structure; vrThe effective volume of the artificial core with the fracture-cavity/fracture structure; vcThe volume of the ellipsoidal capsule body for making the hole; vfThe volume of the seam making strip body; vwThe volume of the injection well;
is the cavern porosity;
is the fracture porosity.
According to the invention, in step (5), the casting conditions include: the temperature is 20-45 ℃ and the time is 36-72 h; preferably, the temperature is 25-30 ℃ and the time is 48-60 h.
According to the invention, the pouring is carried out by adopting a pouring material, and the pouring material comprises epoxy resin and a curing agent; preferably, when the pouring is carried out by adopting the pouring material, the pouring thickness is 20-30 mm.
According to the invention, based on the total weight of the pouring material, the content of the epoxy resin is 75-90 wt%, and the content of the curing agent is 10-25 wt%; preferably, the content of the epoxy resin is 80-85 wt% and the content of the curing agent is 15-20 wt% based on the total weight of the casting material.
In a second aspect, the invention provides an artificial core with a fracture-cavity/fracture structure prepared by the method.
According to the invention, the compressive strength of the artificial core with the fracture-cavity/fracture structure is 2-5MPa, and preferably 3-4 MPa.
According to the invention, the artificial core with the fracture-cavity/fracture structure comprises the following parts: matrix materials, seam making materials, well distribution materials and pouring materials. The matrix material of the rock core mainly comprises different kinds of diagenetic mineral powder (carbonate minerals such as calcite and dolomite and non-carbonate minerals such as quartz, feldspar and clay) and a cementing agent, and the mineral composition analysis is firstly carried out on the natural rock core taken from a target complex oil-gas reservoir, so that the specific mineral components and the proportion are determined; then according to the determined mass percentage ratio, fully and uniformly stirring different diagenetic mineral powder and cementing agent, and sieving for later use; the seam making material of the core mainly comprises complex seam hole/seam moulds (containing ellipsoidal capsule bodies and strip bodies) with different specifications and sizes and 2-camphor powder; the well distribution material of the core is mainly equal-diameter metal thin tubes with different lengths; the pouring material of the rock core mainly comprises epoxy resin and a curing agent.
According to a preferred embodiment of the present invention, a method for nondestructively preparing an artificial core having a fracture-cavity/fracture structure comprises:
the method comprises the following steps: assembled core die
According to the assembly sequence designed by the figure 1, a bottom plate, a main side plate, an auxiliary side plate and a cover plate of the core mold are assembled in sequence, and grease is uniformly coated on the inner wall of the space of the core mold for standby.
Step two: slot/crack delineation
And combining geological model data of an actual research block, selecting a geological prototype diagram of a target layer position of the complex oil and gas reservoir, and carving and drawing a representative complex fracture-cave/fracture structure, so that the artificial core with the fracture-cave/fracture structure is close to the actual oil and gas reservoir in aspects of fracture-cave ratio, fracture-cave density, fracture distribution, fracture number and the like.
Step three: preparing core material
The invented artificial core with a fracture-cavity/fracture structure comprises the following parts: matrix materials, seam making materials, well distribution materials and pouring materials. The matrix material of the rock core mainly comprises diagenetic mineral powder and cementing agent of different types, and mineral component analysis is firstly carried out on a natural rock core taken from a target complex oil and gas reservoir to determine the specific mineral components and the proportion; then according to the determined mass percentage ratio, fully and uniformly stirring different diagenetic mineral powder (carbonate minerals such as calcite and dolomite and non-carbonate minerals such as quartz, feldspar and clay) and a cementing agent, and sieving for later use; the seam making material of the core mainly comprises complex seam hole/seam moulds (containing ellipsoidal capsule bodies and strip bodies) with different specifications and sizes and 2-camphor powder; the well distribution material of the core is mainly equal-diameter metal thin tubes with different lengths; the pouring material of the rock core mainly comprises epoxy resin and a curing agent.
Step four: artificial core filling
The design height of the core is h, a diagenetic mixture consisting of diagenetic mineral powder and a cementing agent is equally divided into n parts (n is 6 or 8), and the diagenetic mixture is sequentially and uniformly filled into a core mould to reach the filling height h/2. Designing a corresponding complex fracture-cave/fracture combination scheme according to the actually drawn fracture-cave/fracture structure of the oil and gas reservoir, respectively pressing complex fracture-cave/fracture molds with different specifications and sizes in the fracture-making material into the rock-forming mixture according to the designed positions, arranging injection and production wells at the corresponding positions, performing compression treatment for 1-2h, and taking out all the complex fracture-cave/fracture molds after the first rock-forming mixture in the molds has certain strength to form the complex fracture-cave/fracture structure. Filling sufficient 2-camphene powder into the complex slot/crack, recording the mass of the added 2-camphene powder, and recording as m0. And continuously and uniformly filling the second rock forming mixture into the core mould to the designed height h.
Step five: artificial core pressing
Covering a core mould cover plate, placing the filled core mould on a special hydraulic press, pressing for 1-2h according to the set stable pressure, taking off the core mould cover plate, weighing the total mass of the artificial core with a fracture hole/fracture structure for 3 times before curing, and recording the average value of the total mass as m1。
Step six: artificial core curing
And (3) placing the pressed core mould and the artificial core in a vacuum-pumped constant temperature box, setting the curing temperature to be 80-90 ℃, and carrying out constant temperature treatment for 30-36h to fully cure the artificial core with the slot/crack structure, wherein 2-camphene powder serving as a complex slot/crack filler is completely sublimated in the temperature range, so that a complete complex slot/crack structure can be formed in the artificial core.
Step seven: slot/crack detection
(1) Method for detecting mass difference
After the artificial core is solidified and cooled to room temperature, disassembling the core mould, weighing the total mass of the artificial core with a fracture-cave/fracture structure for 3 times after solidification, and recording the average value of the total mass as m2. Calculating the structural integrity N of the complex fracture-cave/fracture by the following formula:
N＝(m1-m2)/m0；
in the formula, m0The mass of 2-camphor powder for filling complex slot/crack structure; m is1The total mass of the artificial core with the structure of the fracture hole/fracture before the solidification treatment; m is1The total mass of the artificial core having a fracture-cavity/fracture structure after curing treatment. The value range of N is 0.8-1.0, and the closer the value of N is to 1.0, the more complete 2-camphene powder sublimation in the complex slot/crack structure is shown, namely the more complete the complex slot/crack structure in the artificial rock core is.
At this time, the cavern porosity of the artificial core having a fracture-cave/fracture structure
And crack porosity
Quantitative calculations can be performed, and the calculation formula is as follows:
Vr＝V-Vw；
wherein V is a structure having a seam/fissure junctionTotal volume of the constructed artificial core; vrIs the effective volume of an artificial core with a fracture-cavity/fracture structure; vcThe volume of the ellipsoidal capsule body for making the hole; vfIs the volume of the strip body for making the seam; vwIs the volume of the injection well.
(2) Nuclear magnetic assay method
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, and scanning the representative region of the artificial rock core with the fracture-cave/fracture structure by means of a large-aperture nuclear magnetic resonance imaging analyzer to obtain the T of the prepared artificial rock core with the fracture-cave/fracture structure2And (4) determining a complex fracture-cave/fracture structure distribution rule in the rock core by using the spectrogram, carrying out nuclear magnetic resonance imaging processing on the scanned rock core, and accurately identifying spatial structures such as internal fractures and karst caves of the rock core, namely realizing nondestructive detection of the complex fracture-cave/fracture.
Step eight: artificial rock core pouring
And after the detection is qualified, uniformly pouring the whole rock core by using a pouring material outside the rock core, and carrying out molding treatment for 48-60h at 25-30 ℃ to form a poured fracture-cavity/fracture-type artificial rock core with certain compressive strength.
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples:
large-aperture nuclear magnetic resonance imaging analyzer: available from NYMI Analyzer, Suzhou under the model MacroMR 12-150H-I.
Example 1
This example illustrates a method for preparing a fracture-cavity type carbonate rock artificial core without damage and a fracture-cavity type carbonate rock artificial core.
The method comprises the following steps: assembled core die
Assembling a core mould according to the figure 1; specifically, the method comprises the following steps: the rock core mould is the hastelloy material, mainly by 1 bottom plate 1, 2 main curb plate 2, 2 vice curb plate 3 and 1 apron 4 are constituteed, the bottom plate is equipped with the first positioning groove of fixed 4 curb plates, the main curb plate side is equipped with the second positioning groove and the fixed round hole of fixed vice curb plate, earlier arrange 2 main curb plates in corresponding first positioning groove during the equipment, arrange 2 vice curb plates in corresponding first positioning groove and second positioning groove again. After preliminary fixed the completion, utilize 4 long bolts 5 and 4 that pass fixed round hole to further fasten whole rock core mould with nut 6, the rock core mould equipment is preliminary accomplished, and butter lubricating grease is evenly paintd to rock core mould space inner wall, prevents that artificial rock core from being too strong to rock core mould cementation.
Step two: carving picture of seam hole structure
And combining geological model data of an actual research block, selecting a geological prototype picture of a target layer position of the fracture-cavity type carbonate rock oil and gas reservoir, and carving and drawing a representative fracture-cavity structure, so that the fracture-cavity type carbonate rock artificial rock core is close to the actual oil and gas reservoir in aspects of fracture-cavity ratio, fracture-cavity density and the like, as shown in fig. 2, and fig. 2 is a typical layered carving and drawing picture of a geological slice of the actual fracture-cavity type carbonate rock oil and gas reservoir.
Step three: preparing core material
The average permeability of the core matrix 8 of the target block was 0.8 × 10-3μm2According to the experimental result of the mineral composition of the natural rock core and the permeability requirement of the rock core, the formula of the rock core matrix material is determined as follows: 85 wt% of diagenetic mineral powder and 15 wt% of cementing agent, wherein the formula of the diagenetic mineral powder comprises: 87.5 wt% calcite, 3.6 wt% dolomite, 2.2 wt% quartz, 0.8 wt% feldspar and 5.9 wt% clay; the formula of the cementing agent is as follows: 75 wt% of bisphenol A type epoxy resin, 20 wt% of curing agent and 5 wt% of diluent. The core hole/seam making material ellipsoidal capsule body 9 and the strip bodies 10 and 11 are made of steel materials, and can be processed by customizing the size, in the embodiment, the ellipsoidal capsule body has a regular shape and comprises a middle part and end parts connected with the middle part, namely, the middle part is a cylinder, the end parts are hemispheroids, the radius of the hemispheroids has two specifications of 15mm and 20mm, and the length of the capsule body is automatically processed according to the physical simulation requirement; the radius of the strip body has two specifications of 1mm and 2mm, the two conditions of a fine crack and a coarse crack are simulated respectively, and the length of the strip body is processed automatically according to the physical simulation requirement. In order to simulate the development modes of different fracture-cavity carbonate reservoirs, the invention is realized by arranging injection and production wells 12 at different positions of the fracture-cavity carbonate reservoirs, wherein the injection and production wells are all thin steel pipes with inner radiuses2.5mm, the outer radius is 3mm, and the length of the injection and production well is automatically processed according to the layout position. The formula of the core external pouring material is as follows: 80 wt% epoxy resin and 20 wt% curing agent.
The parameters of the cave-type carbonate rock artificial core cave-making/seam material in the embodiment are shown in table 1.
TABLE 1
| Serial number | Type (B) | Quantity (number) | Radius (mm) | Length (mm) | Volume (cm)3) |
| 1 | |
1 | 20.0 | 80.0 | 83.78 |
| 2 | |
1 | 20.0 | 60.0 | 58.64 |
| 3 | |
1 | 15.0 | 50.0 | 28.27 |
| 4 | |
1 | 15.0 | 40.0 | 21.21 |
| 5 | |
1 | 15.0 | 36.0 | 18.38 |
| 6 | Strip-shaped |
1 | 2.0 | 200.0 | 2.51 |
| 7 | Strip-shaped |
1 | 2.0 | 180.0 | 2.26 |
| 8 | Strip-shaped body | 2 | 2.0 | 150.0 | 3.77 |
| 9 | Strip-shaped |
1 | 2.0 | 100.0 | 1.26 |
| 10 | Strip-shaped body | 6 | 1.0 | 150.0 | 2.83 |
| 11 | Strip-shaped |
1 | 1.0 | 100.0 | 0.31 |
Step four: artificial core filling
The design size of the core is as follows: length, width and height of 300mm, 100mm and 9000cm318073.1g of calcite, 743.6g of dolomite, 454.4g of quartz, 165.2g of feldspar and 1218.6g of clay are weighed in sequence and mixed uniformly to prepare finished rock mineral powder, 2733.8g of bisphenol A epoxy resin, 729.0g of curing agent and 182.3g of diluent are weighed in sequence and mixed uniformly to prepare cementing agent, and the cementing agent is poured into the finished rock mineral powder and stirred uniformly to pass through a 20-mesh screen for later use. Equally dividing the diagenetic mixture composed of diagenetic mineral powder and cementing agent into 8 parts, uniformly filling 4 parts of the first diagenetic mixture into a core mould to 1/2 designThe height is 50 mm. According to the designed crack and karst cave combination scheme, ellipsoidal capsule bodies, strip-shaped bodies and injection and production wells with different specifications are pressed into a diagenetic mixture according to the designed positions, the mixture is pressed for 2 hours under the condition of 25 ℃ and the stable pressure of 10MPa, after the diagenetic mixture in a mould has certain strength, all the ellipsoidal capsule bodies and the strip-shaped bodies are taken out to form a complex fracture-cave space structure, as shown in figures 3 and 4, figure 3 is a three-dimensional schematic longitudinal section view of the fracture-cave carbonate rock artificial core prepared in the embodiment 1 of the invention; fig. 4 is a schematic longitudinal cross-sectional view of a fracture-cave carbonate artificial core prepared in example 1 of the present invention. Filling sufficient 2-camphene powder into the complex cracks and the karst caves, and recording the mass m of the added 2-camphene powder0221.0g, the core mould was filled with the remaining 4 parts of the second rock-forming mixture to a design height of 100 mm.
The well distribution material parameters of the fracture-cave type carbonate rock artificial core in the embodiment are shown in table 2.
TABLE 2
Step five: artificial core pressing
Covering a core mould cover plate 4 above the diagenetic mixture, placing the filled core mould on a special hydraulic press, applying a stable pressure of 10MPa to press for 2h, taking off the core mould cover plate, weighing the total mass of the fracture-cavity type carbonate rock artificial core before curing for 3 times, and recording m124521.6 g.
Step six: artificial core curing
Placing the pressed core mold and the artificial core in a vacuum-pumped constant temperature box, setting the curing temperature to be 80 ℃, and carrying out constant temperature treatment for 36 hours to fully cure the fracture-cavity type carbonate artificial core, wherein the 2-camphene powder filling the cracks and the caverns can be completely sublimated at the temperature, and a complete complex fracture-cavity structure is formed in the core, as shown in fig. 5, fig. 5 is a three-dimensional schematic diagram of the fracture-cavity type carbonate artificial core prepared in the embodiment 1 of the invention.
Step seven: seam hole structure detection
(1) Method for detecting mass difference
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, weighing the total mass of the fracture-cavity carbonate rock artificial rock core after solidification for 3 times, and recording m224301.9 g. Calculating the structural integrity N of the slot, wherein the calculation formula is as follows:
N＝(m1-m2)/m0＝(24521.6g-24301.9g)/221.0g＝0.99；
in the formula, m0The mass of 2-camphor powder for filling the complex slot structure; m is1The total mass of the fracture-cave type carbonate rock artificial rock core before curing treatment; m is2The total mass of the fracture-cave type carbonate rock artificial rock core after the solidification treatment is shown.
The calculation result shows that the N value is 0.99, which is close to the theoretical maximum value of 1, and the 2-camphene powder in the slot structure is completely sublimated, namely the complex slot structure in the artificial rock core is complete.
At this time, the cavern porosity of the fracture-cavity type carbonate rock artificial core
And crack porosity
Quantitative calculations can be performed, and the calculation formula is as follows:
Vr＝V-Vw；
in the formula, V is the total volume of the fracture-cave carbonate rock artificial rock core; vrThe effective volume of the fracture-cave type carbonate rock artificial rock core; vcThe volume of the ellipsoidal capsule body for making the hole; vfFor making seamsThe volume of the body; vwIs the volume of the injection well.
The porosity parameters of the fracture-cave type carbonate artificial core in the embodiment are shown in table 3.
TABLE 3
(2) Nuclear magnetic assay method
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, and scanning the representative area of the artificial rock core by means of a large-aperture nuclear magnetic resonance imaging analyzer to obtain the T of the prepared fracture-cavity carbonate rock artificial rock core2Spectra.
FIG. 6 shows the low-field NMR T of a representative region of a fracture-cavity carbonate rock core prepared in example 1 of the present invention2A spectrogram; from fig. 6, it can be derived: t is2The spectrogram curve is distributed in a bimodal state, a small peak represents a rock core matrix, a large peak represents a fracture-cavity structure, and the relaxation time and peak area corresponding to the large peak are far larger than those of the small peak, so that the distribution rule of the complex fracture-cavity structure in the artificial rock core is obvious.
FIG. 7 is a low field MRI of a representative region of a fracture-cave carbonate synthetic core prepared in example 1 of the present invention; from fig. 7, it can be derived: a karst cave structure exists in the middle area of the artificial core, and an obvious crack structure is visible in the middle shaft of the whole core, so that the spatial structures such as internal cracks and karst caves of the artificial core are clear and accord with the early-stage design scheme.
Step eight: artificial rock core pouring
And after the fracture-cavity structure is detected to be qualified, uniformly pouring the whole artificial rock core by using a rock core external pouring material, wherein the pouring thickness is 20mm, and the artificial rock core is formed and treated for 60 hours at 25 ℃ to form the poured fracture-cavity carbonate rock artificial rock core with the compressive strength of 3 MPa.
Example 2
This example illustrates a nondestructive preparation method of a fracture-type tight sandstone artificial core and a fracture-type tight sandstone artificial core.
The method comprises the following steps: assembled core die
Assembling a core mould according to the figure 1; specifically, the method comprises the following steps: the rock core mould is the hastelloy material, mainly by 1 bottom plate 1, 2 main curb plate 2, 2 vice curb plate 3 and 1 apron 4 are constituteed, the bottom plate is equipped with the first positioning groove of fixed 4 curb plates, the main curb plate side is equipped with the second positioning groove and the fixed round hole of fixed vice curb plate, earlier arrange 2 main curb plates in corresponding first positioning groove during the equipment, arrange 2 vice curb plates in corresponding first positioning groove and second positioning groove again. After preliminary fixed the completion, utilize 4 long bolts 5 and 4 that pass fixed round hole to further fasten whole rock core mould with nut 6, the rock core mould equipment is preliminary accomplished, and butter lubricating grease is evenly paintd to rock core mould space inner wall, prevents that artificial rock core from being too strong to rock core mould cementation.
Step two: crack structure depiction
Selecting a geological prototype diagram of a target layer of the fractured tight sandstone oil and gas reservoir by combining geological model data of an actual research block, and drawing a representative fracture structure to enable the fractured tight sandstone artificial core to be close to the actual oil and gas reservoir in aspects of fracture distribution, fracture number and the like; as shown in fig. 8, fig. 8 is a typical layered drawing of a geological section of an actual fractured tight sandstone reservoir.
Step three: preparing core material
The permeability of the core matrix 8 of the target block is 0.1 × 10-3μm2According to the experimental result of the mineral composition of the natural rock core and the permeability requirement of the rock core, the formula of the rock core matrix material is determined as follows: 82 wt% of diagenetic mineral powder and 18 wt% of cementing agent, wherein the formula of the diagenetic mineral powder comprises: 2.9 wt% calcite, 1.1 wt% dolomite, 42.5 wt% quartz, 46.0 wt% feldspar and 7.5 wt% clay; the formula of the cementing agent is as follows: 80 wt% of bisphenol A type epoxy resin, 15 wt% of curing agent and 5 wt% of diluent. The strip-shaped body 10 and the strip-shaped body 11 for core seam making are made of steel materials, the size can be customized for processing, the radius of the strip-shaped body in the embodiment has two specifications of 1mm and 2mm, the two conditions of a fine crack and a coarse crack are simulated respectively, and the length of the strip-shaped body is processed automatically according to the physical simulation requirement. For simulating tight sandstone reservoir exploitation of different fracture typesIn the mode, the invention is realized by arranging the injection and production wells 12 at different positions, the injection and production wells are all steel thin tubes, the inner radius is 2.5mm, the outer radius is 3mm, and the length of the injection and production wells is automatically processed according to the arrangement positions. The formula of the core external pouring material is as follows: 80 wt% epoxy resin and 20 wt% curing agent.
The parameters of the fracture-making material of the fracture-type tight sandstone artificial core of the embodiment are shown in table 4.
TABLE 4
| Serial number | Type (B) | Quantity (number) | Radius (mm) | Length (mm) | Volume (cm)3) |
| 1 | Strip-shaped |
1 | 2.0 | 220.0 | 2.76 |
| 2 | Strip-shaped |
1 | 2.0 | 210.0 | 2.64 |
| 3 | Strip-shaped |
1 | 2.0 | 200.0 | 2.51 |
| 4 | Strip-shaped body | 2 | 2.0 | 180.0 | 4.52 |
| 5 | Strip-shaped |
1 | 2.0 | 160.0 | 2.01 |
| 6 | Strip-shaped |
1 | 2.0 | 150.0 | 1.88 |
| 7 | Strip-shaped body | 2 | 2.0 | 100.0 | 2.51 |
| 8 | Strip-shaped body | 3 | 1.0 | 160.0 | 1.51 |
| 9 | Strip-shaped body | 4 | 1.0 | 150.0 | 1.88 |
| 10 | Strip-shaped body | 2 | 1.0 | 140.0 | 0.88 |
| 11 | Strip-shaped body | 2 | 1.0 | 100.0 | 0.63 |
Step four: artificial core filling
The design size of the core is as follows: length, width and height of 300mm, 100mm and 9000cm3567.2g of calcite, 215.1g of dolomite, 8311.7g of quartz, 8996.2g of feldspar and 1466.8g of clay are weighed in sequence and mixed uniformly to prepare diagenetic mineral powder, 3434.4g of bisphenol A epoxy resin, 644.0g of curing agent and 214.7g of diluent are weighed in sequence and mixed uniformly to prepare cementing agent, the cementing agent is poured into the diagenetic mineral powder and stirred uniformly, and the diagenetic mineral powder is screened by a 20-mesh screen for later use. Forming rock composed of forming rock mineral powder and cementing agentThe mixture was equally divided into 8 parts, and 4 parts of the first rock-forming mixture was uniformly filled into the core mold to 1/2 design height, i.e., 50 mm. According to the designed crack combination scheme, strip-shaped bodies and injection and production wells of different specifications are pressed into a diagenetic mixture according to the designed positions, stable pressure of 15MPa is applied for pressing for 1 hour at the temperature of 25 ℃, and after the diagenetic mixture in a mould has certain strength, all the strip-shaped bodies are taken out to form a complex crack space structure; as shown in fig. 9 and 10, fig. 9 is a three-dimensional schematic plan sectional view of a fractured tight sandstone artificial core prepared in example 2 of the present invention; fig. 10 is a schematic plan sectional view of a fractured tight sandstone artificial core prepared in example 2 of the present invention; filling enough 2-camphene powder into the complex crack, and recording the mass m of the added 2-camphene powder0And the weight of the mixture is 23.5g, and the rest 4 parts of second rock forming mixture are continuously and uniformly filled into the core mould until the design height is 100 mm.
The well spacing material parameters of the fractured compact sandstone artificial core of the embodiment are shown in table 5.
TABLE 5
Step five: artificial core pressing
Covering a core mould cover plate 4 above the diagenetic mixture, placing the filled core mould on a special hydraulic press, applying stable pressure of 15MPa to press for 1h, taking off the core mould cover plate, weighing the total mass of the crack type compact sandstone artificial core before curing for 3 times, and recording m123873.5 g.
Step six: artificial core curing
Placing the pressed core mold and the artificial core in a vacuum-pumped constant temperature box, setting the curing temperature to be 90 ℃, and carrying out constant temperature treatment for 36 hours to fully cure the crack type compact sandstone artificial core, wherein the 2-camphene powder filling the crack can be completely sublimated at the temperature, and a complete complex crack structure is formed in the core, as shown in fig. 11, fig. 11 is a three-dimensional schematic diagram of the crack type compact sandstone artificial core prepared in embodiment 2 of the invention.
Step seven: crack structure detection
(1) Method for detecting mass difference
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, weighing the total mass of the solidified fracture type compact sandstone artificial rock core for 3 times, and recording m223850.4 g. And (3) calculating the structural integrity N of the crack, wherein the calculation formula is as follows:
N＝(m1-m2)/m0＝(23873.5g-23850.4g)/23.5g＝0.98；
in the formula, m0The mass of 2-camphor powder for filling complex crack structure; m is1The total mass of the fracture type compact sandstone artificial core before curing treatment; m is2The total mass of the fracture type compact sandstone artificial core after the curing treatment.
According to the calculation result, the N value is 0.98 and is close to the theoretical maximum value of 1, which indicates that the sublimation of the 2-camphene powder in the crack structure is nearly complete, namely the complex crack structure in the artificial rock core is complete.
At this time, the fracture porosity of the fracture type tight sandstone artificial core
Quantitative calculations can be performed, and the calculation formula is as follows:
Vr＝V-Vw；
in the formula, V is the total volume of the fracture type compact sandstone artificial core; vrThe effective volume of the artificial rock core is fracture type compact sandstone; vfIs the volume of the strip body for making the seam; vwIs the volume of the injection well.
The porosity parameters of the fractured tight sandstone artificial core of the embodiment are shown in table 6.
TABLE 6
(2) Nuclear magnetic assay method
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, and scanning the representative area of the artificial rock core by means of a large-aperture nuclear magnetic resonance imaging analyzer to obtain the T of the prepared crack type compact sandstone artificial rock core2Spectra.
FIG. 12 shows the low-field NMR T of a representative region of a fractured compact sandstone artificial core prepared in example 2 of the present invention2A spectrogram; from fig. 12, it can be derived: t is2The spectrogram curve is distributed in a bimodal state, a small peak represents a rock core matrix, a large peak represents a fracture structure, and the relaxation time and peak area corresponding to the large peak are far larger than those of the small peak, so that the distribution rule of the complex fracture structure in the artificial rock core is obvious.
Fig. 13 is a low field nmr image of a representative region of a fractured tight sandstone artificial core prepared in example 2 of the present invention; from fig. 13, it can be derived: obvious crack structures can be seen at the middle shaft of the artificial core, which shows that the internal crack structures of the artificial core are clear and accord with the early design scheme.
Step eight: artificial rock core pouring
And after the crack structure is detected to be qualified, uniformly pouring the whole artificial rock core by using a rock core external pouring material, wherein the pouring thickness is 30mm, and the forming treatment is carried out for 60 hours at 25 ℃ to form the poured crack type compact sandstone artificial rock core with the compressive strength of 4 MPa.
Comparative example 1
Preparing a fracture-cavity type carbonate rock artificial core according to the same method as the embodiment 1, wherein the comparative example 1 is provided with a common filler paraffin for heating and solidifying the core, the process is the same as 2-camphor powder, and the difference is only materials; specifically, the differences are: the "2-borneol powder" was replaced by "solid paraffin", wherein the solid paraffin was purchased from Ducheng Shu plasticator, Inc., semi-refined wax, oil content 1.8%, melting point 58 ℃.
In addition, in step four: artificial core filling
Recording the mass m of paraffin wax added0It was 183.0 g.
Step five: artificial core pressing
Weighing the total mass of the fracture-cave type carbonate rock artificial rock core before curing for 3 times, and recording m124483.0 g.
Step six: artificial core curing
The solid paraffin in the cracks and the karst caves of the artificial rock core has fluidity at the temperature of 80 ℃, but cannot completely flow out of the artificial rock core, so that a large amount of paraffin is remained in the spatial structure of the cracks and the karst caves in the rock core.
Step seven: seam hole structure detection
(1) Method for detecting mass difference
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, weighing the total mass of the fracture-cavity carbonate rock artificial rock core after solidification for 3 times, and recording m224395.9 g. Calculating the structural integrity N of the slot, wherein the calculation formula is as follows:
N＝(m1-m2)/m0＝(24483.0g-24395.9g)/183.0g＝0.48；
in the formula, m0The mass of the paraffin wax for filling the slot structure; m is1The total mass of the fracture-cave type carbonate rock artificial rock core before curing treatment; m is2The total mass of the fracture-cave type carbonate rock artificial rock core after the solidification treatment is shown.
According to the calculation results, the N value is 0.48, the theoretical maximum value is not close to 1, and the solid paraffin in the fracture-cavity structure is incompletely removed, namely the complex fracture-cavity structure in the artificial rock core is incomplete and completely conforms to the early design.
At the moment, the residual solid paraffin in the complex fracture-cave structure is considered, and the cavern porosity of the fracture-cave carbonate rock artificial rock core is considered
And crack porosity
Carrying out quantitative calculation according to the following calculation formula:
Vr＝V-Vw；
in the formula, V is the total volume of the fracture-cave carbonate rock artificial rock core; vrThe effective volume of the fracture-cave type carbonate rock artificial rock core; vcrEffective volume for making a hole; vfrIs the effective volume of the seam; vwIs the volume of the injection well.
The porosity parameters of the fracture-cave type carbonate rock artificial core of the comparative example are shown in table 7.
TABLE 7
In the artificial rock core of the fracture-cavity carbonate rock in the comparative example, a large amount of paraffin is remained, so that the volume of a karst cave and the volume of a crack are both far smaller than those of the example 1, and the porosity of the karst cave and the porosity of the crack are correspondingly reduced, which is not in accordance with the earlier design.
(2) Nuclear magnetic assay method
After the artificial rock core is solidified and cooled to room temperature, disassembling the rock core mould, and scanning the representative area of the artificial rock core by means of a large-aperture nuclear magnetic resonance imaging analyzer to obtain the T of the prepared fracture-cavity carbonate rock artificial rock core2Spectra.
FIG. 14 is a graph of the low-field NMR T of a representative region of a fractured-vuggy carbonate rock core of this example2A spectrogram; from fig. 14, it can be derived: t is2The spectrogram curves are distributed in a bimodal mode, small peaks represent a rock core matrix, large peaks represent a fracture-cavity structure, the relaxation time and the peak area corresponding to the large peaks are larger than those of the small peaks, but the peak values of the two peaks are smaller than those of the small peaks in example 1, which shows that the artificial rock core has the fracture-cavity structure, but paraffin residue influences the fracture-cavity structure, and the karst-cavity volume and the fracture volume are far smaller than those of the example 1.
FIG. 15 is a low field MRI of a representative region of a fracture-vug carbonate synthetic core of this comparative example; from fig. 15, it can be derived: an irregular karst cave structure exists in the middle area of the artificial core, and the crack structure at the middle shaft of the whole core is not clear, which indicates that the artificial core has space structures such as incomplete cracks and karst caves, and the residual solid paraffin can affect the crack cave structure inside the artificial core, so that the volume of the karst caves and the volume of the cracks are far smaller than those in embodiment 1.
Step eight: artificial rock core pouring
And uniformly pouring the whole artificial rock core by using a rock core external pouring material, wherein the pouring thickness is 20mm, and the artificial rock core is formed for 60 hours at 25 ℃ to form a poured fracture-cavity carbonate rock artificial rock core with the compressive strength of 3 MPa.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the specific features in any suitable way, and the invention will not be further described in relation to the various possible combinations in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.
Claims (10)
1. A method for nondestructively preparing an artificial core having a fracture-cavity/fracture structure, the artificial core comprising fracture-cavity carbonate rock and/or fracture-cavity tight sandstone rock, the method comprising:
(1) filling the first rock forming mixture into a core mould;
(2) pressing an ellipsoidal capsule body and/or a strip body corresponding to a karst cave and/or fracture structure of an actual oil-gas reservoir into the first rock-forming mixture, and performing pressing treatment after arranging an injection well and a production well;
(3) taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slit hole/slit structure;
(4) filling 2-camphene powder into the slot/crack structure, and filling a second rock forming mixture into the core mould;
(5) and carrying out pressing, curing, detecting and pouring treatment on the diagenetic mixture to obtain the artificial core with a fracture-cave/fracture structure.
2. The method of claim 1, wherein the first and second formation mixtures are the same, each comprising a formation mineral powder and/or a cementing agent;
preferably, the diagenetic mineral powder is selected from carbonate minerals and/or non-carbonate minerals;
preferably, the cementing agent comprises bisphenol A epoxy resin, a curing agent and a diluent;
preferably, based on the total weight of the cementing agent, the content of the bisphenol A type epoxy resin is 65-87 wt%, the content of the curing agent is 10-25 wt%, and the content of the diluent is 3-10 wt%;
preferably, the diagenetic mineral powder is present in an amount of 75-85 wt% and the consolidating agent is present in an amount of 15-25 wt%, based on the weight of the first diagenetic mixture or the second diagenetic mixture.
3. The method as recited in claim 1, wherein the volume usage of the first diagenetic mixture is 30-70 vol% and the volume usage of the second diagenetic mixture is 30-70 vol% based on the total volume of the core mold.
4. The method of claim 1, wherein the ellipsoidal capsule comprises a middle portion and end portions connected to the middle portion, wherein the middle portion is a cylinder and the end portions are hemispheres;
preferably, the radius of the hemisphere is 15-20 mm;
preferably, the radius of the strip is 1-2 mm;
preferably, the inner radius of the injection well is 1-4mm, and the outer radius of the injection well is 1.5-4.5 mm;
preferably, the ellipsoidal capsule body, the strip body and the injection and production well are all made of metal materials.
5. The method according to claim 1, wherein, in step (2), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5 h;
preferably, in the step (5), the conditions of the press treatment include: the temperature is 20-45 deg.C, the pressure is 5-30MPa, and the time is 0.5-2.5 h.
6. The method according to claim 1, wherein in the step (5), after the curing treatment, the 2-camphene powder is sublimated, and a complex cave/crack structure corresponding to the cave and/or crack structure of the actual hydrocarbon reservoir is formed inside the artificial core;
preferably, the conditions of the curing treatment include: the temperature is 60-120 ℃, and the time is 24-60 h.
7. The method according to claim 1, wherein in step (5), the detection method comprises a mass difference detection method and/or a nuclear magnetic detection method;
preferably, the quality difference detection method includes formula (a), formula (b), formula (c), and formula (d):
N＝(m1-m2)/m0formula (a);
wherein, in the formula (a), m0The mass of 2-camphor powder for filling the complex slot/crack structure; m is1The total mass of the artificial core with the structure of the fracture hole/fracture before the solidification treatment; m is2The total mass of the artificial core with the fracture-cavity/fracture structure after the solidification treatment is obtained;
Vr＝V-Vwformula (b);
wherein in the formula (b), the formula (c) and the formula (d), V is the total volume of the artificial core with the fracture-cave/fracture structure; vrThe effective volume of the artificial core with the fracture-cavity/fracture structure; vcThe volume of the ellipsoidal capsule body for making the hole; vfThe volume of the seam making strip body; vwThe volume of the injection well;
is the cavern porosity;
is the fracture porosity.
8. The method of claim 1, wherein in step (5), the casting conditions include: the temperature is 20-45 ℃ and the time is 36-72 h;
preferably, the pouring is performed by adopting a pouring material, and the pouring material comprises epoxy resin and a curing agent;
preferably, when the pouring is carried out by adopting a pouring material, the pouring thickness is 20-30 mm;
preferably, the content of the epoxy resin is 75-90 wt% and the content of the curing agent is 10-25 wt% based on the total weight of the casting material.
9. An artificial core having a fracture-cavity/fracture structure prepared by the method of any one of claims 1-8.
10. The artificial core according to claim 9, wherein the compressive strength of the artificial core is 2-5MPa, preferably 3-4 MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110805218.4A CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110805218.4A CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113484116A true CN113484116A (en) | 2021-10-08 |
| CN113484116B CN113484116B (en) | 2023-07-14 |
Family
ID=77939822
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110805218.4A Active CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113484116B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114199510A (en) * | 2021-12-06 | 2022-03-18 | 西南石油大学 | Integrated proppant flat conveying experimental device and preparation method thereof |
| CN114330095A (en) * | 2021-11-20 | 2022-04-12 | 广西科学院 | Artificial granite intelligent manufacturing method based on LBM-DEM aggregate grading interface characteristic regulation and control |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2221168A1 (en) * | 1995-05-17 | 1996-11-21 | Nextec Applications, Inc. | Internally-coated porous webs with controlled positioning of modifiers therein |
| JPH11166071A (en) * | 1997-09-30 | 1999-06-22 | Inoac Corporation:Kk | Microporous material and its production |
| CN103822865A (en) * | 2014-03-20 | 2014-05-28 | 中国石油大学(华东) | High-resolution three-dimensional digital rock core modeling method |
| WO2017161916A1 (en) * | 2016-03-22 | 2017-09-28 | 西南石油大学 | Direct manufacturing method for large-scale, fractured-core model preserving original oil and water saturations |
| CN109357921A (en) * | 2018-10-10 | 2019-02-19 | 成都理工大学 | A kind of fracture hole oil reservoir Artificial Core Making method that parameter is controllable |
-
2021
- 2021-07-16 CN CN202110805218.4A patent/CN113484116B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2221168A1 (en) * | 1995-05-17 | 1996-11-21 | Nextec Applications, Inc. | Internally-coated porous webs with controlled positioning of modifiers therein |
| JPH11166071A (en) * | 1997-09-30 | 1999-06-22 | Inoac Corporation:Kk | Microporous material and its production |
| CN103822865A (en) * | 2014-03-20 | 2014-05-28 | 中国石油大学(华东) | High-resolution three-dimensional digital rock core modeling method |
| WO2017161916A1 (en) * | 2016-03-22 | 2017-09-28 | 西南石油大学 | Direct manufacturing method for large-scale, fractured-core model preserving original oil and water saturations |
| CN109357921A (en) * | 2018-10-10 | 2019-02-19 | 成都理工大学 | A kind of fracture hole oil reservoir Artificial Core Making method that parameter is controllable |
Non-Patent Citations (2)
| Title |
|---|
| DAI CAILI ETC.: "Spontaneous imbibition investigation of self-dispersing silica nanofluids for enhanced oil recovery in low-permeability cores", ENERGY & FUELS * |
| 孙天一等: "利用化学方法进行岩心制备的几点认识", 当代化工 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114330095A (en) * | 2021-11-20 | 2022-04-12 | 广西科学院 | Artificial granite intelligent manufacturing method based on LBM-DEM aggregate grading interface characteristic regulation and control |
| CN114330095B (en) * | 2021-11-20 | 2022-06-21 | 广西科学院 | Artificial granite intelligent manufacturing method based on LBM-DEM aggregate grading interface characteristic regulation and control |
| CN114199510A (en) * | 2021-12-06 | 2022-03-18 | 西南石油大学 | Integrated proppant flat conveying experimental device and preparation method thereof |
| CN114199510B (en) * | 2021-12-06 | 2024-04-12 | 西南石油大学 | Integrated propping agent flat plate conveying experimental device and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113484116B (en) | 2023-07-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113484116A (en) | Method for nondestructively preparing artificial core with fracture-cavity/fracture structure and artificial core | |
| CN105628470B (en) | A kind of preparation method of the perforation crack rock sample based on 3D printing technique | |
| CN102053026B (en) | Material and method for manufacturing carbonate cave oil reservoir physical model | |
| CN104458383B (en) | A kind of preparation method of artificial core | |
| CN100573092C (en) | A kind of method for making of artificial rock core containing clay | |
| WO2018141118A1 (en) | Preparation method for large model microcrack rock core having low permeability | |
| CN103926122B (en) | To shake out rock core and making apparatus thereof and method for making | |
| WO2017024701A1 (en) | Method for preparing drill core | |
| CN103868772B (en) | A kind of synthetic core preparation method for rock drillability test | |
| CN107884257B (en) | Preparation method of artificial rock core for testing fracturing performance of rock containing controllable cracks | |
| CN105675365A (en) | Method for preparing fractured rock mass samples with filler | |
| CN105651572B (en) | A kind of preparation method of the prismatical joint rock mass sample of the blind joint containing filling | |
| CN106769341A (en) | A kind of rocks sample preparation device and preparation method containing blind joint | |
| CN108225859A (en) | A kind of method that Single Fracture rock sample is prepared based on 3D printing technique | |
| CN107063826B (en) | Method for manufacturing three-dimensional large-size artificial rock core | |
| CN107271235B (en) | Preparation method of rock and mortar combined sample based on rock-mortar interface gas permeation test | |
| CN109238799B (en) | Preparation method of carbonate rock platy rock core with finely characterized crack structure | |
| CN108717005B (en) | A kind of preparation method of artificial viscous crude sandstone | |
| CN108414304A (en) | A kind of mold and method made for coupled shear-flow test joint samples | |
| CN109342138A (en) | The artificial shale core production method of densification and its molding die for having stratification | |
| CN112943233B (en) | Method for simulating proppant transport under reservoir conditions | |
| CN203965204U (en) | The making apparatus of rock core shakes out | |
| CN108801739B (en) | Method for manufacturing artificial physical rock core | |
| US20200300054A1 (en) | Method for preparing artificial core to simulate fluvial sedimentary reservoir | |
| CN110186728B (en) | Core cementing die for sand consolidation formula performance evaluation and experimental method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |