CN117849319A - CO (carbon monoxide) 2 Dynamic tightness evaluation method for injection well annulus sealing system - Google Patents
CO (carbon monoxide) 2 Dynamic tightness evaluation method for injection well annulus sealing system Download PDFInfo
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- 238000007789 sealing Methods 0.000 title claims abstract description 114
- 238000002347 injection Methods 0.000 title claims abstract description 90
- 239000007924 injection Substances 0.000 title claims abstract description 90
- 238000011156 evaluation Methods 0.000 title claims abstract description 38
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 title claims description 5
- 239000004568 cement Substances 0.000 claims abstract description 104
- 238000005260 corrosion Methods 0.000 claims abstract description 85
- 230000007797 corrosion Effects 0.000 claims abstract description 85
- 239000004575 stone Substances 0.000 claims abstract description 52
- 238000012360 testing method Methods 0.000 claims abstract description 29
- 230000035699 permeability Effects 0.000 claims abstract description 24
- 230000008859 change Effects 0.000 claims abstract description 23
- 230000000694 effects Effects 0.000 claims abstract description 11
- 239000012530 fluid Substances 0.000 claims description 41
- 238000000034 method Methods 0.000 claims description 23
- -1 polytetrafluoroethylene Polymers 0.000 claims description 20
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 20
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 11
- 238000006243 chemical reaction Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 238000012423 maintenance Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000011148 porous material Substances 0.000 claims description 4
- 238000002441 X-ray diffraction Methods 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 239000008398 formation water Substances 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims description 3
- 239000012798 spherical particle Substances 0.000 claims description 3
- 230000006835 compression Effects 0.000 claims description 2
- 238000007906 compression Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000001764 infiltration Methods 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000009919 sequestration Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
- G01N33/383—Concrete or cement
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/088—Investigating volume, surface area, size or distribution of pores; Porosimetry
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
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Abstract
The invention relates to a CO 2 The dynamic tightness evaluation method of the injection well annulus sealing system comprises the steps of preparing a full-size annular variable load annulus sealing system tightness evaluation device, connecting a pore-permeation joint measuring instrument with a central injection pipe, and measuring porosity and permeability; CO is processed by 2 The dynamic corrosion injector is also connected with the central injection pipe, and then corrosion test is carried out; after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion; obtaining the CO-bearing cement stone through the expression of dynamic tortuosity of cement stone under corrosion damage 2 The greater the tortuosity increase rate shows that the cement stone blocks CO 2 The stronger the corrosion effect, the smaller the permeability increasing rate, the stronger the corrosion sealing performance of the cement stone. The invention conforms to CO 2 The practical working condition of the well bore of the injection well avoids the limitation of judging the overall change by the local permeability change of the cement stone,Can realize the variable load effect of the cement stone and CO at the same time 2 Dynamic corrosion and high practicability.
Description
Technical field:
the invention relates to a CO for petroleum industry 2 Dynamic sealing capability evaluation technology of injection well annulus sealing system, in particular to a CO (carbon monoxide) 2 An injection well annulus sealing system dynamic tightness evaluation method.
The background technology is as follows:
carbon capture, utilization and sequestration (Carbon Capture Utilization and Storage, CCUS) is one of the most widely practiced carbon abatement technologies currently in use. The carbon emission reduction is realized mainly by supercritical carbon dioxide (SC-CO 2 ) Fracturing reforms unconventional reservoirs, CO 2 Enhanced Oil Recovery (EOR) flooding and CO to offshore or land depleted reservoirs 2 And (5) geological storage. The well bore annulus sealing system comprises a sleeve, a cement ring and a cementing interface of the sleeve and the cement ring, and the tightness of the annulus sealing system determines whether CO can be successfully realized 2 The key of oil displacement and burying technology. But CO 2 Injection wells have the following problems: in one aspect, the CO-containing 2 The periodic variation of the internal pressure of the shaft formed by repeated injection of the fluid can cause plastic damage accumulation of the cement sheath, so that the cement sheath body is irrecoverably deformed, and a micro annular gap appears at the well cementation interface; on the other hand, CO 2 The low pH value carbonate water is dissolved in stratum water to form low pH value carbonate water, and the low pH value carbonate water is diffused and moved to corrode the sleeve and the cement ring, so that the wall thickness of the sleeve is reduced, the mechanical property of cement stone is reduced, the permeability is increased, the bearing capacity of a shaft is reduced, and meanwhile, the sealing performance of the annular sealing system is seriously influenced due to the damage of the annular sealing system caused by an actual production process.
Currently, the device for evaluating the annular tightness of a shaft mainly comprises the following aspects, lin Yuanhua et al design a full-size device and method for simulating the corrosion of a well cementation cement sheath under the true working condition, wherein the device is mainly used for evaluating the corrosion of the cement sheath by simulating the internal pressure of the shaft through pressurizing the casings and injecting the corrosion fluid into the annular space between two layers of casings; guo Xinyang et al designed a full-size high-temperature high-pressure cement sheath hydraulic packer evaluation device by pressurizing and logging the inside of a casing, externally applying confining pressure to the annulus, and injecting gas into a gas injection mold through holes at the first and second interfaces of well cementationThe hydraulic packing capacity of the cement sheath is evaluated by the size of the packing pressure difference; lin Yuanhua et al devised a device and method for evaluating the integrity of a full-size cement sheath under downhole conditions by pressurizing the inside of the casing and the inside of the annulus, respectively, and testing the tightness of the cement sheath by liquid tightness experiments; yang Huanjiang A CO 2 Device and method for evaluating integrity of cement sheath of injection well, which mainly comprises pressurizing casing inside and surrounding pressure, injecting supercritical CO into annulus 2 And (5) observing whether bubbles emerge from the upper end surface of the cement sheath, and evaluating the integrity of the cement sheath. Device and method for evaluating annular sealing capacity of well bore mainly evaluate annular sealing performance of integrity of cement sheath and integrity of well cementation interface, and evaluate annular sealing performance of well cementation interface on CO 2 Injection wells also have the following problems:
1. the existing device mainly carries out annulus sealing performance evaluation by only considering the pressure change in the well bore or only considering the confining pressure change of the well bore, and the device is characterized in that the device is used for carrying out annulus sealing performance evaluation under the actual working condition due to CO (carbon monoxide) 2 After multiple injections, the pressure of the stratum near the well is increased or the stratum creep is caused to cause the annular sealing system to be subjected to the combined action of the pressure in the variable well bore and the variable confining pressure.
2. The existing device realizes dynamic corrosion by forming a cavity at one end of a cement sheath and injecting corrosive fluid for corrosion, but does not simulate the injection mode of a shaft and form dynamic contact between the corrosive fluid and annular set cement, and can generate cavity pressure holding to easily cause stress damage to a sleeve-cement sheath assembly, thereby forming measurement errors of the strength change of the cement sheath before and after corrosion.
3. After the components of the corrosive medium of the prior device react with the casing pipe and the cement stone, the concentration of the corrosive component is reduced due to the fact that the fluid is retained in the cavity of the injection end, the corrosion effect is reduced, and the corrosive medium is in flowing contact with the casing pipe and the cement stone in the actual injection process, so that the corrosive component is not changed.
4. The prior method needs to measure the permeability of the standard cylindrical cement stone before corrosion, and measures and evaluates the sealing performance of the cement stone by measuring the permeability after the annular cement stone is cored after corrosion, and the coring operation and the like change the temperature and pressure environment of the cement stone, increase the stress damage of the cement stone again and lead the experimental operation flow to be complex.
CO 2 The problems of the evaluation device and the evaluation method of the injection well can slow down the corrosion effect due to the reduction of the concentration of the corrosive medium, and simultaneously lead the mechanical property and the sealing property of the sleeve and the cement sheath to have hysteresis quality after corrosion and the actual production to seriously influence the guiding effect on the actual production.
The invention comprises the following steps:
the invention aims to provide a CO 2 Method for evaluating dynamic tightness of annular sealing system of injection well, and CO 2 Dynamic tightness evaluation method for injection well annulus sealing system for solving CO in the prior art 2 The injection well evaluation device and method have errors with actual production conditions, and influence the guiding effect on actual production.
The technical scheme adopted for solving the technical problems is as follows: such CO 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system comprises the following steps:
step one: preparing a full-size annular variable-load annular sealing system tightness evaluation device and curing under the condition of simulating formation temperature and pressure, wherein the full-size annular variable-load annular sealing system tightness evaluation device comprises a kettle body, an upper sealing cover and a lower sealing cover, the center of the kettle body is a polytetrafluoroethylene rubber chamber, the outer wall of the polytetrafluoroethylene rubber chamber surrounds an inner cylinder, an outer cylinder is coaxially arranged outside the inner cylinder, an annular space between the kettle body and the outer cylinder is provided with a polytetrafluoroethylene rubber confining pressure chamber, the annular space between the inner cylinder and the outer cylinder is a cement ring formed by pouring cement stone particles, the upper sealing cover and the lower sealing cover seal the upper end opening and the lower end opening of the kettle body, the part of the lower sealing cover corresponding to the cement ring is provided with an annular contact groove, and an outlet pipe is arranged in the lower sealing cover and communicated with the annular contact groove;
step two: closing the fluid outlet above the cement sheath, opening the outlet pipe, and injecting N from the central injection pipe 2 Evacuating, wherein a central injection pipe penetrates through the polytetrafluoroethylene rubber chamber and then is connected with an outlet pipe;
step three: connecting a pore-permeation joint measuring instrument with the central injection pipe to measure the porosity and the permeability;
step four: CO is processed by 2 The dynamic corrosion injector is also connected with the central injection pipe, and then corrosion test is carried out;
step five: after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion injector, using N 2 After evacuation treatment, the porosity and permeability are tested again;
step six: assuming that the cement stone particles are spherical particles and square particles, obtaining the average tortuosity tau a The expression of (2) is:
wherein: phi is the porosity.
According to the porosity change trend under corrosion damage, establishing a porosity change amplitude expression under different corrosion times:
wherein: delta φ (t) is the amplitude of the change in porosity after the corrosion for t time;porosity after corrosion; phi (phi) 0 Is the initial porosity;
and (3) combining the formula (1) and the formula (2) to obtain an expression of dynamic tortuosity of the cement stone under corrosion damage:
obtaining the CO-bearing cement stone through the expression of dynamic tortuosity of cement stone under corrosion damage 2 The greater the tortuosity increase rate shows that the cement stone blocks CO 2 The stronger the corrosion effect, the smaller the permeability increasing rate, the stronger the corrosion sealing performance of the cement stone.
CO in the above scheme 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system comprises the following steps:
step one: preparing a full-size annular variable load annular sealing system tightness evaluation device and curing under the condition of simulating the formation temperature and pressure;
step two: closing the fluid outlet above the cement sheath, opening the outlet pipe, and injecting N from the central injection pipe 2 Evacuating, wherein a central injection pipe penetrates through the polytetrafluoroethylene rubber chamber and then is connected with an outlet pipe;
step three: opening a fluid outlet on the cement sheath, closing an outlet pipe, placing a full-size annular variable-load annular sealing system tightness evaluation device in a high-temperature high-pressure reaction kettle, heating to the simulated stratum temperature, pressurizing to the confining pressure and the internal pressure preset in the test, connecting a pore permeation joint measuring instrument with a central injection pipe, and measuring the porosity and the permeability;
step four: after the measurement of porosity and permeability is completed, closing a fluid outlet on the cement sheath, opening an outlet pipe, heating to the simulated formation temperature, pressurizing to the confining pressure and the internal pressure preset in the test, and adding CO 2 The dynamic corrosion injector is also connected with the central injection pipe;
step five: CO is processed by 2 Gas cylinder and simulated formation water solution access CO 2 The dynamic corrosion injector is used for adjusting the injection pressure or speed of the mixed fluid to inject the mixed fluid through a central injection pipe, an outlet pipe is connected with the outside of the high-temperature high-pressure kettle, a back pressure valve is arranged outside the high-temperature high-pressure kettle, the pressure of the back pressure valve is set to be smaller than the injection pressure by 2MPa, and a corrosion test is performed after a fixed corrosion time is set;
step six: after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion injector, using N 2 After the fluid channel is emptied from the central injection pipe to the outlet pipe, the outlet pipe is closed, and the N is connected through the central injection pipe and the inlet pipe 2 The pore-permeation joint tester of the gas cylinder is connected to test the porosity and the permeability;
step seven: CO-bearing cement stone by using expression of dynamic tortuosity of cement stone under corrosion damage 2 Analyzing and evaluating the change rule of the tortuosity along with time after corrosion;
step eight: and (3) coring or linear cutting the cement stone subjected to the corrosion test in the step (six) to obtain a square sample, and then carrying out compression strength test, SEM scanning electron microscope, XRD analysis and corrosion depth test on the cement stone, sleeve and well cementation interface.
In the scheme, sealing rings are arranged between the inner cylinder and the upper sealing cover and between the inner cylinder and the lower sealing cover; sealing rings are arranged between the outer cylinder and the upper and lower sealing covers.
Before cement stone particles are poured in the scheme, an annular sealing ring is placed in an annular contact groove of a lower sealing cover, the annular sealing ring is matched with the annular contact groove, pouring is carried out, after pouring is carried out, an upper sealing cover and a kettle body are fastened together by bolts, a fluid outlet on the cement ring is opened to ensure that annular water vapor is sufficient during maintenance, a full-size annular variable load annular sealing system tightness evaluation device is placed in a high-temperature high-pressure reaction kettle filled with 1/2 deionized water for maintenance for 7d, and the maintenance conditions simulate the formation temperature and pressure; and after curing, opening the lower sealing cover, taking out the annular sealing ring to obtain an annular contact groove, and reinstalling the lower sealing cover. The annular sealing ring plays a role in preventing the lower sealing cover groove from being blocked during cement pouring and curing.
The invention has the following beneficial effects:
(1) The evaluation device of the invention realizes that CO is contained 2 Fluid injection process and actual CO 2 CO-containing injection well 2 The migration paths of the fluids are consistent, and the stress of the annular sealing system is close to the actual working condition.
(2) The evaluation device provided by the invention realizes constant concentration of the corrosive medium, and the dynamic contact form of the corrosive medium and the sleeve-cement sheath combination body avoids the influence of annulus sealing system damage caused by annulus pressure build-up, and the corrosive environment is close to the real working condition.
(3) According to the evaluation device and the evaluation method, through adopting the pore-infiltration combined measuring instrument, test errors caused by the steps of coring, drying and the like before and after the cement paste corrosion are avoided, the porosity and the permeability of the cement paste ring are measured to be attached to the pore-infiltration characteristics of the cement paste under the real working condition, a dynamic tortuosity model of the cement paste corrosion is established to obtain a tortuosity change rule, and the corrosion tightness of the cement paste is characterized by microscopic combination with macroscopic view.
(4) The evaluation device and the evaluation method avoid the CO-containing caused by that the metal heating sleeve only heats the device main body through the use of the high-temperature high-pressure kettle 2 The fluid has obvious temperature difference change, so that the influence of temperature change in the test process is eliminated;
(5) The evaluation method has simple operation flow and is fit with CO 2 Multiple rounds of alternate water and gas injection and CO injection in injection well 2 And the working conditions such as displacement are novel in method, high in practicability and high in data observability.
(6) The invention provides a set of full-size annular cement stone and sleeve-cement stone interface variable load and CO simulated under high-temperature and high-pressure environment 2 The dynamic tightness evaluation device and method for the annular sealing system with dynamic corrosion function reduce errors under actual production working conditions and provide more accurate guidance for production.
(7) The invention relates to a high-temperature high-pressure reaction kettle and a set of CO for other devices 2 Dynamic corrosion injector and set of hole seepage joint detector, the invention solves the problem of CO 2 Injection well annulus sealing system under high-temperature and high-pressure stratum condition, variable load effect and CO 2 Under the condition of dynamic corrosion, the full-size annular cement stone and sleeve-cement stone well cementation interface sealing capability evaluation method accords with CO 2 The actual working condition of the well bore of the injection well can avoid the limitation of judging the overall change by the local permeability change of the cement stone, and can realize the variable load effect and CO of the cement stone 2 Dynamic corrosion, novel test method, simple operation flow, strong practicality and data dynamic observability, and can be CO 2 The safe operation of the injection well and the carbon burying benefit provide important reference bases.
Description of the drawings:
FIG. 1 is a full-size annular variable load annulus seal system tightness evaluation device;
fig. 2 is a schematic diagram of the apparatus assembly used in the method of the present invention.
In the figure: 1 polytetrafluoroethylene rubber chamber 2 polytetrafluoroethylene rubber confining pressure chamber 3 inner tube 4 outer tube 5 cement ring upper fluid outlet 6 ring seal 7 first seal ring 8 second seal ring 9 third seal ring 10 fourth seal ring 11 upper seal cover 12 lower seal cover 13 kettle 14 internal pressure injection port 15 confining pressure injection port 16 outlet tube 17 center injection tube 18 lower seal cover internal thread interface 19 bolt 20 nut 21 ring contact groove.
The specific embodiment is as follows:
the invention is further described with reference to the accompanying drawings:
such CO 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system comprises the following steps:
step one: the tightness evaluation device of the full-size annular variable load annular sealing system is prepared by a detachable annular polytetrafluoroethylene rubber chamber 1 for internal pressure, an annular polytetrafluoroethylene rubber confining pressure chamber 2 for confining pressure, an inner sleeve metal ring (namely an inner cylinder 3), an outer metal ring (namely an outer cylinder 4), an annular air outlet (namely a fluid outlet 5 on a cement ring), an annular sealing ring 6, a first sealing ring 7, a second sealing ring 8, a third sealing ring 9, a fourth sealing ring 10, an upper sealing cover 11, a lower sealing cover 12 with a fluid passage and a fluid outlet, a kettle body 13, an air inlet for internal pressure (namely an internal pressure injection port 14), an air inlet for confining pressure (namely a confining pressure injection port 15), a lower sealing cover fluid outlet (namely an outlet pipe 16), a simulated downhole fluid main inlet (namely a central injection pipe 17), a lower sealing cover internal thread interface 18, an annular kettle body integrated bolt 19, a nut 20 and a sealing ring removing space which can form a radial contact groove 21 with the sleeve-cement ring, adopting a field well cementation cement slurry system scheme, wherein the inner sleeve metal ring is 2mm thick (playing the roles of fixing cement slurry and transmitting pressure) as a stainless steel ring based on the outer metal ring of the standard GB/T19830-2017 'oil and gas well sleeve or steel pipe for oil pipe', performing cement stone particle pouring on a full-size annular variable load annular sealing system tightness evaluation device according to the GB/T19139-2012 oil well cement test method, installing the inner and outer metal rings, each sealing ring and the annular sealing ring completely before pouring, sealing up and down after pouring, opening a fluid outlet 5 on the annular cement ring, ensuring that annular water vapor is sufficient during maintenance, and placing the device in a high-temperature high-pressure reaction kettle filled with 1/2 deionized water for curing for 7d, wherein the curing conditions simulate the temperature and pressure of the stratum. The sealing rings in the application are polytetrafluoroethylene rubber sealing rings.
Step two: after curing, opening the lower sealing cover of the full-size annular variable load annular sealing system tightness evaluation device, removing the annular sealing ring 6 to form an annular contact groove 21, reinstalling the lower sealing cover, closing the fluid outlet 5 on the cement ring, opening the outlet pipe 16, connecting the central injection pipe 17 with the internal threaded interface 18 of the lower sealing cover through a pipeline, and injecting N from the central injection pipe 17 2 And (5) evacuating.
Step three: and opening a fluid outlet 5 on the cement sheath and closing an outlet pipe 16, connecting a full-size annular variable-load annular sealing system tightness evaluation device with a high-temperature high-pressure reaction kettle, and heating the high-temperature high-pressure reaction kettle to the simulated stratum temperature. After the temperature is stabilized, the inner and outer polytetrafluoroethylene rubber chambers are respectively pressurized to the confining pressure and the internal pressure preset in the test through the confining pressure injection port 15 and the internal pressure injection port 14. And (5) connecting the porous ceramic material with a pore permeation joint tester to measure the porosity and the permeability. All set up the valve in this application each injection pipe, filling opening, outlet pipe, fluid export, the valve is located outside the high temperature high pressure reaction kettle, convenient to use.
Step four: after the initial permeability is measured, the fluid outlet 5 on the cement ring is closed, the outlet pipe 16 is opened, after the temperature is stabilized, the inner polytetrafluoroethylene rubber chamber and the outer polytetrafluoroethylene rubber chamber are respectively pressurized through the confining pressure injection port 15 and the internal pressure injection port 14 and stabilized at the confining pressure and the internal pressure preset in the test, and the CO is introduced 2 And (5) dynamically corroding the implanter.
Step five: CO is processed by 2 Gas cylinder and simulated formation water solution access CO 2 The dynamic corrosion injector is used for injecting the mixed fluid through a central injection pipe 17 by adjusting the injection pressure or speed of the mixed fluid, an outlet pipe 16 is connected with the outside of the high-temperature high-pressure kettle body, a back pressure valve is arranged, the pressure of the back pressure valve is set to be smaller than the injection pressure by 2MPa, and corrosion test is carried out after fixed corrosion time is set.
Step six: after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion injector, using N 2 Evacuating the fluid passage from the central injection pipe 17 to the outlet pipe 16After treatment, the outlet pipe 16 is closed, and the N is connected through the central injection pipe 17 2 And the pore permeation joint tester of the gas cylinder is connected for testing the porosity and the permeability.
Step seven: assuming that the cement stone particles are spherical particles and square particles to obtain average tortuosity tau a The expression of (2) is:
wherein: phi is the porosity.
According to the porosity change trend under corrosion damage, establishing a porosity change amplitude expression under different corrosion times:
wherein: delta φ (t) is the amplitude of the change in porosity after the corrosion for t time;porosity after corrosion; phi (phi) 0 Is the initial porosity.
By combining the formula (1) and the formula (2), the expression of the dynamic tortuosity of the cement stone under the corrosion damage can be obtained:
the porosity measured by the test is brought into (3) to obtain the cement stone subjected to CO 2 The greater the tortuosity increase rate shows that the cement stone blocks CO 2 The stronger the corrosion effect, the smaller the permeability increasing rate, the stronger the corrosion sealing performance of the cement stone.
Step eight: and after the test is finished, coring or linear cutting the annular cement stone to obtain a square sample, and carrying out an interface SEM scanning electron microscope, XRD analysis and corrosion depth test for the compressive strength test, the cement stone, the sleeve and the well cementation.
Step nine: if need to consider CO in the well injection process 2 The inner wall of the sleeve is corroded, the annular polytetrafluoroethylene rubber chamber 1 for detachable internal pressure adding can be directly formed into a sealing chamber after being removed, the connection between the central injection pipe 17 and the internal thread interface 18 of the lower sealing cover is disconnected, the central injection pipe 17 is closed, and fluid injection is carried out from the internal pressure injection port 14; if the pressure change or internal pressure action is required in the corrosion process, the pressure or pressure relief treatment is carried out on the inner and outer polytetrafluoroethylene rubber chambers of the full-size annular load-changing annular sealing system tightness evaluation device. And (5) starting corrosion, and repeating the steps five and six until the test is finished. The pressure control and the data acquisition are controlled by a computer.
The invention realizes that CO is contained 2 Fluid injection process and actual CO 2 CO-containing injection well 2 The migration paths of the fluids are consistent, the stress of the annular sealing system is close to the real working condition, the concentration of the corrosive medium is constant, the corrosive medium is in dynamic contact with the sleeve-cement sheath assembly, the influence of damage of the annular sealing system caused by annular pressure build-up is avoided, the corrosive environment is close to the real working condition, and the CO is attached 2 Multiple rounds of alternate water and gas injection and CO injection in injection well 2 And tools such as displacement and the like have strong practicability.
Claims (4)
1. CO (carbon monoxide) 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system is characterized by comprising the following steps of:
step one: preparing a full-size annular variable-load annular sealing system tightness evaluation device and curing under the condition of simulating formation temperature and pressure, wherein the full-size annular variable-load annular sealing system tightness evaluation device comprises a kettle body, an upper sealing cover and a lower sealing cover, the center of the kettle body is a polytetrafluoroethylene rubber chamber, the outer wall of the polytetrafluoroethylene rubber chamber surrounds an inner cylinder, an outer cylinder is coaxially arranged outside the inner cylinder, an annular space between the kettle body and the outer cylinder is provided with a polytetrafluoroethylene rubber confining pressure chamber, the annular space between the inner cylinder and the outer cylinder is a cement ring formed by pouring cement stone particles, the upper sealing cover and the lower sealing cover seal the upper end opening and the lower end opening of the kettle body, the part of the lower sealing cover corresponding to the cement ring is provided with an annular contact groove, and an outlet pipe is arranged in the lower sealing cover and communicated with the annular contact groove;
step two: closing the fluid outlet above the cement sheath, opening the outlet pipe, and injecting N from the central injection pipe 2 Evacuating, wherein a central injection pipe penetrates through the polytetrafluoroethylene rubber chamber and then is connected with an outlet pipe;
step three: connecting a pore-permeation joint measuring instrument with the central injection pipe to measure the porosity and the permeability;
step four: CO is processed by 2 The dynamic corrosion injector is also connected with the central injection pipe, and then corrosion test is carried out;
step five: after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion injector, using N 2 After evacuation treatment, the porosity and permeability are tested again;
step six: assuming that the cement stone particles are spherical particles and square particles, obtaining the average tortuosity tau a The expression of (2) is:
wherein: phi is the porosity.
According to the porosity change trend under corrosion damage, establishing a porosity change amplitude expression under different corrosion times:
wherein: delta φ (t) is the amplitude of the change in porosity after the corrosion for t time;porosity after corrosion; phi (phi) 0 Is the initial porosity;
and (3) combining the formula (1) and the formula (2) to obtain an expression of dynamic tortuosity of the cement stone under corrosion damage:
obtaining the CO-bearing cement stone through the expression of dynamic tortuosity of cement stone under corrosion damage 2 The greater the tortuosity increase rate shows that the cement stone blocks CO 2 The stronger the corrosion effect, the smaller the permeability increasing rate, the stronger the corrosion sealing performance of the cement stone.
2. The CO according to claim 1 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system is characterized by comprising the following steps of:
step one: preparing a full-size annular variable load annular sealing system tightness evaluation device and curing under the condition of simulating the formation temperature and pressure;
step two: closing the fluid outlet above the cement sheath, opening the outlet pipe, and injecting N from the central injection pipe 2 Evacuating, wherein a central injection pipe penetrates through the polytetrafluoroethylene rubber chamber and then is connected with an outlet pipe;
step three: opening a fluid outlet on the cement sheath, closing an outlet pipe, placing a full-size annular variable-load annular sealing system tightness evaluation device in a high-temperature high-pressure reaction kettle, heating to the simulated stratum temperature, pressurizing to the confining pressure and the internal pressure preset in the test, connecting a pore permeation joint measuring instrument with a central injection pipe, and measuring the porosity and the permeability;
step four: after the measurement of porosity and permeability is completed, closing a fluid outlet on the cement sheath, opening an outlet pipe, heating to the simulated formation temperature, pressurizing to the confining pressure and the internal pressure preset in the test, and adding CO 2 The dynamic corrosion injector is also connected with the central injection pipe;
step five: CO is processed by 2 Gas cylinder and simulated formation water solution access CO 2 The dynamic corrosion injector is used for adjusting the injection pressure or speed of the mixed fluid to inject the mixed fluid through a central injection pipe, an outlet pipe is connected with the outside of the high-temperature high-pressure kettle, a back pressure valve is arranged, the pressure of the back pressure valve is set to be smaller than the injection pressure by 2MPa, and after a fixed corrosion time is setPerforming a corrosion test;
step six: after the set corrosion time is over, the CO is turned off 2 Dynamic corrosion injector, using N 2 After the fluid channel is emptied from the central injection pipe to the outlet pipe, the outlet pipe is closed, and the N is connected through the central injection pipe and the inlet pipe 2 The pore-permeation joint tester of the gas cylinder is connected to test the porosity and the permeability;
step seven: CO-bearing cement stone by using expression of dynamic tortuosity of cement stone under corrosion damage 2 Analyzing and evaluating the change rule of the tortuosity along with time after corrosion;
step eight: and (3) coring or linear cutting the cement stone subjected to the corrosion test in the step (six) to obtain a square sample, and then carrying out compression strength test, SEM scanning electron microscope, XRD analysis and corrosion depth test on the cement stone, sleeve and well cementation interface.
3. The CO according to claim 2 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system is characterized by comprising the following steps of: sealing rings are arranged between the inner cylinder and the upper sealing cover and between the inner cylinder and the lower sealing cover; sealing rings are arranged between the outer cylinder and the upper and lower sealing covers.
4. A CO according to claim 3 2 The method for evaluating the dynamic tightness of the injection well annulus sealing system is characterized by comprising the following steps of: before cement stone particles are poured, an annular sealing ring is placed in an annular contact groove of a lower sealing cover, the annular sealing ring is matched with the annular contact groove, pouring is carried out, after pouring is carried out, an upper sealing cover and a kettle body are fastened together by bolts, a fluid outlet on the cement ring is opened to ensure that annular water vapor is sufficient during maintenance, a full-size annular variable-load annular sealing system tightness evaluation device is placed in a high-temperature high-pressure reaction kettle filled with 1/2 deionized water for maintenance for 7d, and the maintenance conditions simulate stratum temperature and pressure; and after curing, opening the lower sealing cover, taking out the annular sealing ring to obtain an annular contact groove, and reinstalling the lower sealing cover.
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