CN106468163B - Vertical well for steam flooding oil production and heavy oil production method - Google Patents
Vertical well for steam flooding oil production and heavy oil production method Download PDFInfo
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- CN106468163B CN106468163B CN201510521007.2A CN201510521007A CN106468163B CN 106468163 B CN106468163 B CN 106468163B CN 201510521007 A CN201510521007 A CN 201510521007A CN 106468163 B CN106468163 B CN 106468163B
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Abstract
The invention provides a vertical well for steam flooding oil extraction and a method for extracting thick oil. Wherein, a vertical well for steam flooding oil recovery includes: the first oil pipe is arranged in the oil layer, and the bottom end of the first oil pipe is higher than the central position of the oil layer; the second oil pipe is arranged in the oil layer, and the bottom end of the second oil pipe is lower than the central position of the oil layer; the packer is sleeved on the outer side of the second oil pipe and is positioned between the bottom end of the second oil pipe and the bottom end of the first oil pipe; and the oil well casing is sleeved outside the first oil pipe, the second oil pipe and the packer and is provided with a perforation well section positioned in an oil layer. The vertical well realizes effective exploitation of an oil layer in the oil extraction process of steam huff-puff to steam flooding oil extraction; and a well pattern structure in the prior art is abandoned, the same-well injection and production and gravity drainage in a steam flooding oil extraction mode are realized by only utilizing a single straight well, the number of deployed wells is reduced, the cost is reduced, and the economic benefit of the steam flooding oil extraction mode is improved.
Description
Technical Field
The invention relates to the technical field of oil exploitation, in particular to a vertical well for steam flooding oil extraction and a thick oil exploitation method.
Background
Steam stimulation is a common heavy oil thermal recovery method, and the basic process is to inject a certain amount of steam into an oil well, close the well for a period of time, and open the well for production after the heat energy of the steam is diffused to an oil layer. The steam huff and puff operation process can be divided into three stages, namely steam injection, well stewing and recovery. The basic yield-increasing mechanism comprises heating viscosity reduction, release of elastic energy of an oil layer after heating, gravity driving action, waste heat absorption in the recovery process, compaction action of a stratum, blockage removal action of the oil layer, driving action of steam expansion, solvent extraction action, action of improving oil phase permeability, preheating action, action of amplifying differential pressure and the like. Generally, steam huff and puff exploitation belongs to exploitation relying on natural energy, and only after a certain amount of steam is injected artificially and an oil layer is heated, a series of enhanced oil recovery mechanisms are generated, and the effect of reducing viscosity by heating crude oil is mainly achieved. For the ultra-thick oil with the viscosity of the degassed crude oil being more than 2 ten thousand centipoise at the temperature of 50 ℃, the using radius is very limited, the using radius can only reach 15-20m generally, the production degree does not exceed 20%, the initial decline rate reaches 20% -30%, and the effect is rapidly deteriorated after 6-7 times of production.
In order to improve the overall effect of steam injection thermal recovery and the recovery ratio of oil, steam huff and puff recovery is required to be switched to steam drive recovery at a proper time, two common steam drive oil recovery modes in the prior art are respectively oil recovery by adopting a double-horizontal well and oil recovery by adopting a combination of a vertical well and a horizontal well, the main principle is that the crude oil is heated by steam in an auxiliary manner to reduce the viscosity, then oil is drained by virtue of the action of gravity, and the crude oil is continuously recovered in a production well, the operation mode belongs to multi-well combined operation, the steam injection well is specially used for injecting steam, and the production well is specially used for producing. However, for the super heavy oil reservoir with extremely high crude oil viscosity, the two modes have high requirements on the continuity of the oil layer, the horizontal section length is generally required to be more than 400m, and the longitudinal continuous thickness of the oil layer is more than 10m, so that economy and effectiveness can be realized.
Disclosure of Invention
The invention mainly aims to provide a vertical well for steam flooding oil extraction and a thickened oil extraction method, so as to realize effective extraction of thickened oil in the oil extraction process of steam huff-puff-to-steam flooding oil extraction.
In order to achieve the above object, according to one aspect of the present invention, there is provided a vertical well for steam-driven oil production, comprising: the first oil pipe is arranged in the oil layer, and the bottom end of the first oil pipe is higher than the central position of the oil layer; the second oil pipe is arranged in the oil layer, and the bottom end of the second oil pipe is lower than the central position of the oil layer; the packer is sleeved on the outer side of the second oil pipe and is positioned between the bottom end of the second oil pipe and the bottom end of the first oil pipe; and the oil well casing is sleeved outside the first oil pipe, the second oil pipe and the packer and is provided with a perforation well section positioned in an oil layer.
Further, the perforated interval is located on a side adjacent the first tubing.
Further, the perforated well section comprises a first perforated section and a second perforated section, wherein the first perforated section is higher than the central position of the oil layer, and the second perforated section is lower than the central position of the oil layer.
Furthermore, the distance between the first perforation section and the second perforation section is 1-2 m.
Further, the ratio of the length of the first oil pipe in the oil layer to the length of the second oil pipe in the oil layer is 2-4.
Further, the distance between the first oil pipe and the second oil pipe in the oil layer is 15-20 mm.
Further, the vertical well also comprises a temperature measuring instrument and a pressure sensor which are arranged in the second oil pipe.
Further, the average thickness of the oil layer is greater than 7 m.
Furthermore, the distance between the upper surface of the oil layer and the ground is 150-800 m.
According to another aspect of the present invention, there is provided a method for recovering thick oil, comprising the steps of: s1, setting an oil well casing in the oil layer; s2, feeding the first oil pipe and the second oil pipe into the oil well casing; s3, injecting steam through the first oil pipe and the second oil pipe by adopting a steam huff and puff oil extraction mode to extract an oil layer; s4, sending the packer into the oil well casing pipe to enable the packer to be sleeved outside the second oil pipe and located between the bottom end of the second oil pipe and the bottom end of the first oil pipe, and setting the packer to enable the packer to divide the oil well casing pipe into two areas; and S5, converting the steam huff-puff oil extraction mode into a steam drive oil extraction mode, and injecting steam into the first oil pipe to extract the oil layer by using the second oil pipe.
Further, step S1 further includes: the well casing is perforated to form a perforated interval located in the reservoir.
Furthermore, the perforation well section is positioned on one side close to the first oil pipe and comprises a first perforation section and a second perforation section, the first perforation section is higher than the central position of the oil layer, and the second perforation section is lower than the central position of the oil layer.
Further, step S2 further includes: and feeding the temperature measuring instrument and the pressure sensor into the second oil pipe.
Further, in step S3, a steam huff and puff oil production mode is adopted to carry out 3-5 rounds of mining on the oil layer, the cycle of each round of mining is 60-250 days, and the interval cycle is 70-265 days.
Further, in the steam huff and puff oil production mode, the dryness of steam at the bottom of the well is not lower than 0.7, the steam injection amount of the steam in a steam injection wheel is 1000-3000 tons, the steam injection speed is 80-250 tons/day, and the soaking time is 3-5 days.
Further, the distance between the first perforation section and the second perforation section is 1-2 m, and in step S4, the packer is sent into the well casing so that the packer is positioned in the well casing between the first perforation section and the second perforation section.
Further, in a steam flooding oil extraction mode, the steam injection speed is 80-250 tons/day, and the extraction-injection ratio is more than 1.2.
Further, step S5 further includes: and after the oil layer is mined for a preset time by adopting a steam-drive oil extraction mode, injecting mixed gas of nitrogen and steam into the first oil pipe, wherein the volume ratio of the injected nitrogen to the injected steam is 0.2-0.5, and stopping injecting the nitrogen into the first oil pipe when the injection amount of the nitrogen reaches 0.15 PV.
By applying the technical scheme, the invention provides the vertical well for steam-driven oil extraction, and the vertical well comprises the first oil pipe with the bottom end higher than the center of an oil layer, the second oil pipe with the bottom end lower than the center of the oil layer and the packer arranged between the bottom end of the second oil pipe and the bottom end of the first oil pipe, so that steam can be injected and oil extracted by using the first oil pipe and the second oil pipe in a steam huff-puff oil extraction mode, a steam cavity can be formed in the vertical well by using the packer after the steam huff-puff is converted into the steam-driven oil extraction mode, steam can be injected by using the first oil pipe, and oil extraction is carried out by using the second oil pipe, so that the oil layer can be effectively extracted in the oil extraction process of converting the steam huff-puff into the steam-driven oil; and because the first oil pipe and the second oil pipe are both arranged in a straight well, a well pattern structure in the prior art can be abandoned, and the injection and production and gravity drainage of the same well in a steam flooding oil extraction mode are realized by only using a single straight well, so that the number of deployed wells is greatly reduced, the cost is reduced, and the economic benefit of the steam flooding oil extraction mode is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 shows a schematic diagram of a vertical well for steam-driven oil recovery provided by an embodiment of the present invention;
FIG. 2 shows a schematic diagram of a vertical well for use in a steam stimulation mode of oil recovery provided by an embodiment of the present invention; and
fig. 3 is a schematic diagram showing the heavy oil recovery method according to the embodiment of the present invention after the heavy oil recovery method is shifted to the steam flooding oil recovery method.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The two common steam flooding oil extraction modes in the prior art are respectively oil extraction by adopting a double horizontal well and oil extraction by adopting a combination of a vertical well and a horizontal well, but for an ultra-heavy oil reservoir with extremely high crude oil viscosity, the two modes have higher requirements on the continuity of an oil layer. The inventors of the present invention have studied the above problems and provide a vertical well for steam-driven oil production, as shown in fig. 1, comprising: the first oil pipe 10 is arranged in the oil layer 60, and the bottom end of the first oil pipe 10 is higher than the central position of the oil layer 60; the second oil pipe 20 is arranged in the oil layer 60, and the bottom end of the second oil pipe 20 is lower than the central position of the oil layer 60; the packer 30 is sleeved on the outer side of the second oil pipe 20, and the packer 30 is located between the bottom end of the second oil pipe 20 and the bottom end of the first oil pipe 10; and the oil well casing 40 is sleeved outside the first oil pipe 10, the second oil pipe 20 and the packer 30, and the oil well casing 40 is provided with a perforated well section 50 positioned in the oil layer 60.
The vertical well for steam flooding oil extraction comprises the first oil pipe, the second oil pipe and the packer, wherein the bottom end of the first oil pipe is higher than the center of an oil layer, the bottom end of the second oil pipe is lower than the center of the oil layer, and the packer is arranged between the bottom end of the second oil pipe and the bottom end of the first oil pipe, so that steam can be injected and oil can be extracted by using the first oil pipe and the second oil pipe in a steam huff and puff oil extraction mode, a steam cavity can be formed in the vertical well by using the packer after the steam huff and puff is converted into a steam flooding oil extraction mode, steam can be injected by using the first oil pipe, and oil can be extracted by using the second oil pipe, so that the oil layer can be effectively extracted; and because the first oil pipe and the second oil pipe are both arranged in a straight well, a well pattern structure in the prior art can be abandoned, and the injection and production and gravity drainage of the same well in a steam flooding oil extraction mode are realized by only using a single straight well, so that the number of deployed wells is greatly reduced, the cost is reduced, and the economic benefit of the steam flooding oil extraction mode is improved.
In the vertical well for steam-driven oil production provided by the present invention, preferably, the perforated well section 50 is located on a side close to the first tubing 10. In the steam flooding oil extraction mode, the steam can be more effectively injected into the oil layer 60 by using the first oil pipe 10, so that the steam can be more favorably heated to the oil layer 60, and the extraction efficiency of crude oil in the oil layer 60 can be improved. Moreover, the steam flooding oil extraction mode in the invention comprises an SAGD oil extraction mode, namely steam assisted gravity drainage.
In the vertical well for steam-driven oil production provided by the present invention, preferably, the perforated well section 50 includes a first perforated section 510 and a second perforated section 520, the first perforated section 510 is higher than the central position of the oil layer 60, and the second perforated section 520 is lower than the central position of the oil layer 60. The preferred arrangement can more reasonably utilize the perforation segment, so that the perforation well segment 50 effectively avoids the position of the packer 30 arranged on the oil well casing 40, thereby effectively avoiding the waste of the ground perforation process caused by improper perforation segment position (such as being positioned at the center of the oil layer 60).
In the above preferred embodiment, the distance between the first perforated section 510 and the second perforated section 520 is 1 to 2 m. By adopting the preferable parameter range, the packer 30 can effectively avoid the position of the perforation well section 50, thereby avoiding the blockage of the packer 30 to the perforation well section 50 and enabling the perforation well section 50 to more effectively inject steam into the oil layer 60.
In the vertical well for steam-driven oil production provided by the invention, preferably, the ratio of the length of the first oil pipe 10 in the oil reservoir 60 to the length of the second oil pipe 20 in the oil reservoir 60 is 2-4. More preferably, the distance between the first oil pipe 10 and the second oil pipe 20 in the oil layer 60 is 15-20 mm. By adopting the preferable parameter range, the first oil pipe 10 and the second oil pipe 20 arranged in the vertical well can more effectively inject steam and recover oil, so that the oil recovery efficiency of the first oil pipe 10 and the second oil pipe 20 is improved.
In the vertical well for steam-driven oil production provided by the present invention, preferably, the vertical well further comprises a temperature measuring instrument and a pressure sensor which are arranged in the second oil pipe 20. The temperature measuring instrument is arranged in the second oil pipe 20, so that the environmental temperature in the second oil pipe 20 can be effectively tested; in addition, the pressure sensor is arranged in the second oil pipe 20, so that the environmental pressure in the second oil pipe 20 can be effectively tested, the environmental conditions in the vertical well can be monitored in real time through the measured environmental temperature and environmental pressure, and the process conditions in the oil extraction process can be regulated and controlled in real time. The temperature measuring instrument may be a thermocouple, and the pressure sensor may be a capillary.
Preferably, the vertical well for steam flooding oil recovery of the present application is used for the recovery of a shallow super heavy oil reservoir, wherein the average thickness of the oil layer 60 is greater than 7m, the distance between the upper surface of the oil layer 60 and the ground is 150 m-800 m, the porosity of the oil layer 60 is greater than 0.2, the horizontal permeability is greater than 300md, the ratio of the vertical permeability to the horizontal permeability is greater than 0.3, and the remaining oil saturation is greater than 0.50.
According to another aspect of the present invention, there is provided a method for recovering thick oil, comprising the steps of: s1, setting the oil well casing 40 in the oil layer 60; s2, feeding the first oil pipe 10 and the second oil pipe 20 into the oil well casing 40; s3, injecting steam through the first oil pipe 10 and the second oil pipe 20 to produce the oil reservoir 60 by a steam stimulation oil production method; s4, feeding the packer 30 into the oil well casing 40, so that the packer 30 is sleeved outside the second oil pipe 20, the packer 30 is located between the bottom end of the second oil pipe 20 and the bottom end of the first oil pipe 10, and setting the packer 30 so that the packer 30 divides the oil well casing 40 into two areas; s5, converting the steam stimulation oil recovery mode into a steam flooding oil recovery mode, and injecting steam into the first oil pipe 10 to recover the oil reservoir 60 by using the second oil pipe 20.
In the production method, the bottom end of the first oil pipe is higher than the central position of an oil layer, the bottom end of the second oil pipe is lower than the central position of the oil layer, and the packer is arranged between the bottom end of the second oil pipe and the bottom end of the first oil pipe, so that steam injection and oil production can be carried out by using the first oil pipe and the second oil pipe in a steam injection oil production mode, a steam cavity can be formed in a vertical well by using the packer after the steam injection is converted into a steam drive oil production mode, steam injection is carried out by using the first oil pipe, and oil production is carried out by using the second oil pipe, so that the effective production of the oil layer is realized in the oil production process of converting the steam injection into; and because the first oil pipe and the second oil pipe are both arranged in a straight well, a well pattern structure in the prior art can be abandoned, and the injection and production and gravity drainage of the same well in a steam flooding oil extraction mode are realized by only using a single straight well, so that the number of deployed wells is greatly reduced, the cost is reduced, and the economic benefit of the steam flooding oil extraction mode is improved.
Fig. 2 shows a vertical well for steam stimulation oil recovery according to the present invention, which includes: the first oil pipe 10 is arranged in the oil layer 60, and the bottom end of the first oil pipe 10 is higher than the central position of the oil layer 60; the second oil pipe 20 is arranged in the oil layer 60, and the bottom end of the second oil pipe 20 is lower than the central position of the oil layer 60; and the oil well casing 40 is sleeved outside the first oil pipe 10, the second oil pipe 20 and the packer 30, and the oil well casing 40 is provided with a perforated well section 50 positioned in the oil layer 60.
An exemplary embodiment of the method for producing thick oil according to the present invention will be described in more detail with reference to fig. 1 and 2. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to only the embodiments set forth herein. It should be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art.
First, step S1 is executed: an oil well casing 40 is disposed in the oil reservoir 60. In the steps, the oil reservoir coarse screening is carried out, the burial depth of the selected oil layer 60 is less than 800m, the thickness of the oil layer 60 is more than 7m, the porosity of the oil layer 60 is more than 0.2, the horizontal permeability is more than 300md, the ratio of the vertical permeability to the horizontal permeability is more than 0.3, the saturation of the residual oil is more than 0.50, and continuous shale interlayers do not develop in the oil layer 60.
In a preferred embodiment, the step S1 further includes: the well casing 40 is perforated to form a perforated interval 50 located in the reservoir 60. More preferably, the perforated interval 50 is located on a side near the first tubing 10, the perforated interval 50 includes a first perforated segment 510 and a second perforated segment 520, the first perforated segment 510 is above a central location of the oil formation 60, and the second perforated segment 520 is below the central location of the oil formation 60. The preferred embodiment described above enables the formation of perforated intervals 50 that effectively avoid the location where packers 30 are placed on well casing 40, thereby effectively avoiding the waste of perforating operations due to improper perforation intervals (e.g., centered in reservoir 60).
After step S1 is completed, step S2 is performed: the first tubing 10 and the second tubing 20 are run into the well casing 40. Preferably, the ratio of the length of the first oil pipe 10 in the oil reservoir 60 to the length of the second oil pipe 20 in the oil reservoir 60 is 2-4. More preferably, the distance between the first oil pipe 10 and the second oil pipe 20 in the oil layer 60 is 15-20 mm. By adopting the preferable parameter range, the first oil pipe 10 and the second oil pipe 20 arranged in the vertical well can more effectively inject steam and extract oil, so that the oil extraction efficiency of the first oil pipe 10 and the second oil pipe 20 is improved, and the oil extraction rate of the final crude oil is further improved.
In a preferred embodiment, the step S2 further includes: a temperature gauge and a pressure sensor are fed into the second tubing 20. The temperature measuring instrument sent to the second oil pipe 20 can effectively test the ambient temperature in the second oil pipe 20; moreover, the pressure sensor sent to the second oil pipe 20 can effectively test the environmental pressure in the second oil pipe 20, and further can monitor the environmental conditions in the vertical well in real time through the measured environmental temperature and environmental pressure, so that the process conditions in the oil extraction process can be regulated and controlled in real time. The temperature measuring instrument may be a thermocouple, and the pressure sensor may be a capillary.
After step S2 is completed, step S3 is performed: and injecting steam through the first oil pipe 10 and the second oil pipe 20 by adopting a steam huff and puff oil recovery mode to recover the oil reservoir 60. In the steam huff and puff oil extraction mode, firstly, the first oil pipe 10 and the second oil pipe 20 are both used for injecting steam, the well is closed for a period of time, after the heat energy of the steam is diffused to the oil layer 60, the well is opened, and oil extraction is carried out by utilizing the first oil pipe 10 and the second oil pipe 20. Because the first oil pipe 10 and the second oil pipe 20 are both arranged in a vertical well, a well pattern structure in the prior art can be abandoned, and a steam huff and puff oil production mode is realized by only using a single vertical well, so that the number of deployed wells is greatly reduced, the cost is reduced, and the economic benefit of the steam huff and puff oil production mode is improved.
In a preferred embodiment, in the step S3, the steam stimulation oil recovery method is used to perform 3-5 production rounds on the oil layer 60, wherein the production cycle per round is 60-250, and the interval cycle is 70-265. The above preferred parameter range can function to preheat the oil reservoir 60, and simultaneously, a certain amount of crude oil can be produced at a higher oil production rate in the initial stage of steam stimulation, thereby improving the oil production rate of the final crude oil.
In a preferred embodiment, in the steam huff and puff oil recovery mode, the dryness of steam at the bottom of the well is not lower than 0.7, the steam injection amount in the steam injection is 1000-3000 tons, the steam injection speed is 80-250 tons/day, and the soaking time is 3-5 days. By adopting the preferable parameter range, the crude oil can be effectively exploited in a steam huff and puff oil exploitation mode aiming at the vertical well provided by the application, so that the oil recovery rate of the final crude oil is improved.
After step S3 is completed, step S4 is executed: and sending the packer 30 into the oil well casing 40, sleeving the packer 30 on the outer side of the second oil pipe 20, setting the packer 30 between the bottom end of the second oil pipe 20 and the bottom end of the first oil pipe 10, and separating the oil well casing 40 into two areas by the packer 30. In the above steps, the packer 30 is set by thermal or pressure action, so that an SAGD steam cavity can be formed in the oil reservoir 60 in the steam-drive oil production mode, further, the first oil pipe 10 is used for steam injection, and the second oil pipe 20 is used for oil production, thereby realizing effective production of crude oil in the steam-drive oil production mode.
In a preferred embodiment, the first and second perforated sections 510 and 520 are spaced apart by 1-2 m, and the packer 30 is run into the well casing 40 such that the packer 30 is located in the well casing 40 between the first and second perforated sections 510 and 520 in step S4. The preferred embodiment described above enables the packer 30 to effectively avoid the location of the perforated interval 50, thereby avoiding plugging of the perforated interval 50 by the packer 30 and enabling the perforated interval 50 to more effectively inject steam into the oil formation 60 in a steam-driven oil recovery mode.
After step S4 is completed, step S5 is executed: the steam huff-puff oil recovery mode is converted into a steam drive oil recovery mode, and the first oil pipe 10 is injected with steam, so that the second oil pipe 20 is used for recovering the oil layer 60. In the above steps, the first oil pipe 10 is only used for injecting steam, the second oil pipe 20 is only used for exploiting the oil layer 60, and the first oil pipe 10 and the second oil pipe 20 are both arranged in a straight well, so that a well pattern structure in the prior art can be abandoned, and a steam flooding oil production mode is realized by using only a single straight well, thereby greatly reducing the number of deployed wells, reducing the cost, and improving the economic benefit of the steam flooding oil production mode; and moreover, the operation is switched to a steam flooding oil extraction mode (SAGD), the oil yield in the steam huff and puff stage is directly reduced, the oil enters the stable production stage, the extremely high crude oil recovery rate can be achieved under the action of gravity drainage, and the final recovery rate can be increased by 10-25% compared with the steam huff and puff and can reach more than 20-45%.
The production schematic diagram after the heavy oil production method provided by the application is converted into a steam-drive oil production mode is shown in fig. 3, steam is injected through a first oil pipe 10, a packer 30 forms an SAGD steam cavity in an oil layer 60 after being sealed, the steam cavity drives non-condensable gas to diffuse to the top of the oil layer on one hand, and on the other hand, hot oil is brought into a second oil pipe 20 of a vertical well from the bottom of the oil layer by using condensate liquid for oil production; moreover, as can be seen from the figure, the steam range formed by the SAGD steam cavity is far larger than the range of the steam huff and puff area formed by steam in the steam huff and puff oil extraction mode, so that the effective exploitation of crude oil in an oil layer can be realized in the later stage of oil extraction by adopting the steam flooding oil extraction mode, and the recovery ratio of the crude oil in the oil layer is further improved.
In a preferred embodiment, in the steam-drive oil recovery mode, the steam injection speed is 80-250 tons/day, and the extraction-injection ratio is more than 1.2. By adopting the preferable parameter range, the crude oil can be effectively exploited by aiming at the vertical well provided by the application in a steam-drive oil extraction mode, so that the oil recovery rate of the final crude oil is improved.
In a preferred embodiment, the step S5 further includes: and after the oil layer 60 is mined for a preset time by adopting the steam-drive oil extraction mode, injecting mixed gas of nitrogen and steam into the first oil pipe 10, wherein the volume ratio of the injected nitrogen to the injected steam is 0.2-0.5, and stopping injecting the nitrogen into the first oil pipe 10 when the injection amount of the nitrogen reaches 0.15 PV. Preferably, the predetermined time is 1 to 3 years. The nitrogen is injected after the production preset time for assistance, so that the pressure of the steam cavity is maintained, the steam wave volume and uniformity are further increased, and the nitrogen can be covered and insulated on the top of the oil layer 60, thereby reducing the heat loss and increasing the heat efficiency.
The following will further explain the method for producing vertical well and thick oil for steam flooding provided by the present application with reference to the examples.
Example 1
The embodiment provides a thickened oil exploitation method:
(1) and (3) carrying out oil reservoir coarse screening, wherein the burial depth of a selected oil layer is 300m, the thickness of the oil layer is 8m, the porosity of the oil layer is 0.25, the horizontal permeability is 800md, the ratio of the vertical permeability to the horizontal permeability is 0.7, the saturation of the remaining oil is 0.68, continuous mudstone and shale interlayers do not develop in the oil layer, and the viscosity of the degassed crude oil is 3 ten thousand centipoise at 50 ℃.
(2) An oil well casing is arranged in the single-port vertical well, a first oil pipe and a second oil pipe are arranged in the oil well casing, the first oil pipe is arranged at the middle upper part of an oil layer, the second oil pipe is arranged at the bottom of the oil layer, and a thermocouple and a capillary tube are arranged at the same time to measure the temperature and the pressure near a pump port.
(2) The oil layer is perforated in sections before steam huff and puff production, a 2m area is reserved in the middle of the oil layer without perforation, double-pipe steam injection and production are adopted for 3 times, the steam injection amount is 3000 tons, the steam injection speed is 250 tons/day, and the soaking time is 3 days.
(3) And (4) after the 3 rd round of production is finished, setting the packer in the middle of a reserved area in the middle of an oil layer.
(4) Continuously injecting steam into the first oil pipe, and continuously producing the second oil pipe, wherein the steam injection speed is 250 tons/day, the extraction-injection ratio is 1.2, and the Sub-Cool at the position of a pump port is always kept between 5 and 15 ℃; and, the packer grips the well casing and the second tubing under the thermal action of the steam.
(5) And after 2 years of production, injecting a mixed fluid of nitrogen and steam into the first oil pipe, wherein the underground volume ratio is 0.5, stopping injection when the total injection quantity of the nitrogen reaches 0.15PV, and continuously producing the second oil pipe during the period of injecting the mixed fluid of the nitrogen and the steam into the first oil pipe, wherein the production injection ratio is 1.2.
(6) And continuing to inject steam into the second oil pipe, wherein the steam injection speed is 250 tons/day, the injection and extraction ratio is 1.2, and the Sub-Cool at the position of a pump opening is always kept between 5 and 15 ℃ until the production is finished.
Example 2
The embodiment provides a thickened oil exploitation method:
(1) and (3) carrying out oil reservoir coarse screening, wherein the buried depth of a selected oil layer is 450m, the thickness of the oil layer is 15m, the porosity of the oil layer is 0.28, the horizontal permeability is 1500md, the ratio of the vertical permeability to the horizontal permeability is 0.8, the saturation of the remaining oil is 0.70, continuous mudstone and shale interlayers do not develop in the oil layer, and the viscosity of the degassed crude oil at 50 ℃ is 4 ten thousand centipoise.
(2) An oil well casing is arranged in the single-port vertical well, a first oil pipe and a second oil pipe are arranged in the oil well casing, the first oil pipe is arranged at the middle upper part of an oil layer, the second oil pipe is arranged at the bottom of the oil layer, and a thermocouple and a capillary tube are arranged at the same time to measure the temperature and the pressure near a pump port.
(2) The oil layer is perforated in sections before steam huff and puff production, a 2m area is reserved in the middle of the oil layer without perforation, 5 times of double-pipe steam injection and production are adopted, the steam injection amount is 2000 tons, the steam injection speed is 100 tons/day, and the soaking time is 3 days.
(3) And (5) after the production of the 5 th round is finished, setting the packer in the middle of a reserved area in the middle of an oil layer.
(4) Continuously injecting steam into the first oil pipe, and continuously producing the second oil pipe, wherein the steam injection speed is 100 tons/day, the injection and extraction ratio is 1.2, and the Sub-Cool at the position of a pump opening is always kept between 5 and 20 ℃; and, the packer grips the well casing and the second tubing under the thermal action of the steam.
(5) And after 2 years of production, injecting a mixed fluid of nitrogen and steam into the first oil pipe, wherein the underground volume ratio is 0.5, stopping injection when the total injection quantity of the nitrogen reaches 0.15PV, and continuously producing the long pipe during the period of injecting the mixed fluid of the nitrogen and the steam into the first oil pipe, wherein the production injection ratio is 1.2.
(6) And continuing short-pipe steam injection with the steam injection speed of 150 tons/day and the extraction-injection ratio of 1.2, and keeping the Sub-Cool at the position of the pump opening between 5 and 20 ℃ all the time until the production is finished.
Comparative example 1
This comparative example provides a method of producing heavy oil:
(1) and (3) carrying out oil reservoir coarse screening, wherein the buried depth of a selected oil layer is 450m, the thickness of the oil layer is 15m, the porosity of the oil layer is 0.28, the horizontal permeability is 1500md, the ratio of the vertical permeability to the horizontal permeability is 0.8, the saturation of the remaining oil is 0.70, continuous mudstone and shale interlayers do not develop in the oil layer, and the viscosity of the degassed crude oil at 50 ℃ is 2 ten thousand centipoise.
(2) An oil well casing is arranged in the single-port vertical well, an oil pipe is put into the oil well casing, and a dual-purpose injection and production pump is put into the oil well casing.
(3) Perforating in an oil layer before steam production, reserving 1/4 holes with the thickness of the oil layer at the top of the oil layer, injecting steam and producing for 8 times, injecting steam for 2000 tons, injecting steam at a speed of 100 tons/day, and stewing for 3 days until the production is finished.
The recovery and oil-to-steam ratios of the above examples 1 to 2 and comparative example 1 were tested and the results are shown in the following table:
| recovery ratio of | Oil to steam ratio, f | |
| Example 1 | 35 | 0.18 |
| Example 2 | 38 | 0.25 |
| Comparative example 1 | 18 | 0.13 |
As can be seen from the above table, compared with the conventional steam huff and puff oil recovery method, the recovery ratio of the heavy oil recovery method in example 1 is increased by 17%, and the oil-to-steam ratio is increased by 0.05; example 2 compared with the conventional steam huff and puff oil recovery mode, the recovery rate is improved by 20 percent, and the oil-gas ratio is improved by 0.12.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
(1) firstly, 3-5 steam huff-puff rounds are adopted, so that the effect of preheating an oil layer can be achieved, and a certain amount of crude oil can be produced at a higher oil production speed in the initial steam huff-puff stage;
(2) the steam huff and puff oil production mode is converted into a steam drive oil production mode for operation, the oil yield decrease in the steam huff and puff stage is directly stopped, the oil enters a stable production stage, the extremely high crude oil recovery rate can be achieved under the action of gravity oil drainage, and the final recovery rate can be increased by 10-25% compared with the steam huff and puff and can reach more than 20-45%;
(3) nitrogen is injected for assistance after the production is carried out for a preset time, so that the effects of maintaining the pressure of a steam cavity and further increasing the steam swept volume and uniformity are achieved, and the nitrogen can be covered and insulated on the top of an oil layer, so that the heat loss is reduced, and the heat efficiency is increased;
(4) the invention abandons the oil extraction mode of multi-well combined operation in the prior art, only adopts a single straight well to carry out steam injection and oil extraction in the steam huff and puff oil extraction mode and the steam injection and oil extraction in the steam drive oil extraction mode, and realizes the same-well injection and oil extraction and gravity drainage in the steam drive oil extraction mode, thereby greatly reducing the number of deployed wells, reducing the cost and improving the economic benefit of the steam drive oil extraction mode.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for producing thick oil, characterized in that a vertical well for steam-driven oil production is used, the vertical well comprising:
the first oil pipe (10) is arranged in an oil layer (60), and the bottom end of the first oil pipe (10) is higher than the central position of the oil layer (60);
the second oil pipe (20) is arranged in the oil layer (60), and the bottom end of the second oil pipe (20) is lower than the central position of the oil layer (60);
the packer (30) is sleeved on the outer side of the second oil pipe (20), and the packer (30) is located between the bottom end of the second oil pipe (20) and the bottom end of the first oil pipe (10);
an oil well casing (40) surrounding the first tubing (10), the second tubing (20) and the packer (30), the oil well casing (40) having a perforated well section (50) in the oil formation (60),
the mining method comprises the following steps:
s1, setting an oil well casing (40) in the oil layer (60);
s2, feeding the first oil pipe (10) and the second oil pipe (20) into the oil well casing (40);
s3, injecting steam through the first oil pipe (10) and the second oil pipe (20) by adopting a steam huff and puff oil extraction mode to extract the oil layer (60);
s4, feeding a packer (30) into the oil well casing (40), enabling the packer (30) to be sleeved outside the second oil pipe (20), enabling the packer (30) to be located between the bottom end of the second oil pipe (20) and the bottom end of the first oil pipe (10), and setting the packer (30) to enable the packer (30) to divide the oil well casing (40) into two areas;
s5, converting the steam huff-puff oil recovery mode into a steam drive oil recovery mode, injecting steam into the first oil pipe (10), and utilizing the second oil pipe (20) to recover the oil layer (60),
in the steam flooding oil extraction mode, the steam injection speed is 80-250 tons/day, the extraction-injection ratio is equal to 1.2,
the step S5 further includes:
and after the oil layer (60) is mined for a preset time by adopting the steam-drive oil extraction mode, injecting mixed gas of nitrogen and steam into the first oil pipe (10), wherein the volume ratio of the injected nitrogen to the injected steam is 0.2-0.5, and stopping injecting the nitrogen into the first oil pipe (10) when the injection amount of the nitrogen reaches 0.15 PV.
2. A production method according to claim 1, wherein the first tubing (10) and the second tubing (20) are spaced apart by 15-20 mm in the reservoir (60).
3. The production method according to claim 1, wherein the average thickness of the oil reservoir (60) is greater than 7 m.
4. The mining method according to claim 1, characterized in that the upper surface of the reservoir (60) is located at a distance of 150-800 m from the surface.
5. The mining method according to claim 1, wherein the step S1 further includes:
perforating the well casing (40) to form a perforated interval (50) in the reservoir (60).
6. A production method according to claim 5, wherein the perforated interval (50) is located close to one side of the first tubing (10), the perforated interval (50) comprising a first perforated interval (510) and a second perforated interval (520), the first perforated interval (510) being above a central position of the oil reservoir (60) and the second perforated interval (520) being below a central position of the oil reservoir (60).
7. The mining method according to claim 1, wherein the step S2 further includes:
feeding a temperature gauge and a pressure sensor into the second tubing (20).
8. The production method according to claim 1, wherein in the step S3, the steam stimulation oil recovery mode is adopted to perform 3-5 production rounds of the oil layer (60), wherein the production rounds are performed for 60-250 days, and the interval period is 70-265 days.
9. The mining method according to claim 1, wherein in the steam huff-puff oil recovery mode, the dryness of steam at the bottom of the well is not less than 0.7, the steam injection amount in the steam-huff-puff oil recovery mode is 1000 to 3000 tons, the steam injection speed is 80 to 250 tons/day, and the soaking time is 3 to 5 days.
10. A production method according to claim 6, wherein the first perforation section (510) and the second perforation section (520) are spaced apart by 1-2 m, and in step S4, the packer (30) is run into the well casing (40) with the packer (30) in the well casing (40) between the first perforation section (510) and the second perforation section (520).
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| CN111434885B (en) * | 2019-01-15 | 2022-06-03 | 中国石油天然气股份有限公司 | Thickened oil recovery method |
| CN110029976B (en) * | 2019-04-23 | 2021-02-23 | 中国石油大学(华东) | Hot nitrogen-assisted heavy oil reservoir steam huff-puff oil production system and method |
| CN114165202B (en) * | 2020-08-20 | 2024-04-16 | 中国石油化工股份有限公司 | Method for improving radius for throughput after high-pass throughput |
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| CN202325428U (en) * | 2011-11-24 | 2012-07-11 | 中国石油天然气股份有限公司 | Driving-drainage composite oil production system |
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