Oil well production enhancement method and its application in buried hill oil reservoir

Abstract

The present application provides a method for increasing oil production in a buried hill reservoir well, and its use. The method comprises the steps of S1 construction preparation, S2 water plugging construction, S3 foam huff-and-puff enrichment construction, S4 channel unblocking construction, and S5 production construction, wherein S3 further comprises a method of injecting a composite lime emulsion water plugging agent. The present invention comprehensively utilizes processes such as gas huff-and-puff, water plugging, and acid unblocking, and creatively uses a composite lime emulsion plugging agent for plugging. While ensuring the integrity of the buried hill formation, the present invention blocks the deep water-producing area of ​​the buried hill, promotes the radial migration of residual oil along the weathering crust fracture zone at the top of the buried hill, communicates with the unused residual oil in the distal fractures, dredges (recreates) the oil production channel, and thus improves the residual oil recovery rate.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas fields, and in particular to a method for increasing oil production in a buried hill oil reservoir well and its application. Background Art

[0002] The cracks in some buried-hill oil reservoirs develop vertically, resulting in a large amount of residual oil around the wellbore that cannot be recovered. Currently, simply using measures such as throughput, plugging, unplugging, and fracturing cannot effectively expand the recovery range and improve crude oil recovery rates. A new oil-increasing and recovery process for buried-hill oil reservoirs is needed.

[0003] At present, the main measure for increasing oil production in buried hills is to simply use gas huff-and-puff technology to enrich and develop the remaining oil near the wellbore of the buried hill reservoir. However, due to the impact of bottom water intrusion and the lack of effective lateral gap communication, the effective period is short and the oil production effect is not obvious. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a method for increasing the production of buried hill oil reservoirs. On the premise of effectively protecting the original longitudinal cracks of the buried hill oil reservoir, the lower water outlet is blocked, a new channel for crude oil migration to the wellbore is created, the oil and gas resources around the wellbore are enriched, the production range is effectively expanded, and the residual oil recovery rate of oil wells with developed longitudinal cracks is improved.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present invention is to provide a method for increasing the production of buried hill oil reservoirs. By allowing the cracks to develop longitudinally, the previous method of open-hole production in the buried hill oil reservoir is changed. The water-producing parts in the buried hill are first sealed, and then perforation production is carried out after oil and gas are enriched in the weathering crust, thereby improving the crude oil recovery rate of the buried hill. At the same time, a method for water blocking in the buried hill oil reservoir is also provided to block water from deep layers.

[0006] That is, the first aspect of the present invention is to provide a method for increasing oil production in a buried hill oil well, comprising the following steps:

[0007] S1: Construction preparation, including

[0008] S10 Well Washing and Killing: Use well washing fluid to perform well washing operations in the form of backwashing;

[0009] S11: pulling out the original production string in the well, wherein the original production string in the well includes the sucker rod string and the oil pipe string;

[0010] S12 downhole testing: 40-arm logging technology is used to determine the wellbore condition of the target section for plugging;

[0011] S13 Well cleaning: After the well is cleaned, the well is cleaned with well cleaning fluid and the well string is pulled out;

[0012] S14 Isolate and plug the upper layer: Use chemical water plugging method to plug the upper layer;

[0013] S2: Water blocking construction, including

[0014] S21 is lowered into the water plugging pipe string to the designed depth. The water plugging pipe string includes a bell mouth and a D73mm thickened oil pipe.

[0015] S22 water absorption measurement operation;

[0016] S23: inject water-displacing agent: inject gel water-displacing agent and isolation displacement fluid into the target plugging area;

[0017] S24: injecting water plugging agent: injecting composite lime milk water plugging agent to displace the isolation displacement fluid;

[0018] S3: Foam huff-and-puff enrichment construction

[0019] S31 perforation: perforation is carried out in the weathered crust section at the top of the buried hill;

[0020] S32 injects carbon dioxide;

[0021] S33 blowout: Use casing valve to release the well pressure;

[0022] S4: Channel unblocking construction:

[0023] S41 Replace the acidizing wellhead: Replace the wellhead according to the unblocking pressure;

[0024] S42: injecting plugging agent and blocking the well;

[0025] S43 blowout: Use casing valve to release the well pressure;

[0026] S5: Production and construction:

[0027] S51 Wellhead replacement: Replace the wellhead according to production requirements;

[0028] S52 pump-down completion: After running the tubing string combination according to the engineering design, the well is completed and production resumes.

[0029] Furthermore, the well washing fluid in step S10 includes 2-3 times the volume of the wellbore of treated oilfield de-oiled produced water, to which 1% of HRV-2 viscosity reducer is added.

[0030] Furthermore, the well washing fluid in step S10 is heated to 70°C-75°C, and is washed by backwashing from the annulus of the casing and out of the oil pipe. The pump pressure of the well washing pump truck is controlled within 15.0 MPa, and the displacement is controlled to be within 300 L / min corresponding to the displacement of the casing with an outer diameter of 139.7 mm.

[0031] Furthermore, after the well flushing operation in step S10, the step of configuring a calcium chloride well killing hydraulic well according to the formation pressure is also included.

[0032] Furthermore, the step S13 of well cleaning includes cleaning the well with a well cleaning gauge of 118 mm in outer diameter and a thickened oil pipe of 73 mm in diameter. After the well is cleaned beyond the construction section, the well is cleaned with a normal temperature well cleaning fluid of 2-3 times the volume of the wellbore, the cleaning string is pulled out, and the condition of the well cleaning gauge is checked and described.

[0033] Furthermore, the gel water-displacing agent in step S23 includes a gel water-displacing agent with a volume of 0.1-0.6 times the pore volume of the target plugging portion, the gel water-displacing agent includes a polyacrylamide aqueous solution with a mass fraction of 0.2%, and the isolation displacement fluid has a volume of 1.5 times the annular space of the casing; and / or the pump pressure in step S23 does not exceed 25 MPa, and the water-displacing agent is determined to be injectable after solidification and water absorption measurement.

[0034] Furthermore, the composite lime milk water blocking agent of step S24 comprises 10%-50% quicklime by mass and 2%-30% oil well cement by mass; and / or the volume of the composite lime milk water blocking agent comprises 20-40m 3 , and / or the pump pressure in step S24 does not exceed 25 MPa, wait for solidification and measure water absorption again to verify the sealing effect.

[0035] Furthermore, the injection amount of carbon dioxide in step 32 is calculated based on the displacement radius, and is injected under a pump pressure of less than 20 MPa, at an injection rate of 40-80 tons / day, and then the well is sealed for 10-60 days.

[0036] Furthermore, the completion pipe is run before the carbon dioxide is injected in step 32 or before the plugging remover is injected in step 42.

[0037] The present invention also provides application of the method in increasing oil production and yield in oil wells of buried hill oil reservoirs.

[0038] Compared to existing technologies, this invention offers at least the following advantages: It utilizes a combination of gas huff-and-puff, water plugging, and acidification to remove plugs, and innovatively uses a composite lime emulsion for plugging. While maintaining the integrity of the buried-hill formation, it seals the deep, water-producing areas within the buried-hill, promoting radial migration of residual oil along the weathering crust fracture zone at the top of the buried-hill. This facilitates the communication of unused residual oil in distal fractures, unblocking (recreating) oil production pathways, and thereby improving residual oil recovery. This method has been applied on two oil wells, achieving a 100% success rate and an average daily oil increase of 8.9 tons. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the specific embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0041] Some embodiments of the present invention provide a method for increasing production of a buried hill oil reservoir, comprising the following steps:

[0042] S1: Construction preparation;

[0043] S2: Water blocking construction;

[0044] S3: Foam huff-and-puff enrichment construction;

[0045] S4: Channel unblocking construction:

[0046] S5: Production and construction.

[0047] According to some specific embodiments of the present invention, step S1 further includes S11 well washing and killing: using 2-3 times the wellbore volume of treated oilfield de-oiled produced water, adding 1% HRV-2 viscosity reducer to prepare a well washing fluid, heating it to 70°C-75°C, and performing backwashing via the casing annulus and out the tubing. The well washing pump truck maintains a pump pressure of less than 15.0 MPa, and the displacement is controlled from low to high, within 300 L / min (for 139.7 mm outer diameter casing). After the well washing operation is completed, a calcium chloride well killing hydraulic well is deployed according to the formation pressure.

[0048] The above-mentioned HRV-2 viscosity reducer is produced by Xinji Xinshuntong Chemical Co., Ltd.; Yang Fumin et al. published "Development and Evaluation of HRV-2 Heavy Oil Viscosity Reducer" in "Petroleum Drilling Technology" Vol. 18, No. 3 in 1996, which provides a detailed description of its performance.

[0049] According to some specific embodiments of the present invention, the step S12 of lifting the original well string includes lifting the original production string in the well, and the original production string in the well includes a sucker rod string and an oil tubing string.

[0050] According to some specific embodiments of the present invention, step 13 includes using 40-arm logging technology to delineate the casing condition and determine the wellbore condition of the target section for plugging. 40-arm logging technology is clearly described in "Research on Caliper Testing Technology for Cased Wells," presented by Zhao Qinghai, Chen Wenyan, et al. at the First International Conference on Mechanical Engineering. The caliper testing method is well known to those skilled in the art and will not be described in detail here.

[0051] According to some specific embodiments of the present invention, step S14 includes selecting a 118mm outer diameter well gauge (139.9mm diameter casing) and a 73mm diameter thickened oil pipe for well cleaning. After the well is cleaned beyond the working section, it is flushed with 2-3 times the wellbore volume of medium-temperature killing fluid. The well string is then pulled out, and the well gauge is inspected and described. Well gauges are commonly used tools in the petroleum industry and are commercially available. The well cleaning process is well known to those skilled in the art and will not be described in detail here.

[0052] According to some specific embodiments of the present invention, step S5 includes sealing the upper stratum using a chemical water plugging method using cement slurry. This plugging method is described in detail in Li Zhongcheng's master's thesis, "Research on Chemical Water Plugging Technology in Fuyu Oilfield." The relevant materials are commercially available. The chemical water plugging method is well known to those skilled in the art and will not be described in detail here.

[0053] According to some specific embodiments of the present invention, step S2 of the water plugging operation further includes: step S21 of installing a bellmouth and thickening the oil pipe to a D73mm depth to the designed depth. Both the bellmouth and the oil pipe are national standard components and are commercially available. The method for lowering the water plugging pipe string is well known to those skilled in the art and will not be described in detail here.

[0054] According to some specific embodiments of the present invention, the water absorption test method in step S22 further includes testing the water absorption capacity of the formation by squeezing out clean water for 5 minutes at a pump pressure of 2-3 MPa and a displacement of 400 L / min. The water absorption test operation is well known to those skilled in the art and will not be described in detail here.

[0055] According to some specific embodiments of the present invention, step S23 of injecting a water-displacing agent includes injecting a gel water-displacing agent at a volume of 0.1-0.6 times the pore volume of the target plugging site, and an isolation displacement fluid at a volume of 1.5 times the annular volume of the casing, at a pump pressure not exceeding 25 MPa, waiting for 3 days, and then measuring water absorption again to confirm that the composite lime emulsion plugging agent is injectable. The gel water-displacing agent is a 0.2% by mass aqueous solution of polyacrylamide, which is commercially available.

[0056] According to some specific embodiments of the present invention, the step S24 of injecting a water blocking agent includes injecting 20-40 m of a composite lime milk water blocking agent. 3, reverse displacement fluid of 1.5 times the wellbore volume, the pump pressure does not exceed 25MPa, wait for 3 days, and measure the water absorption again to verify the sealing effect.

[0057] According to some specific embodiments of the present invention, the composite lime milk water plugging in step S24 includes quicklime and

[0058] The mass fractions of oil well cement are 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 20%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% and 30%. All materials used are available on the market.

[0059] According to some specific embodiments of the present invention, step S3 further includes step S31 of perforating, i.e., perforating the weathered crust layer at the top of the buried hill. The perforating process is well known to those skilled in the art and will not be described in detail here.

[0060] According to some specific embodiments of the present invention, step S32 includes calculating the amount of carbon dioxide to be injected based on the displacement radius, injecting the carbon dioxide at a pump pressure of less than 20 MPa at a rate of 40-80 tons / day, and then sealing the well for 30 days. Carbon dioxide is available at various gas filling stations. The carbon dioxide injection and sealing process are described in detail in "Carbon Dioxide Huff-and-Puff Experiment at Well Su-88" by Cheng Dongjian et al.

[0061] According to some specific embodiments of the present invention, step S33 includes using a casing valve to release the wellbore pressure. The release operation is well known to those skilled in the art and will not be described in detail here.

[0062] According to some specific embodiments of the present invention, step S4 further includes step S41 of replacing the wellhead according to the unblocking pressure. The wellhead replacement operation is well known to those skilled in the art and will not be described in detail here.

[0063] According to some specific embodiments of the present invention, step S42 includes injecting 20m of blocking agent. 3The well was blocked for 48 hours. The injection of a plugging remover and the subsequent blocking of the well are discussed in detail in Li Zhengye et al.'s article, "A Preliminary Study on Acidizing Plug Removal, Descaling, and Production Increase Technology in the Zhongyuan Oilfield." The plugging remover is 31% dilute hydrochloric acid with 6% by weight of an organic retarding acid, 1.3% by weight of an iron ion stabilizer, and 1.3% by weight of a drainage aid (zwitterionic surfactant). All ingredients are commercially available and are mature industrial products.

[0064] According to some specific embodiments of the present invention, step S43 includes using a casing valve to perform a blowout operation on the well pressure.

[0065] According to some specific embodiments of the present invention, step S5 further includes:

[0066] S51 Wellhead replacement: Replace the wellhead according to production requirements. The wellhead replacement operation is well known to those skilled in the art and will not be described in detail here.

[0067] S51 pump down and completion: After running the tubing string combination according to the engineering design, the well is completed and production is resumed.

[0068] According to some specific embodiments of the present invention, in order to speed up the production progress, a completion pipe is sometimes run before injecting carbon dioxide or injecting a plugging agent to speed up the production progress. In this way, the production operation only involves changing the wellhead and completing the well.

[0069] The implementation process of the present invention is further illustrated below by taking Jingu 14-1X well as an example.

[0070] Jingu 14-1X well is an oil well in a buried hill oil reservoir. Due to the high water cut caused by bottom water coning, the recovery rate of recoverable reserves is low. It is necessary to use the present invention to transform the reservoir to improve the recovery rate.

[0071] Step 1: Construction Preparation

[0072] (1) Well washing and pressure: Use 40m3 of treated oilfield de-oiled produced water 3 , add 1% HRV-2 viscosity reducer to prepare a well-washing fluid, heat it to 70°C, and backwash the well. The pump pressure of the well-washing pump truck is controlled within 15.0 MPa, and the displacement is controlled from small to large, within 300 L / min. According to the construction design, there is no need to configure a special calcium chloride well-killing hydraulic well process.

[0073] (2) Lift the original well tubing; lift out all the original production tubing in the well.

[0074] (3) Using 40-arm logging: There is no obvious deformation of the wellbore, which meets the construction requirements.

[0075] (4) Well cleaning: Use 118mm outer diameter well cleaning gauge + D73mm diameter thickened oil pipe for well cleaning. After the well cleaning exceeds the construction well section, use 40m3 (1) The wellbore was washed with normal temperature washing fluid, and the wellbore string was pulled out. The wellbore gauge was checked and no obvious scratches were found. There was no obvious scaling protrusion on the inner wall of the wellbore. The wellbore condition was good.

[0076] Step 2: Water blocking construction

[0077] (1) Lower the water plugging pipe string: bell mouth + D73mm thickened oil pipe to 2241.88m.

[0078] (2) Water absorption test: pump pressure 2-3MPa, displacement 400L / min, test to squeeze clean water into the well for 5 minutes 0.26m 3 , the water absorption capacity of the formation meets the requirements.

[0079] (3) Injection of water-displacing agent: Inject 300m3 of gel water-displacing agent 3 , clean water isolation displacement fluid 10m 3 , the pump pressure does not exceed 25MPa, wait for 3 days, and measure the water absorption again to confirm that the composite lime emulsion plugging agent can be injected.

[0080] (4) Injection of water blocking agent: Inject 30m3 of composite lime milk water blocking agent 3 , replace the replacement fluid with clean water 30m 3 , the pump pressure does not exceed 25MPa, wait for 3 days, and measure the water absorption again to verify the sealing effect.

[0081] Step 3: Foam carbon dioxide huff and puff construction

[0082] (1) Perforation: Perforation is carried out in the weathered crust section at the top of the buried hill using 102mm gun 127mm composite bullets.

[0083] (2) Lowering the completion pipe and rod: Lower the completion pipe and rod according to the design.

[0084] (3) Injection of carbon dioxide: The injection volume of carbon dioxide is calculated based on the displacement radius. 300 tons of liquid carbon dioxide are injected at a pump pressure of less than 20 MPa and a temperature of -17°C, and then the well is sealed for 30 days.

[0085] (4) Blowout: Use casing valve to release the pressure in the well.

[0086] Step 4: Channel unblocking construction

[0087] (1) Replace the acidizing wellhead: Replace the KL-S DN65 35MPa acidizing wellhead according to the unblocking pressure.

[0088] (2) Injection of plugging agent: Inject plugging agent at a pressure limit of 35 MPa for 20 m 3 , sealed the well for 48 hours.

[0089] (3) Blowout: Use casing valve to release the pressure in the well.

[0090] Step 5: Production and Construction

[0091] (1) Replace the wellhead: Replace the KY65 / 25 oil production wellhead according to production requirements, complete the well and resume production.

[0092] The oil production increase effect of Jingu 14-1X well is good: the daily output was zero before the measures, and 11.2 tons of crude oil was produced after the measures.

[0093] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for increasing oil production in a buried hill oil well, comprising the following steps: S1: Construction preparation, including S10 Well Washing and Pressure Reduction: Use well washing fluid to wash the well in a backwashing manner. The well washing fluid is heated to 70-75°C and is introduced from the casing annulus and returned from the tubing. The pump pressure of the well washing pump truck is controlled within 15.0 MPa, and the displacement is controlled within 300 L / min for a casing with an outer diameter of 139.7 mm. S11: pulling out the original production string in the well, wherein the original production string in the well includes the sucker rod string and the oil pipe string; S12 downhole testing: 40-arm logging technology is used to determine the wellbore condition of the target section for plugging; S13 Well cleaning: After the well is cleaned, the well is cleaned with well washing fluid and the well cleaning string is pulled out; S14 Isolate and plug the upper layer: Use chemical water plugging method to plug the upper layer; S2: Water blocking construction, including S21 is lowered into the water plugging pipe string to the designed depth. The water plugging pipe string includes a bell mouth and a D73mm thickened oil pipe. S22 water absorption measurement operation; S23: injecting a water-displacing agent: injecting a gel water-displacing agent and an isolation displacement fluid into the target plugging area; the gel water-displacing agent comprises a gel water-displacing agent with a volume of 0.1-0.6 times the pore volume of the target plugging area, and the gel water-displacing agent comprises a 0.2% by mass polyacrylamide aqueous solution; the pump pressure in step S23 does not exceed 25 MPa, and the water absorption is measured to confirm that the water-displacing agent can be injected; S24: injecting water plugging agent: injecting composite lime emulsion water plugging agent to displace the isolation displacement fluid; the composite lime emulsion water plugging agent includes 10% to 50% quicklime by mass and 2% to 30% oil well cement by mass; the volume of the composite lime emulsion water plugging agent includes 20 to 40m 3 The pump pressure in step S24 does not exceed 25 MPa, and the water absorption is measured again to verify the sealing effect. S3: Foam huff-and-puff enrichment construction S31 perforation: perforation is carried out in the weathered crust section at the top of the buried hill; S32 injects carbon dioxide; the amount of carbon dioxide injected is calculated based on the displacement radius, and the injection is carried out at a pump pressure of less than 20 MPa, at an injection rate of 40 to 80 tons per day, and then the well is blocked for 10 to 60 days; S33 blowout: Use casing valve to release the well pressure; S4: Channel unblocking construction: S41 Replace the acidizing wellhead: Replace the wellhead according to the unblocking pressure; S42: injecting plugging agent and blocking the well; S43 blowout: Use casing valve to release the well pressure; S5: Production and construction: S51 Wellhead replacement: Replace the wellhead according to production requirements; S52 pump-down completion: After running the tubing string combination according to the engineering design, the well is completed and production resumes.

2. The method for increasing oil production in a buried hill oil reservoir according to claim 1, wherein: The well washing fluid in step S10 includes 2-3 times the volume of the wellbore of treated oilfield de-oiled produced water, which is prepared by adding 1% of HRV-2 viscosity reducer.

3. The method for increasing oil production in a buried hill oil reservoir according to claim 1, wherein: After the well flushing operation in step S10, the step of configuring a calcium chloride well killing hydraulic well according to the formation pressure is also included.

4. The method for increasing oil production in a buried hill oil reservoir according to claim 1, wherein: The step S13 includes cleaning the well with a 118mm outer diameter cleaning gauge and a 73mm diameter thickened oil pipe. After the well is cleaned beyond the construction section, 2-3 times the wellbore volume of the cleaning fluid is used to clean the well in a forward washing manner, the cleaning pipe string is pulled out, and the cleaning gauge is checked.

5. The method for increasing oil production in a buried hill oil reservoir according to claim 1, wherein: The completion pipe is run before the carbon dioxide is injected in step 32 or before the plugging remover is injected in step 42.

6. Use of the method according to any one of claims 1 to 5 in increasing oil production and yield in oil wells in buried hill oil reservoirs.