Method for liquid injection energization and new well production in later period of development of ultra-low permeability tight oil reservoir

Abstract

The invention belongs to the technical field of oil and gas field development, and particularly relates to a method for liquid injection energization and new well production in the later period of ultra-low permeability tight oil reservoir development. The method comprises the following steps: S1, determining an energy supplementing old well range; s2, determining an old well liquid injection and energizing liquid injection amount: based on geological modeling, establishing an old well compact conglomerate volume fractured horizontal well crack propagation numerical model until the pressure recovery degree is not lower than 70%, so as to obtain the liquid injection amount; s3, the liquid injection sequence and the soaking time are optimized, and old well liquid injection energizing construction is monitored; and S4, production is started after old well liquid injection energy increasing and new well fracturing, and the long-acting production capacity of the new and old wells is evaluated through yield prediction. Formation energy is recovered through rapid injection, near-shaft formation pressure is recovered, impact of fracturing interference strong shear force on a casing pipe is effectively resisted, damage to an old well shaft and production caused by new well fracturing due to formation deficiency in a productivity construction area is solved, and meanwhile the new well fracturing commissioning effect is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and gas field development, and particularly relates to a method for liquid injection energy increase and new well production in the late development of a low-permeability tight oil reservoir. BACKGROUND

[0002] The initial production of Mahu tight conglomerate oil reservoir is high, but the decline is fast, and the predicted primary recovery rate is low. At present, the formation pressure of the developed reservoirs is decreasing year by year, and it is difficult to maintain stable production. In the process of new infill horizontal well fracturing production in the developed area of the reservoir, due to large depletion and low pressure maintenance degree of old wells, complex well conditions are prone to occur in old wells after fracturing interference, and the productivity of new wells after production does not meet the expectation. It is believed that the strong shear stress difference formed by fracturing interference is the main reason for the complexity of old wells.

[0003] Chinese patent application CN115544851A discloses a method for fracturing energy increase and improving the productivity of old wells in shale gas, which evaluates the reservoir energy increase potential of old wells based on the physical characteristics of the reservoir, obtains the evaluation results, arranges energy increase new wells based on the evaluation results, calculates the fracture propagation of energy increase new wells and optimizes the fracturing operation parameters, implements new well fracturing operation to connect the fracture zone based on the operation parameters, and monitors the energy increase in real time to obtain monitoring data. Old wells resume normal production based on the monitoring data, and energy increase new wells start production. Finally, the long-term production capacity after energy increase is evaluated through productivity prediction simulation. This method realizes controllable channeling of new wells to old wells through pre-fracturing geomechanics evaluation, monitoring and control during fracturing, and post-fracturing prediction. In the case of not damaging the wellbore and production of old wells, the problem of avoiding channeling is solved, and the control range of single well reserves is increased. However, the energy increase effect of the method is not ideal after the production of the energy increase new well.

[0004] Therefore, there is an urgent need in the art for a method suitable for low-permeability tight oil reservoirs that can effectively resist the impact of strong shear force of fracturing interference on the casing while improving the fracturing production effect of new wells. SUMMARY

[0005] The application provides a method for liquid injection energy increase and new well production in the late development of a low-permeability tight oil reservoir to solve the problems in the prior art.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0007] A method for liquid injection energy increase and new well production in the late development of a low-permeability tight oil reservoir, comprising the following steps:

[0008] S1. Determine the range of energy supplement old wells;

[0009] S2. Determining the liquid injection energy-increasing injection volume of the old well: based on the geological modeling results, a numerical model of fracture propagation of the old well in the dense conglomerate volume is established, and the pressure recovery degree is not less than 70%, that is, the injection volume is obtained;

[0010] S3. Optimizing the liquid injection sequence and soaking time, and monitoring the liquid injection energy-increasing construction of the old well;

[0011] S4. After the old well is injected with liquid energy-increasing and the new well is fractured, production is started, and the long-term production capacity of the new and old wells is evaluated through yield prediction.

[0012] The old well is a developed and produced horizontal well, and the new well is an undeveloped and produced horizontal well.

[0013] Preferably, the method for determining the energy-supplementing old well range in step S1 comprises determining the energy-supplementing old well range according to the new well fracturing area, combining the regional reservoir characteristics with the initial fracturing production characteristics of the old well, and determining the interference distance.

[0014] Preferably, the regional reservoir characteristics include porosity, permeability, saturation, and rock mechanics parameters.

[0015] Preferably, the fracturing production characteristics include pressure change, liquid volume change, and water cut change.

[0016] Preferably, the method for determining the energy-supplementing old well range further comprises: calculating the single-well controlled reserves by using the volumetric method according to the well logging interpretation results, and calculating the single-well recovery degree and the depletion degree by combining the produced volume and the fracturing liquid volume.

[0017] Preferably, the geological modeling in step S2 comprises one or more of a fluid model, a rock mechanics model, and a three-dimensional ground stress model.

[0018] Preferably, the parameters of the model in step S2 include the wellbore and the perforation cluster.

[0019] The wellbore and perforation in the model refer to the actual parameters of the well, different injection parameters are designed for comparison, and the pressure recovery degree is analyzed.

[0020] Preferably, step S3 further comprises optimizing a temporary plugging scheme, and the temporary plugging scheme comprises injecting a temporary plugging agent by segmenting and plugging 3-4 levels, accounting for 1 / 4-1 / 3 of the total number of single-well fracturing.

[0021] According to the perforation abrasion of different fracturing processes, the particle size and combination of the temporary plugging are optimized, the effective perforation hole number is calculated according to the difference in the improvement effect, and the liquid slug is designed according to the total liquid volume.

[0022] Preferably, the temporary plugging agent comprises one or more of a temporary plugging knot, a temporary plugging particle, and a temporary plugging powder.

[0023] Preferably, the liquid injection sequence in step S3 is from both sides to the middle.

[0024] Preferably, the soak time in step S3 is 5-8 days per 1000 cubic liquid injection.

[0025] Based on the complex fracture propagation numerical model of the dense conglomerate volume fracturing horizontal well, the pressure field diffusion after liquid injection energy increase is calculated, and the relationship between the injection amount and soak pressure is summarized in combination with the previous field test well.

[0026] Preferably, the monitoring in step S3 includes real-time monitoring of the bottom hole flowing pressure of the adjacent well, the fracturing interference pressure change of the new well, and / or microseismic monitoring.

[0027] If the bottom hole pressure appears a large impact effect, the construction is immediately stopped.

[0028] Through real-time dynamic monitoring inversion of the microseismic signal, it is determined whether the microseismic signal effectively blocks the initial liquid injection dominant channel.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The present application proposes the technical idea of new well fracturing after liquid injection energy supplement of old horizontal well, forms a mode of liquid injection energy supplement and new well production in the late development of ultra-low permeability tight reservoir, restores the formation energy through rapid injection, restores the near wellbore formation pressure, reconstructs the interwell stress field, effectively resists the impact of strong shear force of fracturing interference on the casing, solves the damage to the old well borehole and production caused by the formation depletion in the production capacity construction area after new well fracturing, and improves the new well fracturing production effect. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a comparison chart of water cut recovery and daily oil production of the old well before the same scale fracturing interference of example 1 and the old well after liquid injection energy supplement.

[0032] Figure 2 It is a production curve comparison chart of the new well in the liquid injection energy supplement area of example 1 and the early production old well.

[0033] Figure 3 It is a production curve chart of the liquid injection well B well group of example 2.

[0034] Figure 4 It is a comparison chart of the production of the new infill well after liquid injection energy supplement and the early infill old well of example 2.

[0035] Figure 5 It is a chart of water cut and daily oil production of the typical horizontal well after liquid injection energy supplement in the liquid injection well B well group of example 2. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0037] Example 1

[0038] Taking the conglomerate reservoir horizontal well A well group as an example, a method for liquid injection and energy increase and new well production in the late development of a low-permeability tight oil reservoir is as follows:

[0039] S1. Determining the range of energy-supplementing old wells: according to the fracturing region of a new well, in combination with the regional reservoir characteristics (porosity, permeability, saturation and rock mechanics parameters) and the production characteristics (pressure change, liquid volume change and water cut change) of the old well after initial fracturing, the interference distance is determined to be 2400 meters, and the range of liquid injection and energy increase is determined to be 300-2000 meters around the fractured well. The single-well controlled reserves are calculated by using the volume method according to the logging interpretation results, and the single-well recovery degree is calculated to be 7.7% and the void volume is calculated to be 33745 cubic meters in combination with the current recovery volume and the fracturing liquid volume.

[0040] S2. Determining the liquid injection volume for liquid injection and energy increase of the old well; first, based on the geological modeling results (fluid model, rock mechanics model and three-dimensional ground stress model), a complex fracture propagation numerical model of the old well tight conglomerate volume fracturing horizontal well is established, in which the wellbore and perforation cluster are referred to the actual parameters of the well, different injection parameters are designed for comparison, the pressure recovery degree is analyzed, and the pressure is recovered to more than 70%. At this time, the regional liquid injection volume is 139000 cubic meters.

[0041] S3. Designing the liquid injection sequence based on the evaluation results: in order to improve the overall formation energy of the region and fully play the well group effect, the injection sequence is designed to be advanced from both sides to the middle along the direction of the maximum horizontal principal stress.

[0042] Designing the soak time based on the evaluation results: based on the complex fracture propagation numerical model of the tight conglomerate volume fracturing horizontal well, the pressure field diffusion after liquid injection and energy increase is calculated, and the relationship between the injection volume and the soak pressure is summarized in combination with the previous test well in the field. Generally, the soak time is 7 days for every 1000 cubic meters of liquid injection.

[0043] Monitoring the energy-increasing construction of the old well: the bottom hole flowing pressure and the fracturing interference pressure change of the adjacent vertical well during liquid injection are observed. If the bottom hole pressure appears a large impact effect, the construction is stopped immediately; through real-time dynamic monitoring and inversion of microseismic signals, it is determined whether the microseismic signals effectively block the initial liquid injection dominant channel.

[0044] S4. The old well is normally produced after liquid injection and energy enhancement, and the new well is produced after fracturing. The long-term production capacity of the new and old wells is simulated and evaluated by the production prediction method. The comparison chart of water cut recovery and daily oil production of the old well disturbed by the same scale fracturing in the early stage and the old well after liquid injection and energy enhancement is shown in Figure 1 The comparison chart of production curves of the new well in the liquid injection and energy enhancement area and the early production old well is shown in Figure 2 .

[0045] The formation pressure in the area after liquid injection increases from 30 MPa to 45 MPa. As shown in Figure 1 , the interference recovery time of the old well decreases from 124 days to 105 days, and the oil increase after liquid injection of the liquid injection well is 24,200 tons. As shown in Figure 2 , after the implementation of liquid injection and energy enhancement, the self-flowing period of the new well compared with the early production old well increases from 140 days to 210 days, and the production effect is obviously improved.

[0046] Example 2

[0047] Taking the conglomerate reservoir horizontal well group B as an example, a method for liquid injection and energy enhancement and new well production in the late development of a low-permeability tight reservoir is as follows:

[0048] S1. Determine the energy enhancement old well range: according to the new well fracturing area, combined with the area reservoir characteristics (porosity, permeability, saturation and rock mechanics parameters) and the old well initial fracturing production characteristics (pressure change, liquid volume change and water cut change), the interference distance is determined to be 1000 meters, and the liquid injection and energy enhancement well range is determined to be 500 meters around the fracturing well. According to the logging interpretation results, the volume method is used to calculate the single well controlled reserves, combined with the current recovery volume and the fracturing liquid volume to calculate the single well recovery degree of 15.3% and the void volume of 36,000 cubic meters.

[0049] S2. Determine the liquid injection amount of the old well liquid injection and energy enhancement; first, based on the geological modeling results (fluid model, rock mechanics model and three-dimensional ground stress model), a complex fracture propagation numerical model of the old well tight conglomerate volume fracturing horizontal well is established. In the model, the wellbore and perforation cluster are referred to the actual parameters of the well, different injection parameters are designed for numerical simulation comparison, and the pressure recovery degree is analyzed. When the pressure recovery degree is restored to more than 70%, the area liquid injection volume is 153,550 cubic meters.

[0050] S3. Design a temporary plugging scheme based on the evaluation results: according to the downhole microseismic monitoring results in the early stage of horizontal well liquid injection and energy enhancement, the temporary plugging agent (temporary plugging knots, temporary plugging balls and temporary plugging powder) is added for multi-stage injection by sectional plug. There are 4 stages of temporary plugging agent before the liquid channel, accounting for about 1 / 4 of the total number of single well fracturing stages; according to the perforation abrasion of different fracturing processes, the particle size and combination of temporary plugging are optimized, and the effective perforation hole number is calculated according to the difference of the transformation effect. The liquid slug is designed according to the average total liquid volume.

[0051] Design the injection sequence based on the evaluation results: in order to improve the overall formation energy of the region and fully exert the well group effect, the injection sequence is to advance from both sides to the middle along the direction of the maximum horizontal principal stress.

[0052] Design the soak time based on the evaluation results: based on the numerical model of complex fracture propagation of the volume fracturing horizontal well in the dense conglomerate, the pressure field diffusion after the energy increase by injection is calculated, and the relationship between the injection volume and the soak pressure is summarized based on the previous field test well. Generally, the soak time is 8 days for every 1000 cubic meters of injection.

[0053] Monitor the energy increase construction of the old well: the bottom hole flowing pressure and the fracturing interference pressure of the adjacent vertical well during the injection are observed, if the bottom hole pressure has a large impact effect, the construction is stopped immediately; the real-time dynamic monitoring and inversion of the microseismic signal are used to determine whether the microseismic signal effectively blocks the initial liquid inlet dominant channel.

[0054] S4. After one month of injection energy increase of the early production well in May 2022, the newly added infill well after injection produces normally, the long-term production capacity of the new and old wells is simulated and evaluated by the yield prediction method, the production curve of the injection well group B in 2022-2023 is as shown in Figure 3 , and the production comparison chart of the newly added infill well after injection energy increase and the infill well without injection energy increase is as shown in Figure 4 .

[0055] The regional formation pressure after injection increases from 38.7 MPa to 55.3 MPa. As shown in Figure 3 , the gas-oil ratio of the well group after injection energy increase decreases significantly from 1227 cubic / ton to 350 cubic / ton, and returns to the stage of elastic drive; as shown in Figure 4 , the unit pressure drop daily oil production of the newly added infill well after injection energy increase increases from 256 tons to 318 tons compared with the early infill well without injection energy increase, and the production effect is obviously improved; as shown in Figure 5 , taking a typical horizontal well as an example, the well is shut down before injection energy increase, the daily oil production is 8.8 tons in the early stage (after May 2022) after injection energy increase, and the daily oil production is 3.8 tons in July 2024, and the stage oil increase is 3500 tons.

[0056] The invention is successful in the conglomerate reservoir horizontal well A well group and B well group, and is popularized in other well groups, a total of 57 injection wells, 61.4 million square meters of injection, and no casing damage occurs in the injection energy increase horizontal well, the effective rate is 100%, the injection well liquid supply capacity is obviously improved after the implementation, the production increase effect of the shut-down and low-yield wells is particularly significant, 76 new horizontal wells are added under the new mode, and the capacity of 553,000 tons is built.

[0057] Finally, it should be noted that the above is only to illustrate the technical solutions of the present application, and is not a limitation on the scope of protection of the present application, and simple modifications or equivalent replacements of the technical solutions of the present application by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method for enhancing the production capacity of ultra-low permeability tight oil reservoirs through fluid injection and commissioning of new wells in the later stages of development, characterized in that, Includes the following steps: S1. Determine the scope of the old wells for energy replenishment; S2. Determine the injection volume for energy enhancement in old wells: Based on geological modeling, establish a numerical model of fracture propagation in a horizontal well with tight conglomerate volumetric fracturing in old wells. The injection volume is obtained when the pressure recovery rate is not less than 70%. S3. Optimize the injection sequence and well shut-in time, and monitor the injection and energy enhancement construction of old wells; S4. Production begins after old wells are injected with fluid to enhance energy and after new wells are fracturing. The long-term production capacity of old and new wells is evaluated through production forecasting.

2. The method according to claim 1, characterized in that, The method for determining the range of old wells for energy replenishment in step S1 includes determining the range of old wells for energy replenishment based on the fracturing area of ​​the new well, combined with the regional reservoir characteristics and the initial fracturing production characteristics of the old well, and based on the interference distance.

3. The method according to claim 2, characterized in that, The reservoir characteristics of the region include porosity, permeability, saturation and rock mechanical parameters, and the fracturing production characteristics include pressure changes, fluid volume changes and water cut changes.

4. The method according to claim 2, characterized in that, The method for determining the range of old wells for energy replenishment also includes: calculating the controlled reserves of a single well using the volumetric method based on the well logging interpretation results, and calculating the recovery degree and deficit degree of a single well by combining the produced volume and the volume of fluid injected during fracturing.

5. The method according to claim 1, characterized in that, The geological modeling described in step S2 includes one or more of the following: fluid model, rock mechanics model, and triaxial geostress model.

6. The method according to claim 1, characterized in that, The parameters of the model described in step S2 include the wellbore and the perforation cluster.

7. The method according to claim 1, characterized in that, Step S3 also includes optimizing the temporary plugging scheme, which includes multi-stage injection of a temporary plugging agent in stages to temporarily plug the forward fluid channel in 3-4 stages, accounting for 1 / 4-1 / 3 of the total number of fracturing stages in a single well.

8. The method according to claim 7, characterized in that, The temporary plugging agent includes one or more of the following: temporary plugging knots, temporary plugging particles, and temporary plugging powder.

9. The method according to claim 1, characterized in that, The injection sequence in step S3 is from both sides towards the middle, and the well-closing time is 5-8 days for every 1000 cubic meters of liquid injected.

10. The method according to claim 1, characterized in that, The monitoring described in step S3 includes real-time monitoring of the bottom-hole flowing pressure of adjacent wells, changes in the interference pressure from fracturing in new wells, and / or microseismic monitoring.

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