A method for adjusting and optimizing water injection in water-injection development oilfields

Abstract

This invention provides a method for optimizing water injection in water-injection oilfields. The method includes: performing detailed reservoir description; conducting dynamic production analysis of the water injection well group based on the detailed reservoir description; establishing a geological model based on the detailed reservoir description and the dynamic production analysis of the water injection well group; performing numerical simulation of the water injection well operation based on the geological model and production test data to determine the water injection control strategy; and controlling the water injection process of the water injection wells according to the control strategy during oilfield development. Using this invention, the water injection effect of water injection wells can be improved, providing a more accurate decision-making basis for adjusting the development of water-injection oilfields.

Description

Technical Field

[0001] This invention relates to the fields of petroleum geological exploration and reservoir engineering, specifically to a method for adjusting and optimizing water injection in water-injection development oilfields. Background Technology

[0002] In the petroleum industry, oilfield development often faces a situation where insufficient energy leads to a continuous decline in production. To address this, most oilfields use water injection to supplement formation energy and increase oilfield production. However, the water absorption between different layers in water injection wells varies, which cannot effectively supplement and balance the pressure differences between layers. This is especially true for layered reservoirs with multiple layers, where differences in energy between layers lead to prominent interlayer conflicts, thus hindering the further subdivision of the reservoir and making it extremely difficult to maintain stable production.

[0003] Currently, the methods for adjusting water injection wells in water-injection development oilfields mostly involve adjusting the water injection profile based on the test results of the water injection profile of the water injection wells, and taking measures such as fracturing and acidizing to adjust the water injection profile of the water injection wells. Alternatively, the method of dividing the water injection wells into separate injection wells can be used to solve the problem of uneven water absorption between different layers. However, the specific amount of water to be injected into each layer is currently limited to providing water injection to each layer based on the production needs of the water injection well group. However, the different sedimentary rhythms in the vertical direction within the layers, and the fact that most oil reservoirs have water-wet rocks, especially for oil reservoirs with high permeability, often lead to the oil wells being flooded too quickly when water is injected, resulting in less than ideal water injection effects. Summary of the Invention

[0004] This invention provides a method for adjusting and optimizing water injection in water-injection oilfields to improve the water injection effect of injection wells and provide a more accurate decision-making basis for adjusting the development of water-injection oilfields.

[0005] Therefore, the present invention provides the following technical solution:

[0006] A method for adjusting and optimizing water injection in a water-injection development oilfield, the method comprising:

[0007] Perform detailed reservoir characterization;

[0008] Based on the detailed reservoir description, the production dynamics of the water injection well group are analyzed.

[0009] A geological model was established based on the detailed reservoir description and the production dynamics analysis of the water injection well group.

[0010] Based on the geological model and production test data, numerical simulations were performed on the operation of water injection wells to determine water injection control strategies.

[0011] During oilfield development, the water injection process of injection wells is controlled according to the aforementioned control strategy.

[0012] Optionally, the detailed reservoir description includes:

[0013] Identify low-order faults, which are faults with a dip angle of less than 30 degrees.

[0014] The connectivity of sand bodies is predicted, and the prediction results are obtained.

[0015] Individual sand bodies are identified based on the prediction results.

[0016] Optionally, the identification of low-order tomography includes:

[0017] Low-order faults below 10m were identified through fault forward modeling.

[0018] By combining drilling or logging interpretation results with reservoir development dynamic data, low-order faults can be identified, and low-order fault identification markers can be established.

[0019] Optionally, the prediction of sand body connectivity to obtain the prediction result includes:

[0020] Sensitivity analysis of well logging curves is performed to determine the sensitivity curves of each formation and reservoir.

[0021] The sandstone and shale of different vertical reservoirs are determined based on the aforementioned sensitivity curves;

[0022] Based on the water injection effect analysis data of the water injection well group, the connectivity between the water injection wells and the production wells is determined.

[0023] Optionally, the logging curve includes any one or more of the following curves: sonic transit time curve, density curve, neutron curve, gamma curve, and P-impedance curve.

[0024] Optionally, identifying individual sand bodies based on the prediction results includes:

[0025] Determine the microphase type and establish the microphase model corresponding to the microphase type;

[0026] Based on the microfacies model, single-well facies are divided to determine the vertical gradation of the sedimentary environment and the spatial variation of sedimentary facies.

[0027] Perform planar facies analysis to generate a sedimentary facies planar map.

[0028] Optionally, the production dynamic analysis of the water injection well group includes:

[0029] In the vertical direction, based on the water absorption profile and production profile of the oil wells obtained from the water injection wells at different times in the water injection well group, the water-oil ratio derivative curve, and the operation and production status of the production wells in the water injection well group, the water flooding situation of the perforation layer of the production wells is determined.

[0030] On a plane, the leading edge of the water injection well is qualitatively characterized to determine the main breakthrough direction of the water injection well.

[0031] Optionally, establishing the geological model includes: establishing a rock property model, which includes porosity, permeability, and saturation models.

[0032] Optionally, the method further includes:

[0033] The geological model was validated using known well locations and actual data;

[0034] The geological model was optimized and adjusted based on the verification results.

[0035] Optionally, the step of conducting numerical simulations of the operation of injection wells based on the geological model and production test data to determine the water injection control strategy includes:

[0036] Fit relevant parameters of the water injection well based on the test data;

[0037] Based on the fitting results, the longitudinal and planar propagation of the injected water is quantitatively characterized, and the flooded area and unaffected area are divided to obtain the division results;

[0038] Determine the sensitivity of water injection volume and perforation location in different sections of the injection well;

[0039] Based on the classification results and the sensitivity, a water injection control strategy for injection wells is determined.

[0040] This invention provides a method for adjusting and optimizing water injection in water-injection oilfields. Through a systematic and targeted research strategy, it utilizes reservoir numerical simulation, combined with fitting of multiple test data, and streamline simulation to simulate the flow direction and flow rate of injected water, matching it with actual production analysis. This further improves the accuracy of historical fitting in numerical simulations for water-injection oilfields. Finally, through sensitivity analysis of the perforation section and injection volume of each layer in the injection well, combined with adjustments to the production volume of single wells in the well group, the current water drive sweep range is improved, ensuring uniform advancement of injected water. This significantly enhances the water injection effect of the injection wells and provides a more accurate decision-making basis for adjusting the development of water-injection oilfields.

[0041] Compared with existing technologies, one or more embodiments of the water injection adjustment and optimization method for water injection development oilfields provided by the present invention have the following beneficial effects:

[0042] (1) Based on the detailed reservoir description and production dynamic analysis of water-injected oilfields, the accuracy of static models has been further improved, enabling more accurate identification and characterization of reservoir sand body distribution and connectivity, providing a good foundation for water injection adjustment.

[0043] (2) By using the streamline model method and combining it with actual production, the weakness of the single theoretical description is changed, making the longitudinal water intake and planar propulsion of the injection well more in line with reality, thus ensuring the accuracy of the dynamic model.

[0044] (3) Based on a highly accurate dynamic model, the optimal perforation and water absorption layers for each layer were determined by using sensitivity analysis. Combined with the adjustment of the production volume of the oil well, the uniform advancement of the injected water was ensured, and rapid breakthrough in one direction was prevented.

[0045] (4) Improve the economic and social benefits of oilfield development: Through precise adjustment of water injection wells, ineffective water injection and development costs can be reduced, thereby improving the economic and social benefits of oilfield development.

[0046] (5) Wide applicability and application prospects: This invention is applicable to the research on water injection adjustment during the water injection development stage of various water-injection oil reservoirs. It has broad application prospects and is expected to be widely applied and promoted in the petroleum industry. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart of a water injection adjustment and optimization method for water injection development oilfields provided by the present invention. Detailed Implementation

[0049] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] To address the issue that the existing method of supplying water injection volume to each layer based on the production needs of the water injection well group results in less than ideal water injection effects, this invention provides a method for adjusting and optimizing water injection in water-injection development oilfields. Through a systematic and targeted research strategy, this method utilizes reservoir numerical simulation, combined with fitting of multiple test data, and streamline simulation to simulate the flow direction and flow rate of injected water, matching it with actual production analysis. This further improves the accuracy of historical fitting of numerical simulations in water-injection development oilfields. Finally, through sensitivity analysis of the perforation section of the water injection well and the injection volume of each layer, combined with adjustments to the production volume of single wells in the well group, the current water drive sweep range is improved, ensuring uniform advancement of injected water.

[0052] like Figure 1 The diagram shown is a flowchart of a water injection adjustment and optimization method for water injection development oilfields provided by the present invention, which includes the following steps:

[0053] Step 101: Perform detailed reservoir description.

[0054] Specifically, it can be described in the following aspects:

[0055] (1) Identify low-order faults, which are faults with a dip angle of less than 30 degrees.

[0056] Low-sequence faults are often difficult to detect and identify due to their small dip angles. Therefore, a method can be used to first determine low-sequence faults below 10m by employing fault forward modeling, which utilizes computer simulation software and mathematical models and algorithms to numerically calculate the formation, development, and evolution of faults. Then, combined with drilling or logging interpretation results, sequence stratigraphy can be performed. This not only improves the quantification of vertical stratigraphic division and lateral correlation but also allows for the study of stratigraphic cycles using the morphological combination patterns of logging curves, thereby identifying the alternation of sequence stratigraphic layers. Finally, by combining dynamic data on reservoir development, changes in produced fluid, water cut, and dynamic fluid levels during well production can be used to determine the connectivity between wells, thus achieving the goal of accurately identifying low-sequence faults.

[0057] For example, the existence of small faults can be inferred from well logging interpretation of fault points and differences in oil-water interfaces and pressure systems between adjacent wells. The intersection of the fault plane and the well axis is called a fault point. Fault activity will cause a series of changes in the formation and its attitude. Therefore, the nature, depth, and displacement of fault points can be determined by using well logging data for formation correlation and dip logging data interpretation. After identifying fault points in the well, the fault attitude and planar distribution can be reconstructed through fault point combinations.

[0058] For example, based primarily on the results of fault forward modeling, and combined with the actual analysis of small faults that have been drilled and identified, a seismic identification marker for low-order faults can be established to achieve accurate identification of low-order faults.

[0059] (2) The connectivity of the sand body is predicted and the prediction results are obtained.

[0060] For example, sand body connectivity can be predicted in the following way:

[0061] First, sensitivity analysis is performed on the logging curves to determine the sensitivity curves for each formation and reservoir. The logging curves may include any one or more of the following: sonic transit time curves, density curves, neutron curves, gamma curves, and P-impedance curves. The oil well curves can be generated based on the logging data.

[0062] The sensitive curve refers to the most sensitive curve for each formation reservoir inversion. That is, by analyzing the sensitivity of logging curves (sonic time, density, neutron, gamma and P impedance), the most sensitive curve for each formation is determined, and the inversion method selected for different formations is determined. The optimized inversion curve can accurately distinguish between sandstone and shale.

[0063] Then, sandstone and shale in different vertical reservoirs are determined based on the sensitivity curves.

[0064] Furthermore, reservoir inversion data can be generated based on inversion methods for different strata, and combined with the water injection effect analysis data of the injection well group, the connectivity between the injection wells and production wells can be determined, thus improving the sand body connectivity characterization results.

[0065] (3) Identify individual sand bodies based on the prediction results.

[0066] For example, a single sand body can be identified in the following way:

[0067] First, determine the microfacies type, which is the smallest unit within the subfacies zone that possesses unique lithological structure, texture, thickness, rhythmicity, and other sedimentary characteristics on the cross-section, as well as a certain planar configuration regularity. Establish microfacies models corresponding to the defined microfacies types. Specifically, based on the regional sedimentary characteristics, a progressive approach can be adopted: first, determine the macrofacies, subfacies, and microfacies; then, determine the large standard model (mainly including formation conditions, facies markers, subfacies, and microfacies); next, determine the microfacies type; and finally, establish core and well-logging facies models.

[0068] Then, based on the microfacies model, single-well facies division is performed to determine the vertical gradation law of the sedimentary environment and the spatial variation law of sedimentary facies.

[0069] Finally, planar facies analysis is performed to generate sedimentary facies planar maps. Specifically, microfacies types of the same sedimentary time unit can be distributed at well points, and sedimentary microfacies planar maps are drawn based on sedimentological theory. Combined with the results of single sandbody identification, the distribution characteristics of single sandbody in composite channel sand bodies are accurately identified, providing a basis for more accurate geological modeling of reservoirs and guidance for water injection development adjustments.

[0070] Detailed reservoir description can enhance our understanding of geological factors related to water injection adjustments, integrate geological findings such as small faults, sand body connectivity, and individual sand body characterization, and establish a refined geological model.

[0071] Step 102: Perform production dynamic analysis on the water injection well group based on the detailed reservoir description.

[0072] For example, the main flow direction of the injected water can be described from both the planar and longitudinal directions.

[0073] In the vertical direction, the water flooding situation of the perforation layer of the production well can be determined based on the water absorption profile and production profile of the oil wells obtained from the water injection wells at different times in the water injection well group, the water-oil ratio derivative curve, and the operation and production status of the production wells in the water injection well group.

[0074] On a plane, the water injection advance front of the injection well can be qualitatively characterized by combining production dynamic analysis, and the main breakthrough direction of the injection well can be determined. That is, by using the characteristics of the first well in the injection well group in terms of dynamic fluid level and water-bearing characteristics, the oil well that first achieves water injection breakthrough can be determined, and this direction is the main breakthrough direction of the injection well.

[0075] Step 103: Establish a geological model based on the detailed reservoir description and the production dynamic analysis of the water injection well group.

[0076] Specifically, a rock property model can be established, which includes porosity, permeability, and saturation models.

[0077] In a non-limiting embodiment, known well locations and actual data, such as pressure and water cut variation characteristics during production and saturation test data for each layer of the oil well, can be used to verify the geological model in terms of oil-water interface and trap boundaries. Based on the verification results, the geological model can be optimized and adjusted. For example, if some oil wells do not encounter water layers, the oil-water interface is usually determined by the pure oil bottom of that layer. This method will lead to rapid water flooding of the edge wells, which is inconsistent with reality. Therefore, sensitivity analysis of the oil-water interface depth can be used to determine a reasonable oil-water interface, making the geological model more realistic.

[0078] Step 104: Based on the geological model and production test data, perform numerical simulation of the operation of the injection well to determine the water injection control strategy.

[0079] Specifically, relevant parameters of the injection well can be fitted based on test data to make the simulated operation results of the injection well more realistic.

[0080] The test data may include, but is not limited to, any one or more of the following: formation pressure data from FMT (formation testing) at different time points of the production well, water absorption profile test data from the injection well, and production fluid profile test data from the production well. The relevant parameters of the injection well may include, but are not limited to: water absorption ratio and injection pressure of different sections of the injection well at different times.

[0081] In addition, pressure and water saturation data from new drilling tests and perforated sections can be combined to fit the pressure and water saturation at corresponding time points to enhance the quality control of historical fitting in numerical simulation. For example, the pressure difference at each depth predicted by the new drilling pressure test data in the model should be controlled within 1 MPa, and the difference between the water saturation test results and the water saturation of each section at the same time point of the corresponding well in the model should be controlled within 5%.

[0082] Simultaneously, streamline models are used to simulate and determine the main water flow direction of different injection well groups. Combined with the previous geological and dynamic understanding of the injection well groups, namely the main breakthrough direction of the injection wells obtained in the dynamic analysis and the characteristics of the oil wells in terms of pressure and water content after the effect, the main streamline direction and flow rate of the injection wells are fitted to improve the historical fitting accuracy of the numerical simulation.

[0083] Then, based on the fitting results, the longitudinal and planar propagation of the injected water is quantitatively characterized, and the flooded area and unaffected area are divided.

[0084] Then, the sensitivity of water injection volume and perforation location in different sections of the injection well was determined.

[0085] Finally, based on the classification results and the sensitivity, the water injection control strategy for injection wells is determined.

[0086] By combining the above numerical simulations with adjustments to the production rate of oil wells, the sweep range of injected water can be increased, ensuring uniform advancement of injected water and improving the effectiveness of water injection development.

[0087] Step 105: During the oilfield development process, control the water injection process of the injection wells according to the control strategy.

[0088] It should be noted that, in practice, feedback and optimization can be conducted based on actual development results. Through continuous adjustments and improvements, the effectiveness of water injection adjustments and the economic benefits of oilfield development can be enhanced.

[0089] The water injection adjustment and optimization method for water-injection development oilfields provided by this invention utilizes a systematic and targeted research strategy. It employs reservoir numerical simulation, combined with fitting of multiple test data, and streamline simulation to model the flow direction and flow rate of injected water. This matches the actual production analysis, further improving the accuracy of historical fitting in numerical simulations for water-injection development oilfields. Finally, through sensitivity analysis of the perforation section and injection volume of each layer in the water injection well, combined with adjustments to the production volume of single wells in the well group, the current water drive sweep range is improved, ensuring uniform water injection. This significantly enhances the water injection effect of the water injection wells and provides a more accurate decision-making basis for adjusting the development of water-injection development oilfields.

[0090] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0091] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0092] In the several embodiments provided by the present invention, it should be understood that the disclosed apparatus can be implemented in other ways.

[0093] The present invention also provides a storage medium, which is a computer-readable storage medium storing a computer program thereon, the computer program being executable when it runs. Figure 1 The method shown may include some or all of the steps. The storage medium may include read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc. The storage medium may also include non-volatile memory or non-transitory memory, etc.

[0094] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means.

[0095] The embodiments of the present invention have been described in detail above. Specific implementation methods have been used to illustrate the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and systems of the present invention, and are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention, and the content of this specification should not be construed as a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting and optimizing water injection in a water-injection development oilfield, characterized in that, The method includes: Perform detailed reservoir characterization; Based on the detailed reservoir description, the production dynamics of the water injection well group are analyzed. A geological model was established based on the detailed reservoir description and the production dynamics analysis of the water injection well group. Based on the geological model and production test data, numerical simulations were performed on the operation of water injection wells to determine water injection control strategies. During oilfield development, the water injection process of injection wells is controlled according to the aforementioned control strategy.

2. The method for adjusting and optimizing water injection in water-injected oilfields according to claim 1, characterized in that, The detailed reservoir description includes: Identify low-order faults, which are faults with a dip angle of less than 30 degrees. The connectivity of sand bodies is predicted, and the prediction results are obtained. Individual sand bodies are identified based on the prediction results.

3. The method for adjusting and optimizing water injection in water-injected oilfields according to claim 2, characterized in that, The identification of low-order tomography includes: Low-order faults below 10m were identified through fault forward modeling. By combining drilling or logging interpretation results with reservoir development dynamic data, low-order faults can be identified, and low-order fault identification markers can be established.

4. The method for adjusting and optimizing water injection in water-injected oilfields according to claim 2, characterized in that, The prediction of sand body connectivity yields the following results: Sensitivity analysis of well logging curves is performed to determine the sensitivity curves of each formation and reservoir. The sandstone and shale of different vertical reservoirs are determined based on the aforementioned sensitivity curves; Based on the water injection effect analysis data of the water injection well group, the connectivity between the water injection wells and the production wells is determined.

5. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 4, characterized in that, The logging curves include any one or more of the following curves: sonic transit time curve, density curve, neutron curve, gamma curve, and P-impedance curve.

6. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 2, characterized in that, The step of identifying individual sand bodies based on the prediction results includes: Determine the microphase type and establish the microphase model corresponding to the microphase type; Based on the microfacies model, single-well facies are divided to determine the vertical gradation of the sedimentary environment and the spatial variation of sedimentary facies. Perform planar facies analysis to generate a sedimentary facies planar map.

7. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 1, characterized in that, The production dynamic analysis of the water injection well group includes: In the vertical direction, based on the water absorption profile and production profile of the oil wells obtained from the water injection wells at different times in the water injection well group, the water-oil ratio derivative curve, and the operation and production status of the production wells in the water injection well group, the water flooding situation of the perforation layer of the production wells is determined. On a plane, the leading edge of the water injection well is qualitatively characterized to determine the main breakthrough direction of the water injection well.

8. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 1, characterized in that, The establishment of the geological model includes: A rock property model is established, which includes porosity, permeability, and saturation models.

9. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 8, characterized in that, The method further includes: The geological model was validated using known well locations and actual data; The geological model was optimized and adjusted based on the verification results.

10. The method for adjusting and optimizing water injection in water-injection development oilfields according to claim 1, characterized in that, The numerical simulation of water injection well operation based on the geological model and production test data, and the determination of water injection well control strategies, include: Fit relevant parameters of the water injection well based on the test data; Based on the fitting results, the longitudinal and planar propagation of the injected water is quantitatively characterized, and the flooded area and unaffected area are divided to obtain the division results; Determine the sensitivity of water injection volume and perforation location in different sections of the injection well; Based on the classification results and the sensitivity, a water injection control strategy for injection wells is determined.

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