Method for regulating and controlling injection-production profile of horizontal well by changing injection water quality

Abstract

The invention discloses a method for regulating and controlling the injection-production profile of a horizontal well by changing the water quality of injected water, which comprises the following steps of: 1, preparing injected water with different water qualities, carrying out a one-dimensional core displacement experiment, and calculating a water flooding pollution index; 2, establishing a horizontal well block numerical simulation model, extracting grid permeability distribution data of an injection-production unit, calculating a permeability variation coefficient, and determining a water flooding pollution index of required water injection; 3, clear water is injected into the reservoir of the injection-production unit until a high-permeability area of the reservoir breaks through; and 4, according to the needed water drive pollution index, injected sewage is allocated, a high-permeability channel is blocked, and regulation and control of the injection-production section of the horizontal well are achieved. According to the method, by injecting proper artificially-blended sewage into the reservoir and utilizing suspended solid particles, sulfide and other components in the injected water, a high-permeability channel is blocked, flow field distribution is adjusted, water drive balance is improved, the water injection utilization rate and recovery efficiency are improved, and the construction difficulty and cost of open hole horizontal well water injection profile regulation and control can be reduced.

Description

Technical Field

[0001] This invention relates to the field of water injection development technology for open-hole horizontal wells in oilfields, and more specifically, to a method for controlling the injection-production profile of horizontal wells by altering the water injection quality. Background Technology

[0002] Currently, in the development of open-hole horizontal wells with water injection, the water displacement front often exhibits uneven characteristics due to formation heterogeneity and the unique "heel-toe effect" of horizontal wells, severely impacting development efficiency. Formation heterogeneity is mainly manifested in the spatial distribution of reservoir properties such as porosity, permeability, and fracture development. These factors lead to uneven flow resistance of injected water in different areas, easily forming dominant flow channels in high-permeability regions. Due to the flow friction along the wellbore, water in the "heel" region of horizontal wells penetrates the formation more easily, while the "toe" region has insufficient injection capacity, further exacerbating the uneven flow of injected water. This uneven water displacement front directly results in inefficient or ineffective water circulation, reducing the utilization rate of injected water and increasing water injection energy consumption and development costs. Therefore, it is urgent to strengthen research and practice on horizontal well injection-production profile control to improve the development efficiency of water-driven oilfields and ensure national energy security.

[0003] To address these issues and ensure that injected water in open-hole horizontal wells can more evenly displace residual oil in the formation, thereby achieving effective utilization of injected water, it is crucial to implement injection-production profile control. Currently, most horizontal well profile control technologies rely on downhole water control equipment, such as packers and ICD devices, which are costly, complex to install, and cannot be applied in open-hole horizontal wells, making it difficult to achieve efficient control of the injection-production profile.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] To address the problems of the prior art, this invention provides a method for modifying the injection-production profile of a horizontal well by altering the water injection quality. By injecting appropriately formulated wastewater into the reservoir, the suspended solid particles and sulfides in the injected water are used to block high-permeability channels, adjust the flow field distribution, improve water drive equilibrium, and increase water injection utilization and recovery rates. This method can reduce the construction difficulty and cost of controlling the water injection profile in open-hole horizontal wells.

[0006] This invention is achieved through the following technical solution: This invention provides a method for altering the injection-production profile of a horizontal well to regulate water quality, comprising the following steps: Step 1: Configure water injection with different water qualities, conduct one-dimensional core displacement experiments, and calculate the water drive pollution index of water injection with different water qualities; Step 2: Establish a numerical simulation model of the horizontal well block, select injection and production units, extract grid permeability distribution data of the injection and production units, calculate the permeability variation coefficient of the injection and production units, and determine the water drive pollution index required for water injection based on the permeability variation coefficient. Step 3: Inject clean water that meets the water quality standards into the reservoir of the injection-production unit until the high permeability area of ​​the reservoir is breached; Step 4: Based on the water drive pollution index determined in Step 2, adjust the amount of wastewater to be injected, block high-permeability channels, and achieve control of the injection-production profile of the horizontal well.

[0007] This invention injects appropriately formulated wastewater into the reservoir, utilizing suspended solid particles and sulfides in the injected water to block high-permeability channels, adjust the flow field distribution, and improve water drive uniformity. This can improve the water drive imbalance caused by formation heterogeneity and the "heel-toe effect" of horizontal wells during open-hole horizontal well water injection development, ensuring that the injected water can more evenly displace the remaining oil in the formation, improving the flow path of the injected water, achieving effective utilization of the injected water, increasing the recovery rate of remaining oil in the "toe" area of ​​the injection well, and reducing the construction difficulty and cost of open-hole horizontal well water injection profile control.

[0008] The method of this invention does not rely on downhole water control equipment, effectively reducing the cost of injection-production profile control and improving the efficiency of horizontal well water injection development of oil fields.

[0009] In a specific implementation, in step 1, the water quality indicators for water injection with different water quality include: suspended solids content, suspended solids particle size, oil content, sulfide content, and total iron content.

[0010] In a specific implementation, in step 1, the fitting formula for the water-driven pollution index is as follows: ; In the above formula, K Permeability of the reservoir after injecting wastewater; K i The original permeability of the reservoir; a FLWATR is the water-driven contamination index; FLWATR is the injection volume multiple.

[0011] In a specific implementation, in step 2, the formula for calculating the coefficient of variation of permeability of the injection-production unit is as follows: ; In the above formula, V K is the coefficient of variation of reservoir permeability; is the _____. i The penetration rate of each grid; The average permeability of the reservoir; n This represents the number of grid cells.

[0012] In a specific implementation method, the relationship between the water drive pollution index and the coefficient of variation of permeability in the injection-production unit is as follows: .

[0013] In a specific implementation, in step 3, the clean water that meets the water quality standards refers to water that will not cause reservoir pollution and will not change the reservoir permeability.

[0014] In one specific implementation, in step 3, after the high permeability zone of the reservoir is breached, the water cut of the production well increases.

[0015] In a specific implementation, in step 3, the water quality indicators of the clean water are: suspended solids content 2 mg / L, suspended solids particle size 1.5 μm, oil content 15 mg / L, sulfide content 2.0 mg / L, and total iron content 0.3 mg / L.

[0016] In one specific implementation, in step 4, during the sewage injection process, Python code is embedded in a numerical simulator to monitor changes in injection pressure and reservoir permeability in real time.

[0017] In one specific implementation, step 5 is also included: by monitoring the water absorption profile and numerically simulating it, the effect of sealing the high-permeability channels and the changes in the flow field after the sewage is injected are evaluated, and the water quality plan for the injected water is adjusted in real time.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a method for modifying the injection and production profile of a horizontal well by changing the water injection quality. By injecting suitable artificially prepared wastewater into the reservoir, the suspended solid particles, sulfides and other components in the injected water are used to block high-permeability channels, adjust the flow field distribution, improve water drive balance, and improve water injection utilization and recovery rate. This method can reduce the construction difficulty and cost of water injection profile control in open-hole horizontal wells. 2. The present invention provides a method for modifying the injection and production profile of a horizontal well by changing the water quality of the injection well. This method can improve the uneven water drive caused by the heterogeneity of the formation and the "heel-toe effect" of the horizontal well during the water injection development of the open-hole horizontal well. It ensures that the injected water can more evenly displace the remaining oil in the formation, improves the flow path of the injected water, realizes the effective utilization of the injected water, and improves the recovery of the remaining oil in the "toe" area of ​​the injection well. 3. The present invention provides a method for adjusting the injection-production profile of a horizontal well by changing the water quality of the injection well. This method does not rely on downhole water control equipment, effectively reduces the cost of adjusting the injection-production profile, and is beneficial to improving the efficiency of water injection development of oil fields. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating a method for altering the injection-production profile of a horizontal well to regulate water quality, as provided in an embodiment of the present invention. Figure 2 The reservoir permeability field distribution provided in the embodiments of the present invention; Figure 3 This is the water saturation field distribution provided by an embodiment of the present invention when injecting clean water to break through the hyperpermeability zone; Figure 4 This is an example of the change in the permeability field after injecting and preparing wastewater, as provided in an embodiment of the present invention. Figure 5 The water saturation field distribution after the injection and preparation of wastewater is provided in the embodiments of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0022] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0023] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] In open-hole horizontal well water injection development, due to formation heterogeneity and the unique "heel-toe effect" of horizontal wells, the water displacement front often exhibits uneven characteristics, severely affecting development efficiency. Formation heterogeneity is mainly manifested in the spatial distribution differences of reservoir properties such as porosity, permeability, and fracture development. These factors lead to uneven flow resistance of injected water in different areas, easily forming dominant flow channels in high-permeability regions. Due to the flow friction along the wellbore in horizontal wells, injected water penetrates the formation more easily in the "heel" region, while the "toe" region has insufficient injection capacity, further exacerbating the uneven flow of injected water. This uneven water displacement front directly leads to inefficient or ineffective injected water circulation, reducing the utilization rate of injected water and increasing water injection energy consumption and development costs. Therefore, it is urgent to strengthen research and practice on horizontal well injection-production profile control to improve the development efficiency of water-driven oilfields and ensure national energy security.

[0025] To address the aforementioned issues and ensure that injected water in open-hole horizontal wells can more evenly displace residual oil in the formation and achieve effective utilization of injected water, it is of great significance to conduct injection-production profile control.

[0026] Current horizontal well profile control technologies mostly rely on downhole water control equipment, such as packers and ICD devices, which are costly, complex to install, and cannot be applied in open-hole horizontal wells, making it difficult to achieve efficient control of the injection-production profile. To solve the above technical problems, this invention provides the following technical solution: This invention provides a method for altering the injection-production profile of a horizontal well to regulate water quality, comprising the following steps: Step 1: Configure water injection with different water qualities, conduct one-dimensional core displacement experiments, and calculate the water drive pollution index of water injection with different water qualities; Step 2: Establish a numerical simulation model of the horizontal well block, select injection and production units, extract grid permeability distribution data of the injection and production units, calculate the permeability variation coefficient of the injection and production units, and determine the water drive pollution index required for water injection based on the permeability variation coefficient. Step 3: Inject clean water that meets the water quality standards into the reservoir of the injection-production unit until the high permeability area of ​​the reservoir is breached; Step 4: Based on the water drive pollution index determined in Step 2, adjust the amount of wastewater to be injected, block high-permeability channels, and achieve control of the injection-production profile of the horizontal well.

[0027] This invention injects appropriately formulated wastewater into the reservoir, utilizing suspended solid particles and sulfides in the injected water to block high-permeability channels, adjust the flow field distribution, and improve water drive uniformity. This can improve the water drive imbalance caused by formation heterogeneity and the "heel-toe effect" of horizontal wells during open-hole horizontal well water injection development, ensuring that the injected water can more evenly displace the remaining oil in the formation, improving the flow path of the injected water, achieving effective utilization of the injected water, increasing the recovery rate of remaining oil in the "toe" area of ​​the injection well, and reducing the construction difficulty and cost of open-hole horizontal well water injection profile control.

[0028] The method of this invention does not rely on downhole water control equipment, effectively reducing the cost of injection-production profile control and improving the efficiency of horizontal well water injection development of oil fields.

[0029] In a specific implementation, in step 1, the water quality indicators for water injection with different water quality include: suspended solids content, suspended solids particle size, oil content, sulfide content, and total iron content.

[0030] In a specific implementation, in step 1, the fitting formula for the water-driven pollution index is as follows: ; In the above formula, K Permeability of the reservoir after injecting wastewater; K i The original permeability of the reservoir; a FLWATR is the water-driven contamination index; FLWATR is the injection volume multiple.

[0031] In a specific implementation, in step 2, the formula for calculating the coefficient of variation of permeability of the injection-production unit is as follows: ; In the above formula, V K is the coefficient of variation of reservoir permeability; is the _____. i The penetration rate of each grid; The average permeability of the reservoir; n This represents the number of grid cells.

[0032] In a specific implementation method, the relationship between the water drive pollution index and the coefficient of variation of permeability in the injection-production unit is as follows: .

[0033] In a specific implementation, in step 3, the clean water that meets the water quality standards refers to water that will not pollute the reservoir and will not change the reservoir permeability.

[0034] In one specific implementation, in step 3, after the high permeability zone of the reservoir is breached, the water cut of the production well increases.

[0035] In a specific implementation, in step 3, the water quality indicators of the clean water are: suspended solids content 2 mg / L, suspended solids particle size 1.5 μm, oil content 15 mg / L, sulfide content 2.0 mg / L, and total iron content 0.3 mg / L.

[0036] In one specific implementation, in step 4, during the sewage injection process, Python code is embedded in a numerical simulator to monitor changes in injection pressure and reservoir permeability in real time.

[0037] In one specific implementation, step 5 is also included: by monitoring the water absorption profile and numerically simulating it, the effect of sealing the high-permeability channels and the changes in the flow field after the sewage is injected are evaluated, and the water quality plan for the injected water is adjusted in real time.

[0038] Example like Figure 1 As shown in the flowchart, Figure 2 Taking the horizontal well injection-production mechanism model shown as an example, this embodiment of the invention provides a method for regulating the injection-production profile of a horizontal well by changing the injection water quality, including the following steps: Step 1: Change the quality of the injected water, conduct a one-dimensional core displacement experiment, and calculate the water drive pollution index for different water qualities.

[0039] Step 2: Establish a numerical simulation model for the block, extract grid permeability distribution data, and calculate the coefficient of variation of permeability in the target block as 0.887. Based on the injection-production profile control target, determine the required water drive pollution index as 8.87 × 10⁻⁶. -3 The water quality that meets this water drive pollution index is shown in Table 1.

[0040] Table 1 shows the water drive pollution index is 8.87 × 10⁻⁶. -3 water quality indicators

[0041] Step 3: Inject clean water that meets the water quality standards (i.e., water that will not change the reservoir permeability) into the high-permeability area of ​​the reservoir. The water quality indicators are shown in Table 2, and the water saturation field distribution is as follows. Figure 3 As shown.

[0042] Table 2. Water Quality Indicators for Clear Water

[0043] Step 4: Inject the prepared wastewater to seal the high-permeability channels. During the injection process, monitor the injection pressure and reservoir permeability changes in real time. The changes in reservoir permeability after wastewater injection are as follows: Figure 4 As shown.

[0044] Step 5, Dynamic Effect Evaluation. Using methods such as water absorption profile monitoring and numerical simulation, the effectiveness of the high-permeability channel sealing and the changes in the flow field after sewage injection are evaluated. The final water saturation field after sewage injection is shown in the figure. Figure 5 As shown.

[0045] After implementing this method in the horizontal well injection-production mechanism model, the oil displacement efficiency in the toe region of the horizontal well was significantly improved. After 20 years of simulation, the reservoir recovery rate increased from 18.3% to 22.9%, the overall reservoir water cut decreased from 72.13% to 35.05%, and the cumulative oil production increased by 460,000 cubic meters, achieving good economic benefits.

[0046] In summary, this invention, by injecting appropriately formulated wastewater into the reservoir, utilizes suspended solids and sulfides in the injected water to block high-permeability channels, adjust flow field distribution, improve water drive equilibrium, and enhance water injection utilization and recovery rates. This reduces the construction difficulty and cost of open-hole horizontal well water injection profile control. Furthermore, this invention improves the water drive imbalance caused by formation heterogeneity and the "heel-toe effect" of horizontal wells during open-hole horizontal well water injection development, ensuring that injected water can more evenly displace residual oil in the formation, improving the flow path of injected water, achieving effective utilization of injected water, and increasing the recovery rate of residual oil in the "toe" region of the injection well. Simultaneously, this method does not rely on downhole water control equipment, effectively reducing the cost of injection-production profile control and contributing to improved efficiency in horizontal well water injection development of oilfields.

[0047] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. 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 changing the quality of water injection to regulate the injection-production profile of a horizontal well, characterized in that, The method comprises the following steps: Step 1: configure water injection with different water quality, carry out one-dimensional core displacement experiment respectively, and calculate water drive pollution index of water injection with different water quality; Step 2: establish a numerical simulation model of a horizontal well block, select injection and production units, extract grid permeability distribution data of the injection and production units, calculate the permeability variation coefficient of the injection and production units, and determine the required water drive pollution index of water injection according to the permeability variation coefficient; Step 3: inject water of up-to-standard quality into the reservoir of the injection and production units until the high permeability area of the reservoir is broken through; Step 4: adjust the required injection of sewage according to the water drive pollution index determined in step 2, block the high permeability channel, and realize the regulation and control of the injection and production profile of the horizontal well.

2. The method for changing injection water quality to control injection-production profile of horizontal well according to claim 1, characterized in that, In step 1, the water quality indicators of water injection with different water quality include: suspended solid content, suspended solid particle size, oil content, sulfide content and total iron content.

3. The method for changing injection water quality to control injection-production profile of horizontal well according to claim 1, characterized in that, In step 1, the fitting formula of water drive pollution index is as follows: ； In the above formula, K is the permeability after the reservoir is injected with sewage; K i is the original permeability of the reservoir; a is the water flooding pollution index; FLWATR is the injection volume multiple.

4. The method for changing injection water quality to control injection-production profile of horizontal well according to claim 1, characterized in that, In step 2, the formula for calculating the permeability variation coefficient of the injection and production units is as follows: ； In the above formula, V K is the reservoir permeability variation coefficient; is the permeability of the i-th grid; i i is the reservoir permeability variation coefficient; is the permeability of the i-th grid; is the reservoir average permeability; n is the number of grids.

5. The method for changing injection water quality to control injection-production profile of horizontal well according to claim 4, characterized in that, The relationship between the water drive pollution index and the permeability variation coefficient of the injection and production units is as follows: 。 6. The method of claim 1, wherein the method is characterized by, In step 3, the water of up-to-standard quality refers to the water that will not pollute the reservoir and will not change the permeability of the reservoir.

7. The method of claim 1, wherein the method is characterized by, In step 3, the water cut of the production well increases.

8. The method for changing injection water quality to control injection-production profile of horizontal well according to claim 1, characterized in that, In step 3, the water quality indicators of the water are as follows: suspended solid content 2 mg / L, suspended solid particle size 1.5 μm, oil content 15 mg / L, sulfide content 2.0 mg / L, and total iron content 0.3 mg / L.

9. The method of claim 1, wherein the method is characterized by, In step 4, during the injection of sewage, Python code is embedded in the numerical simulator to monitor the injection pressure and the change of the reservoir permeability in real time.

10. The method of claim 1, wherein the method is characterized by, Step 5 is also included, which comprises monitoring the water absorption profile, numerical simulation, evaluating the high permeability channel blocking effect and flow field change after the injection of sewage, and adjusting the water quality scheme of the injection water in real time.

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