Polymer polymer flooding monitoring system for water-containing recovery period of three types of oil layers

Abstract

The invention relates to the technical field of energy-saving transformation of equipment, in particular to a polymer flooding monitoring system for water-containing recovery periods of three types of oil layers. The system comprises an adjustment system switching judgment module used for calculating an injection electrical efficiency index by continuously monitoring oil production increment and power consumption of an injection pump during injection of a first adjustment system so as to judge whether to switch the adjustment system of an injection well at the current moment; the injection well energy-saving optimization module is used for dividing wells into two types according to an injection pressure space after a system switching condition is met: for an adjustable parameter well, a layered injection allocation scheme is formulated by calculating a layer section energy consumption weight and combining an oil layer thickness so as to realize energy conservation; and for the parameter adjustment limited well, fracturing resistance reduction is conducted on the production well communicated with the parameter adjustment limited well, and collaborative optimization is achieved through injection-production linkage. According to the embodiment, the polymer flooding decision is optimized by quantifying the energy consumption, and energy conservation and consumption reduction are achieved on the premise that the oil displacement effect is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of energy-saving retrofitting technology, specifically to a polymer flooding monitoring system for the water-cut recovery period of three types of oil reservoirs. Background Technology

[0002] With the rapid development and widespread application of polymer flooding technology in Daqing Oilfield, the remaining reserves of Class I oil reservoirs are continuously decreasing. The target of polymer flooding is gradually shifting to Class III oil reservoirs. Compared to Class I reservoirs, Class III reservoirs have smaller effective thicknesses, lower permeability, and stronger interlayer and planar heterogeneity, making it impossible to directly apply the mature tracking and adjustment technologies used in Class I reservoirs. Polymer flooding can be divided into the initial stage of polymer injection, the water cut decline stage, the low water cut stage, the water cut recovery stage, and subsequent water flooding. Among these, the water cut recovery stage is the longest, accounts for a large proportion of stage oil production, and makes a significant contribution to the enhanced oil recovery rate of the block.

[0003] Existing comprehensive adjustment methods for the water-cut recovery phase of polymer flooding mainly include three technical means: first, sealing high-permeability layers through deep profile modification to slow down single-layer fluid inrush; second, combining pressure control and stratified water injection in injection wells to improve the injection profile; and third, using a combination of fracturing and pumping in production wells to utilize low-water-cut, difficult-to-access oil layers. However, this method is mainly based on Class I oil layers with better geological conditions. When applied to Class III oil layers with stronger heterogeneity and poorer physical properties, the system switching decision relies solely on reservoir response indicators such as water cut and fluid absorption profile, lacking quantitative consideration of the energy consumption of injection equipment. This leads to strong subjectivity in decision-making and results in inefficient and high-consumption injections. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a polymer flooding monitoring system for three types of oil reservoirs during the water cut recovery period. The specific technical solution adopted is as follows: This invention proposes a polymer flooding monitoring system for three types of oil reservoirs during the water cut recovery period, the system comprising: The adjustment system switching judgment module is used to measure the difference between the average oil production of all production wells in each preset cycle and the preset benchmark oil production, as well as the power consumption of the injection pump in the injection well, when injecting the preset first adjustment system into all injection wells, and evaluate the injection power efficiency index under each cycle; compare the injection power efficiency index under the previous preset number of cycles with the preset threshold to determine whether to switch the adjustment system of the injection well at the current moment. The injection well energy-saving optimization module is used to, when the switching conditions are met, statistically analyze the injection pressure space of all injection wells to classify all injection wells into adjustable parameter wells and parameter-limited wells; inject a preset second adjustment system into all adjustable parameter wells, and statistically analyze the injection pressure and injection flow rate of each segment in each adjustable parameter well to determine the energy consumption weight of each segment in each adjustable parameter well; based on the energy consumption weight, and statistically analyze the effective thickness of each segment in each adjustable parameter well, to plan the injection volume range of each segment in each adjustable parameter well; For wells with limited parameter adjustment, the perforation thickness of all production wells connected to these wells is statistically analyzed to formulate fracturing schemes for the production wells, which are then used for collaborative optimization of wells with limited parameter adjustment.

[0005] Preferably, the injection power efficiency index for each cycle is the ratio of the difference between the average oil production in each cycle and the preset benchmark oil production to the total power consumption of the injection pumps in all injection wells.

[0006] Preferably, the adjustment system for determining whether to switch injection wells at the current moment includes: If the injection efficiency index has continuously decreased for a preset number of cycles prior to the current moment and is always less than the preset threshold, then the adjustment system of the injection well will be switched at the current moment; otherwise, the adjustment system of the injection well will not be switched at the current moment.

[0007] Preferably, the preset threshold is a preset multiple of the initial peak value of the injection efficiency index after the preset first adjustment system is injected into the injection well.

[0008] Preferably, the division of all injection wells into adjustable parameter wells and parameter-restricted wells includes: Among all injection wells, those with injection pressure space greater than the preset pressure space threshold are denoted as adjustable parameter wells, and all other injection wells are denoted as parameter-restricted wells.

[0009] Preferably, the energy consumption weight of each segment in each adjustable parameter well is the normalized value of the product of the injection pressure and the injection flow rate of each segment.

[0010] Preferably, the planning method for the injection volume range of each layer in each adjustable parameter well is as follows: The energy consumption weight of each segment in each adjustable parameter well is compared with the preset energy consumption threshold to divide all segments in each adjustable parameter well into high-energy-consumption segments and low-energy-consumption segments; based on the effective thickness of the low-energy-consumption segments, the low-energy-consumption segments are further divided into thin segments and thick segments. Different injection intensity ranges are set for thin and thick sections selected in high-energy-consumption and low-energy-consumption sections. The result of multiplying the effective thickness of each section by the corresponding injection intensity range is used as the injection volume range for each section in each adjustable parameter well.

[0011] Preferably, the step of dividing all sections in each adjustable parameter well into high-energy-consumption sections and low-energy-consumption sections includes: In all the layers of each adjustable parameter well, the layers with energy consumption weight greater than the preset energy consumption threshold are designated as high-energy-consumption layers, and all the remaining layers are designated as low-energy-consumption layers.

[0012] Preferably, dividing the low-energy-consumption segment into a thin-layer segment and a thick-layer segment includes: Low-energy-consumption segments with an effective thickness greater than a preset effective thickness threshold are designated as thick segments, and all remaining low-energy-consumption segments are designated as thin segments.

[0013] Preferably, the process of formulating a fracturing plan for the produced well includes: If the perforation thickness of the production well connected to the current parameter-controlled well is greater than the preset perforation thickness threshold, then multi-fracture fracturing is used for the production well; otherwise, conventional fracturing is used.

[0014] The present invention has the following beneficial effects: This application, through an adjustment system switching judgment module, monitors oil production and pump power consumption in real time during the injection of the first adjustment system, and calculates the injection power efficiency index to quantify energy utilization efficiency. When the index continuously decreases and falls below 80% of its initial peak value, the polymer flooding monitoring system automatically triggers system switching, thereby accurately avoiding inefficient and high-consumption injections, which helps to save energy and reduce consumption while ensuring oil displacement effect. Furthermore, after the switching conditions are met, the injection well energy-saving optimization module of this application first divides the well into adjustable parameter wells and parameter-limited wells based on the injection pressure space. For adjustable parameter wells, a refined layered injection scheme is formulated by calculating the energy consumption weight of the layer and combining it with the effective thickness to reduce energy consumption by controlling high and supplementing low. For parameter-limited wells with insufficient pressure space, differentiated fracturing is then implemented on the production wells connected to them to reduce seepage resistance and achieve coordinated energy saving, thereby realizing the linkage optimization of the injection end and the production end, and achieving energy saving and consumption reduction while ensuring oil displacement effect. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A block diagram of a polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs provided in one embodiment of this application; Figure 2 This is a comprehensive comparison chart of the system's anti-clogging effects provided in one embodiment of this application; Figure 3 This is a flowchart illustrating the process of dividing adjustable-parameter wells and parameter-restricted wells according to one embodiment of this application. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] 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 invention pertains.

[0019] The following description, in conjunction with the accompanying drawings, details the specific scheme of a polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs provided by the present invention.

[0020] Please see Figure 1 The diagram shows a block diagram of a polymer flooding monitoring system for three types of oil reservoirs during the water cut recovery period, provided by an embodiment of the present invention. The system includes: an adjustment system switching judgment module 101 and an injection well energy saving optimization module 102.

[0021] The adjustment system switching judgment module 101 is used to measure the difference between the average oil production of each production well in each preset cycle and the preset benchmark oil production, as well as the power consumption of the injection pump in the injection well, when injecting the preset first adjustment system into all injection wells, and to evaluate the injection power efficiency index of each production well in each cycle; and to compare the injection power efficiency index of each production well in the previous preset number of cycles with the preset threshold to determine whether to switch the adjustment system of the injection well at the current moment.

[0022] An injection pump power meter is deployed at the injection wellhead, and a flow meter and water cut meter are deployed at the wellhead of the production well. In all injection wells, a preset first adjustment system is injected first. In this embodiment, the preset first adjustment system is 19 million polymer. This is because the development of the three types of oil layers is mainly characterized by permeability greater than 100mD and less than 200mD. There are few oil layers with permeability greater than 200mD. The system suitable for injection is medium molecular weight polymer. Before the low water cut period, the injection volume of polymer is high in oil layers with permeability greater than 100mD and less than 200mD, and low in permeability greater than 200mD, so it is not fully utilized. Since the viscosity of medium molecular weight polymer is relatively low, its ability to adjust high permeability is poor and its ability to expand the swept volume is low. Therefore, in order to improve the swept volume of high permeability layers, a breakthrough layer plugging system of 19 million polymer that matches the high permeability layers is injected first.

[0023] When injecting the preset first adjustment system into all injection wells, the production volume and water cut of each production well are collected using flow meters and water cut meters deployed in the production wells. The data acquisition frequency is set to f. The collected raw data is processed, and data exceeding 3 are discarded. For outlier data within the range, the empty spaces in the removed outlier data are replaced by the average of the corresponding data at the preceding and following times. Simultaneously, the power consumption of the injection pump in each injection well is collected within each cycle. Furthermore, based on the average distribution of production volume and water cut of each production well at all sampling times within each cycle, the average oil production of each production well in each cycle is calculated. Specifically: First, it should be noted that in this embodiment, the sampling frequency f for the liquid production and water content is set to 1 hour, the length of each cycle is 30 days, and each cycle is divided into multiple time periods, each time period being 1 day in length. In actual application, the implementer can also set the above data according to the specific situation. In this embodiment, the following calculations all use the above sampling frequency, cycle length, and time period length.

[0024] In this embodiment, the expression for the oil production of each producing well at any time period within each cycle is as follows: In the formula, This represents the oil production of well i under time period u within period T, expressed in tons per time period, which in this embodiment is tons per day, t / d. This represents the total fluid production of well i under time period u within period T, expressed in cubic meters (m³). This represents the average water cut of well i produced under time period u within period T, expressed as a percentage (%). This indicates the density of crude oil, expressed in tons per cubic meter (t / m³).

[0025] Furthermore, the sum of the oil production of each producing well in all time periods within each cycle is recorded as the total oil production of each producing well in each cycle. The average of the total oil production of all producing wells in each cycle is taken as the average oil production in each cycle, with the unit being tons / cycle, which is tons / month in this embodiment.

[0026] Simultaneously, a three-dimensional reservoir model is established using geological and logging data. The oil production in each cycle is predicted using the three-dimensional reservoir model, and this oil production is the benchmark oil production. Furthermore, the difference between the average oil production in each cycle and the preset benchmark oil production is divided by the total power consumption of the injection pumps in all injection wells, and the result is used as the injection power efficiency index for each cycle, with the unit being tons / kilowatt-hour. The physical meaning of the injection power efficiency index is the mass of crude oil that can be extracted from the formation for every 1 kWh of electrical energy consumed. The larger the injection power efficiency index, the higher the energy utilization efficiency of the injection system, directly reflecting the energy utilization efficiency.

[0027] For the plugging system of the inrush layer, the affected volume expands rapidly in the early stage of water cut recovery, so the increase in oil production is relatively large. However, as the high-permeability layer is gradually plugged, the marginal benefit of continued injection decreases, resulting in a slowdown or even a decrease in the growth rate of oil production. At the same time, the high viscosity polymer causes the injection pressure to rise continuously, and the power consumption of the injection pump increases. The combination of these two factors causes the injection power efficiency index to decline continuously.

[0028] Furthermore, the injection efficiency index under a preset number of consecutive cycles prior to the current moment is compared with a preset threshold to determine whether to switch the adjustment system of the injection well at the current moment. Specifically: if the injection efficiency index under a preset number of consecutive cycles prior to the current moment continuously decreases and is always less than the preset threshold, then the adjustment system of the injection well is switched at the current moment; otherwise, the adjustment system of the injection well is not switched at the current moment. The preset threshold is a preset value multiple of the initial peak value of the injection efficiency index after the preset first adjustment system is injected into the injection well, where the preset value is 0.8.

[0029] It should be noted that the injection efficiency index reaches a peak at the initial stage of injecting a conditioning system. This peak represents the optimal energy efficiency of the current oil displacement system. As the high-permeability layer is gradually blocked, the production increase effect of continuing to inject the same system will begin to decline. Meanwhile, the injection of high-viscosity polymers leads to a continuous increase in the energy consumption of the injection pump. Both factors together cause the energy efficiency index to continuously decrease. When the index drops to 0.8 times the initial peak value of the injection efficiency index, it means that the oil production return per unit of electricity has significantly decreased by 20%, indicating that the current system has entered an inefficient cycle of high consumption and low efficiency. Therefore, the preset threshold is set to a preset value multiple of the initial peak value of the injection efficiency index to ensure that the conditioning system can be switched in time before energy waste becomes serious, thereby achieving the optimal balance between energy saving and efficiency improvement.

[0030] It should be noted that the preset quantity is set manually. In this embodiment, the preset quantity is 3. In actual application, the implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0031] To facilitate understanding of the above content, a specific data analysis example is provided below: Injection was carried out in the early stage of water cut recovery, with an average injection concentration of 1600 mg / L and an injection rate of 0.20 PV / a (the percentage of polymer volume injected per year to the porosity of the oil layer). The cumulative injected porosity was 0.18 PV during the switching process.

[0032] After injecting 19 million units of polymer, the injection pressure in the study area rose steadily. The polymer mainly migrated in oil layers with permeability greater than 200 mD. After the system was adjusted and injection was completed, the overall injection pressure increased by 0.8 MPa. The relative fluid absorption of oil layers with relatively good fluid absorption decreased by 15.35 percentage points, and the proportion of fluid absorption thickness in oil layers with permeability greater than 200 mD increased by 14.03 percentage points. The rate of water cut recovery in the produced wells was alleviated, and the polymer concentration decreased. Compared with the initial stage of water cut recovery, the rate of water cut recovery slowed from 0.64 percentage points / month to 0.11 percentage points / month, and the polymer concentration decreased by 83 mg / L. As shown in the comprehensive comparison chart of the system's plugging effect provided in this embodiment, that is... Figure 2 As shown.

[0033] Thus, this embodiment adjusts the system switching judgment module to monitor the oil production and pump power consumption in real time when injecting the first adjustment system, and calculates the injection power efficiency index to quantify energy utilization efficiency; when the index continuously decreases and falls below 80% of its initial peak value, the polymer flooding monitoring system automatically triggers system switching, thereby accurately avoiding high-consumption and low-efficiency ineffective injection, which helps to save energy and reduce consumption while ensuring the oil displacement effect.

[0034] The injection well energy-saving optimization module 102 is used to, when the switching conditions are met, statistically analyze the injection pressure space of all injection wells to classify all injection wells into adjustable-parameter wells and adjustable-parameter-restricted wells; inject a preset second adjustment system into all adjustable-parameter wells, and statistically analyze the injection pressure and injection flow rate of each segment in each adjustable-parameter well to determine the energy consumption weight of each segment in each adjustable-parameter well; based on the energy consumption weight, and statistically analyze the effective thickness of each segment in each adjustable-parameter well to plan the injection volume range of each segment in each adjustable-parameter well; for adjustable-parameter-restricted wells, statistically analyze the perforation thickness of all production wells connected to the adjustable-parameter-restricted wells to formulate fracturing schemes for the production wells, which are used for collaborative optimization of adjustable-parameter-restricted wells.

[0035] After the switching conditions are met, the injection pressure space of each injection well is calculated. Among all injection wells, the injection wells with an injection pressure space greater than the preset pressure space threshold are recorded as adjustable parameter wells, and all remaining injection wells are recorded as parameter-limited wells. Here, adjustable parameter wells refer to injection wells with sufficient pressure space, and parameter-limited wells refer to injection wells with insufficient pressure space.

[0036] The injection pressure space is the absolute difference between the current injection pressure of each injection well and the pressure that can be achieved in engineering.

[0037] Preferably, the flowchart of the process for classifying adjustable parameter wells and parameter-restricted wells provided in this embodiment is as follows: Figure 3 As shown.

[0038] It should be noted that the preset pressure space threshold is set manually. In this embodiment, the preset pressure space threshold is set to 2 MPa. Choosing 2 MPa as the pressure space threshold for whether to implement stratified modification of the injection well is a key decision parameter based on the balance between engineering feasibility and economic benefits. The reason for setting the value to 2 MPa in this embodiment is to ensure that after subdividing the layers and implementing differentiated injection, each layer has sufficient pressure margin to overcome additional throttling losses and avoid some layers being unable to be injected due to insufficient pressure. This ensures that the stratified adjustment measures can be successfully implemented and achieve the expected results. At the same time, this threshold also avoids unnecessary cost waste caused by forcibly modifying wells with too small a pressure space.

[0039] Layered pressure sensors (storage type, installed on each layered water distributor, range 0.35MPa, accuracy ±0.15MPa) and layered flow meters (turbine type, range 0.150m³ / d, accuracy ±2%) are deployed at the injection wellhead. Injection pressure and flow rate at the injection wellhead are collected every 10 minutes. The raw data are preprocessed to remove outliers exceeding 3σ, and gaps in the outlier data are filled with the average of the values ​​of the two adjacent time points.

[0040] Stratification refers to the physical separation of three types of oil layers with significant differences in effective thickness and permeability into different independent injection segments in an injection well using downhole packers. Each segment is equipped with an independent injection channel controlled by an injector, thereby achieving differentiated injection. Therefore, a preset second adjustment system is injected into all adjustable parameter wells. The injection pressure and flow rate of each segment in each adjustable parameter well are statistically analyzed to determine the energy consumption weight of each segment in each adjustable parameter well. Based on the energy consumption weight, and by statistically analyzing the effective thickness of each segment in each adjustable parameter well, the injection volume range of each low-energy-consumption segment in each adjustable parameter well is planned. Specifically: First, the normalized value of the product of injection pressure and injection flow rate in each layer of each adjustable parameter well is used as the energy consumption weight of each layer in each adjustable parameter well. The physical meaning of the energy consumption weight is the proportion of hydraulic power consumed to the total hydraulic power, which is used to identify high energy consumption layers.

[0041] It should be further noted that the second adjustment system is preset to a polymer with a molecular weight of 12 million; and in this embodiment, the product of the injection pressure and injection flow rate of each segment in each adjustable parameter well is divided by the sum of the product of the injection pressure and injection flow rate of all segments, and the result is used as the normalized value of the product of the injection pressure and injection flow rate of each segment in each adjustable parameter well; in actual application, as other implementation methods, implementers may also adopt other normalization methods such as the maximum and minimum value normalization method according to specific circumstances. This embodiment does not impose any special restrictions on the selection of normalization methods.

[0042] The process of obtaining the effective thickness is a well-known technique and will not be described in detail here.

[0043] Furthermore, the effective thickness of each segment in each injection well is obtained. The energy consumption weight of each segment in each adjustable parameter well is compared with a preset energy consumption threshold to divide all segments in each adjustable parameter well into high-energy-consumption segments and low-energy-consumption segments. Based on the effective thickness of the low-energy-consumption segments, the low-energy-consumption segments are further divided into thin segments and thick segments. Specifically: In all the layers of each adjustable parameter well, the layers with energy consumption weight greater than the preset energy consumption threshold are designated as high-energy-consumption layers, and all the remaining layers are designated as low-energy-consumption layers; the low-energy-consumption layers with effective thickness greater than the preset effective thickness threshold are designated as thick layers, and all the remaining low-energy-consumption layers are designated as thin layers.

[0044] High-energy-consuming layers typically correspond to oil reservoirs with high permeability. Injecting high-molecular-weight polymers is intended to seal these high-permeability layers, requiring higher injection pressures to maintain the sealing effect. Although these layers represent a smaller percentage of the total, the high injection pressure and flow rate consume a significant portion of the hydraulic power. After switching systems, the high-energy-consuming layers have already been sealed by the previously injected regulating and plugging system; continuing high-intensity injection is ineffective and energy-intensive. Therefore, the injection intensity should be reduced, and these layers should be used as control layers. Low-energy-consuming layers correspond to reinforcement layers; they have a smaller energy consumption percentage but larger reserves. Therefore, the injection intensity should be increased to achieve an optimized energy configuration that controls high-permeability layers and compensates for low-permeability layers.

[0045] It should be further explained that in this embodiment, the preset energy consumption threshold is 0.15, the preset effective thickness threshold is 2m, and the energy consumption weight threshold is 0.15. This is an engineering experience value verified by field data. It can effectively identify those energy-intensive layers that consume disproportionate energy due to high pressure and high flow, even though they have few layers. At the same time, it avoids misjudging normally consuming layers as control layers, thus achieving a balance between energy saving and ensuring basic injection. The effective thickness threshold of 2m reflects the geological characteristics of the three types of oil layers. Thin layers less than 2m have limited reserves and require high-intensity injection to quickly establish effective displacement. Thick layers greater than or equal to 2m have large reserves, and if injected at the same high intensity, the displacement fluid may break through prematurely and form ineffective circulation. Therefore, a gentler injection strategy must be adopted.

[0046] For high-energy-consuming sections, i.e., sections already blocked by the first plugging system, continued high-intensity injection is ineffective and energy-consuming; the injection intensity should be reduced to maintain the plugging state. For low-energy-consuming sections, i.e., reinforcement layers that have not yet been fully utilized, the injection intensity needs to be increased to establish an effective displacement pressure gradient. However, reinforcement layers are divided into thin and thick layers. Thin layers have small reserves and require high-intensity injection to quickly establish displacement pressure; thick layers have large reserves and can adopt a lower-intensity, long-term injection strategy to avoid excessively rapid pressure rise leading to a breakthrough. In this embodiment, different injection intensity ranges are set for selected thin and thick sections in high-energy-consuming and low-energy-consuming sections. The effective thickness of each section is multiplied by the corresponding injection intensity range, and the result is used as the injection volume range for each section in each adjustable parameter well. Specifically: The injection volume range of the intermediate layer q in the adjustable parameter well p The expression is: ; , , These represent the preset first injection intensity range, the preset second injection intensity range, and the preset third injection intensity range, respectively. This indicates the effective thickness of the q section in the adjustable parameter well p; , , These represent the sets of all low-energy-consumption layers in the adjustable parameter well p with an effective thickness less than a preset thickness threshold, the sets of all low-energy-consumption layers in the adjustable parameter well p with an effective thickness greater than or equal to a preset thickness threshold, and the sets of all high-energy-consumption layers in the adjustable parameter well p, respectively.

[0047] It should be noted that in this embodiment, the preset first injection intensity range is 5~15 m³ / (d·m), the preset second injection intensity range is 5~8 m³ / (d·m), and the preset third injection intensity range is 2~4 m³ / (d·m).

[0048] The tiered refueling scheme based on energy consumption weight provided in this embodiment is shown in Table 1: Table 1

[0049] Furthermore, for wells with restricted parameter adjustment, the perforation thickness of all production wells connected to these restricted wells is statistically analyzed to formulate fracturing schemes for the production wells. This is used for collaborative optimization of wells with restricted parameter adjustment. Specifically: The perforation thickness of the produced well is obtained. If the perforation thickness of the produced well connected to the current parameter-adjusted well is greater than the preset perforation thickness threshold, multi-fracture fracturing is used on the produced well with a fracture radius of 30~40m. Otherwise, ordinary fracturing is used with a fracture radius of 25~35m. The comparison table of the fracturing measures and production effects of the produced well provided in this embodiment is shown in Table 2.

[0050] It should be noted that the preset penetration thickness threshold in this embodiment is 1.5m. The reason for choosing 1.5m is that this value is an economic inflection point verified by field practice, which realizes differentiated, economical and efficient transformation of oil layers of different thicknesses.

[0051] Table 2

[0052] At this point, after the switching conditions are met, the energy-saving optimization module for injection wells first divides the wells into adjustable-parameter wells and adjustable-parameter-restricted wells based on the injection pressure space. For adjustable-parameter wells, a refined layered injection scheme is formulated by calculating the energy consumption weight of the layer and combining it with the effective thickness to reduce energy consumption by controlling the high and supplementing the low. For adjustable-parameter-restricted wells with insufficient pressure space, differentiated fracturing is then implemented on the production wells connected to them to reduce seepage resistance and achieve energy saving. This realizes the linkage optimization of the injection end and the production end, achieving energy saving and consumption reduction while ensuring the oil displacement effect.

[0053] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0054] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs, characterized in that, The system includes: The adjustment system switching judgment module is used to measure the difference between the average oil production of all production wells in each preset cycle and the preset benchmark oil production, as well as the power consumption of the injection pump in the injection well, when injecting the preset first adjustment system into all injection wells, and evaluate the injection power efficiency index under each cycle; compare the injection power efficiency index under the previous preset number of cycles with the preset threshold to determine whether to switch the adjustment system of the injection well at the current moment. The injection well energy-saving optimization module is used to, when the switching conditions are met, statistically analyze the injection pressure space of all injection wells to classify all injection wells into adjustable parameter wells and parameter-limited wells; inject a preset second adjustment system into all adjustable parameter wells, and statistically analyze the injection pressure and injection flow rate of each segment in each adjustable parameter well to determine the energy consumption weight of each segment in each adjustable parameter well; based on the energy consumption weight, and statistically analyze the effective thickness of each segment in each adjustable parameter well, to plan the injection volume range of each segment in each adjustable parameter well; For wells with limited parameter adjustment, the perforation thickness of all production wells connected to these wells is statistically analyzed to formulate fracturing schemes for the production wells, which are then used for collaborative optimization of wells with limited parameter adjustment.

2. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The injection power efficiency index for each cycle is the ratio of the difference between the average oil production in each cycle and the preset benchmark oil production to the total power consumption of the injection pumps in all injection wells.

3. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The adjustment system for determining whether to switch injection wells at the current moment includes: If the injection efficiency index has continuously decreased for a preset number of cycles prior to the current moment and is always less than the preset threshold, then the adjustment system of the injection well will be switched at the current moment; otherwise, the adjustment system of the injection well will not be switched at the current moment.

4. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 3, characterized in that, The preset threshold is a preset multiple of the initial peak value of the injection efficiency index after the preset first adjustment system is injected into the injection well.

5. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The classification of all injection wells into adjustable-parameter wells and parameter-restricted wells includes: Among all injection wells, those with injection pressure space greater than the preset pressure space threshold are denoted as adjustable parameter wells, and all other injection wells are denoted as parameter-restricted wells.

6. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The energy consumption weight of each segment in each adjustable parameter well is the normalized value of the product of the injection pressure and the injection flow rate of each segment.

7. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The planning method for the injection volume range of each section in each adjustable parameter well is as follows: The energy consumption weight of each segment in each adjustable parameter well is compared with the preset energy consumption threshold to divide all segments in each adjustable parameter well into high-energy-consumption segments and low-energy-consumption segments; based on the effective thickness of the low-energy-consumption segments, the low-energy-consumption segments are further divided into thin segments and thick segments. Different injection intensity ranges are set for thin and thick sections selected in high-energy-consumption and low-energy-consumption sections. The result of multiplying the effective thickness of each section by the corresponding injection intensity range is used as the injection volume range for each section in each adjustable parameter well.

8. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 7, characterized in that, The method of dividing all sections in each adjustable parameter well into high-energy-consumption sections and low-energy-consumption sections includes: In all the layers of each adjustable parameter well, the layers with energy consumption weight greater than the preset energy consumption threshold are designated as high-energy-consumption layers, and all the remaining layers are designated as low-energy-consumption layers.

9. The polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 7, characterized in that, The division of the low-energy-consumption segment into thin-layer segments and thick-layer segments includes: Low-energy-consumption segments with an effective thickness greater than a preset effective thickness threshold are designated as thick segments, and all remaining low-energy-consumption segments are designated as thin segments.

10. A polymer flooding monitoring system for the water cut recovery period of three types of oil reservoirs according to claim 1, characterized in that, The formulation of a fracturing plan for the production well includes: If the perforation thickness of the production well connected to the current parameter-controlled well is greater than the preset perforation thickness threshold, then multi-fracture fracturing is used for the production well; otherwise, conventional fracturing is used.

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