Establishment and use method of injection-production well adjustment chart for three types of oil reservoirs in polymer flooding recovery rising period

Abstract

A method for establishing tracking and adjustment charts for injection and production wells during the recovery phase of polymer flooding in Class III oil reservoirs addresses the issue that existing polymer flooding tracking and adjustment technologies for Class I oil reservoirs are unsuitable for Class III reservoirs. The method includes establishing adjustment charts for injection and production wells. The injection well adjustment chart is established by using the injection well's fluid absorption thickness as the length of a rectangle (40-100 mm) and the maximum relative fluid absorption of a single layer as the width of a rectangle (0-100 mm). The chart is divided into four zones: a fracturing zone, a subdivision adjustment zone, a enrichment zone, and a rational zone. The production well adjustment chart is established by using the production well's stage of production as the length of a rectangle (0-35 mm) and the water cut as the width of a rectangle (60-100 mm). The chart also includes four zones: a fracturing zone, a rational zone, a enrichment zone, and a fracturing and water shut-off zone.

Description

Technical Field

[0001] This invention relates to the field of tertiary oil recovery technology for three types of oil reservoirs, and in particular to a method for establishing and using an adjustment chart for injection-production wells during the polymer flooding recovery period in three types of oil reservoirs. Background Technology

[0002] According to the evolution of the polymer flooding well network in oilfields, polymer flooding is first carried out in Class I oil layers, and then in other oil layers. With the continuous promotion of industrialization of Class I oil layers, polymer flooding tracking and adjustment technology has been continuously improved and optimized, and a matching adjustment technology for polymer flooding suitable for Class I oil layers has been formed. At the same time, the remaining reserves of Class I oil layers are decreasing year by year. In order to achieve production succession, the future target of polymer flooding will be transformed from Class I oil layers to Class III oil layers. For example, in the polymer flooding well network of Daqing Oilfield, there are significant differences between the Class I and Class III oil layers from a sedimentary perspective. First, the sedimentary environments are significantly different. Class I oil layers are mainly composed of deltaic distributary plain facies sand bodies and deltaic front facies sand bodies. In plan view, channel sands are widely developed, with high drilling rate, large effective thickness, high permeability, and relatively large pore throat radius. Suitable injection systems are high-polymer, ultra-high-polymer, and high-polymer followed by salt-resistant injection system combinations. Class III oil layers are composed of deltaic front facies sand bodies and extra-deltaic front facies sand bodies. In plan view, channel sands are narrow and have a low drilling rate, while inter-channel sands and extra-surface sands are widely developed. The continuity of sand bodies in plan view is relatively poor, and the pore throat diameter is relatively small. There are many oil layers, but the effective thickness is small, the permeability is low, and the interlayer differences are significant. Field tests of polymer flooding in Class III oil layers have shown that Class III oil layers are suitable for injection of medium- and low-polymer polymer systems.

[0003] Because the sedimentary environment, reservoir development, and injection system of Class I and Class III oil reservoirs are significantly different, the relatively complete polymer flooding tracking and adjustment technology obtained for Class I oil reservoirs is not suitable for tracking and adjustment during the polymer flooding stage of Class III oil reservoirs. Therefore, it cannot guide the tracking and adjustment of injection and production wells during the water-cut recovery period. Summary of the Invention

[0004] This invention addresses the problem that existing polymer flooding tracking and adjustment techniques for Class I oil reservoirs are unsuitable for Class III oil reservoirs, thus hindering the tracking and adjustment of injection-production wells during the water-cut recovery period. It provides a method for establishing a tracking and adjustment chart for injection-production wells during the water-cut recovery period in Class III oil reservoirs. This method can guide the tracking and adjustment of polymer flooding in Class III oil reservoirs during the water-cut recovery period, effectively improving the polymer flooding development effect. This invention also provides a method for using the tracking and adjustment chart for injection-production wells during the water-cut recovery period in Class III oil reservoirs.

[0005] The present invention solves its problems through the following technical solution:

[0006] The first aspect of this invention provides a method for establishing a tracking adjustment chart for injection and production wells during the water-cut recovery period of polymer flooding in three types of oil reservoirs, including a method for establishing an adjustment chart for injection wells and a method for establishing an adjustment chart for production wells;

[0007] The method for establishing the injection well adjustment chart includes:

[0008] A rectangular diagram is constructed with the length of the rectangle representing the proportion of the fluid absorption thickness of the injection well, ranging from 40 to 100, in percentage; and the width of the rectangle representing the maximum relative fluid absorption of a single layer of the injection well, ranging from 0 to 100, in percentage.

[0009] The injection well adjustment chart is divided into four areas: fracturing zone, subdivision adjustment zone, enrichment zone, and rational zone.

[0010] The method for establishing the production well adjustment chart includes:

[0011] A rectangular diagram is constructed with the production level of the producing well stage as the length of the rectangle, ranging from 0 to 35%; and the water content of the producing well as the width of the rectangle, ranging from 60 to 100%;

[0012] The production well adjustment chart has four zones: fracturing zone, rational zone, concentration zone, and fracturing and water shut-off zone.

[0013] Furthermore, for the injection well adjustment chart: the rectangular area formed by the long side ranging from 40% to 55% and the wide side ranging from 0% to 70% is the fracturing zone;

[0014] The rectangular area formed by the long side ranging from 40% to 100% and the wide side ranging from 70% to 100% is the subdivision adjustment area;

[0015] The rectangular area formed by a long side range of 55%-100% and a wide side range of 50%-70% is the concentration zone.

[0016] A rectangular area formed by a long side ranging from 55% to 100% and a wide side ranging from 0% to 50% is considered a reasonable range.

[0017] Furthermore, for the production well adjustment chart: the rectangular area formed by the long side ranging from 0% to 10% and the wide side ranging from 60% to 100% is the fracturing zone;

[0018] A rectangular area formed by a long side ranging from 10% to 35% and a wide side ranging from 60% to 90% is considered a reasonable area.

[0019] The rectangular area formed by a long side range of 10%-20% and a wide side range of 90%-100% is the concentration zone;

[0020] A rectangular area formed by a long side range of 20%-35% and a wide side range of 90%-100% is the fracturing and water shut-off zone.

[0021] The second aspect of this invention provides a method for using an injection-production well tracking adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs: the method includes selecting relevant areas for corresponding adjustments based on the constructed injection well adjustment chart and production well adjustment chart, according to relevant adjustment parameters.

[0022] Furthermore, based on the constructed injection well adjustment map, and according to two parameters—the injection well fluid absorption thickness ratio and the maximum relative fluid absorption of a single layer—relevant areas are selected for corresponding adjustments. Specific methods include:

[0023] The injection wells with a fluid absorption thickness ratio ranging from 40% to 55% and a maximum relative fluid absorption of 0% to 70% per layer are located in a rectangular fracturing zone; fracturing is performed on the injection wells located within the fracturing zone;

[0024] Wells with a fluid absorption thickness ratio ranging from 40% to 100% and a maximum relative fluid absorption of 70% to 100% in a single layer are located in a subdivided adjustment zone within a rectangular area; injection wells located within this subdivided adjustment zone are further subdivided and adjusted.

[0025] Wells with a liquid absorption thickness ratio ranging from 55% to 100% and a maximum relative liquid absorption of 50% to 70% in a single layer are located in the concentration zone of a rectangular area; the injection concentration of injection wells located in the concentration zone is increased.

[0026] Wells with a liquid absorption thickness ratio of 55%-100% and a maximum relative liquid absorption of 0%-50% per layer are within the reasonable zone of the rectangular area. For wells within the reasonable zone, maintain the current injection parameters and monitor the well's dynamics. When the well is in other zones, make corresponding adjustments.

[0027] Furthermore, fracturing is performed on injection wells located within the fracturing zone. Specifically, for wells with a cumulative fluid intake exceeding 5 times, fracturing is not performed; for oil layers with a cumulative fluid intake less than 5 times, fracturing is performed. Different fracturing methods are selected based on the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, and conventional fracturing is used for oil layers with a perforation thickness less than 1.5m.

[0028] For injection wells located within the subdivided adjustment zone, the specific method is as follows: When the interlayer thickness exceeds 1.5m, each oil layer is treated as a separate injection segment, and different injection intensities are designed based on the cumulative number of times the injection segment has absorbed fluid: when the cumulative number of times the fluid has absorbed fluid is greater than 5, the layer is a control layer, and the injection volume is reduced by 30%; when the cumulative number of times the fluid has absorbed fluid is greater than 1 but less than 5, the layer is a reinforcement layer, and the injection volume is increased by 40%; for non-fluid-absorbing layers, when the oil layer thickness is ≥2m, the injection volume is designed to be 10m³. 3 When the oil layer thickness is less than 2m, the injection volume is designed to be 5m³. 3 ;

[0029] The injection concentration of injection wells located in the concentration enhancement zone is increased by the following method: when the liquid absorption thickness ratio is ≥90%, the injection concentration is increased by 300 mg / L; when the liquid absorption thickness ratio is ≥70% and less than 90%, the injection concentration is increased by 400 mg / L; and when the liquid absorption thickness ratio is <70%, the injection concentration is increased by 500 mg / L.

[0030] Furthermore, the formula for the liquid absorption thickness ratio of the injection well is:

[0031] H = h in / h oe (1)

[0032] in:

[0033] H - Oil layer absorption thickness percentage, %;

[0034] h in - Liquid absorption thickness, in meters;

[0035] h oe - Effective thickness, m.

[0036] Furthermore, based on the constructed production well adjustment map, and according to two parameters—the production level of the production well stage and the water cut of the well—relevant areas are selected for corresponding adjustments. Specific methods include:

[0037] Wells with a production rate of 0%-10% and a water cut of 60%-100% are located in a rectangular fracturing zone; fracturing is performed on the production wells located within the fracturing zone.

[0038] Wells with a production rate of 10%-35% and a water cut of 60%-90% are within the reasonable area of ​​the rectangular region. For wells within the reasonable area, dynamic changes should be monitored, and adjustments should be made promptly according to the adjustment chart when they are in other areas.

[0039] Wells with a production rate of 10%-20% and a water cut of 90%-100% are located in a rectangular enrichment zone; the injection concentration of injection wells connected to production wells within the enrichment zone is increased.

[0040] Wells with a production rate of 20%-35% and a water cut of 90%-100% are located in a rectangular fracturing and water shut-off zone. For wells located in the fracturing and water shut-off zone, fracturing and water shut-off are performed, with fracturing of poorly functioning oil layers and water shut-off of high-water-cut layers.

[0041] Furthermore, the production wells located within the fracturing zone are subjected to fracturing. Specifically, the following methods are employed: oil layers with a cumulative fluid intake exceeding 5 times in connected injection wells are not fracturing, while oil layers with a cumulative fluid intake less than 5 times in connected injection wells are fracturing; different fracturing methods are selected based on the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, while conventional fracturing is used for oil layers with a perforation thickness less than 1.5m.

[0042] The injection concentration of the injection well connected to the production well in the enrichment zone is increased. Specifically, the injection concentration is increased by 500 mg / L when the stage recovery rate is ≥19% and the water content is ≤95%; when the stage recovery rate is ≥19% and the water content is >95%, the injection concentration is increased by 200 mg / L; when the stage recovery rate is ≥16% and less than 19%, the injection concentration is increased by 400 mg / L; and when the stage recovery rate is less than 16%, the injection concentration is increased by 600 mg / L.

[0043] Furthermore, for the produced wells located in the fracturing and water-stopping zone, fracturing and water-stopping are performed. Specifically, for oil layers with poor fracturing activity, water-stopping is performed on high-water-cut layers. The specific methods are as follows: fracturing is performed on oil layers with a water cut below 95% and a stage recovery rate of less than 15%; multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m; conventional fracturing is used for oil layers with a perforation thickness less than 1.5m; and water-stopping is performed on oil layers with a water cut above 95% and a stage recovery rate above 15%.

[0044] The adjustment chart for injection and production wells during the recovery period of polymer flooding in the three types of oil reservoirs of this invention can be directly applied to the water-cut recovery period of polymer flooding in the three types of oil reservoirs.

[0045] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0046] Given the significant differences between Class III and Class I oil reservoirs, the mature tracking and adjustment techniques for Class I reservoirs cannot be directly applied. Therefore, it is necessary to study a tracking and adjustment method for injection-production wells suitable for the water-cut recovery stage of Class III oil reservoirs to ensure better polymer flooding development results. An adjustment chart for injection-production wells during the water-cut recovery stage of Class III oil reservoirs was established to guide the tracking and adjustment of polymer flooding in Class III oil reservoirs during the water-cut recovery stage, effectively improving the polymer flooding development effect.

[0047] This invention is based on field tests in three types of oil reservoirs. Under the condition of injecting polymer-modified water to prepare a wastewater dilution system, the diagram of this invention is used to guide the tracking and adjustment of injection and production wells during the water-cut recovery period. The application results show that by timely tracking and adjustment of injection and production wells, the active thickness of the oil reservoir in the study area is significantly improved, the water-cut recovery rate of the production well is effectively controlled, and a good polymer flooding development effect is achieved. The injection and production well diagram of this invention can be directly applied in the water-cut recovery period of polymer flooding in three types of oil reservoirs.

[0048] This invention has been applied in the field test area of ​​the Class III oil reservoir in Zone X. Based on the adjustment of injection and production wells, a total of 6 wells were enriched, 2 wells were fractured, and 10 wells were finely adjusted during the water cut recovery period; 3 wells were fractured in the production wells, 7 wells were enriched in the connected injection wells, and 3 wells were fractured to shut off water. After comprehensive adjustment, the rate of water cut increase was effectively controlled, slowing down from 0.55 percentage points / month in the early stage of water cut recovery to 0.08 percentage points / month. Moreover, the water cut in the well area was 3.28 percentage points lower than the numerical model prediction, and the enhanced oil recovery rate was 2.06 percentage points higher than the numerical model prediction, achieving good polymer flooding development results. Attached Figure Description

[0049] Figure 1 An injection well adjustment diagram established for this invention;

[0050] Figure 2 The production well adjustment chart established for this invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0052] like Figure 1 , Figure 2 As shown, a method for establishing an adjustment chart for injection-production wells during the water-cut recovery period of polymer flooding in three types of oil reservoirs includes the following steps:

[0053] This includes methods for establishing adjustment charts for injection wells and production wells;

[0054] (1) Method for establishing the injection well adjustment chart;

[0055] like Figure 1As shown, a rectangular chart is formed with the length of the rectangle representing the proportion of the fluid absorption thickness of the injection well, ranging from 40 to 100 (in percentage points). The width of the rectangle represents the maximum relative fluid absorption of a single layer of the injection well, ranging from 0 to 100 (in percentage points). The chart is divided into four regions:

[0056] The rectangular area formed by the long side ranging from 40% to 55% and the wide side ranging from 0% to 70% is the fracturing zone, and the injection wells located in this zone are subjected to fracturing.

[0057] A rectangular area with a long side range of 40%-100% and a wide side range of 70%-100% is designated as a subdivision adjustment zone, where injection wells within this zone are subdivided and adjusted.

[0058] A rectangular area with a long side range of 55%-100% and a wide side range of 50%-70% is the concentration zone, and the injection concentration of injection wells located in this zone is increased.

[0059] A rectangular area with a long side range of 55%-100% and a wide side range of 0%-50% is considered a reasonable zone. Injection wells located within this zone should maintain their current injection parameters.

[0060] (2) Method for establishing adjustment charts for production wells;

[0061] like Figure 2 As shown, a rectangular chart is formed with the production level of the producing well stage as the length of the rectangle, ranging from 0-35% (in percentage), and the water content of the producing well as the width of the rectangle, ranging from 60-100% (in percentage). The chart has four regions:

[0062] The rectangular area formed by the long side ranging from 0% to 10% and the wide side ranging from 60% to 100% is the fracturing zone, and the production wells located in this zone are subjected to fracturing.

[0063] A rectangular area formed by a long side range of 10%-35% and a wide side range of 60%-90% is a reasonable area, and the current production parameters should be maintained for the producing wells located within this area;

[0064] A rectangular area with a long side range of 10%-20% and a wide side range of 90%-100% is the concentration zone. The injection concentration of the injection well connected to the production well in this area is increased.

[0065] A rectangular area formed by a long side ranging from 20% to 35% and a wide side ranging from 90% to 100% is the fracturing and water shut-off zone. In this zone, the oil layer with poor dynamism in the production well is fracturing, and the high water-cut layer is shut off.

[0066] (3) Using injection well adjustment charts to guide comprehensive injection well adjustment methods include:

[0067] ① The chart has four regions. The relevant region is selected based on the proportion of liquid absorption thickness in the injection well and the maximum relative liquid absorption of a single layer.

[0068] ② Perform fracturing on wells located in fracturing zones;

[0069] ③ Perform further subdivision adjustments on injection wells located in the subdivision adjustment zone;

[0070] ④ The injection concentration of injection wells located in the enrichment zone shall be increased;

[0071] ⑤ For injection wells in the reasonable zone, maintain the current injection parameters and closely monitor the well's dynamics. When the well is in another zone, make corresponding adjustments.

[0072] The injection wells located within the fracturing zone are subjected to fracturing, specifically as follows: no fracturing is performed on oil layers with a cumulative fluid intake exceeding 5 times, and fracturing is performed on oil layers with a cumulative fluid intake less than 5 times; different fracturing methods are selected according to the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, and conventional fracturing is used for oil layers with a perforation thickness less than 1.5m.

[0073] For injection wells located within the subdivided adjustment zone, the specific method is as follows: When the interlayer thickness exceeds 1.5m, each oil layer is treated as a separate injection segment, and different injection intensities are designed based on the cumulative number of times the injection segment has absorbed fluid: when the cumulative number of times the fluid has absorbed fluid is greater than 5, the layer is a control layer, and the injection volume is reduced by 30%; when the cumulative number of times the fluid has absorbed fluid is greater than 1 but less than 5, the layer is a reinforcement layer, and the injection volume is increased by 40%; for non-fluid-absorbing layers, when the oil layer thickness is ≥2m, the injection volume is designed to be 10m³. 3 When the oil layer thickness is less than 2m, the injection volume is designed to be 5m³. 3 ;

[0074] The injection concentration of injection wells located in the concentration enhancement zone is increased by the following method: when the liquid absorption thickness ratio is ≥90%, the injection concentration is increased by 300 mg / L; when the liquid absorption thickness ratio is ≥70% and less than 90%, the injection concentration is increased by 400 mg / L; and when the liquid absorption thickness ratio is <70%, the injection concentration is increased by 500 mg / L.

[0075] (4) The methods for guiding the comprehensive adjustment of produced wells using the production well adjustment chart include:

[0076] ①The map has four areas. The relevant area is selected based on the production level of the well at each stage and the water content of the well.

[0077] ② Perform fracturing on production wells located in fracturing zones;

[0078] ③ The injection concentration of the production well connected to the injection well in the enrichment zone shall be increased;

[0079] ④ For production wells located in fracturing and water-blocking zones, fracturing and water-blocking are carried out, including fracturing poorly functioning oil layers and water-blocking of high-water-cut layers;

[0080] ⑤ Closely monitor dynamic changes in production wells within reasonable zones, and promptly adjust them according to the adjustment charts when wells are located in other zones.

[0081] The production wells located within the fracturing zone are subjected to fracturing. Specifically, the following methods are used: oil layers with a cumulative fluid intake of more than 5 times in connected injection wells are not fracturing, while oil layers with a cumulative fluid intake of less than 5 times in connected injection wells are fracturing; different fracturing methods are selected according to the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, while conventional fracturing is used for oil layers with a perforation thickness less than 1.5m.

[0082] The injection concentration of the injection well connected to the production well in the enrichment zone is increased. Specifically, the injection concentration is increased by 500 mg / L when the stage recovery rate is ≥19% and the water content is ≤95%; when the stage recovery rate is ≥19% and the water content is >95%, the injection concentration is increased by 200 mg / L; when the stage recovery rate is ≥16% and less than 19%, the injection concentration is increased by 400 mg / L; and when the stage recovery rate is less than 16%, the injection concentration is increased by 600 mg / L.

[0083] For the produced wells located in the fracturing and water-stopping zone, fracturing and water-stopping are performed. For oil layers with poor fracturing activity, water-stopping is performed on high water-cut layers. The specific methods are as follows: fracturing is performed on oil layers with a water cut of less than 95% and a stage recovery rate of less than 15%; multi-fracture fracturing is used on oil layers with a perforation thickness of ≥1.5m; conventional fracturing is used on oil layers with a perforation thickness of less than 1.5m; and water-stopping is performed on oil layers with a water cut of more than 95% and a stage recovery rate of more than 15%.

[0084] Example 1

[0085] To make the objectives, technical solutions, and advantages of this invention clearer, the following description, using the X-zone Class III oil reservoir test area as an example, will be further detailed with reference to the accompanying drawings.

[0086] This invention applies to the X-zone, a test area of ​​three types of oil reservoirs. The area contains 14 injection wells and 21 production wells. Polymer flooding began in February 2020. After an injection pore volume of 0.489 PV, the study area entered the water cut recovery period. During this period, 6 injection wells underwent enrichment, 2 wells underwent fracturing, and 10 wells underwent fine-tuning; 3 production wells underwent fracturing, 7 injection wells underwent enrichment, and 3 wells underwent fracturing and water shut-off. After comprehensive adjustments, the rate of water cut increase was effectively controlled, decreasing from 0.55 percentage points / month in the early stages of water cut recovery to 0.08 percentage points / month. Furthermore, the water cut in the well area was 3.28 percentage points lower than the numerical model prediction, and the enhanced oil recovery rate was 2.06 percentage points higher than the numerical model prediction, achieving good polymer flooding development results.

[0087] (1) Use the injection well adjustment chart to guide the comprehensive adjustment of injection wells:

[0088] ① Further explanation of the injection well adjustment chart for fracturing well A1-1 located in the fracturing zone.

[0089] Basic information about Well A1-1: Effective thickness 9.3m, injection pressure 10.4MPa, daily injection volume 33m³. 3 With an injection concentration of 1929 mg / L and a fluid absorption thickness of 3.8 m, the fluid absorption thickness ratio of the oil layer in well A1 can be calculated using the following formula:

[0090] H = h in / h oe (1)

[0091] in:

[0092] H - Oil layer absorption thickness percentage, %

[0093] h in -Liquid absorption thickness, m

[0094] h oe -Effective thickness, m

[0095] Calculations showed that the oil layer fluid absorption thickness ratio of well A1-1 was 40.86%, and the maximum relative fluid absorption of a single layer was 60%. Based on this fluid absorption thickness ratio and maximum relative fluid absorption of a single layer, the area where well A1 was located was identified as a fracturing zone on the injection well adjustment chart, and fracturing was promptly initiated in this well. Compared with before fracturing, the injection pressure decreased from 10.4 MPa to 7.8 MPa, and the daily injection volume decreased from 33 m³ / h. 3 Increased to 59m 3The proportion of liquid absorption thickness increased from 40.86% to 91.40%, and the maximum relative liquid absorption of a single layer decreased from 60% to 35%. The liquid absorption between layers was more uniform. Based on the proportion of liquid absorption thickness and the maximum relative liquid absorption of a single layer in well A1-1 after fracturing, the area in the chart was identified. The results show that well A1-1 is in a reasonable range after fracturing.

[0096] During the water-cut recovery period, according to the injection well adjustment chart, fracturing was performed on two injection wells located in the fracturing zone, achieving good fracturing results. Compared with before fracturing, the average single-well injection pressure decreased from 11.4 MPa to 9.2 MPa, and the daily injection volume decreased from 37 m³ / h. 3 Increased to 73m 3 The proportion of fluid absorption thickness increased from 41.72% to 82.12%, and the maximum relative fluid absorption of a single layer decreased from 61% to 37%. Based on the proportion of fluid absorption thickness and the maximum relative fluid absorption of a single layer after fracturing of the injection well, the injection well adjustment chart was compared with the results. The results show that both fracturing wells are in the reasonable range (see Table 1 for the basic conditions and effect statistics of fracturing injection wells in the study area).

[0097] Table 1

[0098]

[0099] ② Further explanation of the well adjustment chart for well A2-1, located in the enrichment zone, regarding the enrichment process.

[0100] Basic information about Well A2-1: Effective thickness 3.6m, injection pressure 10.5MPa, daily injection volume 25m³. 3 The injection concentration was 1434 mg / L, and the liquid absorption thickness was 3.6 m. Substituting these values ​​into formula (1), the liquid absorption thickness ratio of well A2-1 was calculated to be 100%. The liquid absorption profile showed that the maximum relative liquid absorption of a single layer in this well was 52%. Based on the liquid absorption thickness ratio and the maximum relative liquid absorption of a single layer in this well, the area where well A2-1 is located was identified as a concentration zone on the injection well adjustment chart, and the well was promptly concentrated. Compared with before the adjustment, the injection pressure increased from 10.5 MPa to 11.1 MPa, and the daily injection volume remained at 25 m³ / L. 3 The injection concentration was increased from 1434 mg / L to 1728 mg / L, the liquid absorption thickness ratio was kept at 100%, and the maximum relative liquid absorption of a single layer was reduced from 52.07% to 36.62%. Based on the adjusted liquid absorption thickness ratio and the maximum relative liquid absorption of a single layer of well A2-1, the area in the chart was identified. The results show that well A2-1 is now in a reasonable range after the adjustment.

[0101] During the water-cut recovery period, adjustments were made to six injection wells in the enrichment zone according to the injection well adjustment chart, and the adjustments achieved good results. Compared with before the adjustments, the average single-well injection pressure increased from 10.9 MPa to 11.6 MPa, and the daily injection volume increased from 263 m³ / h. 3 Increased to 295m 3 The proportion of liquid absorption thickness increased from 73.14% to 87.48%, and the maximum relative liquid absorption of a single layer decreased from 52.96% to 31.62%. Based on the adjusted proportion of liquid absorption thickness and the maximum relative liquid absorption of a single layer of the injection wells, and referring to the adjustment chart of the injection wells, the results show that all 6 injection wells are now in a reasonable range (see Table 2 for the basic conditions and adjustment effects of the concentrated injection wells in the study area).

[0102] Table 2

[0103]

[0104] ③ Further explanation of the injection well adjustment chart is provided for well A3-1, which is located in the subdivided adjustment zone.

[0105] Basic information about Well A3-1: Effective thickness 9.9m, injection pressure 11.0MPa, daily injection volume 25m³. 3 The injection concentration was 1124 mg / L, and the liquid absorption thickness was 5.2 m. Substituting these values ​​into formula (1), the liquid absorption thickness ratio of well A3-1 was calculated to be 52.53%. The liquid absorption profile showed that the maximum relative liquid absorption of a single layer in this well was 80%. Based on the liquid absorption thickness ratio and the maximum relative liquid absorption of a single layer in this well, the area where well A3-1 is located was identified as a subdivided adjustment zone on the injection well adjustment chart, and the well was subdivided and adjusted in a timely manner. Compared with before the adjustment, the injection pressure increased from 11.0 MPa to 11.5 MPa, and the daily injection volume increased by 5 m³. 3 The injection concentration was increased from 1124 mg / L to 1454 mg / L, the liquid absorption thickness ratio increased from 52.53% to 92.93%, and the maximum relative liquid absorption of a single layer decreased from 80% to 36.59%. Based on the adjusted liquid absorption thickness ratio and the maximum relative liquid absorption of a single layer of well A3-1, the area in the chart was identified. The results show that well A3-1 is now in a reasonable range after the adjustment.

[0106] During the water-cut recovery period, adjustments were made to 10 injection wells in subdivided adjustment areas according to the injection well adjustment chart, and the adjustments achieved good results. Compared with before the adjustments, the average single-well injection pressure increased from 10.6 MPa to 11.6 MPa, and the daily injection volume increased from 473 m³ / h. 3 Descended to 434m 3The proportion of liquid absorption thickness increased from 61.92% to 89.31%, and the maximum relative liquid absorption of a single layer decreased from 81.50% to 34.40%. Based on the adjusted proportion of liquid absorption thickness and the maximum relative liquid absorption of a single layer of the subdivided adjustment wells, and in comparison with the injection well adjustment chart, the results show that all 10 subdivided adjustment wells are in the reasonable range (see Table 3 for the basic conditions and adjustment effects of the subdivided adjustment injection wells in the study area).

[0107] Table 3

[0108]

[0109] (2) Use the production well adjustment chart to guide the comprehensive adjustment of production wells:

[0110] ① Further explanation of the adjustment chart for production well B1-1, located in the fracturing zone, regarding fracturing.

[0111] Basic information about Well B1-1: The well has a water cut of 91.70% and a stage recovery rate of 7.49%. Based on the data from this well, the area where Well B1-1 is located was identified as a fracturing zone on the production well adjustment chart, and fracturing was promptly implemented. Compared with before fracturing, daily fluid production increased from 53t to 91t, and daily oil production increased from 4.4t to 9.7t, achieving good results.

[0112] During the water cut recovery period, three production wells in the fracturing zone were fracturing according to the production well adjustment chart. Compared with before fracturing, daily fluid production increased from 101t to 197t, daily oil production increased from 6.9t to 22.9t, and the overall water cut decreased from 93.14% to 88.38%, achieving a good effect of increasing oil production and reducing water cut. The statistics of the fracturing production well effects in the study area are shown in Table 4.

[0113] Table 4

[0114]

[0115] ② Further explanation of the adjustment chart for the production well B2-1, which is located in the fracturing and water shut-off zone.

[0116] Basic information about well B2-1: This well has a water cut of 93.00% and a stage recovery rate of 20.48%. Based on the data from this well, the area where well B2-2 is located was identified as a fracturing and water-stopping zone on the production well adjustment chart, and corresponding measures were promptly taken for this well. Compared with before the measures, daily fluid production increased from 47t to 53t, daily oil production increased from 3.3t to 5.4t, and the water cut decreased from 93.00% to 89.90%, achieving good results.

[0117] During the water cut recovery period, fracturing and water shut-off were carried out on three production wells located in the fracturing and water shut-off area according to the production well adjustment chart. Compared with before the measures, daily fluid production increased from 111t to 162t, daily oil production increased from 6.5t to 17.4t, and the overall water cut decreased from 94.14% to 89.28%, achieving a good effect of increasing oil production and reducing water. The statistics of the fracturing and water shut-off production well effects in the study area are shown in Table 5.

[0118] Table 5

[0119]

[0120] ③ The injection concentration of the production well B3-1 connected to the injection well in the enrichment zone is increased, and further explanation is provided on the production well adjustment chart.

[0121] Basic information about Well B3-1: The well has a water cut of 95.30% and a stage recovery rate of 17.43%. Based on the data from this well, the area where Well B3-1 is located was identified as an enrichment zone on the production well adjustment chart. The concentrations of the injection wells connected to this well were promptly increased. Compared to before the adjustment, the average single-well injection pressure increased by 0.7 MPa, the injection concentration increased by 400 mg / L, the daily oil production of the production well increased from 0.8 t to 1.9 t, and the water cut decreased from 95.30% to 89.20%, achieving a good adjustment effect.

[0122] During the water cut recovery period, according to the production well adjustment chart, the seven production wells in the enrichment zone were connected to the injection wells for enrichment. Compared with before the adjustment, the average single-well injection pressure increased from 11.4 MPa to 12.1 MPa, and the injection concentration increased from 1185 mg / L to 1607 mg / L. After the adjustment, the production wells showed the effect of the adjustment, with daily fluid production decreasing from 146 t to 134 t, daily oil production increasing from 6.6 t to 13.6 t, and the overall water cut decreasing from 95.51% to 89.83%, achieving a good adjustment effect. The statistics of enrichment effect in the study area are shown in Table 6.

[0123] Table 6

[0124]

[0125] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A method for establishing a tracking and adjustment chart for injection-production wells during the recovery period of polymer flooding in three types of oil reservoirs, characterized in that: This includes methods for establishing adjustment charts for injection wells and production wells; The method for establishing the injection well adjustment chart includes: A rectangular diagram is constructed with the length of the rectangle representing the proportion of the fluid absorption thickness of the injection well, ranging from 40 to 100, in percentage; and the width of the rectangle representing the maximum relative fluid absorption of a single layer of the injection well, ranging from 0 to 100, in percentage. The injection well adjustment chart is divided into four areas: fracturing zone, subdivision adjustment zone, enrichment zone, and rational zone. The method for establishing the production well adjustment chart includes: A rectangular diagram is constructed with the production level of the producing well stage as the length of the rectangle, ranging from 0 to 35%; and the water content of the producing well as the width of the rectangle, ranging from 60 to 100%; The production well adjustment chart has four zones: fracturing zone, rational zone, concentration zone, and fracturing and water shut-off zone.

2. The method for establishing a tracking and adjustment chart for injection-production wells during the recovery period of polymer flooding in three types of oil reservoirs according to claim 1, characterized in that: For the injection well adjustment chart: the rectangular area formed by the long side range of 40%-55% and the wide side range of 0%-70% is the fracturing zone; The rectangular area formed by the long side ranging from 40% to 100% and the wide side ranging from 70% to 100% is the subdivision adjustment area; The rectangular area formed by a long side range of 55%-100% and a wide side range of 50%-70% is the concentration zone. A rectangular area formed by a long side ranging from 55% to 100% and a wide side ranging from 0% to 50% is considered a reasonable range.

3. The method for establishing a tracking and adjustment chart for injection-production wells during the recovery period of polymer flooding in three types of oil reservoirs according to claim 1, characterized in that: For production well adjustment charts: the rectangular area formed by the long side range of 0%-10% and the wide side range of 60%-100% is the fracturing zone; A rectangular area formed by a long side ranging from 10% to 35% and a wide side ranging from 60% to 90% is considered a reasonable area. The rectangular area formed by a long side range of 10%-20% and a wide side range of 90%-100% is the concentration zone; A rectangular area formed by a long side range of 20%-35% and a wide side range of 90%-100% is the fracturing and water shut-off zone.

4. A method for using a tracking and adjustment chart for injection-production wells during the recovery period of polymer flooding in three types of oil reservoirs, established according to any one of claims 1 to 3, characterized in that: Based on the constructed injection well adjustment map and production well adjustment map, relevant areas are selected for corresponding adjustments according to the relevant adjustment parameters.

5. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 4, characterized in that: Based on the constructed injection well adjustment map, and according to two parameters—the injection well fluid absorption thickness ratio and the maximum relative fluid absorption of a single layer—relevant areas are selected for corresponding adjustments. Specific methods include: The injection wells with a fluid absorption thickness ratio ranging from 40% to 55% and a maximum relative fluid absorption of 0% to 70% per layer are located in a rectangular fracturing zone; fracturing is performed on the injection wells located within the fracturing zone; Wells with a fluid absorption thickness ratio ranging from 40% to 100% and a maximum relative fluid absorption of 70% to 100% in a single layer are located in a subdivided adjustment zone within a rectangular area; injection wells located within this subdivided adjustment zone are further subdivided and adjusted. Wells with a liquid absorption thickness ratio ranging from 55% to 100% and a maximum relative liquid absorption of 50% to 70% in a single layer are located in the concentration zone of a rectangular area; the injection concentration of injection wells located in the concentration zone is increased. Wells with a liquid absorption thickness ratio of 55%-100% and a maximum relative liquid absorption of 0%-50% per layer are within the reasonable zone of the rectangular area. For wells within the reasonable zone, maintain the current injection parameters and monitor the well's dynamics. When the well is in other zones, make corresponding adjustments.

6. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 5, characterized in that: The injection wells located within the fracturing zone are subjected to fracturing, specifically as follows: no fracturing is performed on oil layers with a cumulative fluid intake exceeding 5 times, and fracturing is performed on oil layers with a cumulative fluid intake less than 5 times; different fracturing methods are selected according to the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, and conventional fracturing is used for oil layers with a perforation thickness less than 1.5m. For injection wells located within the subdivided adjustment zone, the specific method is as follows: When the interlayer thickness exceeds 1.5m, each oil layer is treated as a separate injection segment, and different injection intensities are designed based on the cumulative number of times the injection segment has absorbed fluid: when the cumulative number of times the fluid has absorbed fluid is greater than 5, the layer is a control layer, and the injection volume is reduced by 30%; when the cumulative number of times the fluid has absorbed fluid is greater than 1 but less than 5, the layer is a reinforcement layer, and the injection volume is increased by 40%; for non-fluid-absorbing layers, when the oil layer thickness is ≥2m, the injection volume is designed to be 10m³. 3 When the oil layer thickness is less than 2m, the injection volume is designed to be 5m³. 3 ; The injection concentration of injection wells located in the concentration enhancement zone is increased by the following method: when the liquid absorption thickness ratio is ≥90%, the injection concentration is increased by 300 mg / L; when the liquid absorption thickness ratio is ≥70% and less than 90%, the injection concentration is increased by 400 mg / L; and when the liquid absorption thickness ratio is <70%, the injection concentration is increased by 500 mg / L.

7. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 5, characterized in that: The formula for the fluid absorption thickness ratio of an injection well is: H=h in / h oe (1) in: H - Oil layer absorption thickness percentage, %; h in - Liquid absorption thickness, in meters; h oe - Effective thickness, m.

8. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 4, characterized in that: Based on the constructed production well adjustment map, and according to the two parameters of the production well stage and the water cut of the well, relevant areas are selected for corresponding adjustments. Specific methods include: Wells with a production rate of 0%-10% and a water cut of 60%-100% are located in a rectangular fracturing zone; fracturing is performed on the production wells located within the fracturing zone. Wells with a production rate of 10%-35% and a water cut of 60%-90% are within the reasonable area of ​​the rectangular region. For wells within the reasonable area, dynamic changes should be monitored, and adjustments should be made promptly according to the adjustment chart when they are in other areas. Wells with a production rate of 10%-20% and a water cut of 90%-100% are located in a rectangular enrichment zone; the injection concentration of injection wells connected to production wells within the enrichment zone is increased. Wells with a production rate of 20%-35% and a water cut of 90%-100% are located in a rectangular fracturing and water shut-off zone. For wells located in the fracturing and water shut-off zone, fracturing and water shut-off are performed, with fracturing of poorly functioning oil layers and water shut-off of high-water-cut layers.

9. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 8, characterized in that: The production wells located within the fracturing zone are subjected to fracturing. Specifically, the following methods are used: oil layers with a cumulative fluid intake of more than 5 times in connected injection wells are not fracturing, while oil layers with a cumulative fluid intake of less than 5 times in connected injection wells are fracturing; different fracturing methods are selected according to the perforation thickness of the fracturing layer: multi-fracture fracturing is used for oil layers with a perforation thickness ≥ 1.5m, while conventional fracturing is used for oil layers with a perforation thickness less than 1.5m. The injection concentration of the injection well connected to the production well within the enrichment zone is increased. Specifically, the injection concentration is increased by 500 mg / L when the stage recovery rate is ≥19% and the water content is ≤95%; when the stage recovery rate is ≥19% and the water content is >95%, the injection concentration is increased by 200 mg / L; and when the stage recovery rate is ≥16% and <19%, the injection concentration is increased by 400 mg / L. When the recovery rate is less than 16%, the injection concentration is increased by 600 mg / L.

10. The method for using the injection-production well tracking and adjustment chart during the recovery period of polymer flooding in three types of oil reservoirs according to claim 8, characterized in that: For the produced wells located in the fracturing and water-stopping zone, fracturing and water-stopping are performed. For oil layers with poor fracturing activity, water-stopping is performed on high water-cut layers. The specific methods are as follows: fracturing is performed on oil layers with a water cut of less than 95% and a stage recovery rate of less than 15%; multi-fracture fracturing is used on oil layers with a perforation thickness of ≥1.5m; conventional fracturing is used on oil layers with a perforation thickness of less than 1.5m; and water-stopping is performed on oil layers with a water cut of more than 95% and a stage recovery rate of more than 15%.

11. The injection-production well adjustment chart for the polymer flooding recovery period of the three types of oil reservoirs established by the method according to any one of claims 1 to 3 can be directly applied to the water-cut recovery period of polymer flooding in the three types of oil reservoirs.

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