Method for identifying, regulating and controlling low-efficiency and ineffective water circulation in later period of water-flooding development of pore and fracture dual-medium low-porosity, low-permeability and high-coagulation heavy oil reservoir

Abstract

The invention discloses a method for identifying, regulating and controlling low-efficiency and ineffective water circulation in the later period of water injection development of a pore and crack dual-medium low-porosity, low-permeability and high-solidification-point heavy oil reservoir, and relates to the technical field of oilfield development. Comprising the steps that the water content under the economic limit is determined based on the cost and the current oil price, and then an invalid well is obtained; dividing each small layer of the low-efficiency well and the ineffective well into an ineffective layer, an effective layer and a reinforcing layer according to the water absorption condition; based on the characteristics of the ineffective layer and the effective layer, identifying low-efficiency ineffective water circulation by adopting a plurality of combination identification modes; respectively identifying an invalid water circulation field and a low-efficiency water circulation field through the invalid water circulation boundary of the invalid layer and the low-efficiency water circulation boundary of the low-efficiency layer; various modes of treatment are implemented for an invalid water circulation field and a low-efficiency water circulation field, and the secondary oil recovery effect is improved. According to the method, the low-efficiency layer and the invalid layer can be accurately identified, the effective rate of treatment measures is improved, interlayer interference is effectively removed, the main flow line is directly changed, and the water drive reserve utilization degree is improved.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, specifically to a method for identifying and controlling inefficient and ineffective water circulation in the later stages of water injection development of low-porosity, low-permeability, and high-pour-point-weight oil reservoirs with dual-medium pore-fracture systems. Background Technology

[0002] The development of an oilfield is essentially a continuous and dynamic interaction between oil, gas, and water, as well as a process of deepening human understanding and continuous strategic adjustments. Throughout this process, reservoir geological research must be ongoing to ensure close monitoring of reservoir dynamics. Based on the unique properties of the reservoir and its specific development stage, scientifically sound control strategies should be formulated and implemented to optimize development results and ultimately maximize the economic recovery rate of the oilfield.

[0003] For low-porosity, low-permeability, high-pour-point-weight oil reservoirs composed of both pore and fracture media, water injection development is particularly complex and challenging. The intricate development of primary fractures in these reservoirs significantly increases the difficulty of water injection. Traditional oil enhancement methods rely heavily on hydraulic fracturing, but this leads to difficulties and insufficient precision in fracture evaluation, making it impossible to accurately predict the dominant flow direction of water drive based solely on the actual development of fractures. Therefore, during water distribution, precise allocation to different layers is often difficult, resulting in a significant reduction in the effectiveness of water injection.

[0004] Furthermore, due to the low porosity and low permeability of the rock matrix itself, and the exacerbation of fracture fingering during water injection, if effective remediation measures are not taken in a timely manner, water flooding and water channeling in the near-wellbore zone of the well group can easily occur in a short period of time, severely limiting the planar sweep range of water injection displacement and thus affecting the overall development effect. Summary of the Invention

[0005] The purpose of this invention is to propose a method for identifying and controlling inefficient and ineffective water circulation in the later stages of water injection development of low-porosity, low-permeability, and high-pour-point-weight oil reservoirs with dual-medium porous fractures. This method involves reasonable classification based on identification criteria, control as needed, improving the water flooding condition of oil wells, increasing the utilization of water-driven reserves in water wells, and improving oil well production.

[0006] According to a first aspect of the present disclosure, a method for identifying and controlling inefficient and ineffective water circulation in the later stages of water injection development of low-porosity, low-permeability, and high-pour-point-weight oil reservoirs with dual-medium pore-fracture media is provided, comprising the following steps:

[0007] Based on cost and current oil prices, the water cut under the economic limit is determined, thereby identifying ineffective wells;

[0008] The sub-layers of inefficient and ineffective wells are divided into ineffective layers, effective layers, and reinforced layers according to their water absorption.

[0009] Based on the characteristics of the ineffective layer and the effective layer, multiple combined identification methods are used to identify inefficient and ineffective water circulation; the ineffective water circulation field and the inefficient water circulation field are identified by the ineffective water circulation boundary of the ineffective layer and the inefficient water circulation boundary of the low effective layer, respectively.

[0010] Multiple methods are implemented to address ineffective and inefficient water circulation fields, thereby improving the secondary oil recovery effect.

[0011] Furthermore, the water content under the economic limit is determined based on cost and current oil prices:

[0012] Applying the formula Profit = Output - Input to oil production and operation, we get: Output = Profit per ton of oil * Oil production = (Oil price - Taxes per ton of oil - Variable costs) * Crude oil commodity rate * Oil production + (Gas price - Gas tax per thousand cubic meters) * Gasoline ratio * Natural gas commodity rate * Gas ​​production (1)

[0013] When the economic limit is reached, output = input = fixed cost, therefore equation (1) can be written as:

[0014] Fixed cost = Profit per ton of oil * Daily liquid production * (1-Fw) * 365 (2)

[0015]

[0016] Where: Fwel is the economic limit moisture content; Fw is the overall moisture content of the block; Q L The average daily liquid production of the block is expressed in t / day. The block cost and profit per ton of oil are substituted into equation (3) to obtain the threshold of the economic limit water cut of the block. If the water cut of a well is greater than this threshold, it is considered an invalid well.

[0017] Furthermore, the method for classifying the sub-layers of inefficient and ineffective wells into ineffective, effective, and reinforced layers based on water absorption is as follows: using water absorption profile data of water wells, the water absorption ratio, effective water absorption intensity, inter-layer and intra-layer weighted permeability difference, coefficient of variation, and breakthrough coefficient of each layer in inefficient and ineffective wells are determined. Combined with the production profile and dynamic fluid level changes of oil wells, each water-absorbing layer is classified into ineffective, effective, and reinforced layers.

[0018] Furthermore, the effective water absorption strength

[0019] =Injected water volume Q * water absorption ratio of small layer / effective water absorption thickness of small layer Hi (4)

[0020]

[0021]

[0022] In the formula: Kmax is the maximum permeability, Kmin is the minimum permeability. This represents the average penetration rate.

[0023] Furthermore, the identification methods for the invalid layer, effective layer, and strengthening layer are as follows:

[0024] When the effective water absorption intensity > N11, the weighted permeability breakthrough coefficient per meter > N12, the weighted permeability difference per meter > N13, and the weighted permeability variation coefficient per meter > N14, and the flowing fluid level of the oil well rises, and the liquid production of the corresponding layer is mainly water production, this layer is an invalid layer;

[0025] When the effective water absorption intensity > N21, the weighted permeability breakthrough coefficient per meter > N22, the weighted permeability difference per meter > N23, and the weighted permeability variation coefficient per meter > N24, and the flowing fluid level of the oil well is stable, and the liquid production of the corresponding layer is mainly water production, this layer is an effective layer;

[0026] When the effective water absorption intensity < N21, the weighted permeability breakthrough coefficient per meter < N22, the weighted permeability difference per meter < N23, and the weighted permeability variation coefficient per meter < N24, and the flowing fluid level of the oil well drops slowly, and the liquid production of the corresponding layer is relatively low and mainly oil production, this layer is a strengthening layer.

[0027] Furthermore, multiple combination identification methods include: geological and logging data analysis, analysis of the dynamic changes in the production of oil and water wells, analysis of the dynamic changes in water absorption capacity, and analysis of the changes in recovery factor.

[0028] Furthermore, the analysis of the dynamic changes in the production of oil and water wells includes:

[0029] Determine the connectivity of each layer of the oil and water wells in the well group through the reservoir profile and grid diagram;

[0030] Monitor the water breakthrough time of the corresponding oil well when the water injection well is converted to injection, and determine the water injection effectiveness relationship of each layer;

[0031] Monitor the water breakthrough time of the corresponding oil well when the water injection well stops injection for a long time and then resumes injection, and combine the influence of dynamic allocation to determine the production dynamics of each layer and the dynamic effectiveness relationship between the oil and water wells;

[0032] Based on the water breakthrough time and the change in water cut, divide the strongly, moderately, and weakly effective wells and effective layers.

[0033] Furthermore, the analysis of the dynamic changes in water absorption capacity is as follows: If the apparent water absorption index suddenly increases, it indicates that the single-layer water absorption capacity of the water injection well suddenly strengthens, forming a large water flow channel, resulting in inefficient and ineffective water circulation in the well group;

[0034]

[0035] Furthermore, the analysis of the changes in recovery factor is as follows: Use the Type A water drive curve to calibrate the recovery factor;

[0036] The Type A water drive formula involved in this analysis: After the oilfield has been in production for a period of time, W p and N PThere will be a certain linear relationship between them, i.e., lnW p =A+BN P

[0037] The relationship between cumulative oil production and water cut is as follows:

[0038]

[0039] This analysis involves Tong's plate formula:

[0040]

[0041] Among them W p For cumulative water production; N P A represents cumulative oil production; A is the water drive constant f. W For overall moisture content; E R R represents the recovery rate; R represents the degree of extraction in the block.

[0042] Furthermore, governance can be achieved through multiple methods, including:

[0043] The treatment methods for ineffective and inefficient water circulation fields in oil wells include layer adjustment, fracturing, and combined water shut-off and production.

[0044] The treatment methods for ineffective and inefficient water circulation fields in wells include layered reorganization, intermittent water injection, and jet nozzles.

[0045] Compared with the prior art, the above technical solutions adopted in this invention have the following advantages: This invention can accurately identify inefficient layers and ineffective layers, improve the effectiveness of treatment measures, effectively remove interlayer interference, directly change the mainstream line, and improve the utilization of water drive reserves.

[0046] Based on the classification criteria for oil well effectiveness and the boundaries of the main controlling factors, inefficient and ineffective water circulation standards are divided. This has led to the development of identification and control technologies for inefficient and ineffective water circulation in low-porosity, low-permeability, and high-viscosity oil reservoirs with a dual pore-fracture medium. According to the identification criteria, water wells are rationally classified and controlled as needed. This optimizes the water well injection and carding methods, the injection intensity of each layer, reduces the water injection rate in the dominant direction, improves the water flooding condition of oil wells, and enhances the effectiveness of water injection in other directions of the well group. Ultimately, this increases the utilization of water-driven reserves in water wells and improves oil well production. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0048] Figure 1 This is a chart analyzing the changes in geological and well logging data.

[0049] Figure 2This is a diagram illustrating the dynamic changes in the water absorption profile.

[0050] Figure 3 A graph showing the dynamic changes in oil and water well production;

[0051] Figure 4 This is a graph showing the dynamic changes in water absorption capacity.

[0052] Figure 5 This is a graph analyzing changes in oil recovery rate.

[0053] Figure 6 A comparison chart of the fracture pressure of inefficient and ineffective layers with that of normal oil wells;

[0054] Figure 7 A comparison chart of the annual water cut rise rate of inefficient and ineffective wells with that of normal oil wells;

[0055] Figure 8 A comparison chart of the apparent water absorption index of inefficient and ineffective water injection layers and that of normal water injection wells;

[0056] Figure 9 A comparison chart of the surge coefficients of inefficient and ineffective layers with those of normal layers;

[0057] Figure 10 This is a comparison chart of the water absorption intensity of a known inefficient and ineffective layer with that of a normal well.

[0058] Figure 11 This is a diagram showing the distribution of inefficient and ineffective water circulation in the oil reservoir. Specific implementation methods

[0059] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0060] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0061] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0062] Example 1:

[0063] This embodiment identifies water-bearing strata and water inflow direction through dynamic analysis of pressure, production, and water cut changes; it also understands the characteristics of reservoir structure, reservoir, and fluids by utilizing geological and logging data, analyzes oil-water movement patterns, and fills the gap in the identification and control of inefficient and ineffective water circulation in low-porosity, low-permeability, and high-pour-point-weight oil reservoirs with a dual-medium pore-fracture system. Specifically, it includes the following steps:

[0064] S1. Identify ineffective wells based on water cut;

[0065] Specifically, the water content under the economic limit is determined by considering block cost, profit per ton of oil, and average daily liquid production per block.

[0066] Applying the formula Profit = Output - Input to oil production and operation, we get: Output = Profit per ton of oil * Oil production = (Oil price - Taxes per ton of oil - Variable costs) * Crude oil commodity rate * Oil production + (Gas price - Gas tax per thousand cubic meters) * Gasoline ratio * Natural gas commodity rate * Gas ​​production (1)

[0067] When the economic limit is reached, output = input = fixed cost, therefore equation (1) can be written as:

[0068] Fixed cost = Profit per ton of oil * Daily liquid production * (1-Fw) * 365 (2)

[0069]

[0070] Where: Fwel is the economic limit moisture content; Fw is the overall moisture content of the block; Q L The average daily liquid production of the block is expressed in tons per day. The block cost and profit per ton of oil are substituted into equation (3) to obtain the threshold of the economic limit water cut of the block, such as 94%. If the water cut of a well is greater than 94%, it is considered an ineffective well. In this embodiment, high water cut wells with a water cut of more than 85% in the block are identified as inefficient wells.

[0071] S2. Divide the water-absorbing layers of inefficient and ineffective wells into ineffective layers, effective layers, and reinforced layers;

[0072] Specifically, using water well water absorption profile data, the water absorption ratio, effective water absorption intensity, inter-layer and intra-layer weighted permeability difference, coefficient of variation, and breakthrough coefficient of each layer in inefficient and ineffective wells are determined. Combined with the production profile and dynamic fluid level changes of oil wells, each water-absorbing layer is divided into ineffective layer, effective layer, and reinforced layer.

[0073] To address the unique characteristics of the block, it was discovered that post-fracturing reservoir property changes prevented direct qualitative analysis of heterogeneity. Therefore, effective water absorption intensity and layer-weighted permeability formulas adapted to the block were developed. Furthermore, layer-weighted permeability ranges, coefficients of variation, and surge coefficients suitable for fracturing layer analysis were derived, as follows:

[0074] The effective water absorption strength

[0075] =Injected water volume Q * water absorption ratio of small layer / effective water absorption thickness of small layer Hi (4)

[0076]

[0077]

[0078] In the formula: Kmax is the maximum permeability, Kmin is the minimum permeability. This represents the average penetration rate.

[0079] Based on the parameters obtained above, and combined with the changes in the production profile and dynamic fluid level of the oil wells in the well group, the ineffective layer, effective layer, and reinforcing layer are divided as follows:

[0080] ① Ineffective layer: Effective water absorption intensity > 3.5, permeability breakthrough coefficient per meter > 3.5, permeability gradient per meter > 10, permeability variation coefficient per meter > 5, corresponding to the rise of dynamic fluid level in oil well, the corresponding layer produces mainly water, water cut > 94%. The above parameters can be adjusted according to actual working conditions.

[0081] ② Effective layer: Effective water absorption intensity > 1.5, permeability breakthrough coefficient per meter > 2, permeability gradient per meter > 5, permeability variation coefficient per meter > 2, corresponding to stable dynamic fluid level of oil well, corresponding layer production is mainly water production, water cut > 60%. The above parameters can be adjusted according to actual working conditions;

[0082] ③ Reinforced layer: Effective water absorption intensity <1.5, permeability breakthrough coefficient per meter <2, permeability gradient per meter <5, permeability variation coefficient per meter <2, corresponding to a slow decline in the dynamic fluid level of the oil well, with low fluid production in the corresponding layer, mainly producing oil, and water cut <60%. The above parameters can be adjusted according to the actual working conditions.

[0083] S3. Based on the ineffective layer and the effective layer, a variety of combined identification methods are used to obtain the inefficient and ineffective water cycle; the ineffective water cycle boundary of the ineffective layer and the inefficient water cycle boundary of the low effective layer are respectively obtained to obtain the ineffective water cycle field and the inefficient water cycle field.

[0084] Specifically, multiple combined identification methods are used, including: geological and logging data analysis, dynamic change analysis of oil and water well production, dynamic change analysis of water absorption capacity, and analysis of recovery rate changes.

[0085] 1) Geological and well logging data analysis:

[0086] By combining parameters such as porosity and permeability from well logging data with the interpreted oil layers, the changes in the interpretation of oil and water layers at different times in the same layer of each single well can be compared between wells. For example, if the oil layer is side-drilled after water injection for a period of time, the corresponding layer is interpreted as a weakly water-flooded layer or a moderately strong water-flooded layer. This allows for a direct determination of the water injection effect of the water well on the oil well, thereby revealing the inefficient and ineffective water circulation.

[0087] 2) Analysis of dynamic changes in oil and water well production, the main steps are as follows:

[0088] ① Determine the connectivity of each layer in the oil and water wells of the well group by using reservoir profile and grid diagrams;

[0089] ② Monitor the water breakthrough time of the corresponding oil wells for water well conversion and determine the water injection effect relationship of each layer;

[0090] ③ Monitor the water breakthrough time of the corresponding oil wells after the water well has been stopped for a long time and then resumed. Combine this with the impact of dynamic allocation to determine the production dynamics of each layer and the dynamic effect relationship between oil and water wells.

[0091] ④ Based on the time of water breakthrough and changes in water cut, classify wells and effective layers into strong, medium, and weak effective wells and effective layers.

[0092] A. In areas with incomplete well networks, the initial injection wells have low water cut:

[0093] Strong effectiveness: Water exposure time <20 days, water content change >20%

[0094] Moderately effective: Time to water exposure < 60 days, water content change > 10%

[0095] Weakly effective: Water exposure time > 60 days, water content change < 10%

[0096] B. Well-developed well network, long-term production area, high water content in oil wells:

[0097] Strong effectiveness: Water exposure time <10 days, water content change >10%

[0098] Medium effectiveness: Water exposure time <20 days, water content change >5%

[0099] Weak effectiveness: Water exposure time > 20 days, water content change < 5%

[0100] 3) Dynamic analysis of water absorption capacity:

[0101] Vertical heterogeneity of the reservoir can lead to uneven water absorption in different layers of the well. Over a long period of time, dominant channels will appear in the water-absorbing layers, which are the channels where inefficient and ineffective water circulation most often occurs.

[0102] A sudden increase in the apparent water absorption index indicates a sudden increase in the water absorption capacity of a single layer of the well, forming a large water flow channel, which leads to inefficient and ineffective water circulation in the well group.

[0103]

[0104] 4) Analysis of changes in recovery rate:

[0105] Type A waterdrive curves describe the relationship between cumulative oil production, water production, and fluid production during water injection development in an oilfield. Type A waterdrive curves can be used for oil recovery calibration.

[0106] This analysis involves the Type A waterflooding formula: After a period of oilfield production, W... p With N P There will be a certain linear relationship between them, i.e., lnW p =A+BN P

[0107] The relationship between cumulative oil production and water cut is as follows:

[0108]

[0109] The Tong's Plate Method, proposed by Academician Tong Xianzhang in 1978, has been adopted by my country's national standards for the oil and gas industry and named the Tong Xianzhang Plate Method. This method is characterized by its intuitiveness, simplicity, and ease of use. The Tong's Plate method is based on a limiting water cut of 98%, establishing plates for different limiting water cuts. By fitting the water cut values, the recovery rate of water-driven oilfields can be determined. This analysis involves the Tong's Plate formula:

[0110]

[0111] Among them W p For cumulative water production; N P A represents cumulative oil production; A is the water drive constant f. W For overall moisture content; E R R represents the recovery rate; R represents the degree of extraction in the block.

[0112] 5) Based on the division of ineffective and effective layers, and combined with the above research, the boundaries between ineffective and inefficient water cycles are further defined as follows:

[0113] Based on the current production status of oil wells in the block, evaluation criteria for inefficient and ineffective water circulation wells were established, and a chart was created. The criteria for inefficient circulation are: production well fracture pressure < 35 MPa, annual water cut increase rate > 6%, water absorption ratio of strong absorption layers in injection wells > 20%, apparent water absorption index > 6, and water absorption intensity of a single sand body > 2.3 m³. 3 / m, single sand body inrush coefficient > 2.5; Ineffective water circulation criteria: oil well fracture pressure < 28 MPa, annual water cut rise rate > 9%, water absorption ratio of strong absorption layer in injection well > 50%, apparent water absorption index > 8, single sand body water absorption intensity > 3.5m 3 / m, single sand body advance coefficient >3.5, the above parameters can be adjusted according to actual working conditions.

[0114] S4. Implement various methods to treat ineffective and inefficient water circulation fields to improve the secondary oil recovery effect.

[0115] Specifically, for inefficient and ineffective water circulation fields that are difficult to manage through water injection adjustments, multiple methods are implemented to control inefficient and ineffective water injection in high-permeability layers and areas, suppress single-layer inrush and localized tongue-like inrushes, expand the water drive sweep area, and improve secondary oil recovery performance. The details are as follows:

[0116] For oil wells:

[0117] Repairing and replenishing layers: This includes water shut-off repairing layers, ash squeezing and re-injection, etc., to seal the identified high-permeability water-producing layers, avoid the inefficient and ineffective layers identified by other oil wells in the well group, and select new layers with low water flooding and good oil content for repairing layers, thereby reducing the water cut of a single well and increasing oil production.

[0118] Fracturing: Small-scale fracturing is carried out on low-water-bearing layers of oil wells in non-mainstream directions to improve flow efficiency, change the water flow lines of the well group, expand the planar sweep range, and increase the water drive control reserves;

[0119] Combined water shut-off and extraction: This includes combined water shut-off and extraction, chemical water shut-off, and increased drainage and extraction, etc., which are used to block and suppress the identified high-permeability water-producing layers to improve the utilization of water-drive reserves.

[0120] For water wells:

[0121] Layer reorganization: This includes further subdivision and reorganization of water wells. In well groups during the high water cut period, the water injection intensity of strong water-absorbing layers is controlled by a single well, the water injection intensity of weak water-absorbing layers is enhanced, the vertical mobilization effect is improved, and the water drive sweep volume is expanded.

[0122] Intermittent water injection: including dynamic injection, intermittent injection, periodic water injection, etc., to suppress inefficient and ineffective layers at the source. Through the new water injection management concept of "intercepting the source and limiting the flow, suppressing ineffectiveness, changing the flow line and expanding the impact", the water control and oil increase effect with low investment and low cost can be achieved.

[0123] Jet nozzles: Their main function is to improve the injection profile by addressing pollution caused by substandard injected water quality, such as excessive levels of oil, suspended solids, median suspended solids particle size, sulfate-reducing bacteria, iron bacteria, and saprophytic bacteria.

[0124] By employing the above methods, we can improve the water flooding condition of oil wells, enhance the effectiveness of water injection in other directions of the well group, and confirm the distribution and movement of oil and water in each oil layer, changes in water absorption and oil production capacity, changes in water cut and production, changes in oil layer and fluid properties, reserve utilization and remaining oil distribution, etc., thus providing a basis for tapping the potential of oil layers.

[0125] Using the method of this invention, inefficient and ineffective water circulation management was carried out to improve the utilization of reserves. In a certain block, through water shut-off and combined production, layer adjustment and replenishment, and fracturing of adjacent wells, a total of 47 wells were managed, resulting in a cumulative increase in oil production of 11,738 tons. Correspondingly, 11 water wells were managed through layer reorganization, intermittent water injection and other methods, resulting in a cumulative increase in water absorption thickness of 221.8 meters. This provides favorable support for the practicality and scalability of this invention and has reference value for similar oil reservoirs.

[0126] Figure 1 It involves analyzing changes in geological and logging data. After a period of water injection, side-drilling is performed on the oil layer, and the corresponding layer is interpreted as changing from an oil layer to a weakly water-flooded layer or a moderately strong water-flooded layer. After a second side-drilling, the degree of water flooding changes again, which can intuitively determine the water injection effect of the water well on the oil well.

[0127] Figure 2 It is a dynamic change analysis of water absorption profile. The vertical heterogeneity of the reservoir will lead to uneven water absorption in each layer of the well. In the long term, the water-absorbing layer will have a dominant channel, which is the channel where inefficient and ineffective water circulation most often occurs.

[0128] Figure 3 It is an analysis of the dynamic changes in oil and water well production. In well groups with perfect injection-production relationships and normal effectiveness, adjustments to water wells will lead to changes in oil wells. Inefficient and ineffective circulation of water wells will cause the water cut of oil wells to rise rapidly and the oil production to decline.

[0129] Figure 4 It is a dynamic change analysis of water absorption capacity. A sudden increase in the water absorption index indicates that the water absorption capacity of a single layer of the well has suddenly increased, forming a large water flow channel, which leads to inefficient and ineffective water circulation in the well group.

[0130] Figure 5 The analysis of recovery rate changes shows that inefficient and ineffective water circulation will lead to a faster rate of increase in water cut in the block, a reduction in recoverable reserves, and ultimately a significant decrease in recovery rate.

[0131] Figure 6 The comparison between the fracture pressure of known inefficient and ineffective layers and that of normal oil wells shows that the fracture pressure of inefficient and ineffective layers is significantly lower.

[0132] Figure 7 The comparison between the annual water cut rise rate of known inefficient and ineffective layers and that of normal oil wells shows that the annual water cut rise rate of inefficient and ineffective layers is significantly faster.

[0133] Figure 8 The comparison between the apparent water absorption index of inefficient and ineffective water injection layers and that of normal water injection wells shows that the apparent water absorption index of inefficient and ineffective layers is significantly higher.

[0134] Figure 9 The comparison between the known inefficient and ineffective layer's ramp coefficient and the normal layer shows that a higher ramp coefficient makes it easier to form an inefficient and ineffective layer.

[0135] Figure 10 The comparison between the water absorption intensity of known inefficient and ineffective layers and that of normal wells shows that the water absorption intensity of inefficient and ineffective layers is significantly higher than that of normal wells.

[0136] right Figure 11 The parameters of the selected oil and water wells were adjusted, and further research revealed that the main influencing factors of inefficiency and ineffectiveness were the geological parameters of the water wells, while the geological parameters of the oil wells served as auxiliary identification conditions. The regulation should focus on the planar control and vertical mobilization of the water wells, with the adjustment and replenishment of the oil wells as a supplement, so as to achieve a virtuous cycle of identification-regulation-change-re-identification-re-regulation.

[0137] Based on the actual situation on site and relying on the results of this invention, a total of 47 wells were treated through methods such as water shut-off and combined production, layer adjustment and replenishment, and fracturing to induce effects; corresponding to 11 water wells, a total of 18 wells were treated through methods such as layer reorganization and intermittent water injection, as shown in the table below.

[0138] Table 1 Oil Well Treatment Status

[0139] governance methods Jingji, mouth Initial daily oil increase, t Cumulative increase in oil, t Adjustment layer 13 10.8 1625 fracture 21 33.1 8102 Water blocking and combined mining 13 10.6 2011 total 47 54.5 11738

[0140] Table 2. Well Treatment Status

[0141] governance methods Jingji, mouth Strong suction thickness reduction, m Increased absorbency thickness, m Segment Reorganization 12 62.2 148.4 Intermittent water injection 5 29.2 42.4 jet nozzle 1 21 31 total 18 112.4 221.8

[0142] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0143] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A method for identifying and regulating inefficient water circulation in the late stage of water injection development of a low-porosity, low-permeability, high-viscosity, and heavy oil reservoir of a pore-fracture dual medium, characterized in that, The method comprises the following steps: Determine the water cut under the economic limit based on the cost and the current oil price, and then obtain the invalid well; Divide each layer of the low-efficiency well and the invalid well into invalid layer, effective layer and enhanced layer according to the water absorption condition; Identify the low-efficiency and invalid water circulation based on the characteristics of the invalid layer and the effective layer by using multiple combination identification methods; identify the invalid water circulation field and the low-efficiency water circulation field by using the invalid water circulation limit of the invalid layer and the low-efficiency water circulation limit of the low-efficiency layer respectively; Implement multiple ways to manage the invalid water circulation field and the low-efficiency water circulation field to improve the secondary oil recovery effect.

2. The method for identifying and regulating the inefficient water circulation in the late water injection development of the low porosity and low permeability and high viscosity and heavy oil reservoir of the pore-fracture double medium according to claim 1, characterized in that, Determine the water cut under the economic limit based on the cost and the current oil price: Put the profit = output - input into the oil production operation to obtain: output = ton of oil profit * oil production = (oil price - ton of oil tax and fee - variable cost) * crude oil commodity rate * oil production + (gas price - thousand square feet of gas tax) * gasoline ratio * natural gas commodity rate * gas production (1) When reaching the economic limit, output = input = fixed cost, so formula (1) is written as: Fixed cost = ton of oil profit * daily liquid production * (1-Fw) * 365 (2) In the formula: Fwel is the economic limit water cut; Fw is the comprehensive water cut of the block; Q L is the average daily liquid production of the block, unit t / day; the threshold value of the economic limit water cut of the block is obtained by bringing the cost of the block and the profit per ton of oil into formula (3), and if the water cut of a well is greater than the threshold value, the well is considered to be an invalid well.

3. The method for identifying and regulating the inefficient water circulation in the late water injection development stage of the low-porosity and low-permeability and high-viscosity and heavy oil reservoirs of the pore-fracture double medium according to claim 1, characterized in that, The way of dividing each layer of the low-efficiency well and the invalid well into invalid layer, effective layer and enhanced layer is: using the water absorption profile data of the water well to determine the water absorption proportion, effective water absorption intensity, interlayer and intralayer meter weighted permeability difference, variation coefficient and breakthrough coefficient of each layer in the low-efficiency well and the invalid well, and combining the liquid production profile and dynamic liquid level change of the oil well to divide each water absorption layer into invalid layer, effective layer and enhanced layer.

4. The method for identifying and regulating the inefficient water circulation in the late water injection development stage of the low-porosity and low-permeability high-viscosity and heavy oil reservoirs of the pore-fracture double medium according to claim 3, characterized in that, The effective water absorption intensity = injection water volume Q* fraction of water absorption of sublayer / effective thickness of water absorption of sublayer Hi(4) as described above The The The where: Kmax is the maximum permeability, Kmin is the minimum permeability, and K is the average permeability.

5. The method for identifying and regulating the inefficient water circulation in the late stage of water injection development of the low porosity and low permeability and high density and viscous oil reservoir of the pore-fracture double medium according to claim 4, characterized in that, The identification way of the invalid layer, effective layer and enhanced layer is: When effective water absorption intensity > N11, meter weighted permeability breakthrough coefficient > N12, meter weighted permeability difference > N13, meter weighted permeability variation coefficient > N14, and the oil well dynamic liquid level rises, the corresponding layer liquid production is mainly water, and the layer is invalid layer; When effective water absorption intensity > N21, meter weighted permeability breakthrough coefficient > N22, meter weighted permeability difference > N23, meter weighted permeability variation coefficient > N24, and the oil well dynamic liquid level is stable, the corresponding layer liquid production is mainly water, and the layer is effective layer; When effective water absorption intensity < N21, meter weighted permeability breakthrough coefficient < N22, meter weighted permeability difference < N23, meter weighted permeability variation coefficient < N24, and the oil well dynamic liquid level slowly drops, the corresponding layer liquid production is low and mainly oil, and the layer is enhanced layer.

6. The method for identifying and regulating the inefficient water circulation in the late water injection development of the low porosity and low permeability and high density and viscous oil reservoir of the pore-fracture double medium according to claim 1, characterized in that, The multiple combination identification methods include: geological and logging data analysis, oil and water well production dynamic change analysis, water absorption capacity dynamic change analysis and recovery factor change analysis.

7. The method for identifying and regulating the inefficient water circulation in the late water injection development stage of the low-porosity and low-permeability and high-viscosity and heavy oil reservoirs of the pore-fracture double medium according to claim 6, characterized in that, The oil and water well production dynamic change analysis includes: Determine the connection condition of each layer of the oil and water well of the well group through the reservoir profile graph and the grid graph; Determine the injection effect relationship of each layer by monitoring the water injection corresponding oil well water breakthrough time; Determine the production dynamic and the oil and water well dynamic effect relationship by monitoring the water injection corresponding oil well water breakthrough time after long-term injection of the water well and then re-injection, and combining the dynamic allocation influence; Divide the strong, medium and weak effect wells and effect layers according to the water breakthrough time and the water content change.

8. The method for identifying and regulating the inefficient water circulation in the late water injection development stage of the low-porosity and low-permeability and high-viscosity and heavy oil reservoirs of the pore-fracture double medium according to claim 6, characterized in that, The dynamic analysis of water absorption capacity is: if the water absorption index increases suddenly, it means that the single-layer water absorption capacity of the water well is suddenly strengthened, forming a large water flow channel, resulting in low-efficiency and ineffective water circulation of the well group; 9. The method for identifying and regulating the inefficient water circulation in the late water injection development stage of the low-porosity and low-permeability and high-viscosity and heavy oil reservoirs of the pore-fracture double medium according to claim 6, characterized in that, The recovery rate change analysis is: using the type A water drive curve to calibrate the recovery rate; The analysis involves the formula of water drive type A: after a period of oilfield production, W p and N P will show a certain linear relationship, that is, lnW p = A + BN P The relationship between cumulative oil production and water cut is: This analysis involves Tong's chart formula: where W p is cumulative water production; N P is cumulative oil production; A is the water drive constant f W is the overall water cut; E R is the recovery factor; and R is the block recovery.

10. The method for identifying and regulating inefficient water circulation in the late stage of water injection development of a low-porosity and low-permeability and high-viscosity and heavy oil reservoir with pore-fracture double media according to claim 1, characterized in that, Various treatment methods include: For the treatment of oil well ineffective water circulation field and low-efficiency water circulation field, the treatment methods include adjusting and supplementing layers, fracturing, and water plugging and combination production; For the treatment of water well ineffective water circulation field and low-efficiency water circulation field, the treatment methods include layer reorganization, intermittent water injection, and jet nozzle.

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