Method for sealing reserves after water flooding well releases chemical flooding

Abstract

The invention relates to a method for sealing reserves after chemical flooding is released by a water flooding well, and relates to the technical field of oil exploitation, and the method specifically comprises the following steps: selecting a well located on a diversion line of a target block as a target well according to acquired stratum interpretation data and well pattern plane position data; according to the obtained dynamic production data, the target well is optimized, and the well with the oil production and the water content meeting the preset requirements is determined as the optimized well; and determining a non-riverway layer, the upper part of the riverway layer and a layer of which the effective thickness of a small layer is smaller than or equal to a preset thickness in the preferable well as preferable layers according to the stratum interpretation data, unsealing and opening the preferable layers by utilizing the water drive well, carrying out water drive development, and completing the release of the sealed reserves of the target block. The problems that the sealed reservoir cannot provide yield, the thickness of a production layer is insufficient and remaining oil cannot be excavated to the maximum extent due to the fact that part of oil reservoir reserves need to be sealed for storage when the reservoir is subjected to up-down development in the past are solved.

Description

Technical Field

[0001] The invention relates to the technical field of oil exploitation, and in particular to a method for releasing sealed storage capacity after chemical flooding by using a water flooding well. Background Art

[0002] my country's oil resources are distributed in sedimentary oil-generating environments dominated by continental strata, most of which are sandstone reservoirs, accounting for more than 90%. The development method is mainly water injection development, which has the characteristics of severe heterogeneity and high oil density. The oil fields dominated by continental sandstone reservoirs include Daqing Oilfield, Shengli Oilfield, Yanchang Oil Mine, Liaohe Oilfield, Xinjiang Oilfield and Changqing Oilfield.

[0003] Since 1996, the oil field has clearly carried out tertiary oil recovery development for two types of oil layers, namely Class I (river sand with permeability greater than 800md and effective thickness greater than 4m) and Class II (river sand with permeability greater than 100md and effective thickness greater than 1m). At present, all Class I oil layers have been put into tertiary oil recovery development, and Class II oil layers have been gradually put into polymer flooding development in 2002. As of now, the remaining geological reserves of Class II oil layers exceed 780 million tons, and the remaining developable strata range from 1 to 5 sets.

[0004] At present, there are multiple displacement methods coexisting in the oil field, including water drive and polymer drive. Because the polymer drive well network utilizes upflow and the sealed reserves are still the largest and earliest in the country and even in the world, the Class II oil layers have begun secondary upflow development. As the secondary upflow and downflow reserves of the Class II oil layers increase year by year, the first set of upflow layer systems have been gradually sealed. As of the end of 2021, the first set of reserves of the Class II oil layers has been sealed at 96.03 million tons.

[0005] With the tertiary oil recovery well network of the second type oil layer utilizing the upper and lower return to develop other strata, the reserves of the original strata are sealed, which seriously affects the production contribution of the sealed strata. At the same time, after the water drive well network cooperates with the upper and lower return chemical drive to seal the target stratum, the effective thickness of the production stratum is obviously insufficient, and the sealed reserves are returned to the water drive well development. In order to better coordinate the water and polymer drive well networks, it is necessary to design a development method that utilizes the water drive well network to unseal the sealed strata and maximize the exploitation of the remaining oil. Summary of the invention

[0006] The present invention proposes a method for releasing sealed reserves after chemical flooding by using water flooding wells, so as to solve the problem that part of the oil layer reserves need to be sealed for up and down development of the reservoir in the past, resulting in the sealed reservoir being unable to provide production, the production layer thickness is insufficient, and the remaining oil cannot be mined to the maximum extent.

[0007] According to one aspect of the present invention, there is provided a method for releasing the stored capacity after chemical flooding by using a water flooding well, comprising:

[0008] Obtain stratigraphic interpretation data, well network plane position data and dynamic production data of each well network in the target block;

[0009] According to the formation interpretation data and the well pattern plane position data, a well on the diversion line of the target block is selected as a target well, and the flooding degree of the target well must be lower than the average flooding degree of the wells on the main flow line;

[0010] According to the dynamic production data, the target wells are selected to determine the wells whose oil production and water content meet the predetermined requirements as the preferred wells;

[0011] According to the stratigraphic interpretation data, the non-channel layer, the upper part of the channel layer and the small layer with an effective thickness less than or equal to the predetermined thickness in the preferred well are determined to be the preferred layers, and the preferred layers are unsealed and opened by using water drive wells for water drive development to complete the release of the sealed storage capacity in the target block.

[0012] Preferably, the predetermined requirements include:

[0013] The oil production is less than 1 ton, and the water content is higher than 96%.

[0014] Preferably, the method of unsealing and opening the preferred layer by using a water drive well comprises:

[0015] Determine whether the non-channel layer, the upper part of the channel layer, and the small layer with a thickness less than or equal to a predetermined thickness have been perforated, if yes, unblock the perforation position of the layer, if not, supplement the layer with perforation;

[0016] After the plugging or supplementary injection is completed, water injection development is carried out using the water drive wells connected to the preferred layer.

[0017] Preferably, the predetermined thickness is: 1 meter.

[0018] Preferably, before unsealing and opening the preferred layer by using a water drive well, the method further comprises:

[0019] If the total thickness of all the preferred layers in the preferred well is greater than or equal to 5 m, then determine whether there are layers with a producing degree greater than a predetermined producing degree and layers with a water washing degree greater than a predetermined water washing degree in the preferred layers;

[0020] If yes, then in the preferred layer, one or more layers among the layers with a mobilization degree greater than a predetermined mobilization degree and a layer with a water washing degree greater than a predetermined water washing degree are eliminated, and the total thickness of the preferred layer after elimination is ensured to be greater than or equal to 5m.

[0021] Preferably, the method for determining whether there is a layer in the preferred layer whose utilization degree is greater than a predetermined utilization degree includes:

[0022] Obtaining a water absorption profile corresponding to the preferred layer;

[0023] If the water absorption ratio of the layer on the water absorption profile is greater than 80%, the mobilization degree of the preferred layer is greater than the predetermined mobilization degree.

[0024] Preferably, the method for judging whether there is a layer having a water washing degree greater than a predetermined water washing degree in the preferred layer comprises:

[0025] Acquire the completed closed coring well data of the preferred layer;

[0026] According to the data of the completed closed coring well, it is determined that the thickness ratio of the water-washed section corresponding to the preferred layer is greater than 85%, and the water-washing degree of the preferred layer is greater than the predetermined water-washing degree.

[0027] Preferably, it also includes:

[0028] The oil production of the preferred layer after development is predicted by using water drive law curve, decline curve and comprehensive curve method;

[0029] Determine the operating cost required for opening the preferred layer by water flooding wells and conducting water flooding development;

[0030] Based on the oil production prediction result and the operating cost, determine whether the preferred layer of the block can release the sealed storage capacity.

[0031] The present invention has at least the following beneficial effects:

[0032] The present invention proposes a method for releasing sealed storage after chemical flooding by using water-flooding wells. According to the stratigraphic interpretation data, plane position data and dynamic production data of the stratum well network of the currently developed block, the distribution characteristics of the remaining oil after chemical flooding in the block are determined, the preferred wells and preferred layers in the block are selected for releasing the sealed storage, and the development mode of the water-flooding well network to unseal the sealed layers is determined, so that the coordination of the water-flooding and polymer-flooding well networks is more reasonable and the remaining oil is excavated to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present invention and, together with the specification, are used to explain the technical solutions of the present invention.

[0034] Figure 1 A flow chart showing a method for releasing sealed storage capacity after chemical flooding by using a water flooding well according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of a well pattern of block A according to an embodiment of the present invention is shown;

[0036] Figure 3A schematic diagram of the well locations in the northern part of Block A according to an embodiment of the present invention is shown;

[0037] Figure 4 A schematic diagram of well locations in the south-central part of Block A according to an embodiment of the present invention is shown;

[0038] Figure 5 A schematic diagram of well locations in the southern part of Block A according to an embodiment of the present invention is shown;

[0039] Figure 6 A schematic diagram of well locations in the transition zone of Block A according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0040] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0041] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0042] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0043] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0044] Figure 1 A flow chart showing a method for releasing sealed storage capacity after chemical flooding by using a water flooding well according to an embodiment of the present invention; Figure 2 A schematic diagram of a well pattern of block A according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of the well locations in the northern part of Block A according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of well locations in the south-central part of Block A according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of well locations in the southern part of Block A according to an embodiment of the present invention is shown; Figure 6A schematic diagram of the well locations in the transition zone of Block A according to an embodiment of the present invention is shown. Figure 1-6 As shown, a method for releasing sealed storage after chemical flooding by using water-flooding wells comprises: step S01: acquiring formation interpretation data, well network plane position data and dynamic production data of each set of well networks on the target block; step S02: selecting a well on the diversion line of the target block as a target well according to the formation interpretation data and the well network plane position data, and the water flooding degree of the target well must be lower than the average water flooding degree of the wells on the main line; step S03: optimizing the target wells according to the dynamic production data, and determining the wells whose oil production and water content meet the predetermined requirements as the preferred wells; step S04: determining the non-channel layer, the upper part of the channel layer and the layer with the effective thickness of the small layer less than or equal to the predetermined thickness in the preferred wells according to the formation interpretation data as the preferred layer, unsealing and opening the preferred layer by using the water-flooding well, carrying out water-flooding development, and completing the release of the sealed storage in the target block.

[0045] The method for releasing the stored capacity after chemical flooding by using a water flooding well provided in an embodiment of the present invention specifically comprises the following steps:

[0046] Step S01: Acquire the stratigraphic interpretation data, well pattern plane position data and dynamic production data of each set of well patterns in the target block.

[0047] In the embodiment of the present invention, the deployment and development status of each set of water drive and polymer drive well networks on the block since it was put into production are obtained, and the relationship between each set of well networks is clarified according to the plane position data of the well network; the static data of the perforation layer includes depth and effective thickness; various types of well networks are clarified, the water drive well network includes basic, primary infill, secondary infill, and tertiary infill wells, and the polymer drive well network includes the dynamic production data of the first set and second set of well networks of the first oil layer and the second oil layer, including the total number of wells, the number of wells opened, daily liquid production, daily oil production and water content.

[0048] Step S02: According to the formation interpretation data and the well pattern plane position data, a well on the diversion line of the target block is selected as a target well, and the flooding degree of the target well must be lower than the average flooding degree of the wells on the main flow line.

[0049] In the embodiment of the present invention, wells on the diversion line can be found in the plane position of the well pattern according to the formation interpretation data. Usually, the water flooding degree of the diversion line wells is lower than that of the main line wells. To select which wells on the diversion line as candidate wells for subsequent unblocking, i.e., target wells, it is necessary to compare the average water flooding degree of the wells on the diversion line with that of the wells on the main line. If the well is on the diversion line and the water flooding degree is lower than the average of the main line wells, the well can be used as the target well; if the water flooding degree is higher than the average of the main line wells, it means that although the well is on the diversion line, its water flooding degree is too high and it is not suitable for subsequent unblocking.

[0050] Step S03: According to the dynamic production data, the target wells are optimized, and the wells whose oil production and water content meet the predetermined requirements are determined as the preferred wells.

[0051] In the present invention, the predetermined requirements include: the oil production is less than 1 ton, and the water content is higher than 96%.

[0052] In the embodiment of the present invention, according to the statistical results of the effects of previous unsealing and plugging wells, it is shown that the higher the water content and the lower the oil production before plugging, the better the effect after plugging or unplugging. Wells with a water content of more than 96% have obvious oil increase, and wells with a water content of more than 98% have an average oil increase of 1.046t. There are 11 wells with a daily oil production of less than 0.26t, and the average single well oil increase is 0.951t.

[0053] Step S04: According to the stratigraphic interpretation data, the non-channel layer, the upper part of the channel layer, and the small layer with an effective thickness less than or equal to a predetermined thickness in the preferred well are determined as the preferred layer, and the preferred layer is unsealed and opened by using a water drive well to carry out water drive development, thereby completing the release of the sealed storage capacity of the target block.

[0054] In the present invention, the predetermined thickness is: 1 meter.

[0055] In the embodiment of the present invention, for the non-river layer, its flooding degree is lower than that of the river layer, then it is necessary to select the non-river layer for unsealing; for the river layer, the flooding degree of the upper part is lower than that of the lower part, then it is necessary to unseale the upper part of the river layer; the larger the thickness of the small layer, the higher the flooding degree, then it is necessary to select a thin layer with an effective thickness of less than or equal to 1m for unsealing.

[0056] In the present invention, the method of unsealing and opening the preferred layer by using a water drive well comprises: judging whether the non-channel layer, the upper part of the channel layer and the layer with a small layer thickness less than or equal to a predetermined thickness have perforations, and if so, unplugging the perforation position of the layer, and if not, supplementing the layer; after unplugging or supplementing, water injection development is carried out by using a water drive well connected to the corresponding preferred layer.

[0057] In the embodiment of the present invention, after perforation or plugging removal is completed, water injection development is carried out using the water wells connected to the preferred layer to complete the release of the storage volume of the preferred layers in all the preferred wells.

[0058] In the present invention, before the preferred layer is unsealed and opened by using a water drive well, it also includes: if the total thickness of all the preferred layers in the preferred well is greater than or equal to 5m, then it is determined whether there are layers with a production degree greater than a predetermined production degree and layers with a water washing degree greater than a predetermined water washing degree in the preferred layer; if so, then in the preferred layer, one or more layers of the layers with a production degree greater than the predetermined production degree and the layers with a water washing degree greater than the predetermined water washing degree are removed, and it is ensured that the total thickness of the preferred layers after removal is greater than or equal to 5m.

[0059] In the embodiment of the present invention, if the total thickness of all existing non-channel layers, channel layers, and small layers with an effective thickness of less than or equal to 1m in the preferred well is greater than or equal to 5m, the thickness of the reservoir that can be unsealed in the preferred well is relatively large. In order to save development costs, the layers with a high degree of water washing and production can be removed and not unsealed. If the total thickness of all preferred layers in the preferred well is less than 5m, the thickness of the reservoir that can be unsealed in the preferred well is relatively small. At this time, if the water-washed layers and the layers with a high degree of production are removed, the overall production after unsealing is low and cannot meet the needs, so they are not removed.

[0060] In the present invention, the method for determining whether there is a layer in the preferred layer whose mobilization degree is greater than the predetermined mobilization degree includes: obtaining the water absorption profile corresponding to the preferred layer; if the water absorption ratio on the water absorption profile of the layer is greater than 80%, then the mobilization degree of the preferred layer is greater than the predetermined mobilization degree.

[0061] In the present invention, a method for determining whether there is a layer in the preferred layer whose water washing degree is greater than a predetermined water washing degree comprises: obtaining data of a completed drilled and closed coring well of the preferred layer; and determining, based on the data of the completed drilled and closed coring well, that the thickness ratio of the water washing section corresponding to the preferred layer is greater than 85%, then the water washing degree of the preferred layer is greater than the predetermined water washing degree.

[0062] In an embodiment of the present invention, a method for water-drive development of the preferred layer includes: determining a water-drive well network for developing the preferred wells in the block, and using the water wells in the water-drive well network that are connected to the preferred layer to water-drive development of the preferred layer. Among them, the method for determining a water-drive well network for unblocking the preferred wells in the block includes: selecting a water-drive well network that is interconnected with the preferred layer and has the most water-drive wells on the diversion line among all water-drive well networks, or selecting a water-drive well network that is interconnected with the preferred layer and has not been developed for the preferred layer. Among them, if a preferred layer corresponds to multiple water wells in the water-drive well network determined to be unblocked, the water well with the highest water content is selected for water-drive development.

[0063] In the embodiments of the present invention and Figure 2In the A area, it was put into development in 1974. The water drive well network includes the basic well network, primary, secondary and tertiary infill wells, and the polymer drive well network includes the first and second sets of well networks for Class I oil layers and Class II oil layers. Among them, there are 5 sets of primary infill well networks, including well networks with numbers "4 to 8", and the secondary infill well network includes two sets of well networks with numbers "1" and "2". The wells with numbers "7" and "6" in the primary well network and the wells with numbers "2" in the secondary infill wells are in the same well field as the basic wells.

[0064] As of March 2022, there are 1,230 wells in total, including 705 oil production wells and 525 injection wells. 1,188 wells are in normal operation, including 684 oil production wells, with an average daily oil production of 1.8 tons per well, a comprehensive water cut of 96.6%, a cumulative oil production of 42.5865 million tons, a cumulative oil production of 39.4608 million tons, and a recovery rate of 53.0%. The dynamic production of oil production wells in Area A is shown in Table 1 below.

[0065] Table 1: Production status of oil wells in Area A

[0066]

[0067]

[0068] From the interpretation results of water flooding of new wells drilled in Area A since 2015, the SIII4-10 oil layer is mainly flooded with high and medium levels, with 83.8% of the area being flooded with high and medium levels, 14.4% being flooded with low levels, and 1.8% being unflooded. The thickness of the low unflooded layer of SIII4-10 is 1.65m, accounting for 16.2% of the effective thickness of the area. There are 27 wells with a low unflooded thickness of less than 0.5m, accounting for 13%, and 12 wells with a low unflooded thickness of more than 4m.

[0069] The flooding degree of the wells in the diversion line in area A is lower than that of the wells in the main flow line. The low flooding degree of the wells in the diversion line is nearly 5 percentage points higher than that of the wells in the main flow line, and the high flooding ratio is 7.36%. Therefore, it is necessary to unblock the wells on the diversion line.

[0070] In area A, the proportion of layers with a thickness of less than 0.5 meters that were not flooded was 6.7%, and the layers with a thickness of more than 1 meter were all flooded. Therefore, it is necessary to select small layers with a thickness of less than 1m for unsealing.

[0071] The non-channel layer in area A has a higher degree of non-flooding than the channel layer, and the effective thickness ratio of the non-channel layer is 10.7 percentage points higher than that of the channel development layer, and the high flooding ratio is 16.48% lower. Therefore, the non-channel layer is selected for unsealing.

[0072] The flooding degree of the lower part of the river channel layer in area A is significantly higher than that of the upper part. The lower part of the river channel is flooded, and the proportion of high flooding is 18.6% higher than that of the upper part, and the proportion of low flooding is 5.9% lower. Therefore, the upper part of the river channel layer is selected for unblocking.

[0073] Finally, a total of 40 preferred wells were selected in Area A, dividing the block into four parts: the north, central-south, south, and transition zone. For each part, a suitable water drive well network was selected to unblock the preferred wells in that part.

[0074] like Figure 3 As shown, the well network in the northern part of the block includes four water drive well networks, namely the basic well network, the "2" well network, the "6" well network and the transition zone "0" well network. According to the well network relationship, the "2" well network is located on the diversion line of the second-class oil layer polymer drive well network. The production layer is an oil layer with low permeability. The water flooding degree of the upper part of the thick oil layer with remaining oil is 18.6% lower than that of the lower part, and the non-river layer is less flooded than the river layer. The "2" well network with enlarged well spacing to 300m (relative to the 150m well spacing of the second-class oil layer polymer drive) is selected to unseal the preferred layers of the preferred wells in the north, and to open up the top of the river layer and the non-river layer that have not been perforated. This unsealing method has a small workload and only requires unplugging and re-perforating of the currently sealed wells. It requires low costs and has great promotion potential. Attachment Figure 3 .

[0075] like Figure 4 As shown, in the central and southern part of the block, there are 4 sets of water drive well networks, namely "1", "7", "8" and the basic well network. Among them, the "1" well and the "8" well have never exploited the SIII group oil layer. The basic well network and the "1" well and the "8" well form a 150m five-point area well network, change the injection and production flow line, and the "1" well and the "8" well completely open the top of the river layer and the non-river layer of the SIII4-10 oil layer. The higher the water content of the water drive oil well, the better the oil increase effect after unblocking. The basic well network with higher water content is preferably used to construct a well group for release. The change of the original injection and production flow line is conducive to the potential of the remaining oil; the original development layer of the "8" well network is GI6-GII18, and the SIII4-10 oil layer is a newly produced layer. In the future, this method can be used for unblocking when the three types of oil layers are tertiary oil production.

[0076] like Figure 5 As shown in the figure, the southern part of the block enters the oil and gas buffer zone of the block, and also develops 4 sets of water drive well networks, which are composed of "1", "7", "8" and the basic well network. Only the basic well network is used to develop the preferred layer. In order to avoid gas channeling in the oil and gas zone and take into account the cost, the basic well network is used to form a row well network to release the sealed storage capacity. This unsealing method has a small workload and only requires unplugging and re-perforating the currently sealed wells, which requires low costs.

[0077] like Figure 6As shown in the figure, there are three sets of water drive well networks in the transition zone, including the basic well network, "2" and "0" well networks. The basic well network is only distributed in one of the belts in the transition zone, and the "0" well network is all oil wells. According to the conditions that the water flooding degree of the diversion line wells is lower than that of the main line wells, and the high water flooding ratio is less than 7.36%, in order to form a transfer line well network to develop the remaining oil in the diversion line of the original polymer drive well network, the transition zone uses the "2" water wells and the "0" oil well network to form a 212m five-point method well network, forming a variable well spacing well network development, filling holes and unlocking the top of the river layer (thick oil layer) and the non-river oil layer, and fully tapping the potential of the remaining oil.

[0078] The present invention also includes: using a water drive law curve, a decline curve, and a comprehensive curve method to predict the oil production of the preferred layer after development; determining the operating cost required for the water drive development process of unsealing the preferred layer using a water drive well; and determining whether the preferred layer of the block can release the sealed storage capacity based on the oil production prediction result and the operating cost.

[0079] In the embodiment of the present invention, multiple methods such as water drive law curve, decline curve and comprehensive curve method are used to predict development indicators to ensure that the prediction accuracy is reliable and the evaluation results are available.

[0080] According to the workload of development and design such as perforation repair and water-to-oil conversion, various cost indicators are given, including operating costs and test expenses, and combined with production data, economic benefit evaluation under different oil prices is carried out. By comparing two oil prices, the ladder oil price: 40 US dollars / barrel in the first year, 40 US dollars / barrel in the second year, 50 US dollars / barrel in the third year, and 60 US dollars / barrel from then to the tenth year, and the financial net present value, total profit, internal rate of return and investment payback period under the 10-year crude oil price of 60 US dollars / barrel, the feasibility of the unblocking development method is determined.

[0081] In the embodiment of the present invention, the method for releasing sealed storage capacity according to the present invention is implemented in a total of 67 wells in Area A, including 40 oil wells and 27 water wells. It is predicted that the cumulative oil production in 10 years will be 433,700 tons, and the oil production will increase by 93,700 tons. The detailed prediction results are shown in Table 2 below.

[0082] Table 2: Development results prediction table

[0083]

[0084]

[0085] According to the analysis, the operating cost of the plan for 10 years is 229.75 million yuan, including 19.627 million yuan for the test. The crude oil price is calculated at 60 US dollars per barrel, the financial net present value is 7.028 million yuan, the total profit is 2.257 million yuan, the financial internal rate of return after income tax is 16.4%, and the investment payback period is 4.2 years, which is economically feasible. The specific profit forecast results are shown in Table 3 below.

[0086] Table 3: Revenue forecast analysis results

[0087]

[0088] According to the operating costs of the above-mentioned method of releasing sealed storage capacity and the production revenue results after release, the operating costs of the development investment in the preferred layer are less than the revenue brought by the oil production forecast results, and it is determined that the sealed storage capacity of the preferred layer of the block can be released.

[0089] It can be understood that the above-mentioned various method embodiments mentioned in the present invention can be combined with each other to form a combined embodiment without violating the principle logic. Due to space limitations, the present invention will not go into details.

[0090] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0091] The present invention determines the distribution of remaining oil after chemical flooding in the block based on the plane position data, formation interpretation data and dynamic production data of the stratum well network of the currently developed block, and creatively proposes a method for releasing sealed storage capacity. The method for releasing sealed storage capacity of the present invention can determine the unsealing and development mode of the water-driven well network, so that the coordination of the water-driven and polymer-driven well networks is more reasonable, and the remaining oil is excavated to the maximum extent. At the same time, it provides a reference for the development of the potential of the future sealed blocks. This method for releasing sealed storage capacity is the first of its kind at home and abroad, providing technical support for the unsealing of sealed storage capacity and the comprehensive utilization of water-driven well networks in the future, and plays a huge role in supporting the comprehensive utilization and adjustment technology of the well network of my country's continental oil fields.

[0092] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for releasing the stored capacity after chemical flooding by using a water flooding well, characterized in that: include: Obtain stratigraphic interpretation data, well network plane position data and dynamic production data of each well network in the target block; According to the formation interpretation data and the well pattern plane position data, a well on the diversion line of the target block is selected as a target well, and the flooding degree of the target well must be lower than the average flooding degree of the wells on the main flow line; According to the dynamic production data, the target wells are selected to determine the wells whose oil production and water content meet the predetermined requirements as the preferred wells; According to the stratigraphic interpretation data, the non-channel layer, the upper part of the channel layer and the small layer with an effective thickness less than or equal to the predetermined thickness in the preferred well are determined to be the preferred layers, and the preferred layers are unsealed and opened by using water drive wells for water drive development to complete the release of the sealed storage capacity in the target block.

2. The method for releasing the stored capacity after chemical flooding by using a water flooding well according to claim 1, characterized in that: The reservation requirements include: The oil production is less than 1 ton, and the water content is higher than 96%.

3. The method of releasing the stored capacity after chemical flooding by using a water flooding well according to claim 1, characterized in that: The method of unsealing and opening the preferred layer by using a water drive well comprises: Determine whether the non-channel layer, the upper part of the channel layer, and the small layer with a thickness less than or equal to a predetermined thickness have been perforated, if yes, unblock the perforation position of the layer, if not, supplement the layer with perforation; After the plugging or supplementary injection is completed, water injection development is carried out using the water drive wells connected to the preferred layer.

4. The method of releasing the stored capacity after chemical flooding by using a water flooding well according to claim 1, characterized in that: The predetermined thickness is: 1 meter.

5. The method of releasing the stored capacity after chemical flooding by using water flooding wells according to claim 1, characterized in that: Before the preferred layer is unsealed and opened by using a water drive well, the method further includes: If the total thickness of all the preferred layers in the preferred well is greater than or equal to 5 m, then determine whether there are layers with a producing degree greater than a predetermined producing degree and layers with a water washing degree greater than a predetermined water washing degree in the preferred layers; If yes, then in the preferred layer, one or more layers among the layers with a mobilization degree greater than a predetermined mobilization degree and a layer with a water washing degree greater than a predetermined water washing degree are eliminated, and the total thickness of the preferred layer after elimination is ensured to be greater than or equal to 5m.

6. The method of releasing the stored capacity after chemical flooding by using a water flooding well according to claim 5, characterized in that: The method for determining whether there is a layer in the preferred layer whose utilization degree is greater than a predetermined utilization degree includes: Obtaining a water absorption profile corresponding to the preferred layer; If the water absorption ratio of the layer on the water absorption profile is greater than 80%, the mobilization degree of the preferred layer is greater than the predetermined mobilization degree.

7. The method of releasing the stored capacity after chemical flooding by using a water flooding well according to claim 1, characterized in that: The method for determining whether there is a layer having a water washing degree greater than a predetermined water washing degree in the preferred layer comprises: Acquire the completed closed coring well data of the preferred layer; According to the data of the completed closed coring well, it is determined that the thickness ratio of the water-washed section corresponding to the preferred layer is greater than 85%, and the water-washing degree of the preferred layer is greater than the predetermined water-washing degree.

8. The method for releasing the stored capacity after chemical flooding by using a water flooding well according to any one of claims 1 to 7, characterized in that: Also includes: The oil production of the preferred layer after development is predicted by using water drive law curve, decline curve and comprehensive curve method; Determine the operating cost required for opening the preferred layer by water flooding wells and conducting water flooding development; Based on the oil production prediction result and the operating cost, determine whether the preferred layer of the block can release the sealed storage capacity.

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