A method and device for determining large pore volume of high-middle permeability oilfield small layer

Abstract

The present application relates to the technical field of oilfield water flooding development adjustment, and particularly relates to a method and device for determining pore volume of large pore channels in small layers in a medium-high permeability oilfield, which comprises the following steps: determining the mobility before and after the development of large pore channels according to the water absorption of small layers, porosity, effective thickness of small layers, bottom hole flowing pressure of injection wells, bottom hole flowing pressure of production wells, injection-production well spacing and wellbore radius; determining the mobility variation before and after the development of large pore channels according to the mobility before and after the development of large pore channels, and determining the water absorption variation before and after the development of large pore channels according to the water absorption of small layers before and after the development of large pore channels; determining the seepage time of injected water from the bottom of a water well to the bottom of an oil well according to the mobility variation, and determining the pore volume of well groups according to the seepage time and the water absorption variation. The present application takes into account factors such as irregular well pattern and heterogeneity, and can obtain accurate pore volume of large pore channels in different small layers, thereby providing a basis and guidance for the optimization of oilfield development adjustment parameters.

Description

Technical Field

[0001] This invention relates to the field of oilfield water drive development and adjustment technology, and in particular to a method and apparatus for determining the pore volume of small-level large-channel pores in medium-to-high permeability oilfields. Background Technology

[0002] Medium- and high-permeability oilfields are the mainstay of my country's crude oil production and efficiency development, playing a vital role in ensuring national energy security. With the deepening development of these oilfields, they have generally entered the high and ultra-high water-cut development stage. After long-term water injection erosion, the oil reservoirs have formed complex large-scale channels with ineffective water injection circulation, leading to a year-on-year decline in oilfield production and low water injection efficiency. This poses a severe challenge to the stable production and efficient development of these oilfields.

[0003] Water injection, profile control, and water shut-off are the main methods for managing large pores during the high water-cut development phase, but they suffer from poor effectiveness and short-term sustainability. To improve oilfield development, it is necessary to accurately determine the pore volume of large pores during the high water-cut phase, guiding the optimization design of injection and production parameters for water injection, profile control, and water shut-off techniques. This will help control water cut, ensure continuous oilfield production, and improve the effectiveness and benefits of water injection development. Therefore, accurately calculating the pore volume of large pores in medium-to-high permeability oilfields is of significant practical importance for improving the water-driven development of older high water-cut oilfields.

[0004] Currently, existing methods for calculating the pore volume of large channels have the following main problems: 1. Existing methods cannot calculate the pore volume of large channels under complex well network conditions. Medium-to-high permeability oilfields have large effective thicknesses and numerous sub-layers. Based on the permeability and effective thickness of each sub-layer, layer combinations are made, and different well networks are used for different types of combined layers, resulting in diverse well network forms and varying well and row spacing. Existing methods do not consider this factor and are only applicable to rectangular regular well network conditions (square five-point method, inverse nine-point method well network), and are not applicable to complex well network conditions; 2. Existing methods cannot calculate the pore volume of large channels in small layers. Medium-to-high permeability reservoirs have strong planar and vertical heterogeneity, and the degree of ineffective circulation varies among different sub-layers, resulting in large differences in the pore volume of large channels. Layered calculations are required, but existing methods do not consider this factor. They often consider the oilfield or well group as a whole when calculating the pore volume of large channels, leading to large discrepancies between the calculated results and the actual situation on site, resulting in poor treatment effects. Summary of the Invention

[0005] This invention proposes a method and apparatus for determining the pore volume of large channels in small layers of medium-high permeability oilfields. This addresses the problems of existing methods for calculating the pore volume of large channels, which suffer from poor applicability, significant limitations, large discrepancies between calculation results and field conditions, inability to accurately calculate the pore volume of large channels in small layers, inability to effectively guide oilfield development adjustments, and failure to meet the needs of precise development in medium-high permeability, high water-cut old oilfields.

[0006] According to one aspect of the present invention, a method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields is provided, comprising:

[0007] The study area obtained the water absorption, porosity, effective thickness of the sub-layers before and after the development of large channels, the bottom-hole flowing pressure of injection wells before and after the development of large channels, the bottom-hole flowing pressure of production wells, the injection-production well spacing, and the wellbore radius before and after the development of large channels.

[0008] Based on the water absorption of the sublayer, porosity, effective thickness of the sublayer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well distance, and wellbore radius, determine the flowability before and after the development of large channels;

[0009] Based on the flow rate before and after the development of the large pores, determine the change in flow rate before and after the development of the large pores; based on the water absorption of the small layer before and after the development of the large pores, determine the change in water absorption of the small layer before and after the development of the large pores.

[0010] Based on the change in mobility, the seepage time of injected water from the bottom of the water well to the bottom of the oil well is determined, and based on the seepage time and the change in water absorption, the pore volume of the well group is determined.

[0011] Preferably, the method for determining the mobility before and after large-channel development based on the sublayer's water absorption, porosity, effective thickness, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well spacing, and wellbore radius includes:

[0012] Based on the water absorption of the small layer before the development of the large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the water injection well, as well as the effective thickness, porosity, injection-production well spacing and well radius of the small layer, the flowability before the development of the large pores is determined.

[0013] Based on the water absorption of the sub-layer after the development of the large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the water injection well, as well as the effective thickness of the sub-layer, porosity, injection-production well spacing and wellbore radius, the flow rate after the development of the large pores is determined.

[0014] Preferably, the method for determining the mobility before the development of large pores based on the water absorption of the small layer before the development of large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness, porosity, injection-production well spacing and wellbore radius of the small layer, includes:

[0015] The flowability Λ1 before the development of large channels is calculated using equation (1);

[0016]

[0017] In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P Xi The bottom-hole flowing pressure of the injection well before the development of large channels, in MPa; P XwThe bottomhole flowing pressure of the production well before the development of large pores is denoted as MPa; L is the injection-production well distance, m; r w Let be the radius of the wellbore, in meters (m).

[0018] Preferably, the method for determining the mobility after the development of large pores based on the water absorption of the small layer after the development of large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness of the small layer, porosity, injection-production well spacing and wellbore radius, includes:

[0019] The flowability Λ2 before the development of large channels is calculated using equation (2);

[0020]

[0021] In the formula: Q2 is the water absorption of the small layer after the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P i The bottom-hole flowing pressure of the injection well after the development of large-channel water injection is measured in MPa; P w The bottomhole flowing pressure of the production well after the development of large pores is in MPa; L is the injection-production well distance in meters; r w Let be the radius of the wellbore, in meters (m).

[0022] Preferably, the method for determining the change in flow rate before and after the development of the large-aperture channel based on the flow rate before and after the development of the large-aperture channel includes:

[0023] The change in flowability Λ before and after the development of large channels was calculated using equation (3);

[0024] Λ=Λ2-Λ1 (3);

[0025] In the formula: Λ1 is the flowability before the development of large pores, D / (mPa·s); Λ2 is the flowability after the development of large pores, D / (mPa·s).

[0026] Preferably, the method for determining the change in water absorption of the sublayer before and after the development of the macropores, based on the water absorption of the sublayer before and after the development of the macropores, includes:

[0027] The change in water absorption Q of the sublayer before and after the development of large pores was calculated using equation (4);

[0028] Q = Q2 - Q1 (4);

[0029] In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 Q2 represents the water absorption of the sublayer after the development of large pores, in meters. 3 .

[0030] Preferably, the method for determining the seepage time of injected water from the bottom of a water well to the bottom of an oil well based on the change in mobility includes:

[0031] The seepage time T of the injected water from the bottom of the water well to the bottom of the oil well is calculated using equation (5);

[0032]

[0033] In the formula: φ is porosity, L is the injection-production well distance (m); r w Λ is the wellbore radius, in meters; D is the change in fluid mobility before and after the development of large pores, in meters per second (mPa·s); P is the fluid velocity. w The bottom hole flowing pressure of the oil well after the development of large pores; P i The bottom-hole flowing pressure of the injection well after the development of large-channel systems; f w ′(S w ) represents the water saturation level S w The rate of increase in water production rate under the given conditions, %.

[0034] Preferably, the method for determining the pore volume of the well group based on the seepage time and the change in water absorption includes:

[0035] The well group pore volume Φ is calculated using equation (6);

[0036] Φ=QT (6);

[0037] In the formula: Q represents the change in water absorption in the microlayer before and after the development of macropores, in meters. 3 T represents the seepage time of the injected water from the bottom of the water well to the bottom of the oil well.

[0038] Preferably, before obtaining the effective thickness of the sublayer, the method for determining the effective thickness of the sublayer includes:

[0039] The effective thickness H of the sublayer is calculated using equation (7);

[0040]

[0041] Where: h i Let be the effective thickness of the sublayer in the i-th well, in m; i is a constant, and 0 ≤ i ≤ n.

[0042] Preferably, before obtaining the injection-production well spacing, the injection-production well spacing is determined, and the method includes:

[0043] The injection-production well spacing L is calculated using equation (8);

[0044]

[0045] In the formula: a is the distance between the water well row and the oil well row, in meters; b is half the distance between adjacent oil wells, in meters.

[0046] According to one aspect of the present invention, a device for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields is provided, comprising:

[0047] The acquisition unit is used to acquire the water absorption, porosity, effective thickness of the sublayer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and well radius of the study area before and after the development of large channels.

[0048] The mobility determination unit is used to determine the mobility before and after the development of large channels based on the water absorption of the sub-layer, porosity, effective thickness of the sub-layer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well distance, and wellbore radius.

[0049] The unit for determining the change in flowability and water absorption of the small layer is used to determine the change in flowability before and after the development of the large pores based on the flowability before and after the development of the large pores, and to determine the change in water absorption of the small layer before and after the development of the large pores based on the water absorption of the small layer before and after the development of the large pores.

[0050] The pore volume determination unit is used to determine the seepage time of injected water from the bottom of the water well to the bottom of the oil well based on the change in mobility, and to determine the pore volume of the well group based on the seepage time and the change in water absorption.

[0051] The present invention has at least the following beneficial effects:

[0052] This invention proposes a method and apparatus for determining the pore volume of large channels in small layers of medium-high permeability oilfields. By obtaining parameters, the change in mobility before and after the development of large channels is determined, and the pore volume of large channels in small layers is determined based on this change in mobility. Taking into account factors such as irregular well pattern and heterogeneity, the method can obtain accurate pore volumes of large channels in different small layers, which can provide a basis and guidance for optimizing adjustment parameters in oilfield development. Attached Figure Description

[0053] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the specification, serve to explain the technical solutions of the present invention.

[0054] Figure 1 A flowchart illustrating a method for determining the pore volume of large channels in small layers of medium-high permeability oilfields according to an embodiment of the present invention is shown.

[0055] Figure 2 The diagram shows the well location of the Wei 21 well group in the PI9 layer according to an embodiment of the present invention. Detailed Implementation

[0056] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0057] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0058] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0059] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without certain specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0060] Figure 1 A flowchart illustrating a method for determining the pore volume of large channels in small layers of medium-high permeability oilfields according to an embodiment of the present invention is shown. Figure 2 This diagram shows the well location of the Wei-21 well group in the PI9 layer according to an embodiment of the present invention. Figure 1 and 2 As shown, a method for determining the pore volume of a small-layer large-channel structure in a medium-to-high permeability oilfield includes: Step S01: Obtaining the water absorption, porosity, effective thickness of the small layer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and wellbore radius of the small layer before and after the development of the large-channel structure; Step S02: Determining the mobility before and after the development of the large-channel structure based on the water absorption, porosity, effective thickness, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and wellbore radius of the small layer; Step S03: Determining the change in mobility before and after the development of the large-channel structure based on the mobility before and after the development of the large-channel structure, and determining the change in water absorption of the small layer before and after the development of the large-channel structure based on the water absorption of the small layer before and after the development of the large-channel structure; Step S04: Determining the seepage time of injected water from the bottom of the water well to the bottom of the oil well based on the change in mobility, and determining the pore volume of the well group based on the seepage time and the change in water absorption.

[0061] The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields provided in this embodiment of the invention specifically includes the following steps:

[0062] Step S01: Obtain the water absorption, porosity, effective thickness of the sublayer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well distance, and wellbore radius of the study area before and after the development of large pores.

[0063] In this embodiment of the invention, some of the parameters obtained above can be obtained through a development database and indoor experimental data, specifically including: the bottom-hole flowing pressure P of the oil well after the development of large-channel pores. w After the development of large-channel water injection wells, the bottom-hole flowing pressure P i Porosity φ and wellbore radius r w .

[0064] Step S02: Determine the flow rate before and after the development of large channels based on the water absorption of the sub-layer, porosity, effective thickness of the sub-layer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well distance, and wellbore radius.

[0065] In this invention, the method for determining the mobility before and after the development of large-pore channels based on the water absorption of the sub-layer, porosity, effective thickness of the sub-layer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well spacing, and wellbore radius includes: determining the mobility before the development of large-pore channels based on the water absorption of the sub-layer before the development of large-pore channels, the bottom-hole flowing pressure of the production well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness of the sub-layer, porosity, injection-production well spacing, and wellbore radius; and determining the mobility after the development of large-pore channels based on the water absorption of the sub-layer after the development of large-pore channels, the bottom-hole flowing pressure of the production well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness of the sub-layer, porosity, injection-production well spacing, and wellbore radius.

[0066] In this invention, the method for determining the flowability before the development of large pores based on the water absorption of the small layer before the development of large pores, the bottom flow pressure of the oil well and the bottom flow pressure of the injection well, as well as the effective thickness of the small layer, porosity, injection-production well spacing and well radius, includes: calculating the flowability Λ1 before the development of large pores using formula (1);

[0067]

[0068] In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P Xi The bottom-hole flowing pressure of the injection well before the development of large channels, in MPa; P Xw The bottomhole flowing pressure of the production well before the development of large pores is denoted as MPa; L is the injection-production well distance, m; r w Let be the radius of the wellbore, in meters (m).

[0069] In this embodiment of the invention, in formula (1), the bottom-hole flowing pressure P of the injection well before the development of large channels is... Xi Before the development of large-channel oil wells, the bottom hole flowing pressure P XwThe effective thickness H of the block sublayer is determined based on the effective thickness h of each well within the well group and the number of injection and production wells n; the distance L between injection and production wells is determined based on the distance between the water well bank and the oil well bank, as well as the distance between adjacent production wells; the wellbore radius r... w The porosity φ and the water absorption of the small layer before the development of large pores Q1 were obtained from the development data database and indoor experimental data.

[0070] Substituting the water absorption, porosity, effective thickness of the small layer, bottom flow pressure of the oil production well and water injection well, injection-production well distance and well radius into equation (1), the flowability Λ1 before the development of the large pores is calculated.

[0071] In this invention, the method for determining the flowability after the development of the large pores based on the water absorption of the small layer after the development of the large pores, the bottom flow pressure of the oil well and the bottom flow pressure of the injection well, as well as the effective thickness of the small layer, porosity, injection-production well spacing and well radius, includes: calculating the flowability Λ2 before the development of the large pores using formula (2);

[0072]

[0073] In the formula: Q2 is the water absorption of the small layer after the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P i The bottom-hole flowing pressure of the injection well after the development of large-channel water injection is measured in MPa; P w The bottomhole flowing pressure of the production well after the development of large pores is in MPa; L is the injection-production well distance in meters; r w Let be the radius of the wellbore, in meters (m).

[0074] In this embodiment of the invention, in equation (2), the bottom-hole flowing pressure P of the injection well after the development of large channels is... i Before the development of large-channel oil wells, the bottom hole flowing pressure P w It can be obtained through the development of a data database and indoor experimental data; the effective thickness H of the block sublayer is determined based on the effective thickness h of each well in the well group and the number of injection and production wells n; the distance L between injection and production wells is determined based on the distance between the water well row and the oil well row, as well as the distance between adjacent production wells; the wellbore radius r w The porosity φ and the water absorption of the small layer before the development of large pores Q2 were obtained from the development data database and indoor experimental data.

[0075] Substituting the water absorption, porosity, effective thickness of the sublayer, bottom flow pressure of oil production and water injection wells, injection-production well distance, and well radius into equation (2), the flowability Λ2 after the development of large pores is calculated.

[0076] In this invention, before obtaining the effective thickness of the sublayer, the effective thickness of the sublayer is determined, and the method includes: calculating the effective thickness H of the sublayer using formula (7);

[0077]

[0078] Where: h i Let be the effective thickness of the sublayer in the i-th well, in m; i is a constant, and 0 ≤ i ≤ n.

[0079] In this embodiment of the invention, the effective thickness H of the sublayer in equations (1) and (2) is calculated using equation (7).

[0080] Among them, the number of injection and production wells in the well group n, and the effective thickness of the sublayer h of the i-th well. i This can be obtained through statistical analysis of the dynamic database of injection and production wells.

[0081] In this invention, the method for determining the change in flowability before and after the development of the large-aperture based on the flowability before and after the development of the large-aperture includes: calculating the change in flowability Λ before and after the development of the large-aperture using formula (3);

[0082] Λ=Λ2-Λ1 (3);

[0083] In the formula: Λ1 is the flowability before the development of large pores, D / (mPa·s); Λ2 is the flowability after the development of large pores, D / (mPa·s).

[0084] In this embodiment of the invention, after obtaining the flowability before and after the development of the large channel according to formulas (1) and (2), the flowability before and after the development of the large channel is calculated by substituting it into formula (3).

[0085] In this invention, the method for determining the change in water absorption of the small layer before and after the development of the large pores based on the water absorption of the small layer before and after the development of the large pores includes: calculating the change in water absorption Q of the small layer before and after the development of the large pores using formula (4);

[0086] Q = Q2 - Q1 (4);

[0087] In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 Q2 represents the water absorption of the sublayer after the development of large pores, in meters. 3 .

[0088] In this embodiment of the invention, the water absorption of the sublayer before and after the development of the macropores can be obtained by developing a database. The water absorption of the sublayer before and after the development of the macropores is obtained by substituting the obtained water absorption of the sublayer before and after the development of the macropores into equation (4) to calculate the change Q of water absorption of the sublayer before and after the development of the macropores.

[0089] In this invention, the method for determining the seepage time of injected water from the bottom of a water well to the bottom of an oil well based on the change in flowability includes: calculating the seepage time T of injected water from the bottom of a water well to the bottom of an oil well using formula (5);

[0090]

[0091] In the formula: φ is porosity, L is the injection-production well distance (m); r w Λ is the wellbore radius, in meters; D is the change in fluid mobility before and after the development of large pores, in meters per second (mPa·s); P is the fluid velocity. w The bottom hole flowing pressure of the oil well after the development of large pores; P i The bottom-hole flowing pressure of the injection well after the development of large-channel systems; f w ′(S w ) represents the water saturation level S w The rate of increase in water production rate under the given conditions, %.

[0092] In this embodiment of the invention, porosity φ and water saturation S are... w The rate of increase in water content f w ′(S w ), wellbore radius r w After the development of large-channel wells, the bottom-hole flowing pressure P w After the development of large-channel water injection wells, the bottom-hole flowing pressure P i The distance L between injection and production wells can be obtained through the development of a data database and indoor experimental data. The distance between water wells and oil wells and the distance between adjacent production wells are determined. The change in fluid flowability Λ before and after the development of large channels is calculated according to the above formula (3).

[0093] Substituting the above parameters into equation (5), the corresponding seepage time T of the injected water from the bottom of the water well to the bottom of the oil well is calculated.

[0094] In this invention, before obtaining the injection-production well distance, the injection-production well distance is determined, and the method includes: calculating the injection-production well distance L using formula (8);

[0095]

[0096] In the formula: a is the distance between the water well row and the oil well row, in meters; b is half the distance between adjacent oil wells, in meters.

[0097] In this embodiment of the invention, the injection-production well distance in equation (5) can be calculated using equation (8). The distance between the water well bank and the oil well bank, as well as the distance between adjacent production wells, can be obtained from a statistical injection-production well dynamic database.

[0098] In this invention, the method for determining the pore volume of the well group based on the seepage time and the change in water absorption of the sublayer includes: calculating the pore volume Φ of the well group using formula (6);

[0099] Φ=QT (6);

[0100] In the formula: Q represents the change in water absorption in the microlayer before and after the development of macropores, in meters.3 T represents the seepage time of the injected water from the bottom of the water well to the bottom of the oil well.

[0101] In this embodiment of the invention, the formula for calculating the seepage time T of the injected water from the bottom of the water well to the bottom of the oil well is substituted into formula (6) to obtain the formula for calculating the pore volume Φ of the well group as shown in formula (6-1) or (6-2).

[0102]

[0103] Right now:

[0104]

[0105] In this embodiment of the invention, taking the Wei-21 well group as an example, such as... Figure 2 The diagram shows the well location of the Wei 21 well group in the PI9 layer. This well group consists of 5 wells, of which Wei 21 is a water injection well, and the other four wells (Wei 1-241-31, Wei 1-241-41, Wei 1-231-31, and Wei 1-231-41) are oil production wells. The specific process for calculating the large-channel pore volume of this well group in the PI9 layer is as follows:

[0106] By developing a data database and using indoor experimental data, the basic parameters of the Pu82-732 well group in the PI8 layer were statistically analyzed, namely the bottom hole flowing pressure P of the oil wells after the development of large pores. w After the development of large-channel water injection wells, the bottom-hole flowing pressure P i a) Distance between water wells and oil wells; b) Half the distance between adjacent production wells; saturation point S. w The rate of increase in water content f w ′(S w ), porosity φ, wellbore radius r w Water absorption of the small layer before the development of large pores (Q1), water absorption of the small layer after the development of large pores (Q2), and bottomhole flowing pressure of the oil well before the development of large pores (P). Xi Before the development of large-channel water injection wells, the bottom-hole flowing pressure P Xw The number of injection and production wells (n) within the well group, and the effective thickness (h) of the injection and production layers within the well group. i The dynamic and static parameters (0≤i≤n) are shown in Table 1.

[0107] Table 1: Dynamic and static data of the Wei21 well group in the PI9 sublayer

[0108]

[0109]

[0110] Substituting the water absorption of the sublayer before the development of the large pores, Q1, and the water absorption of the sublayer after the development of the large pores, Q2, into equation (4), the change in water absorption of the sublayer before and after the development of the large pores, Q, is calculated to be 3.0 m. 3 ;

[0111] Substituting the effective thickness of the sublayers in wells Wei21, Wei1-241-31, Wei1-241-41, Wei1-231-31, and Wei1-231-41 into equation (7), the effective thickness H of the sublayer is calculated to be 1.4m.

[0112] The following parameters were considered before the development of large pores: water absorption Q1, porosity φ, effective thickness H of the small layer, and bottom-hole flowing pressure P of the injection well before the development of large pores. Xi Before the development of large-channel oil wells, the bottom hole flowing pressure P Xw , injection and production well spacing L, wellbore radius r w Substituting into equation (1), the calculated flowability Λ1 before the development of large channels is 0.4533D / (mPa·s).

[0113] The water absorption capacity Q2, porosity φ, effective thickness H of the sublayer after the development of large pores, and bottom-hole flowing pressure P of the injection well after the development of large pores are calculated. i After the development of large-channel wells, the bottom-hole flowing pressure P w , injection and production well spacing L, wellbore radius r w Substituting into equation (2), the calculated flowability Λ2 after the development of large channels is 1.3396D / (mPa·s).

[0114] Substituting the calculated flow rates Λ1 before and after the development of the large-aperture channel into equation (3), the change in flow rate Λ before and after the development of the large-aperture channel is calculated to be 0.8863D / (mPa·s).

[0115] Substituting the distance a between the water well row and the oil well row, and half the distance b between adjacent production wells into equation (8), the injection-production well distance L is calculated to be 175m.

[0116] The above-mentioned small layer water absorption change Q, porosity φ, injection-production well spacing L, and wellbore radius r are used to calculate the water absorption change Q, porosity φ, injection-production well spacing L, and wellbore radius r. w Changes in fluid mobility Λ before and after the development of large-pore channels; and bottomhole flowing pressure P of the oil well after the development of large-pore channels. w After the development of large-channel water injection wells, the bottom-hole flowing pressure P i Water saturation S w The rate of increase in water production under the given conditions, f w ′(S w Substituting into equation (6-1) or (6-2), the calculated pore volume Φ of the large-pore channel in the PI9 sublayer of the Wei 21 well group is 1136.6 m³. 3 .

[0117] It is understood that the various method embodiments mentioned above in this invention can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this invention will not elaborate further.

[0118] The execution entity for the method of determining the pore volume of small-layer large-pore channels in medium-to-high permeability oilfields can be a device for determining the pore volume of small-layer large-pore channels in medium-to-high permeability oilfields. For example, the method can be executed by a terminal device, a server, or other processing equipment. The terminal device can be a user equipment (UE), mobile device, user terminal, terminal, cellular phone, cordless phone, personal digital assistant (PDA), handheld device, computing device, vehicle-mounted device, wearable device, etc. In some possible implementations, this method for determining the pore volume of small-layer large-pore channels in medium-to-high permeability oilfields can be implemented by a processor calling computer-readable instructions stored in memory.

[0119] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0120] This invention also proposes a device for determining the pore volume of small-layer large-channel pores in medium-to-high permeability oilfields, comprising: an acquisition unit for acquiring the water absorption, porosity, effective thickness of the small layer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and wellbore radius of the small layer before and after the development of large-channel pores in the study area; and a mobility determination unit for determining the pore volume based on the aforementioned water absorption, porosity, effective thickness of the small layer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and wellbore radius. The wellbore radius is used to determine the mobility before and after the development of large channels; the mobility and small-layer water absorption change determination unit is used to determine the mobility change before and after the development of large channels based on the mobility before and after the development of large channels, and to determine the small-layer water absorption change before and after the development of large channels based on the small-layer water absorption; the pore volume determination unit is used to determine the seepage time of injected water from the bottom of the water well to the bottom of the oil well based on the mobility change, and to determine the pore volume of the well group based on the seepage time and the water absorption change.

[0121] In some embodiments, the functions or modules and units included in the apparatus provided by the present invention can be used to execute the methods described in the above method embodiments. The specific implementation can be referred to the description of the above method embodiments, and for the sake of brevity, it will not be repeated here.

[0122] This invention includes a self-derived calculation model for the pore volume of large channels in small layers of medium-high permeability oilfields, namely Equations 5 and 6, and a mobility calculation model before and after the development of large channels, namely Equations 1-3. The model comprehensively considers factors such as irregular well network patterns and vertical heterogeneity for the first time, and by substituting the corresponding parameters of the small layers into the formulas, it can accurately calculate the pore volume of large channels in medium-high permeability reservoir wells. Compared with existing methods, this invention considers more comprehensive factors and has stronger applicability. It can provide a reliable basis for addressing inefficient and ineffective circulation in old oilfields during the high water-cut period. By guiding the optimization design and implementation of parameters for water injection, profile control, and water shut-off, it effectively improves the water injection development effect and benefits of oilfields, and provides a basis and guidance for the optimization design of oilfield development adjustment parameters.

[0123] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for determining the pore volume of large-channel pores in small layers of medium-to-high permeability oilfields, characterized in that, include: The study area obtained the water absorption, porosity, effective thickness of the sub-layers before and after the development of large channels, the bottom-hole flowing pressure of injection wells before and after the development of large channels, the bottom-hole flowing pressure of production wells, the injection-production well spacing, and the wellbore radius before and after the development of large channels. Based on the water absorption of the sublayer, porosity, effective thickness of the sublayer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well distance, and wellbore radius, determine the flowability before and after the development of large channels; Based on the flow rate before and after the development of the large pores, determine the change in flow rate before and after the development of the large pores; based on the water absorption of the small layer before and after the development of the large pores, determine the change in water absorption of the small layer before and after the development of the large pores. Based on the change in mobility, the seepage time of injected water from the bottom of the water well to the bottom of the oil well is determined, and based on the seepage time and the change in water absorption, the pore volume of the well group is determined.

2. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 1, characterized in that, The method for determining the mobility before and after large-channel development based on the sublayer's water absorption, porosity, effective sublayer thickness, injection well bottom-hole flowing pressure, production well bottom-hole flowing pressure, injection-production well spacing, and wellbore radius includes: Based on the water absorption of the small layer before the development of the large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the water injection well, as well as the effective thickness, porosity, injection-production well spacing and well radius of the small layer, the flowability before the development of the large pores is determined. Based on the water absorption of the sub-layer after the development of the large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the water injection well, as well as the effective thickness of the sub-layer, porosity, injection-production well spacing and wellbore radius, the flow rate after the development of the large pores is determined.

3. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 2, characterized in that, The method for determining the mobility before the development of large pores based on the water absorption of the small layer before the development of large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness, porosity, injection-production well spacing and wellbore radius of the small layer, includes: The flowability Λ1 before the development of large channels is calculated using equation (1); In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P Xi The bottom-hole flowing pressure of the injection well before the development of large channels, in MPa; P Xw The bottomhole flowing pressure of the production well before the development of large pores is denoted as MPa; L is the injection-production well distance, m; r w Let be the radius of the wellbore, in meters (m).

4. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 2, characterized in that, The method for determining the mobility after the development of large pores, based on the water absorption of the sub-layer after the development of large pores, the bottom-hole flowing pressure of the oil well and the bottom-hole flowing pressure of the injection well, as well as the effective thickness, porosity, injection-production well spacing and wellbore radius of the sub-layer, includes: The flowability Λ2 before the development of large channels is calculated using equation (2); In the formula: Q2 is the water absorption of the small layer after the development of large pores, in meters. 3 φ represents porosity; H represents the effective thickness of the sublayer; P i The bottom-hole flowing pressure of the injection well after the development of large-channel water injection is measured in MPa; P w The bottomhole flowing pressure of the production well after the development of large pores is in MPa; L is the injection-production well distance in meters; r w Let be the radius of the wellbore, in meters (m).

5. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 1, characterized in that, The method for determining the change in flow rate before and after the development of the large-aperture channel based on the flow rate before and after the development of the large-aperture channel includes: The change in flowability Λ before and after the development of large channels was calculated using equation (3); Λ=Λ2-Λ1 (3); In the formula: Λ1 is the flowability before the development of large pores, D / (mPa·s); Λ2 is the flowability after the development of large pores, D / (mPa·s).

6. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 1, characterized in that, The method for determining the change in water absorption of the sublayer before and after the development of the macropores, based on the water absorption of the sublayer before and after the development of the macropores, includes: The change in water absorption Q of the sublayer before and after the development of large pores was calculated using equation (4); Q = Q2 - Q1 (4); In the formula: Q1 is the water absorption of the small layer before the development of large pores, in meters. 3 Q2 represents the water absorption of the sublayer after the development of large pores, in meters. 3 .

7. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 1, characterized in that, The method for determining the seepage time of injected water from the bottom of a water well to the bottom of an oil well based on the change in mobility includes: The seepage time T of the injected water from the bottom of the water well to the bottom of the oil well is calculated using equation (5); In the formula: φ is porosity, L is the injection-production well distance (m); r w Λ is the wellbore radius, in meters; D is the change in fluid mobility before and after the development of large pores, in meters per second (mPa·s); P is the fluid velocity. w The bottom hole flowing pressure of the oil well after the development of large pores; P i The bottom-hole flowing pressure of the injection well after the development of large-channel systems; f w ′(S w ) represents the water saturation level S w The rate of increase in water production rate under the given conditions, %.

8. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to claim 7, characterized in that, The method for determining the pore volume of the well group based on the seepage time and the change in water absorption includes: The well group pore volume Φ is calculated using equation (6); Φ=QT (6); In the formula: Q represents the change in water absorption in the microlayer before and after the development of macropores, in meters. 3 T represents the seepage time of the injected water from the bottom of the water well to the bottom of the oil well.

9. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to any one of claims 1-8, characterized in that, Determining the effective thickness of a sublayer before obtaining the effective thickness of the sublayer includes the following methods: The effective thickness H of the sublayer is calculated using equation (7); Where: h i Let be the effective thickness of the sublayer in the i-th well, in m; i is a constant, and 0 ≤ i ≤ n.

10. The method for determining the pore volume of small-scale large-channel pores in medium-to-high permeability oilfields according to any one of claims 1-9, characterized in that, Before obtaining the injection-production well spacing, the method for determining the injection-production well spacing includes: The injection-production well spacing L is calculated using equation (8); In the formula: a is the distance between the water well row and the oil well row, in meters; b is half the distance between adjacent oil wells, in meters.

11. A device for determining the pore volume of small-layer large-channel pores in medium-to-high permeability oilfields, characterized in that, include: The acquisition unit is used to acquire the water absorption, porosity, effective thickness of the sublayer, bottom-hole flowing pressure of injection wells, bottom-hole flowing pressure of production wells, injection-production well spacing, and well radius of the study area before and after the development of large channels. The mobility determination unit is used to determine the mobility before and after the development of large channels based on the water absorption of the sub-layer, porosity, effective thickness of the sub-layer, bottom-hole flowing pressure of the injection well, bottom-hole flowing pressure of the production well, injection-production well distance, and wellbore radius. The unit for determining the change in flowability and water absorption of the small layer is used to determine the change in flowability before and after the development of the large pores based on the flowability before and after the development of the large pores, and to determine the change in water absorption of the small layer before and after the development of the large pores based on the water absorption of the small layer before and after the development of the large pores. The pore volume determination unit is used to determine the seepage time of injected water from the bottom of the water well to the bottom of the oil well based on the change in mobility, and to determine the pore volume of the well group based on the seepage time and the change in water absorption.

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