Water drive dynamic reserve calculation method for fractured-vug reservoirs

Abstract

The application provides a water drive dynamic reserve calculation method for a fractured-vug type oil reservoir, which comprises the following steps: drawing a water drive characteristic curve corresponding to a single target well in a semi-logarithmic coordinate system, and determining the curve type of the water drive characteristic curve; drawing the dimensionless processed cumulative oil production data and cumulative water production data of the single target well in a dimensionless curve chart to obtain a first type coefficient corresponding to the single target well in each water drive stage; calculating the first type coefficient corresponding to all target wells in each water drive stage; calculating a second type coefficient corresponding to all target wells in each water drive stage through the cumulative oil production data and the cumulative water production data of the single target well; and calculating the dynamic reserve corresponding to all target wells in each water drive stage. The application further improves the type A water drive characteristic curve model in the prior art, and overcomes the defect that the unified proportional coefficient in the prior art leads to a large error in the calculation result.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of complex oil and gas reservoir energy development, in particular to a water drive dynamic reserve calculation method for fracture-cave type reservoirs. BACKGROUND

[0002] Oil and gas reservoir reserves are one of the important bases for formulating and adjusting oilfield development technical schemes, and the determination method thereof is divided into static method and dynamic method. The dynamic method is a method for calculating oil and gas reservoir reserves by using relevant mathematical models based on production dynamic data. The commonly used methods at present include material balance method, decline curve method, water drive characteristic curve method and the like.

[0003] In the prior art, the material balance method is aimed at constant volume reservoirs, the driving energy for the production of crude oil of the reservoirs is entirely from the elastic energy of the reservoirs, there is no supplement of external energy, the reservoirs are not communicated with the outside world, there is no water invasion and gas cap, and no water body is developed in the closed reservoirs, and there is no water invasion. The fluid distribution and flow rule of fracture-cave type carbonate rock reservoirs are complex, the reservoirs are usually supplemented with energy through communication with large water bodies outside, and there is water invasion. At the same time, due to the inactivity of the water bodies of some reservoirs, the energy of the reservoirs needs to be supplemented by water injection. Therefore, the conventional material balance method is difficult to be applied to fracture-cave type carbonate rock reservoirs.

[0004] In the prior art, the decline curve method is usually applied to predict recoverable geological reserves in the later production stage (i.e. the yield appears to decrease), and the recoverable geological reserves are obtained by the decline curve method, which is not dynamic geological reserves, and the physical meanings reflected by the two are different. Therefore, the decline curve method cannot be applied to the calculation of dynamic geological reserves.

[0005] In the prior art, a unified model is usually adopted to determine the dynamic reserves in the water drive characteristic curve method (i.e. formula 6-7). The fluid distribution and flow rule in the fracture-cave type reservoirs are complex, and the water drive characteristic curve usually shows the typical characteristics of double straight line segments or single straight line segment, and if the unified proportionality coefficient M is still adopted, the calculation result will have a large error.

[0006] Therefore, the present application provides a water drive dynamic reserve calculation method for fracture-cave type reservoirs. SUMMARY

[0007] To solve the above problems, the present application provides a water drive dynamic reserve calculation method for fracture-cave type reservoirs, which comprises the following steps:

[0008] Step 1: in a semi-logarithmic coordinate system, a water drive characteristic curve corresponding to a single target well is drawn, and the curve type of the water drive characteristic curve is determined;

[0009] Step 2: Based on the curve type, the cumulative oil production data and the cumulative water production data of the single target well are dimensionlessly processed and plotted on a dimensionless curve chart to obtain the first-class coefficient corresponding to the single target well in each water flooding stage;

[0010] Step 3: Based on the first-category coefficient corresponding to a single target well at each waterflooding stage and combined with the geological reserve data of the single target well, calculate the first-category coefficient corresponding to all target wells at each waterflooding stage;

[0011] Step 4: Calculate the corresponding second-type coefficients of all target wells at each water flooding stage using the cumulative oil production data and cumulative water production data of a single target well;

[0012] Step 5: Based on the first-category coefficients and second-category coefficients corresponding to all target wells in each water flooding stage, calculate the dynamic reserves corresponding to all target wells in each water flooding stage.

[0013] According to one embodiment of the present invention, step 1 specifically includes the following steps: screening all production wells in the fracture-cavity unit to obtain all target wells that meet the requirements, specifically:

[0014] Calculate the recovery rates of all production wells and exclude production wells whose recovery rates are greater than a first threshold;

[0015] Sorting out the process measures of all production wells and eliminating those whose production data fluctuations under multiple process measures are greater than the preset standard;

[0016] The water drive characteristic curves corresponding to all production wells are drawn, and the production wells corresponding to the violent water drive characteristic curves are eliminated.

[0017] According to one embodiment of the present invention, the curve type includes a double straight line segment type and a single straight line segment type, wherein the double straight line segment type has a natural water flooding stage and an artificial water flooding stage, and the single straight line segment type has a natural water flooding stage.

[0018] According to one embodiment of the present invention, step 2 specifically includes the following steps:

[0019] Based on the type A water flooding characteristic curve model, the type A dimensionless water flooding characteristic curve model is obtained by combining the recovery degree expression and the relationship between geological reserves and the second type coefficient.

[0020] According to one embodiment of the present invention, step 2 specifically includes the following steps:

[0021] Based on the preset first-category coefficient data set, the preset recovery factor data set, and the preset dimensionless cumulative oil production data set, a dimensionless cumulative water production data set is calculated using the type A dimensionless water drive characteristic curve model;

[0022] The dimensionless curve chart is plotted in a semi-logarithmic coordinate system based on the dimensionless cumulative water production data set and the preset dimensionless cumulative oil production data set.

[0023] According to one embodiment of the present invention, step 2 specifically includes the following steps:

[0024] Selecting the first type coefficients in the list of candidate first type coefficients in sequence, combining them with geological reserve data of a single target well, and calculating a second type coefficient corresponding to the current first type coefficient;

[0025] Based on the second-type coefficient corresponding to the current first-type coefficient and the cumulative oil production data and cumulative water production data of a single target well in each water flooding stage, the dimensionless cumulative oil production data and dimensionless cumulative water production data of the single target well are calculated.

[0026] According to one embodiment of the present invention, step 2 specifically includes the following steps:

[0027] For each water flooding stage, the dimensionless cumulative oil production data and the dimensionless cumulative water production data are plotted on the dimensionless curve chart to obtain a dimensionless curve corresponding to a single target well;

[0028] When the slope of the dimensionless curve is equal to the second threshold, the current first-category coefficient is selected as the first-category coefficient corresponding to the single target well in each water flooding stage.

[0029] According to one embodiment of the present invention, step three specifically includes the following steps:

[0030] Accumulate the geological reserve data of all target wells to obtain the total geological reserve data corresponding to all target wells;

[0031] According to the weight coefficient corresponding to each target well and the first-category coefficient corresponding to a single target well in each water flooding stage, the first-category coefficients corresponding to all target wells in each water flooding stage are calculated.

[0032] According to one embodiment of the present invention, step 4 specifically includes the following steps:

[0033] The cumulative oil production data and the cumulative water production data of all target wells are accumulated to obtain the total cumulative oil production data and the total cumulative water production data corresponding to all target wells;

[0034] In a semi-logarithmic coordinate system, plotting a relationship curve between the total cumulative oil production data and the total cumulative water production data, and determining a curve type of the relationship curve;

[0035] According to the curve type of the relationship curve, combined with the type A water flooding characteristic curve model, the relationship curve is fitted to obtain the second type coefficient corresponding to all target wells in each water flooding stage.

[0036] According to another aspect of the present invention, there is also provided a device for calculating water-driven reserves in a fracture-vuggy oil reservoir, the device comprising:

[0037] The first module is used to draw a water drive characteristic curve corresponding to a single target well in a semi-logarithmic coordinate system and determine the curve type of the water drive characteristic curve;

[0038] The second module is used to perform dimensionless processing on the cumulative oil production data and the cumulative water production data of the single target well according to the curve type, and then plot them on the dimensionless curve chart to obtain the first type coefficient corresponding to the single target well in each water flooding stage;

[0039] The third module is used to calculate the first type coefficients corresponding to all target wells in each water flooding stage based on the first type coefficients corresponding to the single target well in each water flooding stage and in combination with the geological reserve data of the single target well;

[0040] The fourth module is used to calculate the second type coefficient corresponding to all target wells in each water flooding stage based on the cumulative oil production data and cumulative water production data of a single target well;

[0041] The fifth module is used to calculate the dynamic reserves corresponding to all target wells in each water flooding stage based on the first type coefficients and the second type coefficients corresponding to all target wells in each water flooding stage.

[0042] The water drive dynamic reserve calculation method for fracture-vuggy oil reservoirs provided by the present invention establishes a dynamic reserve calculation method based on the curve characteristics of the water drive characteristic curve presented by the fracture-vuggy oil reservoir, further improves the Type A water drive characteristic curve model in the prior art, and overcomes the defect in the prior art that the use of a unified proportional coefficient will lead to large errors in the calculation results. In addition, different proportional coefficients are proposed for different water drive stages to calculate dynamic reserves, which is more in line with the production rules and can also more accurately obtain the dynamic reserve data of target wells at different stages.

[0043] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 A flow chart of a method for calculating water-driven reserves in fracture-vuggy oil reservoirs according to an embodiment of the present invention is shown;

[0046] Figure 2 A water flooding characteristic curve diagram under multiple process measures according to an embodiment of the present invention is shown;

[0047] Figure 3 A graph showing a characteristic curve of a violent water flooding type according to an embodiment of the present invention is shown;

[0048] Figure 4 A dual linear water flooding characteristic curve diagram according to an embodiment of the present invention is shown;

[0049] Figure 5 A single linear water flooding characteristic curve diagram according to one embodiment of the present invention is shown;

[0050] Figure 6 A dimensionless water flooding characteristic curve diagram of type A according to an embodiment of the present invention is shown;

[0051] Figure 7 Shows a water flooding characteristic curve of the X1 well according to one embodiment of the present invention;

[0052] Figure 8 A dimensionless diagram of the natural water flooding section of the X1 well according to one embodiment of the present invention is shown;

[0053] Figure 9 A dimensionless diagram of the artificial water flooding section of the X1 well according to one embodiment of the present invention is shown;

[0054] Figure 10 shows an X-fracture-cavity unit water flooding characteristic curve according to one embodiment of the present invention; and

[0055] Figure 11 The structure block diagram of a water-driven reserves calculation device for fracture-vuggy oil reservoirs according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions and advantages of the present invention more clear, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0057] In the prior art, the material balance method is a basic reservoir engineering calculation method. The characteristic of this method is that it only focuses on the parameter changes between the initial state of the reservoir and a certain development state, and does not consider the changing process and the complex internal structure of the reservoir.

[0058] The basic principle is: Remaining geological reserves of oil and gas = Original geological reserves of oil and gas - Produced oil and gas volume. First, for a fixed-volume reservoir, the driving energy for crude oil extraction comes entirely from the reservoir's own elastic energy. The reservoir is neither water-injected nor supplemented with other external energy. Elastic energy refers to the elastic energy caused by the expansion of reservoir fluid and compression of rock skeleton due to the reduction of reservoir pressure during the production process. This type of reservoir is not in communication with the outside world, there is no water intrusion or gas cap, and no water body is developed in the closed reservoir. Before water injection to replace oil, almost no water is produced in the oil well. The material balance equation is expressed as follows (1):

[0059] N p B o =NB oi C o (p i -p)

[0060] In formula (1): N p —Cumulative oil production, 10 4 m 3 ; N—produced reserves, 10 4 m 3 ;p i —Original unit pressure, MPa; p—Current unit pressure, MPa; B oi —p i Volume coefficient of crude oil under pressure; B o —Volume coefficient of crude oil under pressure p; C o —Compression coefficient of crude oil, MPa -1 Based on the slope of the curve between cumulative oil production and production pressure difference in formula (1), the corresponding dynamic geological reserves can be obtained.

[0061] In the prior art, the decline curve method is to use the production decline law (a mathematical expression or mathematical model of production changes over time (Formula (2))) obtained from historical oil and gas production data to predict the cumulative oil production at a certain production time in the future (Formula (3)) and the final cumulative oil production at the time of oil field abandonment (Formula (4, also known as recoverable reserves), and reflect the remaining recoverable reserves (Formula (5)) by the difference between recoverable reserves and cumulative oil production.

[0062]

[0063]

[0064]

[0065] N RR =N R -N p (5)

[0066] Where: q f —Production at a certain production time in the future, 10 4 m 3 ;t f —A future production time, year; t r —reference time, year; N p —Predicted cumulative oil production, 10 4 m 3 ; N pr —Cumulative oil production at reference time, 10 4 m 3 ;t abn —Abandonment time, years; N R —Recoverable reserves, 10 4 m 3 ; N RR —Remaining recoverable reserves, 10 4 m 3 .

[0067] In the existing technology, the water drive characteristic curve method is the most commonly used method to determine dynamic reserves. At present, the calculation of dynamic geological reserves using the water drive characteristic curve is mainly based on the statistical law of 25 oil reservoirs at home and abroad proposed by Academician Tong Xianzhang, that is, the dynamic geological reserves are 7.5 times the inverse of the slope of the type A water drive characteristic curve formula (6).

[0068] lgW p =A+BN p (6)

[0069] N=7.5 / B (7)

[0070] Where: W p —Cumulative water production; N p —Cumulative oil production; B—slope of the straight line segment; A—intercept of the straight line segment; N—geological (dynamic) reserves.

[0071] In the prior art, Zheng Songqing, based on the characteristics of fracture-vuggy reservoirs and the changing patterns of water flooding characteristic curves, found that the dynamic data of fracture-vuggy reservoir units and single wells satisfy the D-type water flooding characteristic curve and established a linear relationship between the slope of the D-type straight line segment and geological reserves for fracture-vuggy reservoirs. This method first determines the calculation model by comparing the unit geological reserves with the geological reserves, that is, determining the coefficient m in formula (9), and then uses this model to calculate dynamic reserves.

[0072]

[0073]

[0074] In the formula, L p Cumulative oil production, 10 4 t; N p Cumulative oil production, 10 4 t; W p Cumulative water production, 10 4 t; N - Dynamic reserves, 10 4 t; A, B, M - Constant.

[0075] The present application aims at the deficiencies in the prior art, and combines the water drive characteristic curve features of the fracture-vug carbonate reservoir to establish a water drive dynamic reserves calculation method for the fracture-vug reservoir, relates to the calculation of the water drive dynamic reserves of the fracture-vug carbonate reservoir, and is a feasible and adaptable dynamic reserves calculation method for the fracture-vug carbonate reservoir, as follows:

[0076] Figure 1 A flow chart of the water drive dynamic reserves calculation method for the fracture-vug reservoir according to an embodiment of the present application is shown.

[0077] As Figure 1 In step S101, the water drive characteristic curve corresponding to a single target well is plotted in a semi-log coordinate system, and the curve type of the water drive characteristic curve is determined.

[0078] Specifically, in step S101, all production wells in the fracture-vug unit are screened to obtain all target wells meeting the requirements. In an embodiment, before calculating the dynamic reserves of the fracture-vug reservoir, the production data and well history such as cumulative oil production data and cumulative water production data of all production wells in the fracture-vug unit are analyzed to screen out production wells meeting the requirements as target wells.

[0079] Further, all target wells meeting the requirements are obtained by the following steps:

[0080] First, the recovery factor of all production wells is calculated, and the production well with a recovery factor greater than a first threshold value is removed. Specifically, on the basis of the given geological reserves, the recovery factor of the current production well is calculated (formula 10) in combination with the current cumulative oil production. If the current recovery factor is greater than the first threshold value (the first threshold value can be 100%), the actual production data such as the cumulative oil production data and the cumulative water production data of the well are considered invalid, and the well is not used as a target well.

[0081]

[0082] In the formula, R represents the recovery factor; N p represents the cumulative oil production data; and N represents the geological reserves.

[0083] Afterwards, the process measures of all production wells are sorted out, and production wells whose production data fluctuations under multiple process measures are greater than the preset standard are eliminated. Specifically, because some production wells have adopted multiple process measures during the production process, their production data fluctuates greatly and the data regularity is weak, so such wells cannot be used as target wells. Figure 2 , including various process measures such as intermittent opening, mechanical pumping and water injection to replace oil.

[0084] Finally, the water drive characteristic curves corresponding to all production wells are drawn, and the production wells corresponding to the violent water drive characteristic curves are eliminated. Specifically, since some production wells are in contact with larger water bodies in the production process, resulting in severe water intrusion, the production data fluctuates more, and the cumulative water production data may suddenly increase. The actual cumulative oil and water production data of such wells are considered invalid, and such wells will not be used as target wells (such as Figure 3 ).

[0085] In summary, the cumulative oil and water production data for the three types of production wells mentioned above are considered invalid production data. These three types of wells should be excluded from the analysis. The cumulative oil and water production data for the remaining production wells are considered valid production data and are also the target wells used in this study.

[0086] In step S101, a water drive characteristic curve of each target well is drawn in a semi-logarithmic coordinate system, where the horizontal axis of the water drive characteristic curve is the cumulative oil production data and the vertical axis is the cumulative water production data. The curve trend of the water drive characteristic curve is observed to determine the curve type. Specifically, the curve type includes a double straight line segment type and a single straight line segment type, wherein the double straight line segment type has a natural water drive stage and an artificial water drive stage (such as Figure 4 ), the single straight segment type has the natural water drive stage (such as Figure 5 ).

[0087] In one embodiment, for target wells exhibiting dual straight-line segment characteristics, analysis of the target well's well history indicates that natural water flooding reached a stable displacement state, forming a first straight-line segment, while artificial water injection reached a stable displacement state, forming a second straight-line segment. For target wells exhibiting single straight-line segment characteristics, analysis of the well history of producing wells indicates that natural water flooding reached a stable displacement state, forming a straight-line segment. Such wells are not affected by artificial water injection, and therefore do not have a second straight-line segment.

[0088] like Figure 1 In step S102, based on the curve type, the cumulative oil production data and the cumulative water production data of the single target well are dimensionally processed and plotted on the dimensionless curve chart to obtain the first type coefficient corresponding to the single target well in each water flooding stage.

[0089] In step S102, based on the type-A water drive characteristic curve model, the type-A dimensionless water drive characteristic curve model is obtained by combining the recovery degree expression and the relationship expression between the geological reserves and the second type coefficient.

[0090] In the prior art, the expression of the type-A water drive characteristic curve model is:

[0091] lgW p =A+BN p (11)

[0092] Wherein: W p represents the cumulative water production data; N p represents the cumulative oil production data; B represents the slope of the straight line segment; and A represents the intercept of the straight line segment.

[0093] In formula (11), lgB is added to both ends of formula (11), so that formula (11) can be converted into the following type-A dimensionless water drive characteristic curve:

[0094] lgQ WD =Q OD +C (12)

[0095] Wherein: Q WD =B*W p is the dimensionless cumulative water production; Q OD =B*N p is the dimensionless cumulative oil production; and C=A+lgB is a constant.

[0096] The derivative of both sides of formula (11) is:

[0097]

[0098] The daily (monthly, annual) water production Q w of the oilfield can be expressed as:

[0099]

[0100] The daily (monthly, annual) oil production Q o of the oilfield can be expressed as:

[0101]

[0102] The ratio of the daily (monthly, annual) water production to the daily (monthly, annual) oil production of the oilfield is defined as the (instantaneous) water-oil ratio WOR of the oilfield, that is:

[0103]

[0104] Substituting formula (13) into formula (16) and then taking the logarithm to obtain:

[0105] lgWOR=lg2.303+lgB+lgWp (17)

[0106] Substituting formula (11) into formula (17) yields:

[0107] lgWOR=lg2.303+lgB+A+BN p (18)

[0108] The expression of recovery degree is as follows:

[0109]

[0110] The relationship between geological reserves and the slope B of the straight line segment is:

[0111]

[0112] So formula (18) can be expressed as:

[0113] lgWOR=lg2.303+C+MR (21)

[0114] Generally, the water content is 98% as the economic limit of the oil field, then WOR = 49, and substituting it into the above formula yields:

[0115] C=lg49-lg2.303-MR M (twenty two)

[0116] Where: R M Indicates the recovery rate.

[0117] Substituting Equation (22) into Equation (12), the final expression of the type A dimensionless water flooding characteristic curve can be obtained as follows:

[0118] Q WD =Q OD +1.33-MR M (twenty three)

[0119] In one embodiment, formula (23) is the type A dimensionless water drive characteristic curve model adopted by the present invention.

[0120] In step S102, based on the preset first-category coefficient data set, the preset recovery factor data set, and the preset dimensionless cumulative oil production data set, a dimensionless cumulative water production data set is calculated using the Type A dimensionless water flooding characteristic curve model. Specifically, the first-category coefficient includes the coefficient M in equation (23).

[0121] In step S102, a dimensionless curve chart is drawn in a semi-logarithmic coordinate system based on the dimensionless cumulative water production data set and the preset dimensionless cumulative oil production data set.

[0122] Specifically, based on the M value in the preset first type coefficient data set, the R value in the preset recovery factor data set, M (recovery factor) and Q in the default dimensionless cumulative oil production data set OD (dimensionless cumulative oil production), combined with formula (23), we can calculate Q WD (dimensionless cumulative water production) (as shown in Table 1), the corresponding dimensionless curve containing dimensionless cumulative oil production data and dimensionless cumulative water production data is drawn in the semi-logarithmic coordinate system (as shown in Figure 6 Each straight line in the dimensionless curve represents a different recovery factor. The straight lines are parallel to each other and have a slope of 1.

[0123] Table 1 Q WD Calculation Example Table

[0124]

[0125] In step S102, first-category coefficients in the list of candidate first-category coefficients are selected in sequence, and second-category coefficients corresponding to the current first-category coefficients are calculated in combination with geological reserve data of a single target well.

[0126] Specifically, based on a given geological reserve N, combined with the selected first-category coefficients, the second-category coefficients corresponding to the current first-category coefficients are calculated by B=M / N. Specifically, the second-category coefficients include coefficient B.

[0127] In step S102, dimensionless cumulative oil production data and dimensionless cumulative water production data of a single target well are calculated based on the second type coefficient corresponding to the current first type coefficient and the cumulative oil production data and cumulative water production data of a single target well in each water flooding stage.

[0128] Specifically, the second type of coefficient corresponding to the first type of coefficient obtained by calculation is based on Q WD =B*W p Calculate the dimensionless cumulative water production data according to Q OD =B*N p Dimensionless cumulative oil production data is calculated.

[0129] In step S102, for each waterflooding stage, the dimensionless cumulative oil production data and the dimensionless cumulative water production data are plotted on a dimensionless curve chart to obtain a dimensionless curve corresponding to a single target well. In summary, by combining the characteristics of the dimensionless curve chart with the waterflooding characteristic curve of the target well, the production data (cumulative oil production data and cumulative water production data) corresponding to the straight segments of the waterflooding characteristic curve for each target well are dimensionlessly processed and plotted on the dimensionless curve chart.

[0130] In step S102 , when the slope of the dimensionless curve is equal to the second threshold, the current first-category coefficient is selected as the first-category coefficient corresponding to the single target well in each water flooding stage.

[0131] Specifically, the relationship curve between the dimensionless cumulative oil production data and the dimensionless cumulative water production data of the target well is plotted on the dimensionless curve plate. If the slope of the dimensionless curve is the second threshold (the second threshold can be 1), it means that the currently selected first-class coefficient is reasonable, and the first-class coefficient (M) corresponding to the natural water flooding stage in each target well can be further calculated. 天然-单井 ) and the first type coefficient corresponding to the artificial water flooding stage (M 人工-单井 )value.

[0132] like Figure 1 In step S103, based on the first type coefficient corresponding to a single target well in each water flooding stage and combined with the geological reserve data of the single target well, the first type coefficient corresponding to all target wells in each water flooding stage is calculated.

[0133] In step S103, the geological reserve data of all target wells are accumulated to obtain the total geological reserve data corresponding to all target wells.

[0134] Add up the geological reserves N of all target wells to obtain the oil and gas reserves N of the entire fracture-cavity unit (including all target wells) 总 , as shown in formula (24):

[0135]

[0136] Where: N 总 Indicates the geological reserves of the fracture-cavity unit; N i represents the geological reserves of the i-th target well.

[0137] In step S103 , the first type coefficients corresponding to all target wells in each water flooding stage are calculated based on the weight coefficient corresponding to each target well and the first type coefficient corresponding to a single target well in each water flooding stage.

[0138] Specifically, the percentage of geological reserves of each target well to the geological reserves of the entire fracture-cavity unit is calculated, and the weight coefficient of each well is determined as follows (25):

[0139]

[0140] Where: y i Represents the weight coefficient of the i-th target well.

[0141] Using the corresponding weight coefficient, M 天然-单井 and M 人工-单井 The value determines the M corresponding to the entire fracture unit天然-单元 , as shown in equation (26) and M 人工-单元 , as shown in formula (27):

[0142]

[0143] Where: M 天然-单井 represents the first type coefficient of each target well in the natural water flooding stage; M 天然-单元 It indicates that the first type coefficient of the entire fracture-cavity unit (including all target wells) reaches stable displacement during the natural water flooding stage.

[0144]

[0145] Where: M 人工-单井 represents the first type coefficient of each target well in the artificial water flooding stage; M 人工-单元 It indicates that the first type coefficient of the entire fracture-cavity unit (including all target wells) reaches stable displacement during the artificial water flooding stage.

[0146] like Figure 1 In step S104, the second type coefficients corresponding to all target wells in each water flooding stage are calculated using the cumulative oil production data and the cumulative water production data of a single target well.

[0147] In step S104, the cumulative oil production data and the cumulative water production data of all target wells are accumulated to obtain the total cumulative oil production data and the total cumulative water production data corresponding to all target wells.

[0148] In step S104, a relationship curve between the total cumulative oil production data and the total cumulative water production data is drawn in a semi-logarithmic coordinate system, and the curve type of the relationship curve is determined.

[0149] In step S104, the relationship curve is fitted based on the curve type of the relationship curve and combined with the Type A water flooding characteristic curve model to obtain the second type coefficients corresponding to all target wells in each water flooding stage.

[0150] Specifically, the cumulative oil production data and cumulative water production data of all target wells are added together to obtain the total cumulative oil production data and total cumulative water production data of the entire fracture-cavity unit. The relationship curve between the total cumulative water production data and the total cumulative oil production data of the fracture-cavity unit is plotted in a semi-logarithmic coordinate system, and the relationship between the two is fitted using formula (6) to obtain the corresponding slope (i.e., the second-type coefficient). If the curve presents a double straight line segment, its slope (i.e., the second-type coefficient) is recorded as B1 and B2 respectively. If the curve presents a single straight line segment, its slope (i.e., the second-type coefficient) is recorded as B3.

[0151] like Figure 1In step S105, the dynamic reserves corresponding to all target wells in each water flooding stage are calculated based on the first type coefficients and the second type coefficients corresponding to all target wells in each water flooding stage.

[0152] Specifically, according to the second type coefficients (including B1, B2, B3) corresponding to all target wells in each water flooding stage determined in step S104 and the first type coefficients (including M) corresponding to all target wells in each water flooding stage determined in step S103, 天然-单元 and M 人工-单元 ) Obtain the dynamic reserves under natural water drive stage and the dynamic reserves under artificial water drive.

[0153]

[0154] Where: N 天然 It represents the dynamic reserves of the entire fracture-cavity unit (including all target wells) under the natural water flooding stage.

[0155]

[0156] Where: N 人工 It represents the dynamic reserves of the entire fracture-cavity unit (including all target wells) during the artificial water flooding stage.

[0157] In one embodiment, taking the X fracture-hole unit in the Tahe Oilfield as an example, the production data of the target well in the fracture-hole unit is as shown in Table 2:

[0158] Table 2 X-hole unit production data

[0159] X-hole unit <![CDATA[地质储量(m 3 )]]> Cumulative oil production (m 3 )]]> X1 3.48E+06 9.14E+05 X2 5.88E+05 1.55E+05

[0160] These two wells (X1, X2) both have stable displacement straight line segments in the natural water flooding stage and the artificial water injection stage, and their water flooding characteristic curves show double straight line segment characteristics.

[0161] Taking well X1 as an example, firstly, its cumulative oil production, cumulative water production and other production data are plotted to obtain the water drive characteristic curve ( Figure 7 ), and then the production data corresponding to the natural water flooding stage and the artificial water flooding stage are respectively non-dimensionalized and plotted on the dimensionless curve plate ( Figure 8-Figure 9 ).

[0162] When the M of X1 well 天然-单井 =7.8, the slope of the dimensionless water flooding characteristic curve corresponding to the natural water flooding stage is 1; when M 人工-单井 =1.8, the slope of the dimensionless curve corresponding to the artificial water flooding stage is 1. Therefore, for well X1, when M 天然-单井 =7.8, M 人工-单井=1.8, the slope of the dimensionless water drive characteristic curve is 1, which meets the requirements of the dimensionless water drive characteristic curve theoretical model, so the M value is reasonable.

[0163] The M values ​​of the two target wells in the natural water flooding stage and the artificial water flooding stage are obtained respectively. 天然-单井 、M 人工-单井 Then add up all the geological reserves to get the geological reserves of the entire fracture-cavity unit (Table 3). Calculate the percentage of geological reserves of each target well to the total geological reserves of the fracture-cavity unit and determine the weight coefficient of each well (Table 3); use the corresponding weight coefficient, M 天然-单井 and M 人工-单井 The value determines the M corresponding to the entire fracture unit 天然-单元 and M 人工-单元 Value (Table 3)

[0164] Table 3 Calculation results of M value of X crack hole unit

[0165]

[0166] Based on the cumulative oil and water production data of the two wells, the water drive characteristic curve of the entire fracture-cavity unit is drawn ( Figure 10 ), the slopes B1 and B2 of the curves in the natural water flooding stage and the artificial water flooding stage were obtained by fitting (Table 3). Based on the slopes of the water flooding characteristic curves and the corresponding M values, the dynamic reserves of the entire fracture-cavity unit in the natural water flooding stage and the artificial water flooding stage were calculated (Table 4).

[0167] Table 4 Dynamic reserve calculation results of X fracture-cavity unit

[0168] Fracture unit <![CDATA[M 天然-单元 ]]> <![CDATA[M 人工-单元 ]]> <![CDATA[B1]]> B2 <![CDATA[N 天然 ]]>

[00011] N 人工 ]]> X 8.4 1.8 1.743E-06 5.490E-07 4.82E+06 3.28E+06

[0169] In summary, the present invention first selects appropriate target wells based on the established screening criteria. Based on the analysis of the water drive characteristic curve of the fracture-cavity reservoir, a type A dimensionless water drive characteristic curve model is derived and established, and a dimensionless curve chart is drawn. Secondly, combined with the dimensionless water drive characteristic curve theoretical model, a dimensionless processing method for cumulative oil and water production data is proposed. Simultaneously, the reasonable M values ​​for the natural water drive and artificial water drive stages of each target well are obtained by combining the dimensionless curve chart and the dimensionless cumulative oil and water production data. Based on the given geological reserves, the M values ​​obtained from all target wells are weighted averaged with the geological reserves as the weight to obtain the reasonable M values ​​for the natural water drive and artificial water drive stages of the entire fracture-cavity unit. Finally, the water drive characteristic curve of the entire fracture-cavity unit is drawn by combining the cumulative oil and water production data of all target wells. The slope B value of the straight line segment of the fracture-cavity unit water drive characteristic curve is obtained. Based on the slope B value and the M value, the dynamic reserves of the entire fracture-cavity unit during the natural water drive and artificial water drive stages are obtained.

[0170] Figure 11 The following is a structural block diagram of a water-driven reserve calculation device for fracture-cavity oil reservoirs according to an embodiment of the present invention. Figure 11 , the computing device 1100 includes a first module 1101, a second module 1102, a third module 1103, a fourth module 1104 and a fifth module 1105.

[0171] The first module is used to draw a water drive characteristic curve corresponding to a single target well in a semi-logarithmic coordinate system and determine the curve type of the water drive characteristic curve.

[0172] The second module is used to process the cumulative oil production data and the cumulative water production data of a single target well dimensionally and plot them on a dimensionless curve chart based on the curve type, so as to obtain the first-class coefficient corresponding to the single target well in each water flooding stage.

[0173] The third module is used to calculate the first-category coefficients corresponding to all target wells in each water flooding stage based on the first-category coefficient corresponding to the single target well in each water flooding stage and in combination with the geological reserve data of the single target well.

[0174] The fourth module is used to calculate the second type coefficients corresponding to all target wells in each water flooding stage through the cumulative oil production data and cumulative water production data of a single target well.

[0175] The fifth module is used to calculate the dynamic reserves corresponding to all target wells in each water flooding stage based on the first type coefficients and the second type coefficients corresponding to all target wells in each water flooding stage.

[0176] In summary, the water drive dynamic reserve calculation method for fracture-cavity oil reservoirs provided by the present invention establishes a dynamic reserve calculation method based on the curve characteristics of the water drive characteristic curve presented by the fracture-cavity oil reservoir, further improves the Type A water drive characteristic curve model in the prior art, and overcomes the defect that the use of a unified proportional coefficient in the prior art will lead to large errors in the calculation results; and different proportional coefficients are proposed for different water drive stages to calculate dynamic reserves, which is more in line with the mining law and can more accurately obtain the dynamic reserve data of target wells at different stages.

[0177] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0178] Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" or "an embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0179] Although the present application has been disclosed with reference to the above embodiments, the content mentioned is only for the purpose of facilitating the understanding of the application and is not intended to limit the application. Any modification and change in the form and details of the application can be made by any person skilled in the art without departing from the spirit and scope of the application disclosed, and the patent protection scope of the application shall be subject to the scope defined by the appended claims.

Claims

1. A method for calculating water-driven reserves in fracture-vuggy reservoirs, characterized in that: The method comprises the following steps: Step 1: In a semi-logarithmic coordinate system, a water drive characteristic curve corresponding to a single target well is plotted, and a curve type of the water drive characteristic curve is determined. The curve type includes a double straight line segment type and a single straight line segment type. The double straight line segment type includes a natural water drive stage and an artificial water drive stage, and the single straight line segment type includes a natural water drive stage. Step 2: Based on the curve type, the cumulative oil production data and the cumulative water production data of the single target well are dimensionlessly processed and plotted on a dimensionless curve chart to obtain the first-class coefficient corresponding to the single target well in each water flooding stage; Step 3: Based on the first-category coefficient corresponding to a single target well at each waterflooding stage and combined with the geological reserve data of the single target well, calculate the first-category coefficient corresponding to all target wells at each waterflooding stage; Step 4: Calculate the corresponding second-type coefficients of all target wells at each water flooding stage using the cumulative oil production data and cumulative water production data of a single target well; Step 5: Calculate the dynamic reserves of all target wells at each water flooding stage based on the first and second type coefficients corresponding to all target wells at each water flooding stage; The second step specifically includes the following steps: Select the first-category coefficients in the list of candidate first-category coefficients in sequence, combine them with the geological reserve data of a single target well, and calculate the second-category coefficient corresponding to the current first-category coefficient through B=M / N, where M represents the first-category coefficient, B represents the second-category coefficient, and N represents the geological reserve; According to the second type coefficient corresponding to the current first type coefficient, the cumulative oil production data and cumulative water production data of a single target well in each water flooding stage, the Q WD =B*W p and Q OD =B*N p The dimensionless cumulative oil production data and dimensionless cumulative water production data of a single target well are calculated respectively, where Q WD Indicates dimensionless cumulative water production; Q OD W represents dimensionless cumulative oil production; p Indicates the cumulative water production data; N p Indicates cumulative oil production data; For each water flooding stage, the dimensionless cumulative oil production data and the dimensionless cumulative water production data are plotted on the dimensionless curve chart to obtain a dimensionless curve corresponding to a single target well; When the slope of the dimensionless curve is equal to the second threshold, selecting the current first-category coefficient as the first-category coefficient corresponding to the single target well in each water flooding stage; The step 4 specifically includes the following steps: The cumulative oil production data and the cumulative water production data of all target wells are accumulated to obtain the total cumulative oil production data and the total cumulative water production data corresponding to all target wells; In a semi-logarithmic coordinate system, plotting a relationship curve between the total cumulative oil production data and the total cumulative water production data, and determining a curve type of the relationship curve; According to the curve type of the relationship curve, combined with the type A water flooding characteristic curve model, the relationship curve is fitted to obtain the second type coefficient corresponding to all target wells in each water flooding stage; Dynamic reserves under natural water flooding stage: Dynamic reserves during artificial water flooding: Where: N 天然 It represents the dynamic reserves of the entire fracture-cavity unit including all target wells under the natural water flooding stage; N 人工 represents the dynamic reserves of the entire fracture-cavity unit including all target wells in the artificial water flooding stage; M 天然-单元 It indicates the first type coefficient of the entire fracture-cavity unit including all target wells to achieve stable displacement in the natural water flooding stage; M 人工-单元 It represents the first-type coefficient when the entire fracture-cavity unit including all target wells reaches stable displacement in the artificial water flooding stage; B1 and B2 represent the second-type coefficients corresponding to the natural water flooding stage and the artificial water flooding stage, respectively.

2. The method for calculating water-driven reserves for fracture-vuggy oil reservoirs according to claim 1, wherein: The step 1 specifically includes the following steps: screening all production wells in the fracture-cavity unit to obtain all target wells that meet the requirements, specifically: Calculate the recovery rates of all production wells and exclude production wells whose recovery rates are greater than a first threshold; Sorting out the process measures of all production wells and eliminating those whose production data fluctuations under multiple process measures are greater than the preset standard; The water drive characteristic curves corresponding to all production wells are drawn, and the production wells corresponding to the violent water drive characteristic curves are eliminated.

3. The method for calculating water-driven reserves for fracture-vuggy oil reservoirs according to claim 1, wherein: The second step specifically includes the following steps: Based on the type A water flooding characteristic curve model, combined with the recovery degree expression and the relationship between geological reserves and the second type coefficient, a type A dimensionless water flooding characteristic curve model is obtained.

4. The method for calculating water-driven reserves for fracture-vuggy oil reservoirs according to claim 3, wherein: The second step specifically includes the following steps: Based on the preset first-category coefficient data set, the preset recovery factor data set, and the preset dimensionless cumulative oil production data set, a dimensionless cumulative water production data set is calculated using the type A dimensionless water drive characteristic curve model; The dimensionless curve chart is plotted in a semi-logarithmic coordinate system based on the dimensionless cumulative water production data set and the preset dimensionless cumulative oil production data set.

5. The method for calculating water-driven reserves for fracture-vuggy oil reservoirs according to claim 1, wherein: The step three specifically includes the following steps: Accumulate the geological reserve data of all target wells to obtain the total geological reserve data corresponding to all target wells; According to the weight coefficient corresponding to each target well and the first-category coefficient corresponding to a single target well in each water flooding stage, the first-category coefficients corresponding to all target wells in each water flooding stage are calculated.

6. A water-driven reserve calculation device for fracture-cavity oil reservoirs, characterized in that: The method according to any one of claims 1 to 5 is performed, wherein the device comprises: The first module is used to draw a water drive characteristic curve corresponding to a single target well in a semi-logarithmic coordinate system and determine the curve type of the water drive characteristic curve; The second module is used to perform dimensionless processing on the cumulative oil production data and the cumulative water production data of the single target well according to the curve type, and then plot them on the dimensionless curve chart to obtain the first type coefficient corresponding to the single target well in each water flooding stage; The third module is used to calculate the first type coefficients corresponding to all target wells in each water flooding stage based on the first type coefficients corresponding to the single target well in each water flooding stage and in combination with the geological reserve data of the single target well; The fourth module is used to calculate the second type coefficient corresponding to all target wells in each water flooding stage based on the cumulative oil production data and cumulative water production data of a single target well; The fifth module is used to calculate the dynamic reserves corresponding to all target wells in each water flooding stage based on the first type coefficients and the second type coefficients corresponding to all target wells in each water flooding stage.

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