Quantitative calculation method for economic limit thickness of oil layer of fault block oil reservoir

Abstract

The invention provides a fault block oil reservoir oil layer economic limit thickness quantitative evaluation method, and relates to the technical field of exploration and development of petroleum and natural gas geological resources, and the method comprises the following steps: obtaining oil well monthly yield production data and crude oil recovery parameters; processing the monthly yield production data of the oil well to obtain a single-oil monthly yield decline curve; according to the single oil monthly yield decline curve, the present value yield corresponding to the single oil well is obtained through calculation; according to the present value yield corresponding to the single oil well, present value net income and cash outflow are obtained through calculation; calculating the initial economic limit stable yield according to the present net income and the cash outflow; according to the initial economic limit stable yield of the single well and the total number of wells in the target area, the economic limit accumulated oil production is calculated; and calculating the economic limit thickness of the oil layer according to the economic limit accumulated oil production and the crude oil recovery parameters. The oil well yield decline rule is better fitted through the extensive index yield decline model, and the method better conforms to the actual production, so that the calculated economic limit thickness of the oil layer is more reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of exploration and development of petroleum and natural gas geological resources, and in particular relates to a quantitative evaluation method for the economic limit thickness of an oil layer in a fault-block reservoir. Background Art

[0002] In the existing process of solving the economic limit thickness of oil layers, the relationship curve method, the break-even principle and the cash flow method are considered to be combined for calculation. However, in the existing technology, the characteristics of the early production decline of the oil wells in the fault block reservoir and the slow production decline in the later period are not considered in the process of oil production. They are all considered to be a constant output method. However, the above calculation method is obviously different from the actual oil production. Therefore, a quantitative calculation method that can accurately calculate the economic limit thickness of the oil layer in the fault block reservoir is urgently needed. Summary of the invention

[0003] The purpose of the present invention is to provide a quantitative calculation method for the economic limit thickness of oil layers in fault-block reservoirs to solve the above technical problems.

[0004] In order to solve the above technical problems, the specific technical scheme of the method for quantitatively calculating the economic limit thickness of the oil layer in the fault-block reservoir of the present invention is as follows:

[0005] A quantitative calculation method for the economic limit thickness of oil layers in fault-block reservoirs, comprising:

[0006] Obtain monthly production data and crude oil recovery parameters of all oil wells in the target area within a preset period of time;

[0007] The monthly production data of oil wells are normalized to obtain the monthly production decline curve of single oil;

[0008] The present value production corresponding to a single oil well is calculated according to the monthly production decline curve of the single oil well;

[0009] The present value net income and cash outflow corresponding to the single oil well are calculated respectively according to the present value production corresponding to the single oil well;

[0010] The initial economic limit stable production is obtained based on the present value net income and cash outflow corresponding to the single oil well and the break-even point is reached as the calculation basis;

[0011] Calculate the economic limit cumulative oil production in the target area based on the initial economic limit stable production of a single well and the total number of wells in the target area;

[0012] The economic limit thickness of the oil layer is calculated based on the economic limit cumulative oil production in the target area and the crude oil recovery parameters.

[0013] Furthermore, the monthly production data of the oil wells are normalized to obtain the monthly production decline curve of a single oil, including:

[0014] According to the monthly production data of all oil wells, the production of all oil wells at each production time point is accumulated, wherein the length of the production time point is one month;

[0015] According to the total number of oil wells and the cumulative production of all oil wells at each production time point, the average value is obtained to obtain the production of a single oil well at each production time point;

[0016] The production of a single oil well at each production time point is plotted with the horizontal axis starting at 0 as the number of months and the vertical axis as the monthly production, to obtain a single oil monthly production decline curve.

[0017] Furthermore, the present value production corresponding to a single oil well is calculated based on the monthly production decline curve of the single oil well, including:

[0018] Solving the initial theoretical production and time constant in the preset pan-exponential production decline model according to the single oil monthly production decline curve to obtain the initial theoretical production and time constant;

[0019] The annual oil production is calculated based on the initial theoretical production and time constant, where the annual oil production calculation formula is as follows:

[0020]

[0021] Among them, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area; q i is the initial theoretical output at t = 0, t is the production time in months; c is the time constant;

[0022] The present value of production is calculated based on the annual oil production, where the present value of production is calculated as follows:

[0023]

[0024] Among them, NPQ is the present value of production, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area.

[0025] Furthermore, the initial theoretical production and time constant in the preset pan-exponential production decline model are solved according to the single oil monthly production decline curve to obtain the initial theoretical production and time constant, including:

[0026] Construct a preset pan-exponential yield decline model, where the pan-exponential yield decline model is as follows:

[0027]

[0028] Where q is the monthly oil production of the oil well; q i is the initial theoretical output at t = 0; t is the production time, in months; c is the time constant of the pan-exponential production decline model;

[0029] The natural logarithm of the preset pan-exponential yield decline model is used to obtain the linear regression relationship curve, which is as follows:

[0030]

[0031] Taking the natural logarithm of the monthly production decline curve of the single oil, a scatter plot is obtained;

[0032] The scatter plot is fitted according to the relationship curve formula to obtain the initial theoretical yield and time constant.

[0033] Furthermore, the present value net income and cash outflow corresponding to the single oil well are calculated respectively according to the present value production corresponding to the single oil well, including:

[0034] Obtain tax information and crude oil add-on price information;

[0035] The present value net income is calculated based on the tax information, crude oil additive price information and the present value net income, where the present value net income calculation formula is as follows:

[0036]

[0037] Among them, R o is the crude oil commodity rate; P o is the crude oil price; T axo is the crude oil tax; GOR is the gas-oil ratio; R g is the commodity rate of natural gas; P g is the natural gas price; T axg For natural gas taxes.

[0038] Furthermore, the present value net income and cash outflow corresponding to the single oil well are calculated respectively according to the present value production corresponding to the single oil well, including:

[0039] Obtaining capital expenditure costs and expense expenditure costs, wherein the capital expenditure costs include single well construction investment and single well abandonment costs, and the expense expenditure costs include fixed costs and variable costs;

[0040] The cash outflow is calculated based on the present value of output, capital expenditure cost and expense expenditure cost, where the cash outflow calculation formula is as follows:

[0041]

[0042] Among them, I p Investment for single well construction; Cab is the single well abandonment cost; C fo is the fixed cost; C ω is the variable cost; R o is the commodity rate of crude oil.

[0043] Furthermore, the initial economic limit stable production is obtained based on the present value net income and the cash outflow corresponding to the single oil well, taking the break-even point as the calculation basis, wherein the break-even point calculation formula is as follows:

[0044]

[0045] Among them, NPV is the net present value; T is the production time; M is the evaluation period; CI is the cash inflow; CO is the cash outflow; and i is the base discount rate.

[0046] Furthermore, the initial economic limit stable production is obtained based on the present value net income and the cash outflow corresponding to the single oil well, taking the break-even point as the calculation basis, wherein the initial economic limit stable production is calculated as follows:

[0047]

[0048] Among them, q min Initial economic limit stabilizes output.

[0049] Furthermore, the calculation formula for the economic limit cumulative oil production in the target area is as follows:

[0050]

[0051] Among them, EUR min is the economic limit cumulative oil production in the target area, n p is the number of wells in the evaluation area; q min is the initial economic limit stable production of a single well; c is the time constant.

[0052] Furthermore, the calculation formula of the economic limit thickness of the oil layer is as follows:

[0053]

[0054] Among them, h min EUR is the economic limit thickness of the oil layer; min B is the economic limit cumulative oil production in the target area; oi is the crude oil volume coefficient; E oR is the economic recovery factor of crude oil; ρ o is the density of crude oil on the ground; A is the oil-bearing area; is the porosity; S oi is the original oil saturation of the oil layer.

[0055] The beneficial effects of the present invention are:

[0056] The present invention firstly considers economic factors, and then applies a pan-exponential production decline model that is more suitable for the production decline law of fault-block oil reservoirs. Among them, the pan-exponential production decline model is more consistent with the characteristics of the early production decline of oil wells in fault-block oil reservoirs and the slow production decline in the later period. It can better fit the production decline law of oil wells, and the predicted production is more consistent with production reality. Therefore, the calculated economic limit thickness of the oil layer is more reliable.

[0057] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the embodiments of the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0059] Figure 1 It is a schematic diagram of the flow chart of the method for quantitatively calculating the economic limit thickness of oil layers in fault-block reservoirs described in an embodiment of the present invention;

[0060] Figure 2 This is a schematic diagram of a monthly production decline curve of a single oil described in an embodiment of the present invention;

[0061] Figure 3 It is a schematic diagram of scatter plot fitting described in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0063] Embodiment 1:

[0064] like Figure 1As shown, this embodiment provides a quantitative calculation method for the economic limit thickness of the oil layer in a fault block reservoir. In this embodiment, support is provided for the evaluation of the starting standard for the reserve calculation of the fault block reservoir, and a quantitative evaluation method for the economic limit thickness of the oil layer is established by applying the break-even principle and the cash flow method, combined with the law of oil well production decline, and specifically includes steps S1, S2, S3, S4, S5, S6 and S7.

[0065] S1. Obtain monthly production data and crude oil recovery parameters of all oil wells in the target area within a preset time period.

[0066] It should be noted that the factors mentioned in this step include crude oil volume coefficient, crude oil economic recovery rate, ground crude oil density, oil-bearing area, porosity, original oil saturation of the oil layer, etc.

[0067] S2. Normalize the monthly production data of oil wells to obtain the monthly production decline curve of single oil.

[0068] It should be noted that the normalization process of step S2 may further include step S21, step S22 and step S23, including:

[0069] S21. According to the monthly production data of all oil wells, the production of all oil wells at each production time point is accumulated, wherein the length of the production time point is one month.

[0070] It should be noted that in this step, the production volumes of all oil wells in the first month are accumulated as one data, and the production volumes in the second month are accumulated as one data, until the time point with the longest production month.

[0071] S22, according to the total number of oil wells and the cumulative production of all oil wells at each production time point, the average value is calculated to obtain the production of a single oil well at each production time point;

[0072] S23, plotting the production of a single oil well at each production time point with the horizontal axis starting at 0 as the number of months and the vertical axis as the monthly production, to obtain a single oil monthly production decline curve.

[0073] Specifically, see Figure 2 The figure shows the monthly production decline curve for a single oil.

[0074] S3. Calculate the present value production corresponding to the single oil well according to the single oil monthly production decline curve.

[0075] Specifically, the step S3 also includes the following steps to realize the calculation of the present value of output, including step S31, step S32 and step S33.

[0076] S31. Solving the initial theoretical production and time constant in the preset pan-exponential production decline model according to the single oil monthly production decline curve to obtain the initial theoretical production and time constant.

[0077] Specifically, this step S31 also includes the following steps S311, S312, S313 and S314.

[0078] Initial theoretical yields and time constants, including:

[0079] S311. Construct a preset pan-exponential production decline model, wherein the pan-exponential production decline model is as follows:

[0080]

[0081] Where q is the monthly oil production of the oil well; q i is the initial theoretical output at t = 0; t is the production time, in months; c is the time constant of the pan-exponential production decline model;

[0082] It should be noted that the pan-exponential production decline model in this step is not the pan-exponential production decline model with m=0.5 proposed by Chen Yuanqian.

[0083] S312. Taking the natural logarithm of the preset pan-exponential yield decline model, the linear regression relationship curve is obtained, and the relationship is as follows:

[0084]

[0085] Among them, α and β are coefficients.

[0086] S313, taking the natural logarithm of the monthly production decline curve of the single oil to obtain a scatter plot;

[0087] S314. Fit the scatter plot according to the relationship curve to obtain an initial theoretical yield and a time constant.

[0088] Specifically, see Figure 3 The figure shows the scatter plot fitting diagram, that is, t 0.5 With ln q The relationship curve.

[0089] S32. Calculate the annual oil production according to the initial theoretical production and the time constant, wherein the annual oil production calculation formula is as follows:

[0090]

[0091] Among them, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area; q iis the initial theoretical output at t = 0, t is the production time in months; c is the time constant;

[0092] In this step, the future crude oil production is discounted to the production in the starting year of the evaluation period according to the benchmark rate of return, and the present value production calculation formula is obtained.

[0093] S33. Calculate the present value of production based on the annual oil production, where the formula for calculating the present value of production is as follows.

[0094]

[0095] Among them, NPQ is the present value of production, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area.

[0096] S4. Calculate the present value net income and cash outflow corresponding to the single oil well according to the present value production corresponding to the single oil well.

[0097] Specifically, the present application also includes step S41, step S42, step S43 and step S44.

[0098] S41. Obtain tax information and crude oil additive price information;

[0099] S42. Calculate the present value net income based on the tax information, crude oil additive price information and the present value net income, where the present value net income calculation formula is as follows:

[0100]

[0101] Among them, R o is the crude oil commodity rate; P o is the crude oil price; T axo is the crude oil tax; GOR is the gas-oil ratio; R g is the commodity rate of natural gas; P g is the natural gas price; T axg For natural gas taxes.

[0102] It should be noted that in this step, the formula takes into account the crude oil price minus taxes and surcharges, and considers the benefits brought by dissolved gas to obtain the net oil price and combines it with the present value of production to calculate the present value of net income.

[0103] S43, obtaining capital expenditure costs and expense expenditure costs, wherein the capital expenditure costs include single well construction investment and single well abandonment costs, and the expense expenditure costs include fixed costs and variable costs;

[0104] S44. Calculate cash outflow based on the present value of output, capital expenditure cost and expense expenditure cost, where the cash outflow calculation formula is as follows:

[0105]

[0106] Among them, I p Investment for single well construction; C ab is the single well abandonment cost; C fo is the fixed cost; C ω is the variable cost; R o is the commodity rate of crude oil.

[0107] It should be noted that the calculation formula in this step takes into account that cash outflow mainly includes capital expenditure and expense expenditure, among which capital expenditure mainly includes construction investment (I p ), including drilling investment, fracturing investment and surface investment; taking into account the abandonment cost at the end of the evaluation period, and discounting it to the abandonment cost in the initial year at the long-term loan interest rate (C ab ) as capital expenditure. Expenses are mainly operating costs, which are divided into fixed costs (C fo ) and variable costs (C ω ). Taking into account the time value of money, we get the present value of the cash outflows.

[0108] S5. The initial economic limit stable production is obtained based on the present value net income and the cash outflow corresponding to the single oil well and the break-even point is reached as the calculation basis.

[0109] This method is based on the break-even principle to determine the economic limit oil layer thickness that can recover the construction investment, abandonment costs, production and operation costs and related taxes and fees within a certain evaluation period under the existing technical and economic conditions, and meet certain commercial benchmark yield (discount rate) conditions. Therefore, in the process of establishment, combined with the production dynamic characteristics of the single well of the block and considering the time value of funds, the cash flow method is used to convert the input and output into a cumulative net present value of zero in the evaluation starting year as the break-even point. The break-even point calculation formula is:

[0110]

[0111] Among them, NPV is the net present value; T is the production time; M is the evaluation period; CI is the cash inflow; CO is the cash outflow; and i is the base discount rate.

[0112] Then, combining the break-even point calculation formula, cash outflow, present value net income and present value output calculation formula, the initial economic limit stable output calculation formula is as follows:

[0113]

[0114] S6. Calculate the economic limit cumulative oil production in the target area based on the initial economic limit stable production of the single well and the total number of wells in the target area.

[0115] Specifically, the calculation formula for the economic limit cumulative oil production in the target area is as follows:

[0116]

[0117] Among them, EUR min is the economic limit cumulative oil production in the target area, n p is the number of wells in the evaluation area; q min is the initial economic limit stable production of a single well; c is the time constant.

[0118] It should be noted that in this step, the geological reserves are calculated based on the economic limit cumulative oil production of the block and the economic recovery rate of crude oil, and then the economic limit thickness of the oil layer is obtained.

[0119] S7. Calculate the economic limit thickness of the oil layer according to the economic limit cumulative oil production in the target area and the crude oil recovery parameters.

[0120] Specifically, the calculation formula for the economic limit thickness of the oil layer is as follows:

[0121]

[0122] Among them, h min EUR is the economic limit thickness of the oil layer; min B is the economic limit cumulative oil production in the target area; oi is the crude oil volume coefficient; E oR is the economic recovery factor of crude oil; ρ o is the density of crude oil on the ground; A is the oil-bearing area; is the porosity; S oi is the original oil saturation of the oil layer.

[0123] In this method, economic factors are first taken into consideration, and then a pan-exponential production decline model that is more suitable for the production decline law of fault-block reservoirs is applied. Among them, the pan-exponential production decline model is more consistent with the characteristics of fault-block reservoirs, where the production of oil wells decreases quickly in the early stage and slowly in the later stage. It can better fit the production decline law of oil wells, and the predicted production is more consistent with production reality. Therefore, the calculated economic limit thickness of the oil layer is more reliable.

[0124] Embodiment 2:

[0125] This embodiment provides a specific application example, taking 15 oil wells in a certain block of a fault-block reservoir as an example.

[0126] First, the monthly production decline curve of the oil well is normalized.

[0127] Then, take the natural logarithm of the monthly production data and plot t 0.5 With ln qThe relationship curve of the initial theoretical yield q i and the time constant c of the pan-exponential production decline model.

[0128] according to Figure 3 The fitting formula is:

[0129] lnq=6.2929-0.3236t 0.5

[0130] q i =e α =e 6.2929 =540.72

[0131]

[0132] Finally, the economic limit thickness of the oil layer in a block of the oil reservoir is calculated. The parameter table of the economic limit thickness of the oil layer in a block of the oil reservoir is as follows:

[0133]

[0134] The calculation results of the initial economic limit stable output are as follows:

[0135] j=ln(i+1)=ln(0.08+1)=0.077

[0136]

[0137] The calculation results of the economic limit cumulative oil production in the target area are as follows:

[0138]

[0139] The calculation results of the economic limit thickness of the oil layer are as follows:

[0140]

[0141] Finally, the economic limit thickness of the oil layer was calculated to be 0.7m.

[0142] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A quantitative calculation method for the economic limit thickness of oil layers in fault-block reservoirs, characterized in that: include: Obtain monthly production data and crude oil recovery parameters of all oil wells in the target area within a preset period of time; The monthly production data of oil wells are normalized to obtain the monthly production decline curve of single oil; The present value production corresponding to a single oil well is calculated according to the monthly production decline curve of the single oil well; The present value net income and cash outflow corresponding to the single oil well are calculated respectively according to the present value production corresponding to the single oil well; The initial economic limit stable production is obtained based on the present value net income and cash outflow corresponding to the single oil well and the break-even point is reached as the calculation basis; Calculate the economic limit cumulative oil production in the target area based on the initial economic limit stable production of a single well and the total number of wells in the target area; The economic limit thickness of the oil layer is calculated based on the economic limit cumulative oil production in the target area and the crude oil recovery parameters.

2. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The monthly production data of oil wells are normalized to obtain the monthly production decline curve of single oil, including: According to the monthly production data of all oil wells, the production of all oil wells at each production time point is accumulated, wherein the length of the production time point is one month; According to the total number of oil wells and the cumulative production of all oil wells at each production time point, the average value is obtained to obtain the production of a single oil well at each production time point; The production of a single oil well at each production time point is plotted with the horizontal axis starting at 0 as the number of months and the vertical axis as the monthly production, to obtain a single oil monthly production decline curve.

3. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The present value production corresponding to a single oil well is calculated based on the monthly production decline curve of the single oil well, including: Solving the initial theoretical production and time constant in the preset pan-exponential production decline model according to the single oil monthly production decline curve to obtain the initial theoretical production and time constant; The annual oil production is calculated based on the initial theoretical production and time constant, where the annual oil production calculation formula is as follows: Among them, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area; q i is the initial theoretical output at t = 0, t is the production time in months; c is the time constant; The present value of production is calculated based on the annual oil production, where the present value of production is calculated as follows: Among them, NPQ is the present value of production, Q T is the oil production in the Tth year, T is less than M, and M is the evaluation period of the target area.

4. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 3 is characterized in that: The initial theoretical production and time constant in the preset pan-exponential production decline model are solved according to the single oil monthly production decline curve to obtain the initial theoretical production and time constant, including: Construct a preset pan-exponential yield decline model, where the pan-exponential yield decline model is as follows: Where q is the monthly oil production of the oil well; q i is the initial theoretical output at t = 0; t is the production time, in months; c is the time constant of the pan-exponential production decline model; The natural logarithm of the preset pan-exponential yield decline model is used to obtain the linear regression relationship curve, which is as follows: Taking the natural logarithm of the monthly production decline curve of the single oil, a scatter plot is obtained; The scatter plot is fitted according to the relationship curve formula to obtain the initial theoretical yield and time constant.

5. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 3 is characterized in that: The present value net income and cash outflow corresponding to a single oil well are calculated based on the present value production corresponding to the single oil well, including: Obtain tax information and crude oil add-on price information; The present value net income is calculated based on the tax information, crude oil additive price information and the present value net income, where the present value net income calculation formula is as follows: Among them, R o is the crude oil commodity rate; P o is the crude oil price; T axo is the crude oil tax; GOR is the gas-oil ratio; R g is the commodity rate of natural gas; P g is the natural gas price; T axg For natural gas taxes.

6. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The present value net income and cash outflow corresponding to a single oil well are calculated based on the present value production corresponding to the single oil well, including: Obtaining capital expenditure costs and expense expenditure costs, wherein the capital expenditure costs include single well construction investment and single well abandonment costs, and the expense expenditure costs include fixed costs and variable costs; The cash outflow is calculated based on the present value of output, capital expenditure cost and expense expenditure cost, where the cash outflow calculation formula is as follows: Among them, I p Investment for single well construction; C ab is the single well abandonment cost; C fo is the fixed cost; C ω is the variable cost; R o is the commodity rate of crude oil.

7. The method for quantitatively calculating the economic limit thickness of oil layers in fault-block reservoirs according to claim 1, characterized in that: The initial economic limit stable production is obtained based on the present value net income and cash outflow corresponding to a single oil well, taking the break-even point as the calculation basis, wherein the break-even point calculation formula is as follows: Among them, NPV is the net present value; T is the production time; M is the evaluation period; CI is the cash inflow; CO is the cash outflow; and i is the base discount rate.

8. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The initial economic limit stable production is obtained based on the present value net income and cash outflow corresponding to a single oil well when the break-even point is reached. The calculation formula for the initial economic limit stable production is as follows: Among them, q min Initial economic limit stabilizes output.

9. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The calculation formula for the economic limit cumulative oil production in the target area is as follows: Among them, EUR min is the economic limit cumulative oil production in the target area, n p is the number of wells in the evaluation area; q min is the initial economic limit stable production of a single well; c is the time constant.

10. The quantitative calculation method for the economic limit thickness of the oil layer in the fault-block reservoir according to claim 1 is characterized in that: The calculation formula of economic limit thickness of oil layer is as follows: Among them, h min EUR is the economic limit thickness of the oil layer; min B is the cumulative oil production within the target area at the economic limit; oi is the crude oil volume coefficient; E oR is the economic recovery factor of crude oil; ρ o is the density of crude oil on the ground; A is the oil-bearing area; is the porosity; S oi is the original oil saturation of the oil layer.

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