A quantitative identification method for rationality of well spacing in shale oil horizontal well development

Abstract

The present invention discloses a method for quantitatively identifying the rationality of well spacing in shale oil horizontal well development, specifically: establishing a shale oil horizontal well development recovery rate prediction model; using the basic high-pressure physical property parameters of formation crude oil and gas and the average pore volume compression coefficient of the core, through the development recovery rate prediction model, calculating the recovery rate of the shale oil reservoir depletion development throughout the life cycle; calculating the recoverable reserves of a single well in shale oil elastic development according to the production dynamic data of the target block; calculating the single well controlled geological reserves and converting the single well control radius according to the calculated recoverable reserves and recovery rate of a single well in shale oil elastic development; calculating the well spacing rationality degree coefficient according to the single well control radius, and judging the rationality of the well spacing according to the well spacing rationality degree coefficient. The method of the present invention solves the problems of long prediction cycle, high cost and many influencing factors in the existing method.

Description

Technical Field

[0001] The invention belongs to the technical field of shale oil exploitation and relates to a method for quantitatively identifying the rationality of well spacing in shale oil horizontal well development. Background Art

[0002] As an unconventional oil and gas resource, shale oil has become a major strategic resource both internationally and domestically. Due to the low permeability of the reservoir, it is difficult to establish an effective displacement pressure system by water injection under the economic limit well pattern. At present, the "horizontal well + volume fracturing" method is usually adopted for quasi-natural energy development. Since the formation energy cannot be effectively supplemented, the production decline in the shale oil development process is large and the recovery rate is low. Reasonable well spacing for horizontal well development is one of the key parameters in the design of shale oil development technology policy. It not only affects the control degree of reservoir reserves, but also the well pattern density. It is one of the key parameters affecting the effect and benefit of shale oil development. If the horizontal well spacing is too large, the control degree of geological reserves of a single well will be low, resulting in low reserve utilization and waste of resources. If the horizontal well spacing is too small, the number of horizontal wells per unit area will be large, and the drilling, completion and ground investment will be large, which will affect the benefit of shale oil development. At the same time, the rationality of the well spacing of long horizontal wells in developed shale oil is a key link in guiding the formulation of technical policies for horizontal well development in undeveloped shale oil reservoirs.

[0003] At present, the optimization of horizontal well spacing in shale oil development is mainly done by using numerical simulation before development. Through geological modeling and numerical simulation, the production capacity and recovery rate of different horizontal well spacing are optimized. There are few studies on the quantitative identification of the rationality of horizontal well spacing in developed shale oil reservoirs, but numerical simulation can also be used for quantitative research. However, numerical simulation requires fine geological modeling and accurate data such as fluid, reservoir and phase permeability curves. In particular, it is difficult to quantitatively describe the fractures in the geological model after large-scale fracturing, and the accuracy of numerical simulation is also questioned. At the same time, the research cycle of geological modeling and numerical simulation is long and the cost is high. How to quickly and low-cost quantitatively identify the rationality of horizontal well spacing in shale oil is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a method for quantitatively identifying the rationality of the spacing of shale oil horizontal well development wells, which solves the problems of long prediction cycle, high cost and many influencing factors in the existing methods.

[0005] The technical solution adopted by the present invention is a method for quantitatively identifying the rationality of the spacing of shale oil horizontal wells, which is specifically implemented according to the following steps:

[0006] Step 1, establishing a shale oil horizontal well development recovery rate prediction model;

[0007] Step 2: using the basic high-pressure physical property parameters of formation crude oil and gas and the average pore volume compressibility coefficient of the core, and the development recovery factor prediction model established in step 1, calculate the recovery factor of the shale oil reservoir depletion development over the entire life cycle;

[0008] Step 3: Calculate the recoverable reserves of a single well in shale oil elastic development based on the production dynamic data of the target block;

[0009] Step 4, according to the recoverable reserves of a single well in the elastic development of shale oil obtained in step 3 and the recovery factor of the whole life cycle of the depletion development of shale oil reservoir obtained in step 2, calculate the controlled geological reserves of a single well and convert the controlled radius of a single well;

[0010] Step 5, according to the single well control radius obtained in step 4, calculate the rationality coefficient of the well spacing, and judge the rationality of the well spacing according to the rationality coefficient of the well spacing.

[0011] The present invention is also characterized in that

[0012] The shale oil horizontal well development recovery factor prediction model in step 1 is:

[0013] (1)

[0014] (2)

[0015] (3)

[0016] In formulas (1)-(3), R represents the recovery factor of shale oil reservoir depletion development over the entire life cycle, %; represents the elastic flooding recovery factor, %; represents the solution gas drive recovery rate, %; It represents the original crude oil volume coefficient, a decimal; represents the original formation pressure, MPa; Indicates the crude oil saturation pressure, MPa; It represents the volume coefficient of crude oil at saturation pressure, decimal; It represents the two-phase volume coefficient at the abandoned reservoir pressure, a decimal; represents the average production gas-oil ratio, m 3 / m 3 ; represents the original gas-oil ratio, m 3 / m 3 ; It represents the volume coefficient of gas released under the abandoned reservoir pressure, a decimal; Indicates the comprehensive compression coefficient, 1 / MPa; Indicates the compressibility of crude oil, 1 / MPa; Indicates the formation water compressibility, 1 / MPa; Indicates bound water saturation, decimal; Indicates the rock compression coefficient, 1 / MPa; It represents the volume coefficient of degassed formation crude oil at the abandoned reservoir pressure, a decimal; represents the dissolved gas-oil ratio of the formation crude oil after degassing at the abandoned reservoir pressure, m 3 / m 3 .

[0017] Step 2 is implemented as follows:

[0018] Step 2.1, obtaining basic high-pressure physical property parameters of formation crude oil and gas through phase calculation simulation software;

[0019] Step 2.2: By testing the compression coefficient of the shale oil core in the target block, the rock pore volume compression coefficient at the original formation pressure and the saturation pressure is obtained. The average value of the two is the average pore volume compression coefficient of the reservoir rock from the original formation pressure to the saturation pressure. ;

[0020] Step 2.3, the basic high-pressure physical property parameters of the formation crude oil and gas obtained in step 2.1 and the average pore volume compressibility coefficient obtained in step 2.2 are substituted into formula (1) to obtain the recovery factor of the shale oil reservoir depletion development over the entire life cycle.

[0021] Step 2.1 is implemented as follows:

[0022] Step 2.1.1, testing the total hydrocarbon components of the crude oil and the produced gas after ground degassing by gas chromatography;

[0023] Step 2.1.2: the total hydrocarbon components and original gas-oil ratio of the degassed crude oil and produced gas obtained in step 2.1.1 are 2. The density of crude oil after ground degassing is calculated by phase calculation simulation software to combine oil and gas and obtain the composition of formation crude oil;

[0024] Step 2.1.3, splitting the formation crude oil components obtained in step 2.1.2 to obtain a pseudo-component split crude oil model;

[0025] Step 2.1.4, performing phase calculation on the split crude oil model of the pseudo-component obtained in step 2.1.3 to obtain the molecular weight, density, critical temperature, critical pressure, deviation factor, and volume shift coefficient of the split crude oil model of each pseudo-component;

[0026] Step 2.1.5: Perform constant mass expansion experiments on the degassed crude oil and produced gas to obtain the crude oil volume coefficient at the original formation pressure. , Crude oil volume coefficient at saturation pressure , Volume coefficient of degassed crude oil at reservoir abandonment pressure and crude oil compressibility ;

[0027] Step 2.1.6, conduct multi-stage degassing experiments on the crude oil and produced gas after ground degassing to obtain the degassing gas volume coefficient under the abandoned reservoir pressure , Dissolved gas-oil ratio of crude oil after degassing at abandoned reservoir pressure and the average gas-oil ratio of produced gas.

[0028] In step 2.1.3, the pseudo-component split crude oil model is CO 2 、N 2 , C 1 , C 2 -C 6 , C 7 -C 15 , C 16 -C 20 , C 21 -C 27 , C 28 -C 80 .

[0029] The specific process of step 3 is:

[0030] Based on the actual monthly production data, use Excel to make a scatter plot with the cumulative oil production as the horizontal axis and the daily oil production of a single well as the vertical axis. Select at least 12 months of data from late to early to add a trend line. The trend line type is a straight line. According to the regression formula, the recoverable reserves of a single well in the elastic development stage of shale oil are calculated.

[0031] In step 4, the expression of geological reserves controlled by a single well is:

[0032] (4)

[0033] In formula (4), N R represents the recoverable reserves of a single well in the elastic development stage of shale oil, 10 4 t;

[0034] The expression of the single well control radius is:

[0035] (5)

[0036] In formula (5), represents the control radius of a single well, m; Indicates the geological reserves controlled by a single well, 10 4 t; L represents the length of the horizontal well, m; represents the average effective thickness, m; represents the average effective porosity, %; Indicates the density of ground crude oil, g / cm 3 ; Represents bound water saturation, %.

[0037] In step 5, the expression of the rationality coefficient of well spacing is:

[0038] (6)

[0039] In formula (6), Indicates the rationality coefficient of well distance, decimal; Indicates the control radius of 1 well among adjacent horizontal wells, m; Indicates the control radius of two adjacent horizontal wells, m; Represents the spacing between adjacent horizontal wells, m.

[0040] In step 5, the rationality of the well spacing is determined as follows:

[0041] 1) When =1, the rationality of horizontal well spacing is judged to be ideal;

[0042] 2) When 0.9≤ When ≤1.1, the rationality of the well spacing is judged to be high and the current development technology policy is maintained;

[0043] 3) When 0.6< <0.9 or 1.1< When <1.3, the rationality of horizontal well spacing is judged to be moderately reasonable, and it is recommended to maintain the current development technology policy for developed shale oil reservoirs;

[0044] in,

[0045] 0.7≤ When <0.9, the well spacing of undeveloped shale reservoirs is reduced to make the designed well spacing 1 / 2 of the well spacing of developed shale reservoirs. times;

[0046] 1.1< When the well spacing is less than 1.3, the well spacing of undeveloped shale reservoirs should be increased to make the designed well spacing equal to that of developed shale reservoirs. times;

[0047] 4) When ≤0.6 or When ≥1.3, the rationality of horizontal well spacing is judged to be unreasonable;

[0048] in,

[0049] When ≤0.6, it is recommended to add one more well between horizontal wells for developed shale reservoirs; for undeveloped shale reservoirs, it is recommended to reduce the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale reservoirs. times;

[0050] When the well pressure is ≥1.3, it is recommended that two horizontal wells be shut down in turn for developed shale oil reservoirs; for undeveloped shale oil reservoirs, it is recommended to increase the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale oil reservoirs. times.

[0051] The beneficial effect of the present invention is that the present invention provides a quantitative identification method for the rationality of the well spacing of shale oil horizontal well development, combines the recoverable reserves of a single well in the shale oil elastic development stage and the recovery rate of the shale oil reservoir depletion development throughout the life cycle, calculates the controlled geological reserves of a single well, and then converts the well control radius of the horizontal well, and realizes the quantitative identification of the rationality of the well spacing of the horizontal well through the quantitative relationship between the well control radius and the well spacing. Compared with the existing numerical simulation method, it does not require geological modeling and numerical simulation to calculate a large amount of static and dynamic data, has a short prediction period, low cost and few influencing factors, provides a basis for the formulation of shale oil horizontal well development policies, guides the development of new shale oil areas, and further improves the development effect and benefits of shale oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of horizontal well spacing deployment in an embodiment of a method for quantitatively identifying rationality of well spacing for shale oil horizontal well development of the present invention;

[0053] Figure 2 It is a crude oil volume coefficient diagram under different pressures in an embodiment of a method for quantitatively judging the rationality of well spacing in shale oil horizontal well development of the present invention;

[0054] Figure 3 It is a diagram of crude oil compressibility coefficient under different pressures in an embodiment of a method for quantitatively identifying rationality of well spacing for shale oil horizontal well development of the present invention;

[0055] Figure 4 It is a diagram of the volume coefficient of degassed gas and the dissolved gas-oil ratio in the crude oil after degassing at different pressures in an embodiment of a method for quantitatively judging the rationality of well spacing in shale oil horizontal well development of the present invention;

[0056] Figure 5 It is a rock pore volume compression coefficient diagram under different pressures in an embodiment of a method for quantitatively judging the rationality of well spacing in shale oil horizontal well development of the present invention;

[0057] Figure 6 It is a cumulative oil production-daily oil production relationship curve and regression diagram in an embodiment of a method for quantitatively judging the rationality of well spacing in shale oil horizontal well development of the present invention. DETAILED DESCRIPTION

[0058] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] The present invention provides a method for quantitatively identifying the rationality of the spacing of shale oil horizontal well development wells, which is specifically implemented according to the following steps:

[0060] Step 1, establishing a shale oil horizontal well development recovery rate prediction model;

[0061] The recovery factor prediction model for shale oil horizontal well development is:

[0062] (1)

[0063] (2)

[0064] (3)

[0065] In formulas (1)-(3), R represents the recovery factor of shale oil reservoir depletion development over the entire life cycle, %; represents the elastic flooding recovery factor, %; represents the solution gas drive recovery rate, %; It represents the volume coefficient of crude oil at the original formation pressure, decimal; represents the original formation pressure, MPa; Indicates the crude oil saturation pressure, MPa; It represents the volume coefficient of crude oil at saturation pressure, decimal; It represents the two-phase volume coefficient at the abandoned reservoir pressure, a decimal; represents the average production gas-oil ratio, m 3 / m 3 ; represents the original gas-oil ratio, m 3 / m 3 ; It represents the volume coefficient of gas released under the abandoned reservoir pressure, a decimal; Indicates the comprehensive compression coefficient, 1 / MPa; Indicates the compressibility of crude oil, 1 / MPa; Indicates the formation water compressibility, 1 / MPa; Indicates bound water saturation, decimal; It represents the average pore volume compressibility of rock, 1 / MPa; It represents the volume coefficient of degassed crude oil at the abandoned reservoir pressure, a decimal; represents the gas-oil ratio of crude oil after degassing at the abandoned reservoir pressure, m 3 / m 3 ;

[0066] Step 2: using the basic high-pressure physical property parameters of formation crude oil and gas and the average pore volume compressibility coefficient of the core, and the development recovery factor prediction model established in step 1, calculate the recovery factor of the shale oil reservoir depletion development over the entire life cycle;

[0067] Step 2.1, obtaining basic high-pressure physical property parameters of formation crude oil and gas through phase calculation simulation software;

[0068] Step 2.1.1, testing the total hydrocarbon components of the crude oil and the produced gas after ground degassing by gas chromatography;

[0069] Step 2.1.2: the total hydrocarbon components and original gas-oil ratio of the degassed crude oil and produced gas obtained in step 2.1.1 are 2. The density of crude oil after ground degassing is calculated by phase calculation simulation software to combine oil and gas and obtain the composition of formation crude oil;

[0070] Phase calculation simulation software includes CMG-WINPROP, Eclipse-PVTi and FMG-Cloud;

[0071] Step 2.1.3: The formation crude oil components obtained in step 2.1.2 are divided into CO 2 、N 2 , C 1 , C 2 -C 6 , C 7 -C 15 , C 16 -C 20 , C 21 -C 27 , C 28 -C 80 The components are split to obtain a split crude oil model with eight pseudo components;

[0072] The split crude oil model that can be split into other pseudo-components in the actual process belongs to the protection scope of the present invention;

[0073] Step 2.1.4, using the phase state software to perform phase state calculation on the eight-pseudo-component split crude oil model obtained in step 2.1.3 to obtain characteristic parameters of the split crude oil model of each pseudo-component, wherein the characteristic parameters of the split crude oil model of each pseudo-component include: molecular weight, density, critical temperature, critical pressure, deviation factor, and volume shift coefficient;

[0074] Step 2.1.5: Perform constant mass expansion experiments on the degassed crude oil and produced gas to obtain the crude oil volume coefficient at the original formation pressure. , Crude oil volume coefficient at saturation pressure , Volume coefficient of degassed crude oil at reservoir abandonment pressure and crude oil compressibility ;

[0075] Step 2.1.6, conduct multi-stage degassing experiments on the crude oil and produced gas after ground degassing to obtain the degassing gas volume coefficient under the abandoned reservoir pressure , Dissolved gas-oil ratio of crude oil after degassing at abandoned reservoir pressure and the average gas-oil ratio of produced gas;

[0076] Step 2.2: By testing the compression coefficient of the shale oil core in the target block, the rock pore volume compression coefficient at the original formation pressure and the saturation pressure is obtained. The average value of the two is the average pore volume compression coefficient of the reservoir rock from the original formation pressure to the saturation pressure. ;

[0077] Step 2.3, the basic high-pressure physical property parameters of the formation crude oil and gas obtained in step 2.1 and the average pore volume compressibility coefficient obtained in step 2.2 are substituted into formula (1) to obtain the recovery factor of the shale oil reservoir depletion development over the entire life cycle;

[0078] Step 3: Calculate the recoverable reserves of a single well in shale oil elastic development based on the production dynamic data of the target block;

[0079] Based on the actual monthly production data, use Excel to make a scatter plot with the cumulative oil production as the horizontal axis and the daily oil production of a single well as the vertical axis. Select at least 12 months of data from late to early to add a trend line. The trend line type is a straight line. According to the regression formula, calculate the recoverable reserves of a single well in the elastic development stage of shale oil;

[0080] Step 4, based on the recoverable reserves of a single well in the elastic development stage of shale oil obtained in step 3 and the recovery factor of the whole life cycle of depletion development of shale oil reservoir obtained in step 2, calculate the controlled geological reserves of a single well and convert the controlled radius of a single well; namely:

[0081] The expression of geological reserves controlled by a single well is:

[0082] (4)

[0083] In formula (4), N R represents the recoverable reserves of a single well in the elastic development stage of shale oil, 10 4 t;

[0084] The expression of the single well control radius is:

[0085] (5)

[0086] In formula (5), represents the control radius of a single well, m; Indicates the geological reserves controlled by a single well, 10 4 t; L represents the length of the horizontal well, m; represents the average effective thickness, m; represents the average effective porosity, %; Indicates the density of ground crude oil, g / cm 3 ; represents bound water saturation, %;

[0087] Step 5, calculating the rationality coefficient of the well spacing according to the single well control radius obtained in step 4, and judging the rationality of the well spacing according to the rationality coefficient of the well spacing;

[0088] The expression of the rationality coefficient of well spacing is:

[0089] (6)

[0090] In formula (6), Indicates the rationality coefficient of well distance, decimal; Indicates the control radius of 1 well among adjacent horizontal wells, m; Indicates the control radius of two adjacent horizontal wells, m; represents the spacing between adjacent horizontal wells, m;

[0091] The rationality of well spacing is specifically judged as follows:

[0092] (1) When =1, the rationality of horizontal well spacing is judged to be ideal;

[0093] (2) When 0.9≤ When ≤1.1, the rationality of the well spacing is judged to be high and the current development technology policy is maintained;

[0094] (3) When 0.6< <0.9 or 1.1< When <1.3, the rationality of horizontal well spacing is judged to be moderately reasonable, and it is recommended to maintain the current development technology policy for developed shale oil reservoirs;

[0095] in,

[0096] 0.7≤ When <0.9, the well spacing of undeveloped shale reservoirs is reduced to make the designed well spacing 1 / 2 of the well spacing of developed shale reservoirs. times;

[0097] 1.1< When the well spacing is less than 1.3, the well spacing of undeveloped shale reservoirs should be increased to make the designed well spacing equal to that of developed shale reservoirs. times;

[0098] (4) When ≤0.6 or When ≥1.3, the rationality of horizontal well spacing is judged to be unreasonable;

[0099] in,

[0100] When ≤0.6, it is recommended to add one more well between horizontal wells for developed shale reservoirs; for undeveloped shale reservoirs, it is recommended to reduce the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale reservoirs. times;

[0101] When the well pressure is ≥1.3, it is recommended that two horizontal wells be shut down in turn for developed shale oil reservoirs; for undeveloped shale oil reservoirs, it is recommended to increase the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale oil reservoirs. times.

[0102] Example

[0103] Basic overview of shale oil reservoirs: A typical shale oil reservoir in a western oil field, no edge and bottom water, and the reservoir crude oil formation pressure 16.2MPa, crude oil saturation pressure The average permeability of the reservoir matrix is ​​0.1mD, the porosity is 9.0%, the average thickness of the oil layer is 9m, the crude oil viscosity is 1.21mPa•s, and the density is 0.74g / cm 3 , original gas-oil ratio 107.6m 3 / m 3 , reservoir temperature 58℃, irreducible water saturation The density of ground degassed crude oil is 0.84 g / cm 3 The components of ground degassed oil and produced gas are shown in Tables 1 and 2. The sand body area in the southeast of the reservoir is 2.5 km 2 , deploy 5 horizontal wells for development, the horizontal well length is 1500m, the well spacing is as follows Figure 1 As shown, 1-5 are the well numbers, and the well spacing is 200-500m.

[0104] 1) The total hydrocarbon components of the crude oil and produced gas after ground degassing were tested by gas chromatography, and the results are shown in Tables 1 and 2;

[0105] Table 1 Results of crude oil composition after ground degassing

[0106]

[0107] Table 2 Test results of output gas components

[0108]

[0109] 2) Using the total hydrocarbon components of the degassed crude oil and produced gas in Tables 1 and 2, the original gas-oil ratio and the density of the degassed crude oil in the ground, the oil and gas were combined and calculated using the phase state software according to the gas-liquid equilibrium principle to obtain the formation crude oil components, as shown in Table 3;

[0110] Table 3 Formation crude oil composition

[0111]

[0112] 3) The formation crude oil components are split into 8 components, including CO 2 、N 2 , C 1 , C 2 -C 6 , C 7 -C 15 , C 16 -C 20 , C 21 -C 27 , C 28 -C 80 , then the contents of each component after splitting are shown in Table 4;

[0113] Table 4 Content of each component after splitting of formation crude oil

[0114]

[0115] 4) The phase state calculation of the split crude oil model of eight pseudo-components was performed to obtain the characteristic parameters of the split crude oil model of each pseudo-component, as shown in Table 5;

[0116] Table 5 Characteristic parameters of each component of pseudo-component

[0117]

[0118] 5) Carry out constant quality expansion experiments on the degassed crude oil and produced gas to obtain the crude oil volume coefficient , Crude oil volume coefficient at saturation pressure , Volume coefficient of degassed crude oil at reservoir abandonment pressure and crude oil compressibility ,according to Figure 2 Volume coefficient and pressure of crude oil at different pressures Figure 3 The crude oil compression coefficient under different pressures is 1.1632×10-31 / MPa under the original formation pressure, and 1.4358×10-31 / MPa under the saturation pressure; the crude oil volume coefficient under the original formation pressure is 1.18070, and the crude oil volume coefficient under the saturation pressure is 1.19279;

[0119] 6) Conduct multi-stage degassing experiments on crude oil and produced gas after ground degassing to obtain the degassing gas volume coefficient under the abandoned reservoir pressure , Dissolved gas-oil ratio of crude oil after degassing at abandoned reservoir pressure and the average gas-oil ratio of the produced gas. The results are as follows Figure 4 As shown; Based on the well depth and ground conditions, it is preliminarily determined that the reservoir abandonment pressure is 7MPa, and the average production gas-oil ratio of the test area is 150m3 / m3.

[0120] According to the standard of “Method for Determination of Rock Porosity Volume Compression Coefficient”, the compression coefficient of the target block rock under different pressures is tested.

[0121] According to the petroleum and natural gas industry standard SY / T 5815-2016 "Method for Determining the Pore Volume Compression Coefficient of Rocks", the shale oil core was tested for compression coefficient, and the rock pore volume compression coefficient under the original formation pressure and the rock pore volume compression coefficient under the saturation pressure were obtained. The average of the two was taken as the average pore volume compression coefficient of the reservoir rock when the original formation pressure was reduced to the saturation pressure. The results are as follows: Figure 5 As shown in Figure 2, the rock pore volume compression coefficient under the original formation pressure is 6.77×10 -3 1 / MPa, the rock pore volume compression coefficient under saturated pressure is 6.17×10 -3 1 / MPa, the average pore volume compression coefficient is 6.47×10 -3 1 / Mpa;

[0122] Substituting the above-obtained basic high-pressure physical property parameters of formation crude oil and gas and the average pore volume compressibility coefficient of reservoir rock from the original formation pressure to the saturation pressure into formula (1) to obtain the recovery factor of shale reservoir depletion development over the entire life cycle; among which, the recovery factor of elastic gas drive is 7.3%, the recovery factor of solution gas drive is 0.32%, and the recovery factor of shale reservoir depletion development over the entire life cycle is 7.6%;

[0123] 7) Calculation of recoverable reserves of a single well in elastic development of shale oil

[0124] According to the actual monthly production data, as shown in Table 6, use Excel to make a scatter plot with the cumulative oil production as the horizontal axis and the daily oil production of a single well as the vertical axis. Select at least 12 months of data from late to early to add a trend line. The trend line type is a straight line, such as Figure 6 As shown, according to the regression formula, the recoverable reserves of a single well in the elastic development stage are calculated;

[0125] Table 6 Actual production data of different single wells

[0126]

[0127] According to the regression results, the recoverable reserves of Wells 1 and 2 in the elastic development stage are calculated to be 11,500 tons and 8,500 tons respectively. According to this scheme, the recoverable reserves of Wells 3, 4 and 5 in the elastic development stage are calculated to be 12,500 tons, 13,200 tons and 9,000 tons respectively.

[0128] 8) Calculate the geological reserves controlled by a single well and convert the control radius of a single well

[0129] According to formulas (4) and (5), the single well controlled geological reserves and converted single well controlled radius are calculated. The results are shown in Table 7.

[0130] Table 7 Single well controlled geological reserves and single well controlled radius

[0131]

[0132] 9) Calculate the rationality coefficient of well spacing

[0133] According to formula (6), the rationality coefficient of well spacing between different wells is calculated, where wells 1 and 2 1.04, 2-well and 3-well 0.73, 3-well and 4-well 1.79, 4-well and 5-well It is 0.46.

[0134] According to the judgment criteria, the rationality of well spacing is specifically judged as follows:

[0135] A. Well 1 and Well 2 are judged to be close to the ideal well spacing, and it is recommended to maintain the current development technology policy and continue production;

[0136] B. Wells 2 and 3 are judged to be moderately reasonable in terms of horizontal well spacing, and the current development technology policy and technical production should be maintained;

[0137] C. Wells 3 and 4 are judged to be unreasonable in terms of horizontal well spacing, and it is recommended that one of Wells 3 and 4 be shut down periodically;

[0138] D. The reasonableness of the horizontal well spacing between Wells 4 and 5 is judged to be unreasonable, and a horizontal well can be added between Wells 4 and 5.

Claims

1. A quantitative identification method for rationality of well spacing in shale oil horizontal well development, characterized in that: Follow the steps below to implement it: Step 1, establishing a shale oil horizontal well development recovery rate prediction model; The shale oil horizontal well development recovery rate prediction model in step 1 is: （1） （2） （3） In formulas (1)-(3), R represents the recovery factor of shale oil reservoir depletion development over the entire life cycle, %; represents the elastic flooding recovery factor, %; represents the solution gas drive recovery rate, %; It represents the original crude oil volume coefficient, a decimal; represents the original formation pressure, MPa; Indicates the crude oil saturation pressure, MPa; It represents the volume coefficient of crude oil at saturation pressure, decimal; It represents the two-phase volume coefficient at the abandoned reservoir pressure, a decimal; represents the average production gas-oil ratio, m 3 / m 3 ; represents the original gas-oil ratio, m 3 / m 3 ; It represents the volume coefficient of gas released under the abandoned reservoir pressure, a decimal; Indicates the comprehensive compression coefficient, 1 / MPa; Indicates the compressibility of crude oil, 1 / MPa; Indicates the formation water compressibility, 1 / MPa; Indicates bound water saturation, decimal; represents the average pore volume compressibility, 1 / MPa; It represents the volume coefficient of degassed formation crude oil at the abandoned reservoir pressure, a decimal; represents the dissolved gas-oil ratio of the formation crude oil after degassing at the abandoned reservoir pressure, m 3 / m 3 ; Step 2: using the basic high-pressure physical property parameters of formation crude oil and gas and the average pore volume compressibility coefficient of the core, and the development recovery factor prediction model established in step 1, calculate the recovery factor of the shale oil reservoir depletion development over the entire life cycle; Step 3: Calculate the recoverable reserves of a single well in shale oil elastic development based on the production dynamic data of the target block; Step 4, according to the recoverable reserves of a single well in the elastic development of shale oil obtained in step 3 and the recovery factor of the whole life cycle of the depletion development of shale oil reservoir obtained in step 2, calculate the controlled geological reserves of a single well and convert the controlled radius of a single well; In step 4, the expression of the controlled geological reserves of a single well is: （4） In formula (4), N R represents the recoverable reserves of a single well in the elastic development stage of shale oil, 10 4 t; The expression of the single well control radius is: （5） In formula (5), represents the control radius of a single well, m; Indicates the geological reserves controlled by a single well, 10 4 t; L represents the length of the horizontal well, m; represents the average effective thickness, m; represents the average effective porosity, %; Indicates the density of ground crude oil, g / cm 3 ; represents bound water saturation, %; Step 5, calculating the rationality coefficient of the well spacing according to the single well control radius obtained in step 4, and judging the rationality of the well spacing according to the rationality coefficient of the well spacing; In step 5, the expression of the rationality coefficient of the well spacing is: （6） In formula (6), Indicates the rationality coefficient of well distance, decimal; Indicates the control radius of 1 well among adjacent horizontal wells, m; Indicates the control radius of two adjacent horizontal wells, m; represents the spacing between adjacent horizontal wells, m; In step 5, the rationality of the well spacing is specifically judged as follows: 1) When =1, the rationality of horizontal well spacing is judged to be ideal; 2) When 0.9≤ When ≤1.1, the rationality of the well spacing is judged to be high and the current development technology policy is maintained; 3) When 0.6< <0.9 or 1.1< When <1.3, the rationality of horizontal well spacing is judged to be moderately reasonable, and it is recommended to maintain the current development technology policy for developed shale oil reservoirs; in, 0.7≤ When <0.9, the well spacing of undeveloped shale reservoirs is reduced to make the designed well spacing 1 / 2 of the well spacing of developed shale reservoirs. times; 1.1< When the well spacing is less than 1.3, the well spacing of undeveloped shale reservoirs should be increased to make the designed well spacing equal to that of developed shale reservoirs. times; 4) When ≤0.6 or When ≥1.3, the rationality of horizontal well spacing is judged to be unreasonable; in, When ≤0.6, it is recommended to add one more well between horizontal wells for developed shale reservoirs; for undeveloped shale reservoirs, it is recommended to reduce the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale reservoirs. times; When the well pressure is ≥1.3, it is recommended that two horizontal wells be shut down in turn for developed shale oil reservoirs; for undeveloped shale oil reservoirs, it is recommended to increase the well spacing so that the designed well spacing is 1 / 2 of the well spacing of developed shale oil reservoirs. times.

2. The method for quantitatively identifying the rationality of well spacing in shale oil horizontal well development according to claim 1 is characterized in that: The step 2 is specifically implemented according to the following steps: Step 2.1, obtaining basic high-pressure physical property parameters of formation crude oil and gas through phase calculation simulation software; Step 2.2: Test the compression coefficient of the shale oil core in the target area to obtain the rock pore volume compression coefficient under the original formation pressure and the saturation pressure. The average value of the two is the average pore volume compression coefficient of the reservoir rock from the original formation pressure to the saturation pressure. ; Step 2.3, the basic high-pressure physical property parameters of the formation crude oil and gas obtained in step 2.1 and the average pore volume compressibility coefficient obtained in step 2.2 are substituted into formula (1) to obtain the recovery factor of the shale oil reservoir depletion development over the entire life cycle.

3. A quantitative identification method for rationality of spacing of shale oil horizontal well development according to claim 2, characterized in that: The step 2.1 is specifically implemented according to the following steps: Step 2.1.1, testing the total hydrocarbon components of the crude oil and the produced gas after ground degassing by gas chromatography; Step 2.1.2: the total hydrocarbon components and original gas-oil ratio of the degassed crude oil and produced gas obtained in step 2.1.1 are 2. The density of crude oil after ground degassing is calculated by phase calculation simulation software to combine oil and gas and obtain the composition of formation crude oil; Step 2.1.3, splitting the formation crude oil components obtained in step 2.1.2 to obtain a pseudo-component split crude oil model; Step 2.1.4, performing phase calculation on the split crude oil model of the pseudo-component obtained in step 2.1.3 to obtain the molecular weight, density, critical temperature, critical pressure, deviation factor, and volume shift coefficient of the split crude oil model of each pseudo-component; Step 2.1.5: Perform constant mass expansion experiments on the degassed crude oil and produced gas to obtain the crude oil volume coefficient at the original formation pressure. , Crude oil volume coefficient at saturation pressure , Volume coefficient of degassed crude oil at reservoir abandonment pressure and crude oil compressibility ; Step 2.1.6, conduct multi-stage degassing experiments on the crude oil and produced gas after ground degassing to obtain the degassing gas volume coefficient under the abandoned reservoir pressure , Dissolved gas-oil ratio of crude oil after degassing at abandoned reservoir pressure and the average gas-oil ratio of produced gas.

4. A quantitative identification method for rationality of well spacing in shale oil horizontal well development according to claim 3, characterized in that: In step 2.1.3, the pseudo-component splitting crude oil model is CO2, N2, C1, C2-C6, C7-C 15 , C 16 -C 20 , C 21 -C 27 , C 28 -C 80 .

5. The method for quantitatively identifying the rationality of well spacing in shale oil horizontal well development according to claim 1 is characterized in that: The specific process of step 3 is as follows: Based on the actual monthly production data, use Excel to make a scatter plot with the cumulative oil production as the horizontal axis and the daily oil production of a single well as the vertical axis. Select at least 12 months of data from late to early to add a trend line. The trend line type is a straight line. According to the regression formula, the recoverable reserves of a single well in the elastic development stage of shale oil are calculated.

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