A shale oil horizontal well technology recoverable reserve prediction method, device and medium

Abstract

The present application belongs to the technical field of shale oil exploitation, and provides a shale oil horizontal well technical recoverable reserves prediction method. The method comprises the following steps: delimiting an evaluation unit; matching reservoir geological parameters and geological engineering parameters for the horizontal well to which the evaluation unit belongs; substituting the reservoir geological parameters and the geological engineering parameters into an empirical formula for recoverable reserves estimation to obtain shale oil horizontal well single-well predicted technical recoverable reserves; and summing up the shale oil horizontal well single-well predicted technical recoverable reserves to obtain the technical recoverable reserves of the evaluation unit. The present application simplifies the prediction process of technical recoverable reserves and recovery rate related indexes, shortens the prediction time, reduces the prediction error, and achieves good economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of shale oil extraction technology, and in particular relates to a method, equipment and medium for predicting recoverable reserves of shale oil using horizontal well technology. Background Technology

[0002] Currently, the methods for predicting recoverable reserves of shale oil through centralized development technology using horizontal wells in China are mainly based on the fundamental principles of reservoir physics and employ a phased reservoir energy-driven oil recovery theoretical model for calculation.

[0003] The "SY / T 7463-2019 Shale Oil Reserves Calculation Specification" stipulates that, based on the production dynamics and change patterns of well areas, well groups, or single wells, the cumulative production when production approaches zero is predicted using the decreasing method as the technically recoverable reserves.

[0004] Based on the analysis of the basic reservoir physics principles, the development of a primary well network is considered to go through three stages: fracturing and energy replenishment-driven, formation elastic drive, and dissolved gas drive. Calculations are then performed using corresponding reservoir model formulas. However, this technical approach for predicting the recovery rate of shale oil horizontal wells has certain limitations: First, shale oil reservoirs themselves exhibit strong heterogeneity in important physical properties such as porosity, permeability, and effective layer thickness. The key parameters affecting recovery rate show significant separation, and standard models do not adequately consider reservoir heterogeneity. Unit-based predictions of technically recoverable reserves yield large discrepancies, deviating significantly from actual development results. Second, in practical applications, reliable reservoir properties and pressure / saturation parameters are generally calculated using weighted averages. Therefore, the predicted technically recoverable reserves cannot reflect the differences between horizontal wells with different geological and engineering characteristics.

[0005] Shale oil reserve units typically enter the large-scale development stage after the evaluation well group development and verification phase. At different development stages, the dynamic development data of producing wells differs, and the demand for methods to assess and predict technically recoverable reserves (recovery rate) potential also changes. Traditional methods only consider reservoir physical properties and lack comprehensive consideration of parameters such as well type and process parameters in development deployment, making it impossible to accurately predict technically recoverable reserves and recovery rates. Recovery rate prediction for developed shale oil reserves involves development schemes tailored to different geological backgrounds and differentiated horizontal well designs. Influenced by geological, technological, and production conditions, the development implementation varies significantly between well groups. Although production dynamic data has become more abundant, issues remain regarding data quality and unclear patterns, making existing methods insufficient to meet the need for rapid and effective prediction.

[0006] In summary, existing methods for predicting recoverable reserves and recovery rates in shale oil horizontal well development technology have many shortcomings and cannot adapt to the complex situations at different stages of shale oil development. There is an urgent need for a new method that comprehensively considers multiple factors, has a wide range of applications, simplifies the calculation process, and improves prediction accuracy. Summary of the Invention

[0007] This invention provides a method for predicting recoverable reserves using shale oil horizontal well technology, comprising:

[0008] Delineate assessment units;

[0009] To match reservoir geological parameters and geological engineering parameters to the horizontal wells belonging to the assessment unit;

[0010] By substituting reservoir geological parameters and geological engineering parameters into the empirical formula for recoverable reserves estimation, the technically predicted recoverable reserves of a single horizontal well in shale oil can be obtained.

[0011] The technically recoverable reserves of the included shale oil horizontal wells are summed up to obtain the technically recoverable reserves of the evaluation unit.

[0012] Furthermore, the method includes: determining the sample data range of reservoir geological parameters and geological engineering parameters, and removing overflow data.

[0013] Furthermore, the method includes: the percentage value of the recoverable reserves of a single shale oil horizontal well predicted by the technology to the geological reserves of the assessment unit, which is the predicted recovery rate of the shale oil horizontal well in the assessment unit.

[0014] Furthermore, the reservoir geological parameters include: obtaining the skeleton wells or pilot wells at both ends of the target horizontal well for priority evaluation; or projecting the coordinates of the horizontal well target point onto the relevant contour map of the area to pick up the reservoir geological parameters.

[0015] Furthermore, the reservoir geological parameters include: oil layer thickness, oil saturation, and Ro value.

[0016] Furthermore, the geological engineering parameters include: effective horizontal section length, fracturing fluid volume, fracturing sand volume, number of horizontal well fracturing sections, and number of horizontal well fracturing clusters.

[0017] Furthermore, the empirical formula for estimating recoverable reserves is as follows:

[0018]

[0019] Where: Nr represents the technically recoverable reserves of a single horizontal shale oil well, 10 4 t; L is the effective horizontal section length of a single horizontal well, in meters; Q f The volume of fluid injected into the horizontal well is expressed in m. 3 Q s The amount of sand injected into a horizontal well, in meters. 3 N f N represents the number of fracturing stages in a horizontal well. c Ro represents the number of fracturing clusters in a horizontal well; Ro is the vitrinite reflectance / organic matter thermal evolution degree, %; S o The oil saturation of the target layer is expressed as %.

[0020] Furthermore, the technically recoverable reserves of the assessment unit:

[0021] N R =∑N r ,

[0022] The predicted recovery rate:

[0023]

[0024] Where: N R To assess the technically recoverable reserves of the unit, 10 4 t; E R Technical recovery rate, %; N z For oil geological reserves, 10 4 t.

[0025] The present invention also provides a computer device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method for predicting recoverable reserves of shale oil horizontal well technology.

[0026] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method for predicting recoverable reserves of shale oil horizontal well technology.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. For shale oil reservoirs that are undeveloped, partially developed, or in the early stages of full development, this technology integrates geology and engineering to predict recoverable reserves and recovery rates, taking into account variables such as well type and process.

[0029] 2. Technical assessment and prediction of recoverable reserves (recovery rate) for shale oil development units applicable to long horizontal well development.

[0030] 3. It can be applied to practical work such as reserve planning, well type design adaptability evaluation, development benefit assessment, SEC confirmed reserve assessment, and new production construction and recovery prediction.

[0031] 4. In the calculation of indicators and the preparation of plans for shale oil development related units and well groups, simplify the prediction process of technically recoverable reserves and recovery rate, shorten the prediction time, reduce prediction errors, and achieve better economic benefits.

[0032] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A flowchart of a method for predicting recoverable reserves of shale oil horizontal well technology provided in an embodiment of the present invention is shown;

[0035] Figure 2 A schematic diagram illustrating the relationship between the calibrated recoverable reserves and the predicted recoverable reserves is shown in an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] A method for predicting recoverable reserves using shale oil horizontal well technology, comprising the following specific steps:

[0038] S1: Define the evaluation unit.

[0039] The assessment unit is delineated by weighing single or combined factors such as horizontal well groups, reserve calculation units, similar horizontal well patterns, and mining rights boundaries. The total geological reserves controlled by a single well or the overall controlled geological reserves within the assessment area are used as the baseline for the geological reserves available for use in the assessment unit.

[0040] S2: Match reservoir geological parameters and geological engineering parameters to the horizontal wells belonging to the evaluation unit.

[0041] Matching and calculating key geological parameters of production wells (or designed and deployed horizontal wells) within the target area is crucial. These parameters primarily include reservoir thickness, oil saturation, and Ro value (vitrinite reflectance). Parameter acquisition should prioritize using the skeleton wells or pilot wells at both ends of the target horizontal well (parameter selection priority: core analysis data > well logging analysis data); alternatively, the coordinates of the horizontal well target points can be projected onto relevant contour maps of the region to extract reservoir geological parameters.

[0042] Skeleton wells are typically representative wells within a region, reflecting the overall geological characteristics of that area. Pilot wells, on the other hand, are specifically drilled to obtain specific geological information. Data from these wells can provide a more accurate reference for determining the parameters of horizontal wells.

[0043] Core analysis data is obtained by analyzing rock samples taken directly from the ground, which is more intuitive and accurate, so it has a higher priority. Well logging analysis data is obtained by measuring the well wall and surrounding strata through various logging instruments. Although it has some reference value, its accuracy may be slightly lower than that of core analysis data.

[0044] Contour maps are created by measuring and analyzing geological parameters within a specific area, reflecting the distribution of these parameters. By projecting the target coordinates of a horizontal well onto a contour map, the corresponding geological parameters can be determined based on the contour values ​​at that point.

[0045] Matching and calculating some key geological parameters of production wells and horizontal wells (or designed and deployed horizontal wells) within the target range, mainly including the effective horizontal section length, the amount of fluid injected into the ground through fracturing, the amount of sand injected into the ground through fracturing, the number of fracturing sections in the horizontal well, and the number of fracturing clusters in the horizontal well.

[0046] S3: Determine the sample data range for reservoir geological parameters and geological engineering parameters, and remove overflow data columns.

[0047] To ensure the accuracy of the predicted recoverable reserves (recovery rate) for a single well, the sample data range of the model trained based on the empirical formula for recoverable reserves estimation in this invention is as follows: effective reservoir thickness of horizontal wells is 6.1m to 12.8m, oil saturation is 49.9% to 57.1%, organic matter content is 0.924% to 2.64%, actual drilled horizontal section length of horizontal wells is 1280m to 2800m, and horizontal well fracturing sand addition is 1890m³. 3 ~5183m 3 The volume of fluid injected into the horizontal well during fracturing was 16410 m³. 3 ~44320m 3 Remove the overflow parameter data column.

[0048] S4: Substitute reservoir geological parameters and geological engineering parameters into the empirical formula for estimating recoverable reserves to obtain the technically predicted recoverable reserves of a single horizontal well in shale oil.

[0049]

[0050] Wherein, Nr represents the technically recoverable reserves of a single horizontal shale oil well, 10 4 t; L is the effective horizontal section length of a single horizontal well, in meters; Q f The volume of fluid injected into the horizontal well is expressed in m. 3 Q s The amount of sand injected into a horizontal well, in meters. 3 N f N represents the number of fracturing stages in a horizontal well. c Ro represents the number of fracturing clusters in a horizontal well; Ro is the vitrinite reflectance / organic matter thermal evolution degree, %; S o The oil saturation of the target layer is expressed as %.

[0051] S5: Summarize the predicted technically recoverable reserves of all included shale oil horizontal wells to obtain the technically recoverable reserves of the evaluation unit.

[0052] S6: The percentage of recoverable reserves of a single shale oil horizontal well predicted by the technology to the geological reserves of the assessment unit, representing the predicted recovery rate of shale oil horizontal wells in the assessment unit.

[0053] Predicting technically recoverable reserves:

[0054] N R =∑N r ,

[0055] Predicted technical recovery rate:

[0056]

[0057] Where: N R To assess the technically recoverable reserves of the unit, 10 4 t; E R Technical recovery rate, %; N z For oil geological reserves, 10 4 t.

[0058] An application embodiment of the present invention provides a computer device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of a method for predicting recoverable reserves of shale oil horizontal well technology.

[0059] An application embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of a method for predicting recoverable reserves of shale oil horizontal well technology.

[0060] Example:

[0061] S1: A well group in a shale oil demonstration development area is selected as the prediction and evaluation unit. The well group includes wells 1 to 13, a total of 13 horizontal wells, with a recoverable reserve area of ​​9.31 km². 2 The utilized oil geological reserves are 355.44 × 10 4 t.

[0062] S2: Review the reserve declaration report, reserve appendices, reservoir effective thickness contour maps, reservoir oil saturation contour maps, well logging curves, and other technical data related to reservoir description to match reservoir geological parameters for the horizontal wells of the assessment unit, as shown in Table 1.

[0063] Table 1. Geological Reservoir Parameters for Single Well in Horizontal Wells of the Estimation Unit

[0064]

[0065]

[0066] Review relevant oilfield development plans and drilling engineering design reports, including but not limited to development deployment plans, related drilling reports, fracturing technology design plans, well completion reports, and well testing reports, to match geological engineering parameters for the horizontal wells belonging to the evaluation unit, as shown in Table 2:

[0067] Table 2. Geological Engineering Parameters for Single Horizontal Wells in the Estimation Unit

[0068]

[0069] S3: Check the geological and engineering parameters of the sample wells for prediction and evaluation. All of the above parameters are within the range of the model parameters.

[0070] S4: Using a single well as a unit, substitute the geological and engineering parameters of the above shale oil horizontal wells into the following empirical formula for estimating recoverable reserves to obtain the technically recoverable reserves of a single shale oil horizontal well.

[0071]

[0072] Wherein, Nr represents the technically recoverable reserves of a single horizontal shale oil well, 10 4 t; L is the effective horizontal section length of a single horizontal well, in meters; Q f The volume of fluid injected into the horizontal well is expressed in m. 3 Q s The amount of sand injected into a horizontal well, in meters. 3 N f N represents the number of fracturing stages in a horizontal well. cRo represents the number of fracturing clusters in a horizontal well; Ro is the vitrinite reflectance / organic matter thermal evolution degree, %; S o The oil saturation of the target layer is expressed as %.

[0073] See Figure 2 As shown in Table 3, the technically recoverable reserves of a certain horizontal well group in a certain shale oil field are basically consistent with the predicted technically recoverable reserves and the calibrated technically recoverable reserves.

[0074] Table 3. Estimation of Technically Recoverable Reserves of Horizontal Wells in the Unit

[0075]

[0076]

[0077] S5: Summarize the predicted technically recoverable reserves of all included shale oil horizontal wells to obtain the technically recoverable reserves of the evaluation unit.

[0078] Predicted recoverable reserves of the well group: 29.82 × 10⁻⁶ 4 t.

[0079] S6: The percentage of recoverable reserves of a single shale oil horizontal well predicted by the technology to the geological reserves of the assessment unit, representing the predicted recovery rate of shale oil horizontal wells in the assessment unit.

[0080] Predicted technical recovery rate of the well group: 8.39% (100% × 29.82 × 10) 4 t / 355.44×10 4 t = 8.39%.

[0081] As shown in Table 4, this invention presents a novel method for estimating and predicting the technically recoverable reserves and recovery rates of shale oil reservoirs developed using horizontal wells. It addresses the assessment and prediction of technically recoverable reserves and recovery rates for shale oil reservoirs in undeveloped, partially developed, and early-stage full-scale development phases. This method considers variables such as well type and technology involved in development deployment, achieving a comprehensive geological-engineering factor-based prediction of technically recoverable reserves and recovery rates. This method is applicable to the assessment and prediction of technically recoverable reserves (recovery rates) of shale oil development units using long horizontal wells. In the next 3-5 years, it can be applied to reserve planning, well type design adaptability evaluation, development benefit assessment, SEC-proven reserve assessment, and new production capacity prediction. In the calculation of indicators and planning for shale oil development units and well groups, this method simplifies the prediction process for technically recoverable reserves and recovery rates, shortens the prediction time, reduces prediction errors, and achieves better economic benefits.

[0082] Table 4 Comparison of Recoverable Reserves and Recovery Rate Prediction Methods for Shale Oil Horizontal Well Technology

[0083]

[0084] The foregoing description and accompanying drawings fully illustrate embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Some portions and features of some embodiments may be included or substituted for portions and features of other embodiments. Embodiments of the invention are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from their scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for predicting recoverable reserves using shale oil horizontal well technology, characterized in that, include: Delineate assessment units; To match reservoir geological parameters and geological engineering parameters to the horizontal wells belonging to the assessment unit; By substituting reservoir geological parameters and geological engineering parameters into the empirical formula for recoverable reserves estimation, the technically predictable recoverable reserves of a single horizontal well in shale oil can be obtained. By summing up the predicted technically recoverable reserves of all included shale oil horizontal wells, the technically recoverable reserves of the evaluation unit are obtained.

2. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 1, characterized in that, The method includes: determining the sample data range of reservoir geological parameters and geological engineering parameters, and removing overflow data.

3. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 2, characterized in that, The method includes: the percentage value of recoverable reserves of a single shale oil horizontal well predicted by the technology to the geological reserves of the assessment unit, which is the predicted recovery rate of the shale oil horizontal well in the assessment unit.

4. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 1, characterized in that, The reservoir geological parameters include: obtaining the skeleton wells or pilot wells at both ends of the target horizontal well for priority evaluation; or projecting the coordinates of the horizontal well target points onto the relevant contour map of the area to pick up the reservoir geological parameters.

5. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 4, characterized in that, The reservoir geological parameters include: oil layer thickness, oil saturation, and Ro value.

6. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 1, characterized in that, The geological engineering parameters include: effective horizontal section length, volume of fluid injected into the ground through fracturing, volume of sand injected into the ground through fracturing, number of fracturing sections in the horizontal well, and number of fracturing clusters in the horizontal well.

7. The method for predicting recoverable reserves of shale oil horizontal wells according to any one of claims 1 to 6, characterized in that, The empirical formula for estimating recoverable reserves: Where: Nr represents the technically recoverable reserves of a single horizontal shale oil well, 10 4 t; L is the effective horizontal section length of a single horizontal well, in meters; Q f The volume of fluid injected into the horizontal well is expressed in m. 3 Q s The amount of sand injected into a horizontal well, in meters. 3 N f N represents the number of fracturing stages in a horizontal well. c Ro represents the number of fracturing clusters in a horizontal well; Ro is the vitrinite reflectance / organic matter thermal evolution degree, %; S o The oil saturation of the target layer is expressed as %.

8. The method for predicting recoverable reserves of shale oil horizontal wells according to claim 7, characterized in that, Technically recoverable reserves of the assessment unit: N R =∑N r , The predicted recovery rate: Where: N R To assess the technically recoverable reserves of the unit, 10 4 t; E R For recovery rate, %; N z For oil geological reserves, 10 4 t.

9. A computer device, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the computer program is executed by the processor, it causes the processor to perform the steps of the method for predicting recoverable reserves of shale oil horizontal well technology as described in any one of claims 1-8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it causes the processor to perform the steps of the method for predicting recoverable reserves of shale oil horizontal well technology as described in any one of claims 1-8.

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