A geological modeling method for permeable interlayers in carbonate reservoirs

Abstract

The present invention provides a geological modeling method for a carbonate reservoir with permeable interlayers, the geological modeling method comprising the following steps: (1) selecting a target work area, and sequentially establishing a structural model, a sedimentary phase model, and an attribute model; (2) determining the lower limit standard of the effective thickness of the reservoir, and establishing a net-to-gross ratio model; (3) fitting the geological reserves of the reservoir according to the attribute model obtained in step (1) and the net-to-gross ratio model obtained in step (2); (4) establishing a plate of pore volume and geological reserves according to the reserve fitting standard; (5) defining the upper limit of the pore volume based on the constant volume principle and the plate obtained in step (4), and establishing a variable net-to-gross ratio model; (6) outputting the specific attributes of the model based on the variable net-to-gross ratio model obtained in step (5), and performing numerical simulation fitting. The method provided by the present invention improves the accuracy of the numerical simulation of the formation pressure and water content fitting of the reservoir, thereby ensuring the rationality of the prediction of the indicators of the reservoir development plan.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas development, and relates to a geological modeling method, in particular to a geological modeling method with permeable interlayers in carbonate reservoirs. Background Art

[0002] In the process of reservoir development, except for a very small number of carbonate reservoirs that rely on natural energy depletion for long-term exploitation, most reservoirs will use gas injection, water injection and other technologies to improve the recovery of the reservoir after the first oil production. However, carbonate reservoirs are affected by sedimentation, diagenesis and tectonic action, and the microscopic pore structure of the reservoir is extremely complex. The reservoir heterogeneity is extremely strong in the plane and vertical direction, especially the development of interlayers in carbonate reservoirs. Because of their low porosity and permeability, the heterogeneity of the reservoir is further aggravated, resulting in a complex and changeable relationship between oil and water movement, which in turn affects the distribution of remaining oil in the reservoir and the final development effect. Studies have found that interlayers in carbonate reservoirs are significantly different from mud interlayers and calcareous interlayers in clastic reservoirs in terms of type, genetic mechanism and seepage.

[0003] At present, the research on carbonate interlayers mainly focuses on the definition, classification, identification method, genetic mechanism, distribution law and the impact on reservoir development. It is generally believed that the interlayers in carbonate reservoirs are mainly affected by sedimentation. The high mud content in the rock type leads to poor reservoir properties of the interlayers, which in turn acts as a barrier to fluid migration and pressure propagation. However, the development practice of some oil fields has proved that the interlayers in carbonate reservoirs are not "iron plates" in an absolute sense, and have barrier capabilities. Although the porosity is very low, the interlayers are often affected by the later diagenesis and tectonic action. Microcracks or dissolution cracks exist, which affect the migration and pressure propagation of fluids. Therefore, it is crucial to establish a reasonable geological model for this kind of permeable interlayer, which is crucial for the evaluation of reservoir pressure, water content fitting and reservoir development effect, but there is currently no effective geological modeling method.

[0004] It can be seen that how to provide a geological modeling method with permeable interlayers in carbonate reservoirs, improve the accuracy of numerical simulation of formation pressure and water content fitting in reservoirs, and then ensure the rationality of reservoir development plan indicator prediction has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a geological modeling method for permeable interlayers in carbonate reservoirs. Under the premise of not affecting the reserves of the geological model, the method follows the results of single well logging interpretation and systematically considers the characteristics of the interlayers in carbonate reservoirs having a certain seepage capacity, thereby improving the accuracy of the numerical simulation of the reservoir formation pressure and water content fitting and ensuring the rationality of the prediction of the indicators of the reservoir development plan.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a geological modeling method for a carbonate reservoir having a permeable interlayer, the geological modeling method comprising the following steps:

[0008] (1) Selecting a target work area, and sequentially establishing a structural model, a sedimentary facies model, and an attribute model for the target work area;

[0009] (2) determining the lower limit standard of the effective thickness of the reservoir, and establishing a net-to-gross ratio model based on the lower limit standard;

[0010] (3) fitting the geological reserves of the oil reservoir according to the attribute model obtained in step (1) and the net-to-gross ratio model obtained in step (2);

[0011] (4) Establish a chart of pore volume and geological reserves based on the reserve fitting standard;

[0012] (5) Based on the constant volume principle and the plate obtained in step (4), the upper limit of the pore volume is defined and a variable net-to-gross ratio model is established;

[0013] (6) Based on the variable net-to-gross ratio model obtained in step (5), the specific attributes of the model are output and numerical simulation fitting is performed.

[0014] Compared with the prior art, the geological modeling method provided by the present invention not only follows the process of geological modeling and the principles of geological reserve fitting, but also fully integrates geological knowledge into the process of model construction without changing the "hard data". At the same time, the influence of changes in net-to-gross ratio on model reserves and pore volume can be intuitively observed through the chart, and pressure conduction and fluid migration can be ensured during the diachronic fitting process, thereby improving the accuracy of diachronic fitting and facilitating the prediction of later plans and the study of remaining oil distribution.

[0015] In addition, the geological modeling method provided by the present invention has high repeatability and strong operability. At the same time, a workflow can be compiled in the software to achieve the goal of rapid realization. The established geological model is consistent with geological knowledge and has high temporal fitting accuracy, which is convenient for oilfield development technicians to master and apply.

[0016] Preferably, the property model in step (1) includes a porosity model, a permeability model and a saturation model.

[0017] Preferably, the process of establishing the construction model in step (1) includes the following steps:

[0018] (1.1.1) geological stratification of the wells in the target work area, and correction of the structural surface interpreted by three-dimensional seismic interpretation using the geological stratification;

[0019] (1.1.2) Determine the modeling boundary based on the oil-water interface of the target reservoir and the water body requirements of the numerical model;

[0020] (1.1.3) Establish a fault model based on the fault data interpreted from the seismic analysis;

[0021] (1.1.4) Establish a structural model of the target layer section in the target work area.

[0022] Among them, steps (1.1.1) and (1.1.2) are in no particular order.

[0023] Preferably, the process of establishing the sedimentary facies model in step (1) comprises the following steps:

[0024] (1.2.1) Determine the lithology of the target layer based on the core and thin section data of the target layer;

[0025] (1.2.2) Based on the lithology obtained in step (1.2.1), combined with the regional sedimentary background and sedimentary structure, analyze the sedimentary environment and sedimentary facies;

[0026] (1.2.3) Establish well logging facies standards for the study area and realize the facies division of single wells in the entire work area;

[0027] (1.2.4) Based on the established structural model, combined with the single well sedimentary phase division results and seismic phase plane distribution, the sedimentary phase model is established using geological modeling software and the sequential indicator simulation algorithm.

[0028] Preferably, the process of establishing the attribute model in step (1) includes the following steps:

[0029] (1.3.1) Collecting well logging data of the target work area and performing data analysis on the porosity, permeability and saturation interpreted by the well logging;

[0030] (1.3.2) Data coarsening of the porosity curve is performed, and the porosity model is constructed by adopting the idea of ​​phase-controlled modeling and combining seismic attributes;

[0031] (1.3.3) Based on the correlation between reservoir porosity and permeability, a permeability model is established using the porosity constraint method;

[0032] (1.3.4) Constructing a saturation model for the target layer of the target work area, using any one of the following methods:

[0033] (1.3.4A) For the reservoirs in the small transition zone, the saturation interpreted by single well logging is used as hard data. Through data analysis, the oil column height is used as a constraint, and the sequential Gaussian simulation algorithm is used to establish the saturation model;

[0034] (1.3.4B) For the oil reservoirs in the large transition zone, the J function method is used to establish the saturation model.

[0035] Among them, the area of ​​the small transition zone described in step (1.3.4A) is less than twice the area of ​​the pure oil zone, for example, it can be 0.2 times, 0.4 times, 0.6 times, 0.8 times, 1 times, 1.2 times, 1.4 times, 1.6 times or 1.8 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] The area of ​​the large transition zone described in step (1.3.4B) is ≥ 2 times the area of ​​the pure oil zone, for example, it can be 2 times, 2.2 times, 2.4 times, 2.6 times, 2.8 times, 3 times, 3.2 times, 3.4 times, 3.6 times, 3.8 times or 4 times, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0037] Preferably, step (2) specifically comprises the following steps:

[0038] (2.1) Based on core data, logging interpretation and oil testing, determine the lower limit of effective reservoir thickness;

[0039] (2.2) Based on the lower limit standard obtained in step (2.1), a net-to-gross ratio model of the target work area is established through calculation; wherein the net-to-gross ratio of the effective reservoir is 1, and the net-to-gross ratio of the interlayer is 0.

[0040] Preferably, step (3) specifically comprises the following steps:

[0041] (3.1) Calculating the geological reserves of the target layer section in the target work area according to the reserve calculation module in the geological model;

[0042] (3.2) The porosity and saturation are adjusted to ensure that the error between the geological reserves calculated by the three-dimensional geological model and the geological reserves calculated by the volumetric method is within the range of ±10%, for example, it can be 0, ±1%, ±2%, ±3%, ±4%, ±5%, ±6%, ±7%, ±8%, ±9% or ±10%, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, step (4) specifically comprises the following steps:

[0044] (4.1) Assigning a net-to-gross ratio of all interlayers in the net-to-gross ratio model to 1, and calculating the geological reserves in the model using the reassigned net-to-gross ratio according to the reserve calculation module in the geological model;

[0045] (4.2) Based on the reserve calculation formula in the model and the geological reserves calculated when the net-to-gross ratio of the interlayer is set to 0 and 1 respectively, a chart of pore volume and geological reserves is established.

[0046] Preferably, the reserve calculation formula in step (4.2) is:

[0047]

[0048] Among them, B vi is the gross volume of the i-th grid; NTG i is the net-to-gross ratio of the ith grid; is the porosity of the ith grid, %; S wi is the water saturation of the ith grid, a decimal; B o is the volume coefficient of crude oil.

[0049] In the present invention, according to Archie's formula, it can be known that: porosity The larger the value, the corresponding water saturation (S w For the interlayer above the oil-water interface, its porosity is small (below the lower limit of the effective reservoir), and the corresponding water saturation S w If it is larger, then 1-S w It is relatively small and has little impact on the entire reserve calculation formula.

[0050] The Archie formula is specifically:

[0051]

[0052] Among them, S w is water saturation, decimal; is the porosity, a decimal; a is the lithology coefficient related to lithology, dimensionless; b is the constant related to lithology, dimensionless; m is the cementation index, dimensionless; n is the saturation index, dimensionless; R w is the formation water resistivity, Ω·m; R t is the formation resistivity, Ω·m.

[0053] In the present invention, the data of the net-to-gross ratio model in step (5) is between 0 and 1, and is not either 0 or 1 in the traditional sense.

[0054] Preferably, the specific attributes in step (6) include grid data, well data, porosity, permeability, saturation and net-to-gross ratio.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) Compared with the prior art, the geological modeling method provided by the present invention not only follows the process of geological modeling and the principle of geological reserve fitting, but also fully integrates geological knowledge into the process of model construction without changing the "hard data". At the same time, the influence of the change of net-to-gross ratio on the model reserves and pore volume can be intuitively observed through the chart. It can also ensure the pressure conduction and fluid migration in the process of diachronic fitting, improve the accuracy of diachronic fitting, and facilitate the subsequent prediction of the scheme and the study of the remaining oil distribution.

[0057] (2) The geological modeling method provided by the present invention has high repeatability and strong operability. At the same time, a workflow can be compiled in the software to achieve the purpose of rapid realization. The established geological model is consistent with geological knowledge and has high temporal fitting accuracy, which is convenient for oilfield development technicians to master and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a flow chart of the geological modeling method provided by the present invention;

[0059] Figure 2 It is a comparison diagram of the reservoir layer C in the target work area in the geological modeling method provided in Example 1;

[0060] Figure 3 It is the structural model of the target work area in the geological modeling method provided in Example 1;

[0061] Figure 4 It is the sedimentary facies model of the target work area in the geological modeling method provided in Example 1;

[0062] Figure 5 is the porosity model of the target work area in the geological modeling method provided in Example 1;

[0063] Figure 6 It is the permeability model of the target work area in the geological modeling method provided in Example 1;

[0064] Figure 7 It is the saturation model of the target work area in the geological modeling method provided in Example 1;

[0065] Figure 8 It is a reference map for determining the lower limit standard of the effective thickness of the reservoir in the target work area in the geological modeling method provided in Example 1;

[0066] Fig. 9 It is a plate of pore volume and geological reserves established in the target work area in the geological modeling method provided in Example 1;

[0067] Fig.10It is a comparison chart of pressure fitting in the target work area by changing the net-to-gross ratio model in the geological modeling method provided in Example 1. DETAILED DESCRIPTION

[0068] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0069] The present invention provides a geological modeling method for a carbonate reservoir having a permeable interlayer, such as Figure 1 As shown, the geological modeling method comprises the following steps:

[0070] (1) Selecting a target work area, and sequentially establishing a structural model, a sedimentary facies model, and an attribute model for the target work area;

[0071] (1.1) The process of establishing the construction model includes the following steps:

[0072] (1.1.1) geological stratification of the wells in the target work area, and correction of the structural surface interpreted by three-dimensional seismic interpretation using the geological stratification;

[0073] (1.1.2) Determine the modeling boundary based on the oil-water interface of the target reservoir and the water body requirements of the numerical model;

[0074] (1.1.3) Establish a fault model based on the fault data interpreted from the seismic analysis;

[0075] (1.1.4) Establishing a structural model of the target layer section in the target work area;

[0076] Among them, steps (1.1.1) and (1.1.2) are in no particular order.

[0077] (1.2) The process of establishing the sedimentary facies model includes the following steps:

[0078] (1.2.1) Determine the lithology of the target layer based on the core and thin section data of the target layer;

[0079] (1.2.2) Based on the lithology obtained in step (1.2.1), combined with the regional sedimentary background and sedimentary structure, analyze the sedimentary environment and sedimentary facies;

[0080] (1.2.3) Establish well logging facies standards for the study area and realize the facies division of single wells in the entire work area;

[0081] (1.2.4) Based on the established structural model, combined with the single well sedimentary phase division results and seismic phase plane distribution, the sedimentary phase model is established using geological modeling software and the sequential indicator simulation algorithm.

[0082] (1.3) The process of establishing the attribute model includes the following steps:

[0083] (1.3.1) Collecting well logging data of the target work area and performing data analysis on the porosity, permeability and saturation interpreted by the well logging;

[0084] (1.3.2) Data coarsening of the porosity curve is performed, and the porosity model is constructed by adopting the idea of ​​phase-controlled modeling and combining seismic attributes;

[0085] (1.3.3) Based on the correlation between reservoir porosity and permeability, a permeability model is established using the porosity constraint method;

[0086] (1.3.4) Constructing a saturation model for the target layer of the target work area, using any one of the following methods:

[0087] (1.3.4A) For the reservoirs in the small transition zone, the saturation interpreted by single well logging is used as hard data. Through data analysis, the oil column height is used as a constraint, and the sequential Gaussian simulation algorithm is used to establish the saturation model;

[0088] (1.3.4B) For the oil reservoirs in the large transition zone, the J function method is used to establish the saturation model.

[0089] Among them, the area of ​​the small transition zone in step (1.3.4A) is less than twice the area of ​​the pure oil zone; the area of ​​the large transition zone in step (1.3.4B) is greater than or equal to twice the area of ​​the pure oil zone.

[0090] (2) Determine the lower limit standard of the effective thickness of the reservoir, and establish a net-to-gross ratio model based on the lower limit standard, which specifically includes the following steps:

[0091] (2.1) Based on core data, logging interpretation and oil testing, determine the lower limit of effective reservoir thickness;

[0092] (2.2) Based on the lower limit standard obtained in step (2.1), a net-to-gross ratio model of the target work area is established through calculation; wherein the net-to-gross ratio of the effective reservoir is 1, and the net-to-gross ratio of the interlayer is 0.

[0093] (3) fitting the geological reserves of the oil reservoir according to the attribute model obtained in step (1) and the net-to-gross ratio model obtained in step (2), specifically comprising the following steps:

[0094] (3.1) Calculating the geological reserves of the target layer section in the target work area according to the reserve calculation module in the geological model;

[0095] (3.2) By adjusting the porosity and saturation, the error between the geological reserves calculated by the three-dimensional geological model and the geological reserves calculated by the volumetric method is ensured to be within the range of ±10%.

[0096] (4) According to the reserve fitting standard, a chart of pore volume and geological reserves is established, which specifically includes the following steps:

[0097] (4.1) Assigning a net-to-gross ratio of all interlayers in the net-to-gross ratio model to 1, and calculating the geological reserves in the model using the reassigned net-to-gross ratio according to the reserve calculation module in the geological model;

[0098] (4.2) Based on the reserve calculation formula in the model, combined with the geological reserves calculated when the net-to-gross ratio of the interlayer is set to 0 and 1, a chart of pore volume and geological reserves is established; the reserve calculation formula is:

[0099]

[0100] Among them, B vi is the gross volume of the i-th grid; NTG i is the net-to-gross ratio of the ith grid; is the porosity of the ith grid, %; S wi is the water saturation of the ith grid, a decimal; B o is the volume coefficient of crude oil.

[0101] According to Archie's formula, porosity The larger the value, the corresponding water saturation (S w For the interlayer above the oil-water interface, its porosity is small (below the lower limit of the effective reservoir), and the corresponding water saturation S w If it is larger, then 1-S w The Archie formula is relatively small and has little impact on the entire reserve calculation formula.

[0102]

[0103] Among them, S w is water saturation, decimal; is the porosity, a decimal; a is the lithology coefficient related to lithology, dimensionless; b is the constant related to lithology, dimensionless; m is the cementation index, dimensionless; n is the saturation index, dimensionless; R w is the formation water resistivity, Ω·m; R t is the formation resistivity, Ω·m.

[0104] (5) Based on the constant volume principle and the chart obtained in step (4), the upper limit of the pore volume is defined and a net-to-gross ratio model is established; it should be noted that the data of the net-to-gross ratio model is between 0 and 1, not the traditional meaning of either 0 or 1.

[0105] (6) Based on the variable net-to-gross ratio model obtained in step (5), the model's grid data, well data, porosity, permeability, saturation and net-to-gross ratio are output to perform time-dependent fitting and program preparation in the numerical simulation stage.

[0106] Example 1

[0107] This embodiment provides a geological modeling method for a carbonate reservoir with permeable interlayers. The geological modeling method uses Petrel geological modeling software to sequentially establish a structural model, a sedimentary phase model, and an attribute model, and uses the volume calculation module of the Petrel geological modeling software to calculate the geological reserves in the model, and derives the attributes for numerical simulation, specifically comprising the following steps:

[0108] (1) Based on the oil-water interface, the requirements of the water body for numerical simulation, and the boundary of the mining area, the modeling boundary of the target oil field is determined, and the structural surface of the 3D seismic interpretation is corrected using geological stratification; a fault model is established in combination with the fault data of the 3D seismic interpretation, and finally a structural model of the target layer section of the target work area is established.

[0109] In this example, the carbonate reservoir in the study area is the X oilfield, and the target layer is the Cretaceous M group C layer. There are 31 wells drilled in the work area, of which 20 wells penetrate the target layer, and the rest are horizontal wells, which are distributed in the structural high parts and structural wings on the plane. The three-dimensional seismic coverage in the work area meets the needs of seismic fine interpretation and three-dimensional geological modeling. Three sets of reservoirs are developed vertically in the C layer, and the reservoirs are separated by two sets of interlayers. Interlayers are developed locally. Pressure and production dynamic data confirm that the three sets of reservoirs are interconnected (see Figure 2 ).

[0110] According to the oil-water interface of the C layer of the M group and the demand for water bodies in numerical simulation, the modeling boundary was first determined to be the three-dimensional seismic boundary; secondly, based on the horizon calibration, the seismic interpretation of the top and bottom of the C layer of the M group of the X oilfield was completed, and the correction of the top and bottom structural surfaces of the C layer was completed based on the geological stratification to ensure that the structural surface of the seismic interpretation was consistent with the structural surface of the geological stratification. In addition, the three-dimensional seismic interpretation showed that the X oilfield was a northwest-southeast anticline with no developed faults, so the fault model was not constructed. According to the modeling process, the structural model of the X oilfield was established (see Figure 3 ).

[0111] (2) Based on the structural model established in step (1), according to the results of single well sedimentary facies division, a sedimentary facies model is established by data coarsening, variogram analysis, combined with seismic facies plane distribution, using geological modeling software, and adopting a sequential indicator simulation algorithm.

[0112] According to the core and thin section data of the target layer, it is clear that the C layer of the M group in the X oilfield mainly develops bioclastic limestone, muddy limestone, granular marl and micrite limestone, among which granular limestone, muddy limestone and granular marl are the main reservoirs, and the micrite limestone is relatively dense and has poor pores.

[0113] Previous studies have shown that the sedimentary facies of Group M is a gentle slope carbonate platform, in which the C layer mainly develops bioclastic beaches, shallow open seas and inter-beach seas. The bioclastic beaches are mainly developed at the top of the C layer, mainly composed of bioclastic limestone and mud-grained limestone, with a small amount of granular marlstone; the shallow open sea is mainly composed of mud-grained limestone, with a small amount of granular marlstone and micritic limestone; the water energy of the inter-beach sea during the sedimentary period is relatively weak, and it is mainly composed of fine-grained deposited micritic limestone, which is mostly manifested as interlayers.

[0114] The mud content of bioclastic beaches is low, the pores are relatively developed (some sample pores are filled with cement), and the logging response is low natural gamma and high acoustic time difference. The mud content of shallow open sea is higher than that of bioclastic beaches, and the corresponding natural gamma value is higher than that of bioclastic beaches, and it has a micro-serration, and the acoustic time difference is lower than that of bioclastic beaches. The inter-beach sea has a high mud content and poor physical properties, so the corresponding natural gamma value is high, the sawtooth feature is obvious, and the acoustic time difference is low. According to the logging response characteristics of different microfacies, all wells in the work area were divided into single well phases.

[0115] On the basis of step (1), according to the results of single well sedimentary facies division and referring to the seismic facies plane distribution, the sedimentary facies model was established by using the Petrel geological modeling software, through sedimentary facies data coarsening and variogram analysis, and using the sequential indicator simulation algorithm (see Figure 4 ).

[0116] (3) On the basis of step (2), a porosity model is established by phase-controlled modeling according to the porosity, permeability and saturation data interpreted from single well logging. Then, a permeability model and a saturation model are established based on the porosity model.

[0117] Firstly, the porosity, permeability and water saturation data interpreted from well logging in the work area were analyzed, invalid data were eliminated, and the variogram was analyzed by data coarsening.

[0118] Secondly, the porosity model was established by combining the wave impedance data of seismic inversion with the idea of ​​phase-controlled modeling (see Figure 5 ).

[0119] Then, considering the heterogeneity of carbonate reservoirs, the construction of the C layer permeability model is divided into two steps: first, based on the porosity and permeability relationship established by core analysis, a "deterministic permeability model" is established through the porosity and permeability formula calculation; then, the permeability interpreted by logging is subjected to data coarsening and variogram analysis, and the porosity and "deterministic permeability model" are used as dual constraints to construct the permeability model (see Figure 6 ).

[0120] Finally, considering that reservoir C is an anticline reservoir with a small transition zone and a large pure oil zone, the construction of the saturation model uses the saturation interpreted by single well logging as hard data. Through data analysis and constraint by oil column height, the sequential Gaussian simulation algorithm is used to establish the saturation model (see Figure 7 ).

[0121] (4) On the basis of step (3), based on core data, using logging interpretation as a means, and based on oil testing verification, the lower limit standard of the effective thickness of the reservoir is determined, and based on the obtained lower limit standard, a net-to-gross ratio model is established through calculation.

[0122] The X oilfield M group C layer uses core description, oil testing, cable testing and new well MDT testing to determine the lower limit of effective reservoir thickness as porosity ≥ 9% and water saturation ≤ 55% (see Figure 8 ).

[0123] According to the lower limit standard of effective reservoir thickness, the net-to-gross ratio model of the target work area was established through calculation, in which the net-to-gross ratio of the effective reservoir was set to 1 and the net-to-gross ratio of the interlayer was set to 0.

[0124] (5) According to step (3) and step (4), the geological reserves of the target layer section in the target work area are calculated according to the reserve calculation module in the geological modeling software, and compared with the geological reserves calculated by the volumetric method.

[0125] The geological reserves within the mining rights scope of the C layer model of Group M of X Oilfield are calculated to be 129 million cubic meters, and the geological reserves calculated by the volumetric method are 127.2 million cubic meters. By comparing the geological reserves calculated by the model and the volumetric method, the error between the two is 1.4%, which meets the requirements of geological modeling.

[0126] (6) The net-to-gross ratio of all interlayers is set to 1, and the geological reserves in the geological model are recalculated. Then, the pore volume (B) is established based on the corresponding reserve data when the net-to-gross ratio of the interlayer is set to 0 and 1 respectively. v ×NTG×Φ) and geological reserves (see Fig. 9 ).

[0127] (7) Based on the constant volume principle, according to the plate obtained in step (6), the pore volume (B) is determined on the basis of ensuring that the error between the model reserves and the geological reserves calculated by the volumetric method is within a reasonable range. v ×NTG×Φ), and then establish the final net-to-gross ratio model.

[0128] (8) Output the grid data, well trajectory, porosity, permeability, saturation and net-to-gross ratio model in steps (1), (3) and (7) to perform time fitting and program preparation in the numerical simulation stage.

[0129] Through fitting, it is found that the fitting error of the formation pressure of reservoir C is 31% when using the traditional "fixed" net-to-gross ratio model, while the fitting error of the formation pressure based on the variable net-to-gross ratio model is only 15%, and the fitting accuracy is significantly improved (see Fig.10 ), which laid a solid foundation for the prediction of water drive path and remaining oil distribution after water injection development.

[0130] It can be seen that compared with the prior art, the geological modeling method provided by the present invention not only follows the process of geological modeling and the principle of geological reserve fitting, but also fully integrates geological knowledge into the process of model construction without changing the "hard data". At the same time, the influence of changes in net-to-gross ratio on model reserves and pore volume can be intuitively observed through the chart, and the pressure conduction and fluid migration in the process of diachronic fitting can be ensured, which improves the accuracy of diachronic fitting and facilitates the prediction of later plans and the study of residual oil distribution. In addition, the geological modeling method provided by the present invention has high repeatability and strong operability. At the same time, the workflow can be compiled in the software to achieve the purpose of rapid realization; the established geological model is consistent with geological knowledge, and the diachronic fitting accuracy is high, which is convenient for oilfield development technicians to master and apply.

[0131] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A geological modeling method for permeable interlayers in carbonate reservoirs, characterized in that: The geological modeling method comprises the following steps: (1) Selecting a target work area and sequentially establishing a structural model, a sedimentary facies model and an attribute model for the target work area; (2) Determine the lower limit standard of the effective thickness of the reservoir and establish a net-to-gross ratio model based on the lower limit standard; (3) fitting the geological reserves of the oil reservoir according to the attribute model obtained in step (1) and the net-to-gross ratio model obtained in step (2); (4) Establish a chart of pore volume and geological reserves based on the reserve fitting standard; (5) Based on the constant volume principle and the plate obtained in step (4), define the upper limit of the pore volume and establish a variable net-to-gross ratio model; (6) Based on the variable net-to-gross ratio model obtained in step (5), the specific attributes of the model are output and numerical simulation fitting is performed.

2. The geological modeling method according to claim 1, characterized in that: The attribute model in step (1) includes a porosity model, a permeability model and a saturation model.

3. The geological modeling method according to claim 1 or 2, characterized in that: The process of establishing the construction model in step (1) includes the following steps: (1.1.1) Conducting geological stratification on the wells in the target work area and using the geological stratification to correct the structural surface interpreted by three-dimensional seismic analysis; (1.1.2) Determine the modeling boundary based on the oil-water interface of the target reservoir and the water body requirements of the numerical model; (1.1.3) Establish a fault model based on the fault data interpreted from the earthquake; (1.1.4) Establishing a structural model of the target layer section in the target work area; Among them, steps (1.1.1) and (1.1.2) are in no particular order.

4. The geological modeling method according to claim 3, characterized in that: The process of establishing the sedimentary facies model in step (1) includes the following steps: (1.2.1) Determine the lithology of the target layer based on the core and thin section data of the target layer; (1.2.2) Based on the lithology obtained in step (1.2.1), combined with the regional sedimentary background and sedimentary structure, analyze the sedimentary environment and sedimentary facies; (1.2.3) Establish logging phase standards for the study area and realize phase division of single wells in the entire work area; (1.2.4) Based on the established structural model, combined with the results of single-well sedimentary facies division and seismic facies plane distribution, a sedimentary facies model is established using geological modeling software and a sequential indicator simulation algorithm.

5. The geological modeling method according to claim 4, characterized in that: The process of establishing the attribute model in step (1) includes the following steps: (1.3.1) Collect well logging data of the target work area and perform data analysis on the porosity, permeability and saturation interpreted by the well logging; (1.3.2) Data coarsening of the porosity curve was performed, and the porosity model was constructed by adopting the idea of ​​phase-controlled modeling and combining seismic attributes; (1.3.3) Based on the correlation between reservoir porosity and permeability, a permeability model is established using the porosity constraint method; (1.3.4) Construct a saturation model for the target layer in the target work area, using any of the following methods: (1.3.4A) For reservoirs in the small transition zone, the saturation interpreted by single well logging is used as hard data. Through data analysis, the oil column height is used as a constraint, and the sequential Gaussian simulation algorithm is used to establish a saturation model; (1.3.4B) For the reservoirs in the large transition zone, the saturation model is established using the J function method; Among them, the area of ​​the small transition zone in step (1.3.4A) is less than twice the area of ​​the pure oil zone; the area of ​​the large transition zone in step (1.3.4B) is greater than or equal to twice the area of ​​the pure oil zone.

6. The geological modeling method according to claim 1 or 2, characterized in that: Step (2) specifically includes the following steps: (2.1) Based on core data, logging interpretation and oil testing, determine the lower limit of effective reservoir thickness; (2.2) Based on the lower limit standard obtained in step (2.1), a net-to-gross ratio model of the target work area is established through calculation; wherein the net-to-gross ratio of the effective reservoir is 1, and the net-to-gross ratio of the interlayer is 0.

7. The geological modeling method according to claim 1 or 2, characterized in that: Step (3) specifically includes the following steps: (3.1) Calculating the geological reserves of the target layer section in the target work area according to the reserve calculation module in the geological model; (3.2) The porosity and saturation are adjusted to ensure that the error between the geological reserves calculated by the 3D geological model and the geological reserves calculated by the volumetric method is within ±10%.

8. The geological modeling method according to claim 1 or 2, characterized in that: Step (4) specifically includes the following steps: (4.1) Assign the net-to-gross ratio of all interlayers in the net-to-gross ratio model to 1, and calculate the geological reserves in the model using the reassigned net-to-gross ratio according to the reserve calculation module in the geological model; (4.2) Based on the reserve calculation formula in the model and the geological reserves calculated when the net-to-gross ratio of the interlayer is set to 0 and 1 respectively, a chart of pore volume and geological reserves is established.

9. The geological modeling method according to claim 8, characterized in that: The reserve calculation formula in step (4.2) is: （1） in, is the gross volume of the ith grid; is the net-to-gross ratio of the ith grid; is the porosity of the i-th grid, %; is the water saturation of the ith grid, a decimal; is the volume coefficient of crude oil.

10. The geological modeling method according to claim 1 or 2, characterized in that: The specific attributes in step (6) include grid data, well data, porosity, permeability, saturation and net-to-gross ratio.

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