Optimal selection method and device for five-stage sequence favorable area of glutenite gas reservoir

Abstract

The invention relates to the technical field of oilfield development, in particular to a glutenite gas reservoir five-level sequence favorable area optimal selection method and device, and the method comprises the steps: on the basis of a three-level sequence division result, carrying out four-level sequence division by combining a natural gamma logging curve form with a resistivity logging curve; on the basis of a four-level sequence division result, performing five-level sequence division by using a natural gamma logging curve, a resistivity logging curve and seismic data; overlapping the division results of the effective reservoir distribution area and the effective source fracture area, and determining the overlapping area of the two areas as a source fracture favorable area; and determining an optimal selection result of the glutenite five-level sequence favorable area according to the divided source, fault and storage favorable area and the five-level sequence division result. According to the method, the distribution characteristics of effective reservoirs are defined, the favorable source-fault-reservoir area is determined, and systematic, accurate and rapid optimization of the favorable five-stage sequence area of the glutenite gas reservoir is realized.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and in particular to a method and apparatus for selecting favorable areas of a fifth-order sequence stratigraphy in sandstone and conglomerate gas reservoirs. Background Technology

[0002] With increasingly difficult exploration and discovery of proven reserves, improving production during the development phase is crucial for the sustained and stable production of gas fields. However, the selection of favorable areas during the development phase is far more demanding than that during the exploration phase. Research indicates that current evaluation of favorable areas in sandstone and conglomerate gas reservoirs primarily focuses on the exploration stage, with insufficient research into source-fault-reservoir relationships. The distribution range of favorable areas is unclear, and research on sedimentary facies, reservoirs, and favorable areas remains at the third-order sequence stratigraphy level. The large vertical thickness of the third-order sequence stratigraphy, averaging 324m, results in a large planar area of ​​favorable areas and low prediction accuracy. To address the issue of insufficiently detailed sequence stratigraphic division for selecting favorable areas in sandstone and conglomerate gas reservoirs, it is urgent to establish a method for selecting favorable areas during the development phase of sandstone and conglomerate gas reservoirs to guide precise well placement. Summary of the Invention

[0003] This invention proposes a method and apparatus for selecting favorable areas in a five-level sequence stratigraphy of sandstone and conglomerate gas reservoirs. This method addresses the problem that existing methods for selecting favorable areas often lack clarity regarding the distribution of favorable areas related to source, fault, and reservoir, and only involve three-level sequence stratigraphy. This results in large vertical thickness and insufficient detail in the division, leading to a large area of ​​favorable areas in the plane and low prediction accuracy.

[0004] According to one aspect of the present invention, a method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir is provided, comprising:

[0005] The study area obtained the results of the third-order sequence stratigraphy of reservoirs, natural gamma logging curves, resistivity logging curves, seismic data, effective source fracture zones, and effective reservoir distribution zone delineation.

[0006] Based on the results of the third-level sequence division, the fourth-level sequence division is carried out by combining the natural gamma logging curve morphology with the resistivity logging curve.

[0007] Based on the results of the fourth-order sequence division, a fifth-order sequence division was carried out using the natural gamma logging curves, resistivity logging curves, and seismic data.

[0008] The division results of the effective reservoir distribution area and the effective source-fault zone are superimposed to determine the superimposed area as the source-fault-reservoir favorable area.

[0009] Based on the defined favorable source-fault-reservoir zones and the results of the fifth-order sequence stratigraphy, the preferred results for the fifth-order sequence stratigraphy of sandstone and conglomerate are determined.

[0010] Preferably, before obtaining the effective source-source fracture zone delineation result, the effective source-source fracture zone delineation is performed to obtain the delineation result. The method includes:

[0011] Obtain reservoir source rock distribution maps and fault profile maps for the study area;

[0012] On the source rock distribution map, the favorable source rock area is delineated based on source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectance.

[0013] Based on the fault profile, the location of the fault connecting the source rock and the reservoir is determined;

[0014] Based on the fault location, within the favorable area of ​​the source rock, an effective source fault zone is delineated to obtain the effective source fault zone delineation result.

[0015] Preferably, the method for delineating the favorable source rock zone based on source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectance includes:

[0016] With a source rock thickness greater than 535m and a hydrocarbon generation intensity greater than 20 billion cubic meters per km² 2 The minimum lower limits for defining the favorable source rock area are: total organic carbon (TOC) content greater than 2% and vitrinite reflectance (Ro) greater than 2%.

[0017] Preferably, before obtaining the effective reservoir distribution area delineation result, the effective reservoir distribution area is delineated to obtain the delineation result. The method includes:

[0018] Obtain the sedimentary facies zoning results for the study area;

[0019] Based on well logging curves, select the most sensitive parameters for sandstone and conglomerate lithology.

[0020] Based on the lithology-sensitive parameters and constrained by the sedimentary facies zoning results, facies-controlled sand bodies are predicted, and the distribution areas of dominant sand bodies of sandstone and conglomerate are delineated.

[0021] Based on the well logging curves, select the most sensitive parameters for effective sandstone and conglomerate reservoirs;

[0022] Based on the effective reservoir sensitive parameters, and using the dominant sand bodies as constraints, sand-controlled effective reservoir prediction is performed in the distribution area of ​​the dominant sandstone bodies in the conglomerate, and the effective reservoir distribution area is delineated.

[0023] Preferably, before obtaining the sedimentary facies zoning results of the study area, the sedimentary facies zoning of the study area is performed to obtain the zoning results. The method includes:

[0024] Obtain the single-well sedimentary facies interpretation results for the study area, and draw a single-well sedimentary facies zone map based on the single-well sedimentary facies interpretation results;

[0025] Based on the single-well sedimentary facies map, combined with the sedimentary environment and provenance direction of the study area, the seismic attributes are optimized, and the optimized seismic attributes are used as the sensitive attributes of the sedimentary facies zones.

[0026] Based on the sensitive properties of the sedimentary facies zones, sedimentary facies zones are characterized to obtain sedimentary facies zone characterization results.

[0027] Preferably, the seismic attributes include multi-attribute clustering attributes;

[0028] The multi-attribute clustering attribute is defined as follows: determining the consistency rate between the sedimentary facies characterization result of each seismic attribute and the single-well sedimentary facies interpretation result, and clustering a predetermined number of seismic attributes with the highest consistency rate to obtain the multi-attribute clustering attribute.

[0029] Preferably, the sensitive attribute of the sedimentary facies zone is the root mean square amplitude attribute.

[0030] Preferably, the method for selecting sandstone and conglomerate lithology-sensitive parameters based on well logging curves includes:

[0031] Obtain gamma, acoustic, density, resistivity, and P-wave impedance logging curves for the study area;

[0032] The well logging curves are corrected and standardized.

[0033] The well logging curves after correction and standardization are subjected to rock physical analysis, and the well logging curve that best distinguishes between sandstone and mudstone is taken as the lithology sensitive parameter.

[0034] Preferably, the lithologically sensitive parameter of the conglomerate is the longitudinal wave impedance curve.

[0035] Preferably, the method for predicting facies-controlled sand bodies and delineating the distribution areas of dominant sandstone bodies in conglomerate based on the lithology-sensitive parameters and the sedimentary facies zoning results includes:

[0036] The lithology-sensitive parameters are interpolated to generate a lithology-sensitive parameter volume;

[0037] Based on the lithological sensitive parameter body, and combined with the corresponding threshold values ​​for sandstone and mudstone, the distribution areas of dominant sandstone bodies in sandstone and mudstone are divided.

[0038] Preferably, the method for predicting sand-controlled effective reservoirs and delineating effective reservoir distribution areas based on the effective reservoir sensitive parameters and the dominant sand body distribution areas of the conglomerate, using the dominant sand bodies as constraints, includes:

[0039] Interpolate the effective reservoir sensitive parameters to generate an effective reservoir sensitive parameter body;

[0040] Based on the effective reservoir sensitive parameter body, and combined with the effective reservoir and ineffective reservoir division threshold value corresponding to the effective reservoir sensitive parameter, the effective reservoir distribution area is divided.

[0041] Preferably, the method for performing fourth-order sequence division based on the third-order sequence division results, using the natural gamma logging curve morphology combined with resistivity logging curves, includes:

[0042] If the natural gamma logging curve exhibits a low-value bell shape and a high-value gentle tooth shape, and the resistivity changes from high to low, then the boundary between the two shapes is the stratification boundary.

[0043] If the natural gamma logging curve shows a low-value peak and a high-value funnel shape, and the resistivity changes from high to low, then the boundary between the two shapes is the stratification boundary.

[0044] If the natural gamma logging curve shows a high-value flat linear shape and a low-value funnel shape, and the resistivity changes from low to high, then the boundary between the two shapes is the stratification boundary.

[0045] If the natural gamma logging curve exhibits both a high-value linear shape and a high-value box shape, and the resistivity changes from low to high, then the boundary between the two shapes is the stratification boundary.

[0046] Preferably, the method for performing fifth-order sequence division based on the fourth-order sequence division results, using the natural gamma-ray logging curves, resistivity logging curves, and seismic data, includes:

[0047] Using the natural gamma and resistivity curves, combined with cyclic characteristics, the fifth-order sequence boundary of a single well is delineated within the fourth-order sequence framework.

[0048] Based on the results of the single-well fifth-order sequence boundary division, the amplitude characteristics in the corresponding seismic data are determined;

[0049] Based on the amplitude characteristics, the fifth-order sequence boundary is delineated between wells within the fourth-order sequence grid to obtain the fifth-order sequence delineation result.

[0050] Preferably, the method for delineating the fifth-order sequence boundary of a single well within a fourth-order sequence framework using the natural gamma and resistivity curves, combined with cyclic characteristics, includes:

[0051] Within the four-level sequence grid, the natural gamma curve and resistivity curve are used to identify the water ingress interface, water regression interface and lacustrine flooding surface of the four-level cycle.

[0052] In sandstone-mudstone development zones, the sandstone-mudstone interface closest to the lacustrine flooding surface in the cyclic contact interface is used as the fifth-order sequence boundary for a single well. In sandstone development zones, based on the comprehensive well logging interpretation results, the gas layer, differential gas layer, differential gas boundary layer, and dry layer closest to the water-entry and water-regression interfaces in the cyclic contact interface are used as the fifth-order sequence boundary for a single well.

[0053] Preferably, the method for identifying the water ingress interface, water regression interface, and lacustrine flooding surface of a fourth-order cycle within a fourth-order sequence lattice using the natural gamma curve and resistivity curve includes:

[0054] Based on the gamma and resistivity curves, the cyclic characteristics of the mudstone development area are determined to be either positive or negative cycles.

[0055] In the region with the worst mudstone development, the contact interface between two positive cycles is the water transgression interface, and the contact interface between two negative cycles is the water regression interface.

[0056] In the area where the mudstone is best developed, the contact interface between two positive cycles and the contact interface between two negative cycles are lacustrine flooding surfaces.

[0057] In the moderately developed mudstone region, the contact interface between the positive and negative cycles is the lacustrine flooding surface.

[0058] Preferably, when performing the five-level sequence division, the thickness of the divided sequence is less than 100m.

[0059] Preferably, it further includes:

[0060] To determine the economic and technical limits of sweet spots in sandstone and conglomerate gas reservoirs in the study area, wherein the economic and technical limits include at least: single-well production, reservoir thickness, and horizontal section length;

[0061] Based on the aforementioned economic and technical limits, sweet spots for sandstone gas reservoirs are identified within the favorable zone of the fifth-order sequence stratigraphy of the sandstone.

[0062] Preferably, before obtaining the sweet spot economic and technical limit of the conglomerate gas reservoir in the study area, the method for determining the economic and technical limit includes:

[0063] An economic evaluation model was established, and the whole life cycle evaluation method was applied. The drilling and completion investment, operating costs, natural gas commodity prices and life cycle of sandstone and conglomerate gas reservoirs were combined to comprehensively determine the single well production, reservoir thickness and horizontal section length.

[0064] According to one aspect of the present invention, a device for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir is provided, comprising:

[0065] The acquisition unit is used to acquire the results of the third-order sequence stratigraphy of the reservoir in the study area, natural gamma logging curves, resistivity logging curves, seismic data, effective source fracture zones, and effective reservoir distribution zone delineation results.

[0066] The fourth-level sequence division unit is used to perform fourth-level sequence division based on the results of the third-level sequence division, using the natural gamma logging curve morphology combined with the resistivity logging curve.

[0067] The fifth-order sequence division unit is used to perform fifth-order sequence division based on the fourth-order sequence division results, using the natural gamma logging curves, resistivity logging curves, and seismic data.

[0068] The source-fault-reservoir favorable area determination unit is used to superimpose the division results of the effective reservoir distribution area and the effective source-fault zone to determine the superimposed area as the source-fault-reservoir favorable area.

[0069] The fifth-order sequence favorable area determination unit is used to determine the preferred results of the fifth-order sequence favorable area of ​​sandstone and conglomerate based on the divided source-fault-reservoir favorable areas and the fifth-order sequence division results.

[0070] The present invention has at least the following beneficial effects:

[0071] This invention proposes a method and apparatus for selecting favorable areas of a fifth-order sequence stratigraphy in sandstone and conglomerate gas reservoirs. Based on the third-order sequence stratigraphy, fourth-order and fifth-order sequence stratigraphy are performed using well logging curves and geological data. By combining the results of the effective source-fault zone and the effective reservoir distribution zone, the effective reservoir distribution characteristics are clarified, and favorable source-fault-reservoir zones are determined, thus achieving systematic, accurate, and rapid selection of favorable areas of a fifth-order sequence stratigraphy in sandstone and conglomerate gas reservoirs. Attached Figure Description

[0072] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the specification, serve to explain the technical solutions of the present invention.

[0073] Figure 1 A flowchart illustrating a method for selecting favorable zones in a five-order sequence stratigraphy of a conglomerate gas reservoir according to an embodiment of the present invention is shown.

[0074] Figure 2 This diagram illustrates the seismic reflection characteristics of the second-order and third-order sequence interfaces of the Hezi Formation according to an embodiment of the present invention.

[0075] Figure 3 This diagram illustrates the response characteristics of the third-order sequence logging-lithological sequence interface of the Shahezi Formation according to an embodiment of the present invention.

[0076] Figure 4 An effective through-source fracture diagram is shown according to an embodiment of the present invention;

[0077] Figure 5 This diagram illustrates the effective reservoir distribution area according to an embodiment of the present invention.

[0078] Figure 6 This diagram illustrates the response characteristics of the fourth-order sequence logging-lithological sequence interface of the Shahezi Formation according to an embodiment of the present invention.

[0079] Figure 7 This diagram illustrates the interface response characteristics of the fifth-order sequence of the Shahezi Formation according to an embodiment of the present invention.

[0080] Figure 8 This diagram illustrates the response characteristics of the seismic interface of the fifth-order sequence rock formation in the Shahezi Formation according to an embodiment of the present invention.

[0081] Figure 9 A sequence sweet spot map of a sandstone gas reservoir according to an embodiment of the present invention is shown. Detailed Implementation

[0082] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0083] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0084] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0085] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without certain specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0086] Figure 1 A flowchart illustrating a method for selecting favorable zones in a five-order sequence stratigraphy of a conglomerate gas reservoir according to an embodiment of the present invention is shown. Figure 2 This diagram illustrates the seismic reflection characteristics of the second-order and third-order sequence interfaces of the Hezi Formation according to an embodiment of the present invention. Figure 3 This diagram illustrates the response characteristics of the third-order sequence logging-lithological sequence interface of the Shahezi Formation according to an embodiment of the present invention. Figure 4 An effective through-source fracture diagram is shown according to an embodiment of the present invention; Figure 5 This diagram illustrates the effective reservoir distribution area according to an embodiment of the present invention. Figure 6 This diagram illustrates the response characteristics of the fourth-order sequence logging-lithological sequence interface of the Shahezi Formation according to an embodiment of the present invention. Figure 7 This diagram illustrates the interface response characteristics of the fifth-order sequence of the Shahezi Formation according to an embodiment of the present invention. Figure 8 This diagram illustrates the response characteristics of the seismic interface of the fifth-order sequence rock formation in the Shahezi Formation according to an embodiment of the present invention. Figure 9 A sequence sweet spot map of a sandstone-conglomerate gas reservoir according to an embodiment of the present invention is shown. Figure 1-9 As shown, a method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir includes: Step S01: Obtaining the results of third-order sequence stratigraphy, well logging curves, seismic data, effective source-fault zones, and effective reservoir distribution zones in the study area; Step S02: Based on the results of the third-order sequence stratigraphy, performing fourth-order sequence stratigraphy using the natural gamma ray logging curve morphology combined with resistivity logging curves; Step S03: Based on the results of the fourth-order sequence stratigraphy, performing fifth-order sequence stratigraphy using the natural gamma ray logging curves, resistivity logging curves, and seismic data; Step S04: Overlaying the results of the effective reservoir distribution zones and the effective source-fault zones to determine the overlapping area as a favorable source-fault-reservoir zone; Step S05: Determining the optimal selection results of the favorable fifth-order sequence stratigraphy area in the conglomerate based on the defined favorable source-fault-reservoir zone and the fifth-order sequence stratigraphy results.

[0087] The method for selecting favorable areas in a fifth-order sequence stratigraphy of sandstone and conglomerate gas reservoirs provided in this invention specifically includes the following steps:

[0088] Step S01: Obtain the results of the three-level sequence stratigraphy of the reservoir in the study area, well logging curves, seismic data, effective source fracture zones, and effective reservoir distribution zone delineation.

[0089] In this embodiment of the invention, source rock, fault, and reservoir refer to hydrocarbon source rock, fault, and reservoir. A hydrocarbon source rock is a rock capable of producing or having produced mobile hydrocarbons; it is also known as an oil-generating rock or gas-producing rock. Rich in organic matter, hydrocarbon source rocks can generate and release oil and gas under specific geological conditions, contributing to the formation of commercial oil and gas reservoirs.

[0090] Taking a certain research area as an example, it is first divided into two-level procedures and three-level sequence divisions. The specific process includes:

[0091] 1. Second-level hierarchy:

[0092] (1) Earthquake characteristics: such as Figure 2 As shown, Figure 2 In the diagram, a to e represent the characteristics of the top interface, bottom interface, bottom interface (Sq4), bottom interface (Sq3), and bottom interface (Sq2) of the Shahezi Formation, respectively. First, based on the regional unconformity cut-off and overshoot reflection characteristics in the seismic profile, the bottom interface T42 and top interface T41 of the Shahezi Formation are determined. These two reflection layers correspond to regional unconformities and are regional seismic marker layers that can be continuously tracked and compared, i.e., second-order sequences.

[0093] (2) Well logging characteristics: such as Figure 3 As shown, below the top interface T41, the gamma curve increases and the resistivity change is small. Below the interface T42, the natural gamma curve is a toothed low value, while above the interface it changes to a high value. Below the interface, the resistivity curve is a toothed high value, while above the interface it is a toothed low value.

[0094] 2. Three-level hierarchy:

[0095] (1) Earthquake characteristics: such as Figure 2 As shown, third-order sequence boundaries are characterized by unconformities and traceable conformable boundaries. In the basin margins and relatively uplifted areas, third-order sequence boundaries change to downcut or erosion unconformities, transitioning to conformable contacts towards the depressions. Based on the seismic wave groups in the upper part of the near-source slope break zone showing truncation or scour filling, the seismic wave groups in the slope break zone development area showing overshoot and apparent truncation, and the differences in upper and lower strata indicated by strong amplitude reflection phase axes, three third-order sequence boundaries (T41a, T41b, and T41c) were further identified within the Shahezi Formation. The Shahezi Formation is divided into four third-order sequences: Sq4, Sq3, Sq2, and Sq1, corresponding to four segments of the Shahezi Formation.

[0096] (2) Well logging characteristics: such as Figure 3 As shown, below interface T41 (Sq4), the gamma suddenly increases while the resistivity changes abruptly. Below interface T41a (Sq3), the natural gamma curve transitions from high to low values, the resistivity suddenly decreases, and the acoustic transit time curve changes smoothly. Below interface T41b (Sq2), the natural gamma value is relatively low, showing a box-shaped transition from low to high values, with a smooth gamma value, and the acoustic transit time curve is high with a tendency to level off. Below interface T41c (Sq1), the natural gamma value is smooth, the acoustic transit time curve is smooth, and the resistivity increases.

[0097] (3) Lithological characteristics: such as Figure 3As shown, above interface T41 is Yingcheng Formation tuff, and below interface T41 is Shahezi Formation black mudstone (Sq4). Above interface T41a is gray medium sandstone, and below interface T41b is gray argillaceous siltstone (Sq3). Above interface T41b is gray medium conglomerate, and below interface T41c is gray coarse sandstone, and below interface T42 is black mudstone (Sq1). Above interface T43 is gray fine sandstone, and below interface T44b is green andesite.

[0098] In this invention, before obtaining the effective source-source fracture zone delineation results, the effective source-source fracture zone delineation is performed to obtain the delineation results. The method includes: obtaining a reservoir source rock distribution map and a fault profile map of the study area; on the source rock distribution map, delineating the favorable source rock area based on the source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectance; determining the fault location connecting the source rock and the reservoir based on the fault profile map; and delineating the effective source-source fracture zone within the favorable source rock area based on the fault location, thereby obtaining the effective source-source fracture zone delineation results.

[0099] In this invention, the method for delineating the favorable source rock zone based on source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectivity includes: using a source rock thickness greater than 535m and a hydrocarbon generation intensity greater than 20 billion cubic meters per km². 2 The minimum lower limits for defining the favorable source rock area are: total organic carbon (TOC) content greater than 2% and vitrinite reflectance (Ro) greater than 2%.

[0100] In this embodiment of the invention, the favorable area of ​​the source rock is initially delineated by considering factors that affect the development of the source rock, such as source rock thickness, hydrocarbon generation intensity, total organic carbon content (TOC), and vitrinite reflectance (Ro).

[0101] Based on the analysis of existing regional mining data in the study area, it was determined that the optimal conditions are source rock thickness greater than 535m and hydrocarbon generation intensity greater than 20 billion cubic meters per km². 2 The minimum lower limits were set for the total organic carbon content (TOC) greater than 2% and the vitrinite reflectance (Ro) greater than 2%, and a standard for dividing favorable source rock areas was established, delineating the range of favorable source rock areas on the source rock distribution map.

[0102] On the fault profile map, the development of faults in the early, middle, and late stages was analyzed to obtain the distribution characteristics such as the extension length of the faults. Faults that can connect source rocks and reservoirs are called source-transfer faults. These faults (source-transfer faults) can transport gas generated from the source rock into the reservoir, thus forming gas reservoirs. Therefore, source-transfer faults can serve as effective oil and gas migration channels. By analyzing the development of source-transfer faults, within the favorable source rock area on the source rock distribution map, if the fault (fault) connects the gas source and reservoir without developing into a caprock, then the location of the fault that connects the gas source and reservoir is an effective source-transfer fault zone. The results are as follows: Figure 4 As shown.

[0103] In this invention, before obtaining the effective reservoir distribution area delineation results, the effective reservoir distribution area is delineated to obtain the delineation results. The method includes: obtaining the sedimentary facies zone characterization results of the study area; selecting sandstone and conglomerate lithology sensitive parameters based on well logging curves; predicting facies-controlled sand bodies based on the lithology sensitive parameters and the sedimentary facies zone characterization results, and delineating the distribution area of ​​dominant sandstone and conglomerate sand bodies; selecting effective reservoir sensitive parameters based on well logging curves; and predicting sand-controlled effective reservoirs based on the effective reservoir sensitive parameters and the dominant sand bodies, and delineating the effective reservoir distribution.

[0104] In this invention, before obtaining the sedimentary facies zoning results of the study area, sedimentary facies zoning of the study area is performed to obtain zoning results. The method includes: obtaining single-well sedimentary facies interpretation results of the study area; drawing and generating single-well sedimentary facies zoning maps based on the single-well sedimentary facies interpretation results; performing seismic attribute optimization based on the single-well sedimentary facies zoning maps, combined with the sedimentary environment and source direction of the study area, and using the optimized seismic attributes as sensitive attributes of sedimentary facies zoning; and performing sedimentary facies zoning based on the sensitive attributes of sedimentary facies zoning to obtain sedimentary facies zoning results.

[0105] In this invention, the seismic attributes include multi-attribute clustering attributes; wherein, the multi-attribute clustering attributes are: determining the consistency rate between the sedimentary facies characterization results of each seismic attribute and the single-well sedimentary facies interpretation results, and clustering a predetermined number of seismic attributes with the highest consistency rate to obtain multi-attribute clustering attributes.

[0106] In this invention, the sensitive property of the depositional phase zone is the root mean square amplitude property.

[0107] In this embodiment of the invention, a single-well sedimentary facies map is generated based on the interpretation results of single-well sedimentary facies. Based on the single-well sedimentary facies division, and combined with regional sedimentary environment and provenance direction analysis, seismic attribute optimization is carried out. The optimization process is as follows: different seismic attributes are used to characterize the sedimentary facies zones in the study area. Then, the characterization results (predicted sedimentary facies map) are compared with the known single-well sedimentary facies zones at known well points obtained through well logging (single-well sedimentary facies interpretation results). The consistency rate between the sedimentary facies zone characterization results of each seismic attribute and the known single-well sedimentary facies zones at known well points is determined. A predetermined number of seismic attributes with the highest consistency rate are selected, and these predetermined number of seismic attributes are clustered to obtain multi-attribute clustering attributes. Sedimentary facies zones are characterized using these multi-attribute clustering attributes to obtain characterization results (predicted sedimentary facies map). The consistency rate between the sedimentary facies zone characterization results of these multi-attribute clustering attributes and the single-well sedimentary zones is determined.

[0108] By comparison, the highest value among the consistency rates of sedimentary facies zone characterization results of all seismic attributes (including multi-attribute clustering attributes) with the sedimentary facies zone of a single well is determined. The seismic attribute corresponding to the highest consistency rate is the finally selected sedimentary facies zone sensitive attribute.

[0109] For example, if the predetermined number is 3, the three seismic attributes with the highest consistency rate among all seismic attributes include: root mean square amplitude attribute, average reflection intensity attribute, and instantaneous Q factor attribute. These three attributes have relatively high consistency rates with single-well sedimentary facies, at 87.1%, 77.6%, and 86.3%, respectively.

[0110] Clustering these three attributes yielded multi-attribute clustering attributes, and the predicted sedimentary facies zonation map of the multi-attribute clustering attributes matched the sedimentary facies of a single well with a consistency rate of 86.7%.

[0111] By comparing all the agreement rates, the agreement rate between the predicted sedimentary facies zone map based on the root mean square amplitude attribute and the single-well sedimentary facies was determined to be 87.1%, which is the highest prediction accuracy.

[0112] Therefore, after optimization, the root-mean-square (RMS) amplitude attribute was determined to be the most sensitive seismic attribute to sedimentary facies zones. Using the RMS amplitude attribute, sedimentary facies zones were characterized, revealing that fan delta facies develop in steep slope zones and braided river delta facies develop in gentle slope zones.

[0113] In this invention, the method for selecting the lithological sensitive parameters of sandstone and conglomerate based on well logging curves includes: obtaining gamma, sonic, density, resistivity and P-wave impedance well logging curves of the study area; correcting and standardizing the well logging curves; performing rock physical analysis on the corrected and standardized well logging curves, and selecting the well logging curve that best distinguishes between sandstone and conglomerate and mudstone as the lithological sensitive parameters.

[0114] In this invention, the lithological sensitive parameter of the sandstone and conglomerate is the longitudinal wave impedance curve.

[0115] In this embodiment of the invention, based on the predicted sedimentary facies zone (sedimentary facies zone characterization results), and constrained by the sedimentary facies zone, the optimal selection of lithological sensitive parameters for sandstone and conglomerate is carried out. These lithological sensitive parameters are those that can distinguish sandstone and conglomerate from mudstone.

[0116] For example, after correcting and standardizing logging curves such as gamma, sonic, density, and resistivity, rock physics analysis is carried out. By drawing cross-plots, it is found that logging curves such as gamma, sonic, density, and resistivity cannot effectively distinguish between sandstone and mudstone, while the longitudinal wave impedance curve, which is the product of the density curve and the wave velocity curve (the reciprocal of the sonic curve), can effectively distinguish between sandstone and mudstone. Therefore, the longitudinal wave impedance (the product of the density curve and the reciprocal of the sonic curve) is preferred as a sensitive parameter for sandstone lithology.

[0117] In this invention, the method for predicting facies-controlled sand bodies and delineating the distribution area of ​​dominant sandstone bodies of sand and conglomerate based on the lithology-sensitive parameters and the sedimentary facies characterization results includes: interpolating the lithology-sensitive parameters to generate a lithology-sensitive parameter body; and delineating the distribution area of ​​dominant sandstone bodies of sand and conglomerate based on the lithology-sensitive parameter body and the corresponding sandstone and mudstone division threshold values.

[0118] In this embodiment of the invention, after selecting the preferred lithology-sensitive parameter, the threshold value for the lithology-sensitive parameter to distinguish between sandstone and mudstone is determined.

[0119] By drawing a cross-sectional diagram of transverse and longitudinal wave impedances through statistical analysis, the longitudinal wave impedance can be determined to be 11000 g / cm². 3 ×m / s, used as a threshold value to distinguish between sandstone and mudstone.

[0120] P-wave impedance volume was generated by interpolating the P-wave impedance curves from the well. Combined with the threshold values ​​of sandstone and mudstone, phase-controlled sand body prediction was carried out using wave impedance inversion. The distribution area of ​​sandstone and conglomerate was delineated, and the distribution area of ​​dominant sandstone and conglomerate was preliminarily determined.

[0121] In this invention, the method for predicting effective reservoirs and delineating effective reservoir distribution areas based on the effective reservoir sensitive parameters and using the dominant sand bodies as constraints in the distribution area of ​​the conglomerate sandstone includes: interpolating the effective reservoir sensitive parameters to generate an effective reservoir sensitive parameter body; and delineating the effective reservoir distribution areas based on the effective reservoir sensitive parameter body and the effective and ineffective reservoir delineation threshold values ​​corresponding to the effective reservoir sensitive parameters.

[0122] In this embodiment of the invention, on the distribution map of dominant sand bodies in conglomerate, the selection of sensitive parameters for effective reservoirs in conglomerate is carried out under the constraint of the determined distribution area of ​​dominant sand bodies. An effective reservoir refers to a reservoir whose logging interpretation results indicate it is a gas layer, a poor gas layer, or a poor gas boundary layer. Sensitive parameters for effective reservoirs are parameters that can distinguish effective reservoirs (gas layers, poor gas layers, poor gas boundary layers) from ineffective reservoirs.

[0123] Based on the correction and standardization of logging curves such as gamma, sonic, density, and resistivity, rock physical analysis was carried out. By drawing cross-plots, it was found that logging curves such as gamma, sonic, and resistivity could not distinguish between effective and ineffective reservoirs, while density curves could distinguish between effective and ineffective reservoirs. Therefore, density was selected as the preferred sensitive parameter for effective reservoirs.

[0124] After selecting the effective reservoir sensitive parameters, the threshold value for classifying sandstone and conglomerate reservoirs into effective and ineffective reservoirs is determined.

[0125] The density histogram can be used to determine the density of materials with a density less than 2.6 g / cm³. 3 As a threshold value distinguishing between effective and ineffective reservoirs, density volumes are generated by interpolating the wellbore density curves. Combined with the threshold values ​​for effective and ineffective reservoirs, sand-controlled effective reservoir prediction is conducted, effective reservoir distribution areas are delineated, and the distribution areas of effective reservoirs are preliminarily identified. The results are as follows: Figure 5 As shown.

[0126] Step S02: Based on the results of the third-level sequence division, the fourth-level sequence division is carried out by combining the natural gamma logging curve morphology with the resistivity logging curve.

[0127] In this invention, the method for performing fourth-level sequence division based on the three-level sequence division results, using the natural gamma ray logging curve morphology combined with the resistivity logging curve, includes: if the natural gamma ray logging curve exhibits a low-value bell shape and a high-value gentle tooth shape, and the resistivity transitions from high to low, then the boundary between the two shapes is the stratification boundary; if the natural gamma ray logging curve exhibits a low-value spike shape and a high-value funnel shape, and the resistivity transitions from high to low, then the boundary between the two shapes is the stratification boundary; if the natural gamma ray logging curve exhibits a high-value gentle linear shape and a low-value funnel shape, and the resistivity transitions from low to high, then the boundary between the two shapes is the stratification boundary; if the natural gamma ray logging curve exhibits a high-value linear shape and a high-value box shape, and the resistivity transitions from low to high, then the boundary between the two shapes is the stratification boundary.

[0128] In this embodiment of the invention, taking the Shahezi Formation in the study area as an example, the resistivity logging curves and natural gamma logging curves obtained from well logging are as follows: Figure 6As shown. Within the three-level sequence framework defined by well and seismic analysis, nine fourth-level sequences were further identified and subdivided based on logging curve characteristics; that is, the three third-level sequences Sq3, Sq2, and Sq1 were each subdivided into two fourth-level sequences, and Sq4 was subdivided into three fourth-level sequences, specifically including:

[0129] Below the Mf1 interface, it is divided into four-level sequence Sq1-1, and above the interface, it is divided into four-level sequence Sq1-2. Below the interface, the natural gamma curve is a low-value bell shape, and above it, it is a high-value gentle tooth shape, with the resistivity changing from high to low.

[0130] Below the Mf2 interface, it is divided into four-level sequence Sq2-1, and above the interface, it is divided into four-level sequence Sq2-2. Below the interface, the natural gamma curve is a low-value peak, and above it, it is a high-value funnel shape, with the resistivity changing from high to low.

[0131] Below the Mf3 interface, it is divided into four-level sequence Sq3-1, and above the interface, it is divided into four-level sequence Sq3-2. Below the interface, the natural gamma curve is a low-value peak, and above it, it is a high-value funnel shape, with the resistivity changing from high to low.

[0132] Below the Mf4 interface, it is divided into four-level sequence Sq4-1, and above the interface, it is divided into four-level sequence Sq4-2. Below the interface, the natural gamma curve is a flat line with medium to high values, and above it is a funnel shape with low values. The resistivity changes from low to high values.

[0133] Below the Mf5 interface, it is divided into four-level sequence Sq4-2, and above the interface, it is divided into four-level sequence Sq4-3. Below the interface, the natural gamma curve is a low-value funnel shape, and above it, it is a high-value box shape, with the resistivity changing from low to high.

[0134] The boundary between high and low values ​​is set according to the specific conditions of the reservoirs in the study area and as needed.

[0135] Step S03: Based on the results of the fourth-level sequence division, the fifth-level sequence division is carried out using the natural gamma logging curves, resistivity logging curves, and seismic data.

[0136] In this invention, the method for performing fifth-order sequence division based on the fourth-order sequence division results, using the natural gamma-ray logging curves, resistivity logging curves, and seismic data, includes: using the natural gamma-ray and resistivity curves, combined with cyclic characteristics, to perform single-well fifth-order sequence boundary division within the fourth-order sequence framework; determining the amplitude characteristics in the corresponding seismic data based on the single-well fifth-order sequence boundary division results; and performing inter-well fifth-order sequence boundary division within the fourth-order sequence framework based on the amplitude characteristics, thereby obtaining the fifth-order sequence division results.

[0137] In this invention, the method for delineating the fifth-order sequence boundary of a single well within a fourth-order sequence framework using the natural gamma and resistivity curves, combined with cyclic characteristics, includes: identifying the water-progressive interface, water-regressive interface, and lacustrine flooding surface of a fourth-order cycle within the fourth-order sequence framework using the natural gamma and resistivity curves; in sandstone-mudstone development intervals, using the sandstone-mudstone interface closest to the lacustrine flooding surface in the cycle contact interface as the fifth-order sequence boundary of a single well; and in sandstone development intervals, based on the comprehensive well logging interpretation results, using the interfaces of the gas layer, differential gas layer, differential gas boundary layer, and dry layer closest to the water-progressive and water-regressive interfaces in the cycle contact interface as the fifth-order sequence boundary of a single well.

[0138] In this invention, the method for identifying the transgressive, regressive, and lacustrine flooding interfaces of a fourth-order cycle within a fourth-order sequence stratigraphic framework using the natural gamma curve and resistivity curve includes: determining whether the cycle characteristics of a mudstone development area are positive or negative cycles based on the gamma and resistivity curves; in the area with the worst mudstone development, the contact interface between two positive cycles is the transgressive interface, and the contact interface between two negative cycles is the regressive interface; in the area with the best mudstone development, the contact interface between two positive cycles and the contact interface between two negative cycles are lacustrine flooding interfaces; in the area with moderate mudstone development, the contact interface between positive and negative cycles is a lacustrine flooding interface.

[0139] In this embodiment of the invention, taking the Shahezi Formation in the study area as an example, the deep and shallow lateral resistivity logging curves, natural gamma logging curves, lithology, and comprehensive logging interpretation obtained from well logging are as follows: Figure 7 As shown. Within the defined four-level sequence lattice, preliminary identification of the water ingress and regression interfaces and the floodplain of the four-level cycles is carried out using the characteristics of natural gamma curves and resistivity curves. Specifically, this includes:

[0140] Based on lithology, the mudstone development section is divided into three zones: good, medium, and poor. The specific division principles are set according to the specific conditions of the reservoir in the study area and as needed.

[0141] In the areas with the worst mudstone development, namely sections sq1 and sq2, sandstone dominates with virtually no mudstone. The method for determining positive and negative cycles is as follows: if the natural gamma curve within the fourth-order sequence changes from low to high values ​​from bottom to top, and the resistivity curve changes from high to low values ​​from bottom to top, the corresponding cycle is a positive cycle, i.e., the transgressive stage; conversely, if the gamma curve within the fourth-order sequence changes from high to low values ​​from bottom to top, and the resistivity curve changes from low to high values ​​from bottom to top, the corresponding cycle is a negative cycle, i.e., the regressive stage. The interface between two positive cycles is called the transgressive interface; the interface between two negative cycles is called the regressive interface.

[0142] In the region where mudstone is best developed, i.e., the sq3 stage, mudstone is dominant, with few and thin sandstone layers. If the gamma curve within the fourth-order sequence changes from low to high values ​​from bottom to top, and the resistivity curve changes from high to low values ​​from bottom to top, the corresponding cycle is a positive cycle, which is the flooding stage during the continuous expansion of the lake surface. Conversely, if the gamma curve within the fourth-order sequence changes from high to low values ​​from bottom to top, and the resistivity curve changes from low to high values ​​from bottom to top, the corresponding cycle is a negative cycle, which is the flooding stage during the continuous shrinking of the lake surface. The contact interface between two positive cycles and the contact interface between two negative cycles are both called the flooding surface.

[0143] In areas with moderate mudstone development, i.e., the sq4 stage, sandstone and mudstone are interbedded, with generally uniform thickness. If the gamma curve within the fourth-order sequence changes from low to high values ​​from bottom to top, and the resistivity curve changes from high to low values ​​from bottom to top, the corresponding cycle is a positive cycle, i.e., the transgressive stage. Conversely, if the gamma curve within the fourth-order sequence changes from high to low values ​​from bottom to top, and the resistivity curve changes from low to high values ​​from bottom to top, the corresponding cycle is a negative cycle, i.e., the regressive stage. The interface between the positive and negative cycles is called the lacustrine flooding surface.

[0144] The water ingress interface, water regression interface, and lacustrine flooding surface of the fourth-order sequence were initially identified as the fifth-order sequence boundaries.

[0145] Secondly, based on the preliminary determination of the fifth-order sequence boundary, and combined with sandstone and mudstone analysis and well logging interpretation, the fifth-order sequence boundary of a single well was finally clarified, specifically including:

[0146] In the sandstone and mudstone well-developed sections, namely the sq3 and sq4 stages, the sandstone and mudstone interface closest to the cyclic contact interface (flood surface) is taken as the final single-well fifth-order sequence interface.

[0147] In the sandstone development zone, namely the SQ1 and SQ2 stages, the cyclic contact interface (water transgression and water regression interface) penetrates the sandstone layer and the mudstone is not developed. It is impossible to accurately determine the fifth-order sequence boundary using the sandstone-mudstone interface. Therefore, the results of well logging interpretation are used as the basis, and the boundary of the gas layer, gas-differential layer, gas-differential boundary layer, and dry layer that are closest to the cyclic contact interface (water transgression and water regression interface) is used as the final fifth-order sequence boundary of a single well.

[0148] After obtaining the fifth-order sequence boundary division results at a single well (i.e., the well point), seismic characteristic analysis is carried out. Using the combined well-seismic characteristics, the amplitude characteristics corresponding to the fifth-order sequence boundary at the well point are determined as markers for inter-well fifth-order sequence division.

[0149] like Figure 8As shown in Table 1 below, based on the well point division of the five-level sequence boundary, and combining well and seismic data, the five-level sequence division between wells was determined with the strong amplitude response of the seismic event as the marker.

[0150] Table 1: Specific stratigraphic correspondences of each stratigraphic level in the study area

[0151]

[0152]

[0153] In this invention, when performing the five-level stratification, the stratification thickness is less than 100m.

[0154] In this embodiment of the invention, based on the fourth-order sequence stratigraphy, the wellbore is divided into five-order sequence stratigraphy based on the principle of "lithological combination and cyclic correlation", with the local lacustrine flooding surface (lithological interface) and well logging interpretation as the dividing line (interpretation interface); in seismic analysis, the inter-well stratigraphy is based on the comparability and traceability of gas-bearing intervals, with the strong amplitude of the relatively consolidation interface as the marker, and the well-seismic combination is used to carry out the fifth-order sequence stratigraphy, with the thickness of the fifth-order sequence stratigraphy being less than 100m.

[0155] Step S04: Overlay the division results of the effective reservoir distribution area and the effective source-fault zone to determine the overlapping area as the favorable source-fault-reservoir area.

[0156] In this embodiment of the invention, on the effective reservoir planar distribution map, the effective source fault zone and the effective reservoir distribution zone are superimposed together to delineate the superposition zone of the two. This zone is the favorable zone where the source rock, fault and effective reservoir are superimposed, which is the favorable source-fault-reservoir zone.

[0157] Step S05: Based on the defined favorable source-fault-reservoir areas and the results of the fifth-order sequence stratigraphy, determine the preferred results of the favorable fifth-order sequence stratigraphy areas for sandstone and conglomerate.

[0158] In this embodiment of the invention, the method further includes: obtaining the economic and technical limits of sweet spots in sandstone and conglomerate gas reservoirs in the study area, wherein the economic and technical limits include at least: single well production, reservoir thickness, and horizontal section length; and determining the sweet spot region of sandstone and conglomerate gas reservoirs in the preferred results of the fifth-order sequence stratigraphy of the sandstone and conglomerate based on the economic and technical limits.

[0159] In this invention, before obtaining the sweet spot economic and technical limit of the sandstone and conglomerate gas reservoir in the study area, the method for determining the economic and technical limit includes: establishing an economic evaluation model, applying a full life cycle evaluation method, and comprehensively determining the single well production, reservoir thickness, and horizontal section length by combining the drilling and completion investment, operating costs, natural gas commodity price, and life cycle of the sandstone and conglomerate gas reservoir.

[0160] In this embodiment of the invention, the current success rate of drilling industrial gas wells is only 45.5%, which is relatively low. The selection of sweet spots does not take into account the important indicator of economic and technical limits. Unprofitable development wells that fail to meet these limits are detrimental to the sustainable and stable production of the gas field. Therefore, it is necessary to select sweet spots based on a combination of favorable areas and economic and technical limits.

[0161] Based on the economic and technical limits of gas reservoir sweet spots, sweet spot prediction for reservoir control is carried out, and five-level sequence sweet spots in sandstone and conglomerate gas reservoirs are identified, specifically including:

[0162] An economic evaluation mathematical model is established, and the whole life cycle evaluation method is applied. Combining drilling and completion investment, operating costs, natural gas commodity prices, life cycle, etc., the limits of single well production, reservoir thickness, and horizontal section length are comprehensively determined.

[0163] By analyzing parameters such as the estimated final recovery volume (0.3119 billion cubic meters for vertical wells and 0.546 billion cubic meters for horizontal wells) and life cycle (20 years), the reasonable production of a single well is determined. The minimum reasonable production of a vertical well is 0.4 million cubic meters, and the minimum reasonable production of a horizontal well is 0.8 million cubic meters.

[0164] By analyzing the venting area of ​​a single well (0.64 km for a vertical well). 2 The horizontal well is 1.52 km long. 2 Based on the analysis of parameters such as effective porosity (0.05), gas saturation (0.46), volume factor (0.00332), and recovery rate (0.19 for vertical wells and 0.15 for horizontal wells), the minimum economically effective thickness was determined to be 30m.

[0165] Because production is affected by the reservoir drilling rate, extensive field tests have confirmed that the reasonable length of the horizontal section is 1000m when the drilling rate is 50% to 100% and 1500m when the drilling rate is less than 50%.

[0166] Ultimately, the economic calculation limits were determined: for an effective thickness greater than 30m, the reasonable production rate for a vertical well is 0.4–2.0 (10⁴ m³). 3 / d), the reasonable production rate of horizontal wells is 0.5~6.0 (10 4 m 3 / d) The reasonable length of the horizontal section is 1000m when the drilling encounter rate is 50%–100%, and 1500m when the drilling encounter rate is less than 50%, serving as the economic and technical limit for the sweet spot of the gas reservoir. Constrained by the favorable source-fault-reservoir area, the prediction of the fifth-order sequence sweet spot area for sandstone and conglomerate gas reservoirs is carried out within the favorable source-fault-reservoir area. Ultimately, the fifth-order sequence sweet spot area of ​​the sandstone and conglomerate gas reservoir is identified, such as... Figure 9 As shown.

[0167] It is understood that the various method embodiments mentioned above in this invention can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this invention will not elaborate further.

[0168] The execution entity of the method for selecting favorable areas of a fifth-order sequence stratigraphy in conglomerate gas reservoirs can be a device for selecting favorable areas of a fifth-order sequence stratigraphy in conglomerate gas reservoirs. For example, the method can be executed by a terminal device, a server, or other processing equipment. The terminal device can be a user equipment (UE), mobile device, user terminal, terminal, cellular phone, cordless phone, personal digital assistant (PDA), handheld device, computing device, vehicle-mounted device, wearable device, etc. In some possible implementations, this method for selecting favorable areas of a fifth-order sequence stratigraphy in conglomerate gas reservoirs can be implemented by a processor calling computer-readable instructions stored in memory.

[0169] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0170] This invention also proposes a device for selecting favorable areas of a fifth-order sequence stratigraphy in sandstone and conglomerate gas reservoirs, comprising: an acquisition unit for acquiring the results of third-order sequence stratigraphy of the reservoir in the study area, natural gamma-ray logging curves, resistivity logging curves, seismic data, effective source-fault zones, and effective reservoir distribution area division; a fourth-order sequence stratigraphy unit for performing fourth-order sequence stratigraphy based on the results of the third-order sequence stratigraphy, using the morphology of the natural gamma-ray logging curves combined with the resistivity logging curves; a fifth-order sequence stratigraphy unit for performing fifth-order sequence stratigraphy based on the results of the fourth-order sequence stratigraphy, using the natural gamma-ray logging curves, resistivity logging curves, and seismic data; a source-fault-reservoir favorable area determination unit for superimposing the division results of the effective reservoir distribution area and the effective source-fault zone to determine the superimposed area as the source-fault-reservoir favorable area; and a fifth-order sequence favorable area determination unit for determining the preferred results of the fifth-order sequence stratigraphy favorable areas in sandstone and conglomerate based on the divided source-fault-reservoir favorable areas and the fifth-order sequence stratigraphy results.

[0171] In some embodiments, the functions or modules and units included in the apparatus provided by the present invention can be used to execute the methods described in the above method embodiments. The specific implementation can be referred to the description of the above method embodiments, and for the sake of brevity, it will not be repeated here.

[0172] This invention innovatively employs a fourth-order sequence stratigraphy combined with well-seismic stratigraphy, building upon the third-order sequence stratigraphy, to achieve a vertical five-order sequence division. The fifth-order sequence thickness is less than 100m, superior to the 324m of the third-order sequence, resulting in a more detailed sequence division. In the planar region, source-fault-reservoir, facies-controlled sand, and sand-controlled reservoir technologies are used to clarify the source-fault-reservoir relationship. Based on the analysis of source rocks, faults, and reservoirs, the distribution range of favorable source-fault-reservoir areas is preliminarily delineated. Facies-controlled sand technology is used to identify dominant sand bodies and delineate their distribution areas. Sand-controlled reservoir technology is then used to identify effective reservoirs, clarifying their distribution characteristics. Finally, the favorable source rock area and the well-connected fault fusion technology are used to determine the favorable source-fault-reservoir area. By utilizing reservoir control technology and the economic and technical boundaries of gas reservoir sweet spots, the sweet spot area of ​​the fifth-order sequence in sandstone and conglomerate gas reservoirs can be identified. The range of the sweet spot area is more precise, enabling the systematic, accurate, and rapid selection of favorable areas of the fifth-order sequence in sandstone and conglomerate gas reservoirs, especially tight sandstone and conglomerate gas reservoirs. This can be used for well deployment in the development stage, reducing well placement risks, improving the success rate of drilling into industrial gas flow wells in development wells, and achieving high-efficiency and sustainable development of development wells.

[0173] The method of this invention has been experimentally deployed in 3 development wells, all of which have obtained industrial gas flow. The success rate of drilling industrial gas flow wells is 100%, realizing the high-efficiency and sustainable development of development wells.

[0174] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for selecting favorable areas in a fifth-order sequence stratigraphy of a sandstone-conglomerate gas reservoir, characterized in that, include: The study area obtained the results of the third-order sequence stratigraphy of reservoirs, natural gamma logging curves, resistivity logging curves, seismic data, effective source fracture zones, and effective reservoir distribution zone delineation. Based on the results of the third-level sequence division, the fourth-level sequence division is carried out by combining the natural gamma logging curve morphology with the resistivity logging curve. Based on the results of the fourth-order sequence division, a fifth-order sequence division was carried out using the natural gamma logging curves, resistivity logging curves, and seismic data. The division results of the effective reservoir distribution area and the effective source-fault zone are superimposed to determine the superimposed area as the source-fault-reservoir favorable area. Based on the defined favorable source-fault-reservoir zones and the results of the fifth-order sequence stratigraphy, the preferred results for the fifth-order sequence stratigraphy of sandstone and conglomerate are determined.

2. The method for selecting favorable areas of a fifth-order sequence stratigraphic unit in a conglomerate gas reservoir according to claim 1, characterized in that, Before obtaining the effective source-source fracture zone delineation result, the effective source-source fracture zone delineation is performed to obtain the delineation result. The method includes: Obtain reservoir source rock distribution maps and fault profile maps for the study area; On the source rock distribution map, the favorable source rock area is delineated based on source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectance. Based on the fault profile, the location of the fault connecting the source rock and the reservoir is determined; Based on the fault location, within the favorable area of ​​the source rock, an effective source fault zone is delineated to obtain the effective source fault zone delineation result.

3. The method for selecting favorable areas in a fifth-order sequence stratigraphy of a conglomerate gas reservoir according to claim 2, characterized in that, The method for delineating the favorable source rock zone based on source rock thickness, hydrocarbon generation intensity, total organic carbon content, and vitrinite reflectance includes: With a source rock thickness greater than 535m and a hydrocarbon generation intensity greater than 20 billion cubic meters per km² 2 The minimum lower limits for defining the favorable source rock area are: total organic carbon (TOC) content greater than 2% and vitrinite reflectance (Ro) greater than 2%.

4. The method for selecting favorable areas in a fifth-order sequence stratigraphy of a conglomerate gas reservoir according to claim 1, characterized in that, Before obtaining the effective reservoir distribution area delineation results, the effective reservoir distribution area is delineated to obtain the delineation results. The method includes: Obtain the sedimentary facies zoning results for the study area; Based on well logging curves, select the most sensitive parameters for sandstone and conglomerate lithology. Based on the lithology-sensitive parameters and constrained by the sedimentary facies zoning results, facies-controlled sand bodies are predicted, and the distribution areas of dominant sand bodies of sandstone and conglomerate are delineated. Based on the well logging curves, select the most sensitive parameters for effective sandstone and conglomerate reservoirs; Based on the effective reservoir sensitive parameters, and using the dominant sand bodies as constraints, sand-controlled effective reservoir prediction is performed in the distribution area of ​​the dominant sandstone bodies in the conglomerate, and the effective reservoir distribution area is delineated.

5. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 4, characterized in that, Before obtaining the sedimentary facies zoning results of the study area, the sedimentary facies zoning of the study area is performed to obtain the zoning results. The method includes: Obtain the single-well sedimentary facies interpretation results for the study area, and draw a single-well sedimentary facies zone map based on the single-well sedimentary facies interpretation results; Based on the single-well sedimentary facies map, combined with the sedimentary environment and provenance direction of the study area, the seismic attributes are optimized, and the optimized seismic attributes are used as the sensitive attributes of the sedimentary facies zones. Based on the sensitive properties of the sedimentary facies zones, sedimentary facies zones are characterized to obtain sedimentary facies zone characterization results.

6. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 5, characterized in that: The earthquake attributes include multi-attribute clustering attributes; The multi-attribute clustering attribute is defined as follows: determining the consistency rate between the sedimentary facies characterization result of each seismic attribute and the single-well sedimentary facies interpretation result, and clustering a predetermined number of seismic attributes with the highest consistency rate to obtain the multi-attribute clustering attribute.

7. The method for selecting favorable areas of a fifth-order sequence stratigraphic unit in a conglomerate gas reservoir according to claim 5, characterized in that: The sensitive attribute of the sedimentary facies zone is the root mean square amplitude attribute.

8. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 4, characterized in that, The method for selecting sandstone and conglomerate lithology-sensitive parameters based on well logging curves includes: Obtain gamma, acoustic, density, resistivity, and P-wave impedance logging curves for the study area; The well logging curves are corrected and standardized. The well logging curves after correction and standardization are subjected to rock physical analysis, and the well logging curve that best distinguishes between sandstone and mudstone is taken as the lithology sensitive parameter.

9. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 8, characterized in that: The lithologically sensitive parameter of the conglomerate is the longitudinal wave impedance curve.

10. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 4, characterized in that, The method for predicting facies-controlled sand bodies and delineating the distribution areas of dominant sandstone and conglomerate sand bodies based on the lithology-sensitive parameters and the sedimentary facies zoning results includes: The lithology-sensitive parameters are interpolated to generate a lithology-sensitive parameter volume; Based on the lithological sensitive parameter body, and combined with the corresponding threshold values ​​for sandstone and mudstone, the distribution areas of dominant sandstone bodies in sandstone and mudstone are divided.

11. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 4, characterized in that, The method for predicting sand-controlled effective reservoirs and delineating effective reservoir distribution areas based on the effective reservoir sensitive parameters and the dominant sand body distribution areas of the conglomerate, using the dominant sand bodies as constraints, includes: Interpolate the effective reservoir sensitive parameters to generate an effective reservoir sensitive parameter body; Based on the effective reservoir sensitive parameter body, and combined with the effective reservoir and ineffective reservoir division threshold value corresponding to the effective reservoir sensitive parameter, the effective reservoir distribution area is divided.

12. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 1, characterized in that, The method for performing fourth-order sequence division based on the third-order sequence division results, using the natural gamma ray logging morphology combined with resistivity logging curves, includes: If the natural gamma logging curve exhibits a low-value bell shape and a high-value gentle tooth shape, and the resistivity changes from high to low, then the boundary between the two shapes is the stratification boundary. If the natural gamma logging curve shows a low-value peak and a high-value funnel shape, and the resistivity changes from high to low, then the boundary between the two shapes is the stratification boundary. If the natural gamma logging curve shows a high-value flat linear shape and a low-value funnel shape, and the resistivity changes from low to high, then the boundary between the two shapes is the stratification boundary. If the natural gamma logging curve exhibits both a high-value linear shape and a high-value box shape, and the resistivity changes from low to high, then the boundary between the two shapes is the stratification boundary.

13. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 1, characterized in that, The method for performing fifth-order sequence stratigraphy based on the fourth-order sequence division results, using the natural gamma-ray logging curves, resistivity logging curves, and seismic data, includes: Using the natural gamma and resistivity curves, combined with cyclic characteristics, the fifth-order sequence boundary of a single well is delineated within the fourth-order sequence framework. Based on the results of the single-well fifth-order sequence boundary division, the amplitude characteristics in the corresponding seismic data are determined; Based on the amplitude characteristics, the fifth-order sequence boundary is delineated between wells within the fourth-order sequence grid to obtain the fifth-order sequence delineation result.

14. The method for selecting favorable areas in a fifth-order sequence stratigraphy of a conglomerate gas reservoir according to claim 13, characterized in that, The method for delineating the fifth-order sequence boundary of a single well within a fourth-order sequence framework, using the natural gamma and resistivity curves in conjunction with cyclic characteristics, includes: Within the four-level sequence grid, the natural gamma curve and resistivity curve are used to identify the water ingress interface, water regression interface and lacustrine flooding surface of the four-level cycle. In sandstone-mudstone development zones, the sandstone-mudstone interface closest to the lacustrine flooding surface in the cyclic contact interface is used as the fifth-order sequence boundary for a single well. In sandstone development zones, based on the comprehensive well logging interpretation results, the gas layer, differential gas layer, differential gas boundary layer, and dry layer closest to the water-entry and water-regression interfaces in the cyclic contact interface are used as the fifth-order sequence boundary for a single well.

15. The method for selecting favorable areas in a fifth-order sequence stratigraphy of a conglomerate gas reservoir according to claim 14, characterized in that, The method for identifying the water ingress interface, water regression interface, and lacustrine flooding surface of a fourth-order cycle within a fourth-order sequence lattice using the natural gamma curve and resistivity curve includes: Based on the gamma and resistivity curves, the cyclic characteristics of the mudstone development area are determined to be either positive or negative cycles. In the region with the worst mudstone development, the contact interface between two positive cycles is the water transgression interface, and the contact interface between two negative cycles is the water regression interface. In the area where the mudstone is best developed, the contact interface between two positive cycles and the contact interface between two negative cycles are lacustrine flooding surfaces. In the moderately developed mudstone region, the contact interface between the positive and negative cycles is the lacustrine flooding surface.

16. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 1, characterized in that: When performing the five-level sequence division, the thickness of the divided sequence is less than 100m.

17. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 1, characterized in that, Also includes: To determine the economic and technical limits of sweet spots in sandstone and conglomerate gas reservoirs in the study area, wherein the economic and technical limits include at least: single-well production, reservoir thickness, and horizontal section length; Based on the aforementioned economic and technical limits, sweet spots for sandstone gas reservoirs are identified within the favorable zone of the fifth-order sequence stratigraphy of the sandstone.

18. The method for selecting favorable areas of a fifth-order sequence stratigraphy in a conglomerate gas reservoir according to claim 17, characterized in that, Before obtaining the sweet spot economic and technical limit of the sandstone and conglomerate gas reservoir in the study area, the method for determining the economic and technical limit includes: An economic evaluation model was established, and the whole life cycle evaluation method was applied. The drilling and completion investment, operating costs, natural gas commodity prices and life cycle of sandstone and conglomerate gas reservoirs were combined to comprehensively determine the single well production, reservoir thickness and horizontal section length.

19. A device for selecting favorable areas in a five-level sequence stratigraphy of sandstone and conglomerate gas reservoirs, characterized in that, include: The acquisition unit is used to acquire the results of the third-order sequence stratigraphy of the reservoir in the study area, natural gamma logging curves, resistivity logging curves, seismic data, effective source fracture zones, and effective reservoir distribution zone delineation results. The fourth-level sequence division unit is used to perform fourth-level sequence division based on the results of the third-level sequence division, using the natural gamma logging curve morphology combined with the resistivity logging curve. The fifth-order sequence division unit is used to perform fifth-order sequence division based on the fourth-order sequence division results, using the natural gamma logging curves, resistivity logging curves, and seismic data. The source-fault-reservoir favorable area determination unit is used to superimpose the division results of the effective reservoir distribution area and the effective source-fault zone to determine the superimposed area as the source-fault-reservoir favorable area. The fifth-order sequence favorable area determination unit is used to determine the preferred results of the fifth-order sequence favorable area of ​​sandstone and conglomerate based on the divided source-fault-reservoir favorable areas and the fifth-order sequence division results.

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