A method for identifying ultra-deep lithologic hidden oil and gas reservoirs

Abstract

The present invention discloses a method for identifying ultra-deep lithologic concealed oil and gas reservoirs. The method comprises the following steps: S100, acquiring seismic, geological, and well logging data for a target area; S200, comparing and identifying wells that have undergone phase change among completed wells; S300, based on the results of S200, analyzing the lithology of the completed wells and performing cluster analysis to predict the distribution characteristics of different lithologic zones under well control conditions; performing reservoir formation factor analysis to determine the area where favorable sand bodies are located; S400, combining the well control lithologic classification in S300, selecting characteristic curves sensitive to lithologic changes in the well logging data, performing waveform indication simulation inversion, and predicting the distribution range of the identified lithologic concealed oil and gas reservoirs; S500, combining the predicted results of S400 with single well oil testing and production test data and the results of the reservoir formation factor analysis to propose deployable favorable traps or trap zones for the identified ultra-deep lithologic concealed oil and gas reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum geological exploration and development, and in particular to a method for identifying ultra-deep lithologic concealed oil and gas reservoirs. Background Art

[0002] The ultra-deep oil and gas reservoirs in the present invention refer to the industry standard "SY / T6169-1995 Oil Reservoir Classification", which refers to oil and gas reservoirs with a burial depth of more than 4,000 meters.

[0003] Subtle traps are difficult to identify using conventional techniques and methods. They are primarily caused by sedimentation, paleo-tectonic movement, hydrodynamic changes, and diagenesis. They include stratigraphic overlap, stratigraphic unconformity, updip pinch-outs, lenses, paleo-channels, buried hills, reefs, and fracture traps. Subtle oil and gas reservoirs are the accumulation of oil and gas in subtle traps.

[0004] Lithologic concealed reservoirs are a type of concealed reservoir whose formation is primarily controlled by lithology and are difficult to identify. Currently, identification methods combine sequence stratigraphic studies with seismic prediction. However, due to the unique characteristics of different concealed reservoirs, identification techniques rely on multiple disciplines and techniques, rather than relying on a single technique.

[0005] The identification of ultra-deep lithologic hidden reservoirs presents the following challenges: 1) Stratigraphic correlation is particularly challenging in areas with rapid lithologic change, and the traditional method of using lithologic interfaces as comparison markers cannot effectively identify phase-change wells; 2) Different lithologies exist within a region, requiring clear lithologic classification and distribution under well control conditions; 3) In areas with low well control, seismic technology is required to track and characterize the distribution of interwell sand bodies and the extent of lithologic-controlled sand bodies. However, compared to shallow reservoirs, ultra-deep reservoirs lack distinct low-velocity characteristics on time-difference curves due to differential compaction. Therefore, wave impedance inversion cannot effectively distinguish between sandstone and mudstone, and its prediction accuracy falls short of research needs, necessitating an urgent need for high-resolution reservoir prediction technology. This presents a major challenge in the current prediction of ultra-deep reservoirs.

[0006] Current research methods cannot meet the needs of identifying ultra-deep lithologic and subtle oil and gas reservoirs. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for identifying ultra-deep lithologic concealed oil and gas reservoirs, so as to solve the problems of difficulty in characterizing the reservoir sand bodies of ultra-deep lithologic concealed oil and gas reservoirs and the insensitivity of time difference curves to lithology. The method can realize the tracking and characterization of favorable sand bodies and the analysis of reservoir-forming factors of regional ultra-deep lithologic concealed oil and gas reservoirs, and propose favorable closures or closure zones for rolling evaluation and deployment.

[0008] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for identifying ultra-deep lithologic concealed oil and gas reservoirs, such as Figure 1 As shown, the method includes the following steps:

[0010] S100, obtaining seismic, geological and well logging data of the target area;

[0011] S200, comparing and determining wells where phase change occurs among completed wells;

[0012] S300: Based on the results of S200, the lithology of the wells is analyzed and cluster analysis is performed to predict the distribution characteristics of different lithology zones under well control conditions; the reservoir formation factors are analyzed to clarify the area where favorable sand bodies are located;

[0013] The "well control conditions" mentioned above refer to the well control conditions after completion of drilling.

[0014] S400, combined with the well-controlled lithology classification in S300, selects characteristic curves sensitive to lithology changes in the logging curves to perform waveform indication simulation inversion to predict and identify the distribution range of lithologic subtle oil and gas reservoirs;

[0015] The prediction results of S500 and S400 are combined with the single well oil test, test production data and the analysis results of reservoir formation factors to propose deployable favorable traps or trap zones for the identified ultra-deep lithologic subtle oil and gas reservoirs.

[0016] The following is a detailed description of each step:

[0017] S100. Acquire seismic, geological and logging data of the target area.

[0018] The present invention combines multiple disciplines such as seismology, geology, and well logging to form a set of effective identification technology methods. It is necessary to obtain seismic, geological, and well logging data in the target area.

[0019] S200: Compare and determine the wells where phase change occurs among the completed wells.

[0020] Based on the method of the present invention, preferably, in S200 , the velocity conversion interface of the AC acoustic wave curve is used as a marker layer to compare the wells where phase change occurs.

[0021] Stratigraphic correlation in areas with rapid lithologic changes is particularly challenging. Traditional methods using lithologic interfaces as markers cannot effectively identify phase-change wells. This invention changes the traditional method of using "lithologic interfaces" as marker layers and instead identifies the AC acoustic wave "velocity conversion interface" marker layer, accurately identifying wells experiencing phase change.

[0022] S300: Based on the results of S200, the lithology of the well is analyzed and cluster analysis is performed to predict the distribution characteristics of different lithology areas under well control conditions; the reservoir formation factor analysis is performed to clarify the area where the favorable sand body is located.

[0023] Based on the method of the present invention, preferably, in S300, the cluster analysis is performed using the similarity of well logging curves of the same lithology.

[0024] Based on the method of the present invention, preferably, S300 specifically includes: performing comparative analysis on the lithology and oil content of completed wells, performing cluster analysis using the similarity of well logging curves of the same lithology, clarifying the different lithology areas in the target area, and predicting the distribution characteristics of the different lithology areas under well control conditions; performing reservoir formation factor analysis to clarify the regional scope of the favorable sand body.

[0025] Based on the method of the present invention, preferably, the different lithologic zones include one or more of interlayer development zones, mudstone development zones, and dry layer development zones.

[0026] Based on the method of the present invention, preferably, the favorable sand bodies are distributed in the interlayer development zone; the mudstone development zone is a lithologic pinch-out zone, and the dry layer development zone is a physical property change zone.

[0027] S400, combined with the well-controlled lithology classification in S300, selects characteristic curves that are sensitive to lithology changes in the logging curves to perform waveform indication simulation inversion to predict and identify the distribution range of lithologic subtle oil and gas reservoirs.

[0028] In areas with low well control, the distribution of sand bodies between wells and the range of sand bodies controlled by lithology require seismic technology to track and characterize. However, compared with shallow oil reservoirs, ultra-deep oil reservoirs have no obvious low-speed characteristics on the time difference curve due to differential compaction. Wave impedance inversion cannot effectively distinguish sand and mudstone. Its prediction accuracy cannot meet research needs, and high-resolution reservoir prediction technology is urgently needed. The present invention preferably performs waveform indication simulation inversion on characteristic curves that are sensitive to lithological changes, combines the vertical high-resolution advantage of logging curves with the lateral continuity advantage of seismic waveforms, and achieves high-resolution reservoir prediction effects, solving the difficulty that wave impedance inversion cannot effectively distinguish ultra-deep lithology. Finally, the distribution of sand bodies between wells is characterized, the pinch-out position of the sand bodies is determined, and the distribution range of lithologically concealed oil and gas reservoirs is predicted.

[0029] Based on the method of the present invention, preferably, the characteristic curve sensitive to lithologic changes in S400 is a GR curve.

[0030] Based on the method of the present invention, preferably, S400 specifically includes: applying the characteristic curve waveform indication simulation inversion method, using the GR curve to establish an interpolation model for inversion, extracting layer attributes from the inversion data body, and predicting and identifying the distribution range of lithologic concealed oil and gas reservoirs.

[0031] The prediction results of S500 and S400 are combined with the single well oil test, test production data and the analysis results of reservoir formation factors to propose deployable favorable traps or trap zones for the identified ultra-deep lithologic subtle oil and gas reservoirs.

[0032] Based on the method of the present invention, preferably, in S500, the distribution characteristics of different lithologic zones under well control conditions and the distribution range of the lithologic concealed oil and gas reservoirs identified by waveform indication simulation inversion prediction are used to jointly predict the distribution of favorable sandstones in the reservoir, and the single well oil test, test production data and the results of the reservoir formation factor analysis are combined to conduct an overall rolling evaluation of the target area, and the identified ultra-deep lithologic concealed oil and gas reservoirs are proposed to propose deployable favorable closures or closure zones.

[0033] Based on the method of the present invention, preferably, the method further comprises: deploying wells in a deployable favorable trap or trap zone for evaluation and development.

[0034] The method of the present invention establishes the acoustic wave "velocity conversion interface" as a marker layer to accurately compare phase change wells; it solves the difficulty that conventional inversion cannot effectively distinguish ultra-deep lithology; it tracks and characterizes favorable sand bodies and analyzes the accumulation factors of regional ultra-deep lithological hidden oil and gas reservoirs, and proposes favorable closures or closure zones for rolling evaluation and deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a flow chart of the method for identifying ultra-deep lithologic concealed oil and gas reservoirs according to the present invention.

[0036] Figure 2a and Figure 2b This is the well seismic fine calibration map of Well A in the embodiment of the present invention.

[0037] Figure 3a and Figure 3b This is the well seismic fine calibration map of Well B in the embodiment of the present invention.

[0038] Figure 4 Schematic diagram of a fine stratigraphic comparison cross section in an embodiment of the present invention.

[0039] Figure 5 Schematic diagram of the oil reservoir cross section in an embodiment of the present invention.

[0040] Figure 6 Schematic diagram of high-precision reservoir inversion profile in an embodiment of the present invention.

[0041] Figure 7 This is a schematic diagram of the reservoir inversion plane of the development block in an embodiment of the present invention.

[0042] Figure 8 Schematic diagram of reservoir inversion plan in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0044] The TⅢ group in a certain area of ​​an oilfield is an ultra-deep lithologic subtle reservoir with a burial depth of 4800-5000m and a reservoir thickness of 3-8m. To meet the needs of rolling evaluation of the TⅢ reservoir and analysis of reservoir formation factors in this area, a study on identifying ultra-deep lithologic subtle oil and gas reservoirs was conducted, including the following steps:

[0045] S100. Obtain seismic, geological and logging data of the TⅢ group in the area.

[0046] S200: Compare and determine the wells where phase change occurs among the completed wells.

[0047] First, the AC acoustic velocity interface at the top of TⅢ (“velocity conversion interface”) was identified as the marker layer.

[0048] In this embodiment, two wells W1 and W2 are listed as examples for illustration. Other wells actually drilled are not described here. Figure 2a and Figure 2b As shown in Figure 1, the top of TⅢ in Well W1 is a sandstone top, the lithologic interface is consistent with the acoustic velocity interface, and the phase axis is the main wave peak. Figure 3a and Figure 3b As shown, the top of the sandstone in Well W2 is inconsistent with the acoustic velocity interface. The lithologic interface corresponds to the half-amplitude point below the main wave crest, which indicates axis crossover compared to Well W1. A detailed comparison reveals that due to phase change, the top of Well W2 is mudstone instead of sandstone. The ultra-deep AC curve shows no low-velocity response to the phase-change mudstone section. Therefore, the top of TIII in Well W2 should be adjusted to the AC acoustic velocity interface, which is the corresponding marker layer for the TIII lithologic change zone.

[0049] According to the acoustic velocity conversion interface at the top of TⅢ, the top of TⅢ is adjusted to accurately compare the wells where phase change occurs, e.g. Figure 4 Among wells 1-6 on the cross section shown, wells 4 and 6 are the wells where phase change occurred.

[0050] S300: Based on the results of S200, the lithology of the well is analyzed and cluster analysis is performed to predict the distribution characteristics of different lithology areas under well control conditions; the reservoir formation factor analysis is performed to clarify the area where the favorable sand body is located.

[0051] In this embodiment, wells 7 to 13 on a section in the target area are listed for illustration, and other wells are not described in detail.

[0052] Through the comparative analysis of lithology and oil content of wells 7 to 13, Figure 5 ), cluster analysis was performed using the similarity of the same lithologic logging curves, and it was determined that Block TⅢ was mainly divided into interlayer development area, mudstone development area, and dry layer development area. Through cluster analysis of logging curves, the distribution characteristics of different lithologic areas under well control conditions were predicted (such as Figure 6(As shown). Interlayer-developed areas can seal bottom water, creating conditions for oil and gas accumulation and favoring the formation of lithologic traps. Mudstone-developed areas are lithologic pinch-out zones, while dry-bed-developed areas are zones of physical property variation. Analysis shows that favorable sand bodies are distributed in interlayer-developed areas.

[0053] S400, conduct high-resolution reservoir inversion on ultra-deep lithologic reservoirs to predict the distribution of interlayer development zones where favorable sand bodies are located. Due to the large burial depth of the reservoir and the influence of differential compaction, the mudstone has no obvious low-speed reflection, and conventional wave impedance inversion cannot effectively distinguish the sand bodies. Apply the characteristic curve waveform indication simulation inversion method, and select the GR curve sensitive to lithology to establish an interpolation model, and simulate and invert the reservoir sand bodies controlled by the lithology of the TⅢ group, effectively improving the resolution, and predicting the thickness changes between wells and the pinch-out of the sand bodies, such as Figure 6 The inversion results shown are basically consistent with those of the completed wells (such as Well C and Well D). The layer attributes are extracted from the inversion data volume, and the range of the interlayer development area, lithologic pinch-out area (mudstone development area), and physical property change area (dry layer development area) in the development block are effectively predicted on the plane. Figure 7 High-resolution reservoir inversion technology combined with complete drilling data has achieved the effect of predicting and identifying ultra-deep lithologic oil and gas reservoirs. Figure 6-Figure 8 All of them are part of the inversion prediction results. Figure 6 This is a cross-sectional view of the plane where wells C and D are drilled. Figure 7 and Figure 8 is a plan view, where Figure 7 yes Figure 8 Part of it.

[0054] S500, using the results of regional reservoir prediction for ultra-deep rolling evaluation, combined with single well oil test, test production data and reservoir formation condition analysis results, proposed favorable zones for deployment of lithologic reservoirs identified in the well control low area in the southern part of well area A and well area B. Figure 8 As shown in the figure, two vertical wells were deployed in the well-free zone in the southern part of the region in the northeast, and the oil layers encountered were more than 5m deep, with good implementation effect. This shows that the method of the present invention can accurately predict the distribution range of favorable lithology and effectively identify ultra-deep lithologic concealed oil and gas reservoirs.

[0055] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for identifying ultra-deep lithologic hidden oil and gas reservoirs, characterized in that: The method comprises the following steps: S100, obtaining seismic, geological and well logging data of the target area; S200: In the completed well, the velocity conversion interface of the AC acoustic wave curve is used as the marker layer to compare the wells where phase change occurs; S300, based on the results of S200, conducts comparative analysis of lithology and oil content of completed wells, and uses cluster analysis based on the similarity of well logging curves of the same lithology to identify different lithologic zones in the target area and predict the distribution characteristics of different lithologic zones under well control conditions; conducts reservoir formation factor analysis to identify the area where favorable sand bodies are located; The different lithologic zones include one or more of the interlayer development zone, mudstone development zone, and dry layer development zone; the favorable sand bodies are distributed in the interlayer development zone; the mudstone development zone is a lithologic pinch-out zone, and the dry layer development zone is a physical property change zone; S400, combined with the well-controlled lithology classification in S300, selects the GR curve that is sensitive to lithology changes in the logging curve to perform waveform indication simulation inversion to predict and identify the distribution range of lithologic subtle oil and gas reservoirs; specifically includes: Applying the characteristic curve waveform indication simulation inversion method, the GR curve is used to establish an interpolation model for inversion, extracting layer attributes from the inversion data volume, and predicting and identifying the distribution range of lithologic subtle oil and gas reservoirs; The prediction results of S500 and S400 are combined with the single well oil test, test production data and the analysis results of reservoir formation factors to propose deployable favorable traps or trap zones for the identified ultra-deep lithologic subtle oil and gas reservoirs.

2. The method for identifying ultra-deep lithologic hidden oil and gas reservoirs according to claim 1, characterized in that: S500 uses the distribution characteristics of different lithologic zones under well control conditions and waveform indication simulation inversion to predict the distribution range of identified lithologic subtle oil and gas reservoirs, and jointly predicts the distribution of favorable sandstones in the reservoir. Combined with single well oil testing and production test data and the results of reservoir formation factor analysis, an overall rolling evaluation of the target area is conducted, and favorable traps or trap zones that can be deployed are proposed for the identified ultra-deep lithologic subtle oil and gas reservoirs.

3. The method for identifying ultra-deep lithologic hidden oil and gas reservoirs according to claim 1, characterized in that: The method further includes: deploying wells in the deployable favorable trap or trap zone for evaluation and development.

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