Evaluation method for migration form and distribution position of source fracture cover coupling oil gas to overlying reservoir

Abstract

The invention relates to a method for evaluating migration forms and distribution parts of source-fracture-cap coupling oil and gas to an overlying reservoir, and the method comprises the steps: determining the migration parts of source-fracture coupling different types of source oil and gas by using different types of source oil and gas supply parts and fracture migration parts; determining a fracture cover coupling oil-gas migration form and a distribution part by utilizing the relative thickness of the ancient fracture of the mudstone cover layer; overlapping the two layers to obtain a migration form and a distribution part of the source broken cap coupling oil gas of the research area to the overlying reservoir; according to the method disclosed by the invention, different types of source oil-gas migration parts of source-fault coupling and oil-gas migration forms and distribution parts of fault cover coupling are comprehensively considered, so that the oil-gas distribution parts restricted by oil source fracture in the reservoir above the mudstone cover layer can be accurately reflected, and oil gas of the oil-gas distribution parts can be accurately explored; therefore, effective support is provided for oil and gas discovery and exploration deployment of a ground source broken cover coupling oil and gas reservoir containing an oil and gas basin.

Description

Technical Field

[0001] This disclosure relates to a method for evaluating fractured oil and gas reservoirs in the field of oil and gas exploration, specifically a method for evaluating the migration patterns and distribution locations of source-fault-cap coupled oil and gas to overlying reservoirs. Background Technology

[0002] Continuous exploration of fault-type oil and gas reservoirs has shown that whether oil and gas can accumulate in reservoirs constrained by source faults above mudstone caprocks in oil and gas basins depends not only on other hydrocarbon accumulation conditions, but more importantly on the migration patterns and distribution locations of source-fault-caprock coupled oil and gas into the overlying reservoirs. Only when the migration patterns and distribution locations of source-fault-caprock coupled oil and gas into the overlying reservoirs are favorable can the oil and gas discharged from the underlying source rocks accumulate in the overlying reservoirs, leading to oil and gas discoveries. Therefore, accurately evaluating the migration patterns and distribution locations of source-fault-caprock coupled oil and gas into the overlying reservoirs is crucial for understanding the distribution characteristics of oil and gas in reservoirs constrained by source faults above mudstone caprocks in oil and gas basins and for identifying favorable oil and gas targets.

[0003] There are currently three main methods for studying the favorable locations of source-fault-cap coupled oil and gas migration and accumulation. The first method mainly utilizes the distribution area of ​​mature source rocks and the location of fault migration and accumulation to study the source-fault coupled oil and gas migration location, and takes the overlapping location of the two as the source-fault coupled oil and gas migration and accumulation location (e.g., (1) Li Zhijun, Xiao Yang, Tian Jianzhang, et al., “New Fields and Types of Oil and Gas Exploration Potential and Favorable Directions in the Jizhong Depression of the Bohai Bay Basin” (Acta Petrolei Sinica, Vol. 1, 2025); (2) Liu Huimin, Gao Yang, Qin Feng, et al., “New Fields, Types and Resource Potential of Oil and Gas Exploration in the Jiyang Depression of the Bohai Bay Basin” ( Acta Petrolei Sinica, Vol. 12, 2023. The second method mainly utilizes the relative thickness of the caprock and the fault displacement to study the fault-caprock coupling closure part. The part where the ancient fault retention thickness of the mudstone caprock is greater than the maximum threshold value of the fault retention thickness required for the fault-caprock in the study area is taken as the fault-caprock coupling closure part (e.g., (1) Hu Xinlei, Sanduhaxi Rehati, Liu Yang, et al., “Analysis of the difference in lateral closure of the forward and reverse faults of the Wen'an slope in the Jizhong Depression” (Geological Science, Vol. 4, 2024); 2) Zhi Dongming, Li Jianzhong, Chen Xuan, et al., “New Fields, New Types and Resource Potential of Oil and Gas Exploration in Turpan-Hami Basin” (Acta Petrolei Sinica, No. 3, 2023). The third type is to study the source-fault coupling oil and gas migration sites and the fault-cap coupling sealing sites, and take the overlapping sites of the two as the favorable sites for source-fault-cap coupling oil and gas migration and accumulation (e.g., (1) Fan Jie, Jiang Youlu, Liu Jingdong, et al., “Orderly Distribution of Oil and Gas in Longfengshan Area of ​​Changling Fault Depression in Songliao Basin and Its Main Controlling Factors” (Natural Gas Industry, No. 5, 2018); (2) Fu Guang, Han Xu, “Prediction Method of Oil and Gas Transmission from Fault in Depression Area to Sand Body Transmission and Conversion Site in Slope Area” (Journal of China University of Petroleum (Natural Science Edition), No. 2, 2021).

[0004] The three research methods described above have played a crucial role in clarifying the distribution characteristics of oil and gas constrained by source faults in reservoirs beneath mudstone caprocks in oil-bearing basins with underlying source rocks, and in identifying promising oil and gas exploration targets. However, existing methods only study the migration and accumulation sites of source-fault-caprock coupled oil and gas into overlying reservoirs, without considering the migration sites of different types of source-fault coupled oil and gas, or the migration forms and distribution sites of fault-caprock coupled oil and gas. This fails to accurately reflect the distribution sites of oil and gas constrained by source faults in reservoirs above mudstone caprocks and to precisely explore their oil and gas potential. Therefore, research on evaluation methods for the migration forms and distribution sites of source-fault-caprock coupled oil and gas into overlying reservoirs is of great significance for clarifying the distribution characteristics of oil and gas constrained by source faults in reservoirs above mudstone caprocks in oil-bearing basins with underlying source rocks, and for identifying promising oil and gas exploration targets. Summary of the Invention

[0005] In view of this, this disclosure provides a method for evaluating the migration patterns and distribution locations of source-fault-capped oil and gas to overlying reservoirs, solving the problem that current methods cannot accurately reflect the distribution locations of oil and gas in reservoirs above mudstone caprocks that are constrained by source faults.

[0006] To achieve the aforementioned objectives, the method for evaluating the migration patterns and distribution locations of source-capped oil and gas coupled to overlying reservoirs, as disclosed in this disclosure, includes:

[0007] For the study area, the migration sites of different types of source-supply oil and gas and fault migration sites were determined by utilizing different types of source-fault coupling. The relative thickness of the paleofaults in the mudstone caprock was used to determine the migration patterns and distribution sites of fault-caprock coupling oil and gas. The two were superimposed to obtain the migration patterns and distribution sites of source-fault-caprock coupling oil and gas to the overlying reservoirs in the study area.

[0008] Preferably, the method for determining the source-fracture coupling of different types of source-gas migration sites by utilizing different types of source-supplying oil and gas sites and fracture migration sites includes:

[0009] Identify the fracture migration sites; based on the type of oil and gas supply source to the fracture, obtain the different types of source oil and gas migration sites; superimpose the different types of source oil and gas supply sites and fracture migration sites to determine the source-fracture coupled different types of source oil and gas migration sites.

[0010] Preferably, the method for identifying fracture migration sites includes:

[0011] Based on 3D seismic data, fault displacement is identified, paleofault displacement during hydrocarbon accumulation is calculated, and the paleoactivity rate of faults at different locations is determined by dividing the paleofault displacement by the fault activity time, thus identifying the fault migration sites.

[0012] Preferably, the method for obtaining the migration sites of different types of source oil and gas based on the type of oil and gas supply to the fracture includes:

[0013] Based on drilling data, calculate all oil and gas show wells below the mudstone caprock and above the source rock, and use their distribution area as the external oil and gas supply area;

[0014] Based on drilling, logging and geochemical analysis data, the source rock oil and gas discharge threshold is determined by the relationship between (S1+S2) / TOC and depth, and the source rock oil and gas discharge distribution area is determined by the burial depth of the bottom of the source rock as the source oil and gas supply area;

[0015] By superimposing external oil and gas supply zones and internal oil and gas supply zones, different types of source oil and gas migration sites can be obtained.

[0016] Preferably, the different types of source oil and gas migration sites include:

[0017] Source-disconnected coupling oil and gas migration sites inside and outside the source, source-disconnected coupling oil and gas migration sites outside the source, and source-disconnected coupling oil and gas migration sites inside the source.

[0018] Preferably, the method for determining the migration patterns and distribution locations of fault-capped hydrocarbons by utilizing the relative thicknesses of ancient fault remnants in mudstone caprock includes:

[0019] The locations where the paleo-fault thickness of the mudstone caprock is less than or equal to zero are areas where oil and gas migrate rapidly; the locations where the paleo-fault thickness of the mudstone caprock is greater than zero but less than the maximum threshold required for the mudstone caprock to be damaged by oil source faults in the study area are areas where oil and gas migrate slowly.

[0020] Preferably, the method for determining the paleofault thickness of the mudstone cap layer includes:

[0021] Based on 3D seismic data, the thickness of the mudstone caprock and its internal fault displacement are identified, as well as the paleothickness of the mudstone caprock and its internal fault paleothrust displacement during the hydrocarbon accumulation period. The paleothrust thickness of the mudstone caprock is then reconstructed by subtracting the paleothickness of the mudstone caprock from its original thickness.

[0022] Preferably, the migration patterns and distribution locations of the source-cap coupled oil and gas to the overlying reservoir are as follows:

[0023] The rapid migration patterns and distribution locations of oil and gas from inside and outside the source to the overlying reservoir; the slow migration patterns and distribution locations of oil and gas from inside and outside the source to the overlying reservoir; the rapid migration patterns and distribution locations of oil and gas from outside the source to the overlying reservoir; the slow migration patterns and distribution locations of oil and gas from outside the source to the overlying reservoir; the rapid migration patterns and distribution locations of oil and gas from inside the source to the overlying reservoir; and the slow migration patterns and distribution locations of oil and gas from inside the source to the overlying reservoir.

[0024] Preferably, the evaluation method further includes:

[0025] The rapid migration pattern and distribution of oil and gas from inside and outside the source to the overlying reservoir are evaluated as being conducive to the accumulation and formation of oil and gas above the mudstone cap.

[0026] The slow migration patterns and distribution of oil and gas from inside and outside the source to the overlying reservoir coupled with the source fault cap are evaluated as being more conducive to the accumulation and formation of oil and gas above the mudstone cap.

[0027] The slow migration patterns and distribution of oil and gas from outside the source coupled with the capstone, the rapid migration patterns and distribution of oil and gas from inside the source coupled with the capstone, and the slow migration patterns and distribution of oil and gas from inside the source coupled with the capstone are all considered unfavorable for the accumulation and formation of oil and gas above the mudstone capstone.

[0028] The present invention has the following beneficial effects:

[0029] The method for evaluating the migration patterns and distribution of source-fault-capped oil and gas in overlying reservoirs of this invention comprehensively considers the migration patterns and distribution of oil and gas in different types of source-fault coupling and fault-capped coupling. Therefore, it can accurately reflect the distribution of oil and gas in reservoirs above mudstone caprocks that are constrained by source faults and accurately explore their oil and gas. Thus, it is of great significance for clarifying the oil and gas distribution characteristics in reservoirs above mudstone caprocks in oil and gas basins with underlying source rocks that are constrained by source faults and for exploring favorable oil and gas targets. This provides effective support for the discovery and exploration deployment of oil and gas in source-fault-capped oil and gas reservoirs in oil and gas basins. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0031] Figure 1 This is a diagram illustrating the migration pattern of oil and gas from the source cap coupled with the overlying reservoir.

[0032] Figure 2 This is a flowchart illustrating the evaluation method for the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to embodiments of this disclosure.

[0033] Figure 3 This is a schematic diagram illustrating the determination of the source-disconnected coupling oil and gas migration location in an embodiment of this disclosure;

[0034] Figure 4 This disclosure describes the form and distribution of oil and gas migration via a cap-coupled structure.

[0035] Figure 5 This is a schematic diagram illustrating the determination of the source-cap coupling oil and gas migration pattern and distribution location in an embodiment of this disclosure;

[0036] Figure 6 is a map showing the distribution of oil and gas in the third segment of the eastern section of the Nandagang Fault, which is constrained by the Nandagang Fault in this application example (Figure a: Oil and gas distribution map of the Nandagang Fault and the third segment of the eastern section; Figure b: Seismic profile through the Nandagang Fault).

[0037] Figure 7 This is a publicly available application example of a map showing the location of the migration of the Nandagang Fault within the Shaxia Sub-segment;

[0038] Figure 8 This is a publicly available application example of the relationship between the Nandagang Fault and the internal and external oil and gas supply areas of the Sha-3 Formation;

[0039] Figure 9 This is a map showing the migration patterns and distribution locations of oil and gas coupled to the eastward movement of the mudstone of the Sha-3 section, the Nandagang fault, and the mudstone caprock of the Sha-1 Central Subsection.

[0040] Figure 10 This is a diagram illustrating the coupling of the Nandagang Fault and the mudstone caprock of the Sha-1 Middle Subsection, used in this public application example to determine the migration patterns and distribution locations of oil and gas. Detailed Implementation

[0041] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. Although various aspects of embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise. 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.

[0042] To address the background technical issues, the applicant conducted research on the source-cap coupling oil and gas migration mechanism, such as... Figure 1 As shown, the reason why fracture-capsule coupling oil and gas can migrate is that source-fracture coupling can cause the oil and gas discharged from the source rock to migrate upward along the fracture, fracture-capsule coupling can cause the oil and gas that migrates along the fracture to pass through the caprock, and source-fracture-capsule spatial coupling can cause the oil and gas discharged from the source rock to migrate upward along the fracture through the caprock.

[0043] Based on the aforementioned source-cap coupled hydrocarbon migration mechanism, the technical concept of the source-cap coupled hydrocarbon migration mode and distribution evaluation method for overlying reservoirs designed in this disclosure is as follows:

[0044] For the study area, the migration sites of different types of source-supply oil and gas and fault migration sites were determined by utilizing different types of source-fault coupling. The distribution of fault-capsule coupled oil and gas migration patterns was determined by utilizing the relative thickness of the paleofaults in the mudstone caprock. The two were superimposed to obtain the migration patterns and distribution sites of source-fault-capsule coupled oil and gas to the overlying reservoirs in the study area.

[0045] Based on the above technical concept, the following is a preferred embodiment of the evaluation method for the migration mode and distribution location of oil and gas coupled with cap structure to overlying reservoirs.

[0046] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details.

[0047] Figure 2 This is a flowchart illustrating the evaluation method for the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs, as described in the embodiments of this disclosure. Figure 2 As shown, the method includes the following steps:

[0048] 1. Identify the migration sites of different types of source oil and gas in the source-fracture coupling based on the type of oil and gas supply source to the fracture.

[0049] Combination Figure 3 As shown, based on the different types of oil and gas sources supplying the fracture, the different types of oil and gas migration sites coupled with the fracture are divided into three types: source-fracture coupling sites for oil and gas migration inside and outside the source (…). Figure 3 ①), source disconnection coupling source external oil and gas migration site ( Figure 3 ②) and the oil and gas migration sites within the source coupling source ( Figure 3 ③).

[0050] In this embodiment, the method for identifying different types of source oil and gas migration sites by the source disconnect coupling is as follows:

[0051] Based on drilling data, all oil and gas show wells below the mudstone caprock and above the source rock are calculated, and their distribution areas are used as external oil and gas supply areas. Based on drilling, logging, and geochemical analysis data, the source rock oil and gas discharge threshold is determined by the relationship between (S1+S2) / TOC (where S1+S2 is hydrocarbon generation potential; TOC is total organic carbon content; (S1+S2) / TOC = hydrocarbon production per unit of organic carbon) and depth. The distribution area of ​​source rock oil and gas discharge is determined by the burial depth of the source rock bottom, which is the internal oil and gas supply area. By superimposing the external and internal oil and gas supply areas, the migration locations of different types of source oil and gas are obtained.

[0052] 2. Identify the fracture and migration sites.

[0053] Combination Figure 3 As shown, in this embodiment, the fault displacement is identified based on three-dimensional seismic data. The maximum fault-accumulation subtraction method is applied to calculate the paleo-fault displacement during the hydrocarbon accumulation period. The paleo-activity rate of the fault in different locations is determined by dividing the paleo-activity rate by the fault activity time. The location of the fault migration is identified, that is, the location where the paleo-activity rate of the fault is greater than or equal to the minimum threshold of the activity rate required for the fault to transport hydrocarbons in the study area.

[0054] 3. By superimposing different types of source oil and gas migration sites and fracture migration sites, the source-fracture coupled different types of source oil and gas migration sites can be determined.

[0055] 4. Determine the relative thickness of the ancient fault remnants in the mudstone cap layer.

[0056] Based on 3D seismic data, the thickness of the mudstone caprock and its internal fault displacement are identified, as well as the paleothickness of the mudstone caprock and its internal fault paleodisplacement during the hydrocarbon accumulation period. The paleofault thickness of the mudstone caprock is then reduced by subtracting the latter from the former.

[0057] 5. Identify the location of oil source fractures that damage the mudstone caprock, including the coupling of fracture and caprock oil and gas migration patterns and distribution locations.

[0058] In this embodiment, based on the relative thickness of the ancient fault in the mudstone caprock, the migration patterns and distribution locations of the fault-caprock coupled oil and gas are divided into two types: distribution locations with rapid oil and gas migration and distribution locations with slow migration.

[0059] Combination Figure 4 As shown in this embodiment, the distribution areas where the ancient fault thickness of the mudstone caprock is less than zero are the distribution areas of rapid oil and gas migration. The distribution areas where the ancient fault thickness of the mudstone caprock is greater than zero but less than the maximum fault thickness threshold required for the mudstone caprock to be damaged by the oil source in the study area should be the distribution areas of source-fault coupled oil and gas migration.

[0060] 6. By studying the migration locations of different types of source oil and gas coupled with superimposed source-fracture coupling and the migration forms and distribution locations of source-fracture-cap coupled oil and gas to the overlying reservoir in the study area, the migration forms and distribution locations of source-fracture-cap coupled oil and gas to the overlying reservoir in the study area were obtained.

[0061] Combination Figure 5 As shown, in this embodiment, the migration patterns and distribution locations of source-capped oil and gas coupled to the overlying reservoir are divided into the following six types:

[0062] The first type is the rapid migration mode and distribution location of oil and gas from inside and outside the source to the overlying reservoir through source-cap coupling. Figure 5 ①);

[0063] The second type is the slow migration of oil and gas from inside and outside the source to the overlying reservoir through source-cap coupling, and its distribution location. Figure 5 ②);

[0064] The third type is the rapid migration mode and distribution location of oil and gas from outside the source to the overlying reservoir via source-cap coupling. Figure 5 ③);

[0065] The fourth type is the slow migration of external oil and gas to the overlying reservoir via source-cap coupling and its distribution location. Figure 5 ④);

[0066] The fifth type is the rapid migration mode and distribution location of oil and gas from the source to the overlying reservoir via source-cap coupling. Figure 5 ⑤);

[0067] The sixth type is the slow migration of oil and gas from the source to the overlying reservoir via source-cap coupling and its distribution location. Figure 5 ⑥).

[0068] 7. Evaluate the migration patterns and distribution of source-fault-cap coupled oil and gas to overlying reservoirs in the study area.

[0069] In this embodiment, the first type of rapid migration of oil and gas from inside and outside the source to the overlying reservoir coupled with the source fault cap is evaluated as being conducive to the accumulation and formation of oil and gas above the mudstone cap.

[0070] The second type of source-capped coupling source-external oil and gas slow migration to the overlying reservoir and its distribution location are evaluated as being more conducive to the accumulation and formation of oil and gas on the mudstone cap.

[0071] The third type of source-cap coupled source-external oil and gas rapid migration to overlying reservoirs and its distribution location are evaluated as being more conducive to the accumulation of oil and gas above mudstone caprock.

[0072] The fourth type of source-cap coupled source-external oil and gas slow migration to the overlying reservoir and its distribution location are evaluated as being less favorable for oil and gas to accumulate and form reservoirs above the mudstone cap.

[0073] The fifth type of source-cap coupled source oil and gas rapid migration form and distribution location to the overlying reservoir are evaluated as being less favorable for oil and gas accumulation and formation on the mudstone cap.

[0074] The sixth type of source-fault-cap coupling source-source oil and gas slowly migrates to the overlying reservoir. The distribution of this type of distribution is evaluated as follows: the source rock discharges oil and gas to the fault, which does not supply enough oil and gas. The oil and gas slowly migrates along the fault through the mudstone caprock, which is not conducive to the accumulation of oil and gas on the mudstone caprock.

[0075] The following are application examples of this disclosure.

[0076] Application examples

[0077] This invention uses the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Central Sub-Member in the Qikou Depression of the Bohai Bay Basin as application examples to study and evaluate the migration patterns and distribution locations of oil and gas coupled with the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Central Sub-Member to the east. The results are verified by analyzing the relationship between the research results and the oil and gas in the east of the Sha-3 Member constrained by the Nandagang Fault. This demonstrates the feasibility and effectiveness of the method of this invention in identifying and evaluating the migration patterns and distribution locations of source-fault-caprock coupled oil and gas to the overlying reservoirs, and explains the implementation process of the method of this invention.

[0078] (1) Geological background, faults and oil and gas distribution in the study area.

[0079] The strata revealed by oil and gas drilling in the area where the Nandagang Fault is located, from bottom to top, are Paleogene (Kongshang Formation, Shahejie Formation, Dongying Formation) and Neogene (Guantao Formation, Minghuazhen Formation), with no well-developed Quaternary strata. The Nandagang Fault extends northeastward in the central part of the Qikou Depression, with a length of about 34.3 km. On the cross-section, it extends from the basement upwards to the top of the Minghuazhen Formation. The fault plane dips southeastwards with a relatively small dip angle of 45°~50°, and is a long-developed fault. Figure 6b ).

[0080] Currently, oil and gas have been discovered at the Nandagang Fault, primarily distributed in the lower sub-member of the Shahejie Formation, but oil and gas shows have also been observed in the eastern third member. The oil and gas mainly originate from the dark mudstone developed in the lower Shahejie Formation, the third member of the Shahejie Formation. The source rocks of the third member of the Shahejie Formation and the reservoirs of the eastern third member are separated by the mudstone caprock of the middle sub-member of the Shahejie Formation. The Nandagang Fault, acting as an oil-source fault, transports the oil and gas generated from the underlying source rocks of the third member of the Shahejie Formation to the eastern third member for accumulation. Figure 6a It can be seen that the oil and gas discovered in the eastern section of the Nandagang Fault are mainly found at observation points 2-3, 8, 11-12, and 17-18. This is mainly due to the influence of the migration patterns and distribution locations of oil and gas coupled with the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Central Sub-Member towards the eastern section. Therefore, accurately studying the migration patterns and distribution locations of oil and gas coupled with the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Central Sub-Member towards the eastern section is crucial to clarifying the oil and gas distribution characteristics of the eastern section constrained by the Nandagang Fault and identifying favorable oil and gas exploration targets.

[0081] (2) The migration patterns and distribution of source-fault-cap coupled oil and gas to the overlying reservoir in the study area.

[0082] Based on 3D seismic profiles, the displacement of the Nandagang Fault within the middle segment of the Sha-1 formation was identified. Paleo-faults of the Nandagang Fault within the lower segment of the Sha-1 formation during the middle and late sedimentary stages (hydrocarbon accumulation period) of the Minghuazhen Formation were identified. The paleoactivity rate of the Nandagang Fault within the lower segment of the Sha-1 formation was restored by dividing the fault activity time by the fault activity time. The migration location of the Nandagang Fault within the lower segment of the Sha-1 formation was also determined. Figure 7 ),Depend on Figure 7 It can be seen that, except for observation points 14-15 and 19-20, the Nandagang Fault is a region for oil and gas migration within the Shaxia Sub-segment.

[0083] Based on drilling, logging, and analytical testing data, the oil and gas discharge threshold of the Sha-3 Member source rock in the Qikou Depression is determined to be approximately 3600m. Therefore, based on the burial depth of the Sha-3 Member source rock's base, the oil and gas supply area within the Sha-3 Member source rock in the Nandagang Fault distribution area is mainly distributed in its northeastern part, followed by the southern and central parts. Figure 8 ).

[0084] Based on drilling and well testing data, the external oil and gas supply area of ​​the Sha-3 section in the Nandagang fault distribution area can be delineated. Figure 8 ).Depend on Figure 8As can be seen from the data, the oil and gas supply areas outside the Shahejie Formation are mainly distributed in the northern and central parts and the southern and western parts, with a small number distributed in the southern and eastern border areas.

[0085] By superimposing the migration sites of the Nandagang Fault within the lower segment of the Shahejie Formation and the oil and gas supply areas within and outside the source of the Shahejie Formation, it is possible to identify the different types of source oil and gas migration sites coupled between the source rocks of the Shahejie Formation and the Nandagang Fault. Figure 9 ).Depend on Figure 9 As can be seen from the data, the oil and gas migration sites inside and outside the source rock of the Sha-3 Member and the Nandagang Fault are mainly distributed at observation points 14-17. The oil and gas migration sites outside the source are mainly distributed at observation points 1-6, 7-9 and 9-11, while the oil and gas migration sites inside the source are mainly distributed at observation points 17-19 and 20-21.

[0086] Based on 3D seismic data, the thickness of the mudstone caprock in the middle and late stages of the Sha-1 Central Member and the displacement of the Nandagang Fault within it were identified. The paleothickness of the mudstone caprock in the middle and late stages of the Minghuazhen Formation in the Sha-1 Central Member and the paleothrust of the Nandagang Fault within it were reconstructed. The paleothrust thickness of the mudstone caprock in the Sha-1 Central Member was reconstructed by subtracting the latter from the former. The coupling hydrocarbon migration patterns and distribution locations between the Nandagang Fault and the mudstone caprock in the Sha-1 Central Member were then identified. Figure 10 ).Depend on Figure 10 As can be seen from the data, the rapid migration of oil and gas coupled with the mudstone caprock of the Nandagang Fault and the Sha-1 Middle Subsection is mainly distributed at observation points 4-16, while the slow migration of oil and gas is mainly distributed at observation points 2, 3-4 and 16-17.

[0087] By combining the source rocks of the superimposed Sha-3 Member and the Nandagang Fault, and considering the locations of different types of source oil and gas migrations, as well as the distribution of oil and gas forms coupled with the mudstone caprock of the Nandagang Fault and the Sha-1 Central Member, we can obtain the migration patterns and distribution locations of oil and gas coupled with the source rocks of the Sha-3 Member and the mudstone caprock of the Sha-1 Central Member eastward into the three members. Figure 9 ).Depend on Figure 9 As can be seen from the data, the slow eastward migration of oil and gas from the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Middle Sub-Member is only distributed at observation points 14-17. The rapid eastward migration of oil and gas from the source rocks is mainly distributed at observation points 4-6, 7-8, and 9-11. The slow migration of oil and gas from the source rocks is mainly distributed at observation points 2 and 4. The slow eastward migration of oil and gas from the source rocks is mainly distributed at observation point 17. The rapid eastward migration of oil and gas from both the source rocks and the source rocks is not well developed.

[0088] As shown in Figure 6, the oil and gas in the East Third Member, currently constrained by the Nandagang Fault, are mainly distributed at observation points 2-3, 8, 11-12, and 17-18. These locations are precisely where the source rocks of the Sha-3 Member, the Nandagang Fault, and the mudstone caprock of the Sha-1 Middle Sub-Member are coupled, exhibiting slow migration patterns of oil and gas from both inside and outside the source into the East Third Member, rapid migration patterns of oil and gas from outside the source into the East Third Member, slow migration patterns of oil and gas from outside the source into the East Third Member, and slow migration patterns of oil and gas from inside the source into the East Third Member. This is more conducive to the accumulation and formation of oil and gas from both inside and outside the source of the underlying Sha-3 Member along the Nandagang Fault through the mudstone caprock of the Sha-1 Middle Sub-Member in the East Third Member, which is why oil and gas were discovered during drilling.

[0089] The above examples illustrate the entire process of the method for evaluating the migration patterns and distribution locations of source-fault-cap coupled oil and gas to overlying reservoirs according to the present invention. The evaluation results of the source-fault-cap coupled oil and gas migration patterns and distribution locations to overlying reservoirs can be used for exploration and production of fault-type oil and gas reservoirs, and have the following characteristics:

[0090] (1) By utilizing different types of source-supply oil and gas areas and fault migration locations, the migration locations of different types of source-fault coupled oil and gas were determined. By utilizing the relative thickness of ancient faults in mudstone caprock, the migration forms and distribution locations of source-fault coupled oil and gas were determined. The two were combined to establish a set of evaluation methods for the migration forms and distribution locations of source-fault-caprock coupled oil and gas to overlying reservoirs.

[0091] (2) There are 6 types of migration patterns and distribution locations of source-fault-cap coupled oil and gas to the overlying reservoir, namely, rapid migration pattern and distribution location of source-fault-cap coupled oil and gas inside and outside the source to the overlying reservoir, slow migration pattern and distribution location of source-inside oil and gas to the overlying reservoir, rapid migration pattern and distribution location of source-outside oil and gas to the overlying reservoir, slow migration pattern and distribution location of source-outside oil and gas to the overlying reservoir, rapid migration pattern and distribution location of source-inside oil and gas to the overlying reservoir, and slow migration pattern and distribution location of source-inside oil and gas. The first 3 types are favorable or relatively favorable for oil and gas accumulation and reservoir formation above the mudstone cap, while the latter 3 types are unfavorable for oil and gas accumulation and reservoir formation above the mudstone cap.

[0092] (3) There are four types of eastward migration of oil and gas in the source rocks of the Sha-3 Member, the Nandagang Fault and the mudstone caprock of the Sha-1 Middle Sub-Member in the Qikou Depression of the Bohai Bay Basin. The slow eastward migration of oil and gas from both inside and outside the source is only distributed at observation points 14-17. The rapid eastward migration of oil and gas from outside the source is mainly distributed at observation points 4-6, 7-8 and 9-11. The slow eastward migration of oil and gas from outside the source is mainly distributed at observation points 2 and 4. The slow eastward migration of oil and gas from inside the source is mainly distributed at observation point 17. The observation points 2, 4-6, 7-8, 9-11, and 14-17 show favorable conditions for the accumulation of oil and gas from both inside and outside the source of the lower Sha-3 member in the East 3 member. This is consistent with the current distribution of oil and gas in the East 3 member, which is mainly constrained by the Nandagang Fault, at observation points 2-3, 8, 11-12, and 17-18. This confirms that the method of this invention is feasible and effective for evaluating the migration patterns and distribution of source-fault-cap coupled oil and gas to the overlying reservoir.

[0093] (4) This method is mainly applicable to the study of the migration patterns and distribution of oil and gas from source rocks, extensional normal faults and mudstone caprocks to overlying reservoirs in oil and gas basins with developed lower source rocks.

[0094] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0095] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] The various embodiments of this disclosure 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 evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs, characterized in that, include: For the study area, the migration sites of different types of source-supply oil and gas and fault migration sites were determined by utilizing different types of source-fault coupling. The relative thickness of the paleofaults in the mudstone caprock was used to determine the migration patterns and distribution sites of fault-caprock coupling oil and gas. The two were superimposed to obtain the migration patterns and distribution sites of source-fault-caprock coupling oil and gas to the overlying reservoirs in the study area.

2. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 1, characterized in that, The method for determining the source-fracture coupling of different types of source-gas migration sites by utilizing different types of source-supplying oil and gas sites and fracture migration sites includes: Identify the fracture migration sites; based on the type of oil and gas supply source to the fracture, obtain the different types of source oil and gas migration sites; superimpose the different types of source oil and gas supply sites and fracture migration sites to determine the source-fracture coupled different types of source oil and gas migration sites.

3. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 2, characterized in that, The method for identifying fracture migration sites includes: Based on 3D seismic data, fault displacement is identified, paleofault displacement during hydrocarbon accumulation is calculated, and the paleoactivity rate of faults at different locations is determined by dividing the paleofault displacement by the fault activity time, thus identifying the fault migration sites.

4. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 2, characterized in that, The method for obtaining the migration sites of different types of oil and gas sources based on the type of oil and gas supply to the fracture includes: Based on drilling data, calculate all oil and gas show wells below the mudstone caprock and above the source rock, and use their distribution area as the external oil and gas supply area; Based on drilling, logging and geochemical analysis data, the source rock oil and gas discharge threshold is determined by the relationship between (S1+S2) / TOC and depth, and the source rock oil and gas discharge distribution area is determined by the burial depth of the bottom of the source rock as the source oil and gas supply area; By superimposing external oil and gas supply zones and internal oil and gas supply zones, different types of source oil and gas migration sites can be obtained.

5. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 2, characterized in that, The different types of source oil and gas migration sites include: Source-disconnected coupling oil and gas migration sites inside and outside the source, source-disconnected coupling oil and gas migration sites outside the source, and source-disconnected coupling oil and gas migration sites inside the source.

6. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to any one of claims 1-5, characterized in that, The method for determining the migration patterns and distribution locations of fault-capped hydrocarbons by utilizing the relative thickness of ancient fault remnants in mudstone caprock includes: The locations where the paleo-fault thickness of the mudstone caprock is less than or equal to zero are areas where oil and gas migrate rapidly; the locations where the paleo-fault thickness of the mudstone caprock is greater than zero but less than the maximum threshold required for the mudstone caprock to be damaged by oil source faults in the study area are areas where oil and gas migrate slowly.

7. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 6, characterized in that, The method for determining the paleofault thickness of the mudstone cap layer includes Based on 3D seismic data, the thickness of the mudstone caprock and its internal fault displacement are identified, as well as the paleothickness of the mudstone caprock and its internal fault paleothrust displacement during the hydrocarbon accumulation period. The paleothrust thickness of the mudstone caprock is then reconstructed by subtracting the paleothickness of the mudstone caprock from its original thickness.

8. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 6, characterized in that, The migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs are categorized as follows: The rapid migration patterns and distribution locations of oil and gas from inside and outside the source to the overlying reservoir; the slow migration patterns and distribution locations of oil and gas from inside and outside the source to the overlying reservoir; the rapid migration patterns and distribution locations of oil and gas from outside the source to the overlying reservoir; the slow migration patterns and distribution locations of oil and gas from outside the source to the overlying reservoir; the rapid migration patterns and distribution locations of oil and gas from inside the source to the overlying reservoir; and the slow migration patterns and distribution locations of oil and gas from inside the source to the overlying reservoir.

9. The method for evaluating the migration patterns and distribution locations of source-cap coupled oil and gas to overlying reservoirs according to claim 8, characterized in that, Also includes: The rapid migration pattern and distribution of oil and gas from inside and outside the source to the overlying reservoir are evaluated as being conducive to the accumulation and formation of oil and gas above the mudstone cap. The slow migration patterns and distribution of oil and gas from inside and outside the source to the overlying reservoir coupled with the source fault cap are evaluated as being more conducive to the accumulation and formation of oil and gas above the mudstone cap. The slow migration patterns and distribution of oil and gas from outside the source coupled with the capstone, the rapid migration patterns and distribution of oil and gas from inside the source coupled with the capstone, and the slow migration patterns and distribution of oil and gas from inside the source coupled with the capstone are all considered unfavorable for the accumulation and formation of oil and gas above the mudstone capstone.

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