Wenzhi Zhao, Hongliu Zeng, Zhaohui Xu, Suyun Hu, Qilong Fu
{"title":"宽阔低隆起碳酸盐岩平台的地震沉积学:中国四川盆地磨西-高石梯地区寒武纪龙王庙地层","authors":"Wenzhi Zhao, Hongliu Zeng, Zhaohui Xu, Suyun Hu, Qilong Fu","doi":"10.1306/02242318016","DOIUrl":null,"url":null,"abstract":"Broad, low-relief carbonate platforms are commonly relatively flat lying and show minimal topographic relief. These characteristics make the platforms difficult to interpret using seismic data. To systematically analyze these platforms for reservoirs, a seismic-sedimentological workflow was implemented to investigate the paleogeomorphology and reservoir quality of the Cambrian Longwangmiao Formation (LWM) in the Moxi–Gaoshiti area of the Sichuan Basin, China.Conventional core and wire-line log data indicate that carbonate lithofacies are composed of completely dolomitized grainstones, packstones, and wackestones to mudstones. Associated depositional environments were interpreted as shoal complex (shoal crest, shoal margin, and intershoal), lagoon, and deep shelf. The low (4%–8%) porosity reservoirs are largely related to the shoal complex facies. Two third-order sequences were correlated throughout the field area, each demonstrating an upward-shallowing trend. The reservoir-quality rocks were formed in the highstand systems tracts of the sequences.Lacking diagnostic shallow-water indicative seismic facies (e.g., the topset of clinoforms), seismic paleogeomorphology was assessed by restoring the paleostructure at the top of the LWM and then evaluating the gross thickness of the LWM to establish the accumulation rate of sediments across the area. This approach demonstrated a fair correlation to measured reservoir-thickness data from wire-line logs, indicating that the paleogeomorphology and depositional facies were largely controlled by a syndepositional, en echelon fault system that determined the distribution of shallow-water shoal complexes and deeper shelf areas across the field area. Seismic lithology determination by amplitude analysis of multiple frequency panels provided a quantitative assessment of reservoir distribution, supplementing the qualitative paleogeomorphologic maps for field development and reservoir modeling.","PeriodicalId":7124,"journal":{"name":"AAPG Bulletin","volume":"45 8 1","pages":""},"PeriodicalIF":2.7000,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Seismic sedimentology of a broad, low-relief carbonate platform: The Cambrian Longwangmiao Formation, Moxi–Gaoshiti area, Sichuan Basin, China\",\"authors\":\"Wenzhi Zhao, Hongliu Zeng, Zhaohui Xu, Suyun Hu, Qilong Fu\",\"doi\":\"10.1306/02242318016\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Broad, low-relief carbonate platforms are commonly relatively flat lying and show minimal topographic relief. These characteristics make the platforms difficult to interpret using seismic data. To systematically analyze these platforms for reservoirs, a seismic-sedimentological workflow was implemented to investigate the paleogeomorphology and reservoir quality of the Cambrian Longwangmiao Formation (LWM) in the Moxi–Gaoshiti area of the Sichuan Basin, China.Conventional core and wire-line log data indicate that carbonate lithofacies are composed of completely dolomitized grainstones, packstones, and wackestones to mudstones. Associated depositional environments were interpreted as shoal complex (shoal crest, shoal margin, and intershoal), lagoon, and deep shelf. The low (4%–8%) porosity reservoirs are largely related to the shoal complex facies. Two third-order sequences were correlated throughout the field area, each demonstrating an upward-shallowing trend. The reservoir-quality rocks were formed in the highstand systems tracts of the sequences.Lacking diagnostic shallow-water indicative seismic facies (e.g., the topset of clinoforms), seismic paleogeomorphology was assessed by restoring the paleostructure at the top of the LWM and then evaluating the gross thickness of the LWM to establish the accumulation rate of sediments across the area. This approach demonstrated a fair correlation to measured reservoir-thickness data from wire-line logs, indicating that the paleogeomorphology and depositional facies were largely controlled by a syndepositional, en echelon fault system that determined the distribution of shallow-water shoal complexes and deeper shelf areas across the field area. 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Seismic sedimentology of a broad, low-relief carbonate platform: The Cambrian Longwangmiao Formation, Moxi–Gaoshiti area, Sichuan Basin, China
Broad, low-relief carbonate platforms are commonly relatively flat lying and show minimal topographic relief. These characteristics make the platforms difficult to interpret using seismic data. To systematically analyze these platforms for reservoirs, a seismic-sedimentological workflow was implemented to investigate the paleogeomorphology and reservoir quality of the Cambrian Longwangmiao Formation (LWM) in the Moxi–Gaoshiti area of the Sichuan Basin, China.Conventional core and wire-line log data indicate that carbonate lithofacies are composed of completely dolomitized grainstones, packstones, and wackestones to mudstones. Associated depositional environments were interpreted as shoal complex (shoal crest, shoal margin, and intershoal), lagoon, and deep shelf. The low (4%–8%) porosity reservoirs are largely related to the shoal complex facies. Two third-order sequences were correlated throughout the field area, each demonstrating an upward-shallowing trend. The reservoir-quality rocks were formed in the highstand systems tracts of the sequences.Lacking diagnostic shallow-water indicative seismic facies (e.g., the topset of clinoforms), seismic paleogeomorphology was assessed by restoring the paleostructure at the top of the LWM and then evaluating the gross thickness of the LWM to establish the accumulation rate of sediments across the area. This approach demonstrated a fair correlation to measured reservoir-thickness data from wire-line logs, indicating that the paleogeomorphology and depositional facies were largely controlled by a syndepositional, en echelon fault system that determined the distribution of shallow-water shoal complexes and deeper shelf areas across the field area. Seismic lithology determination by amplitude analysis of multiple frequency panels provided a quantitative assessment of reservoir distribution, supplementing the qualitative paleogeomorphologic maps for field development and reservoir modeling.
期刊介绍:
While the 21st-century AAPG Bulletin has undergone some changes since 1917, enlarging to 8 ½ x 11” size to incorporate more material and being published digitally as well as in print, it continues to adhere to the primary purpose of the organization, which is to advance the science of geology especially as it relates to petroleum, natural gas, other subsurface fluids, and mineral resources.
Delivered digitally or in print monthly to each AAPG Member as a part of membership dues, the AAPG Bulletin is one of the most respected, peer-reviewed technical journals in existence, with recent issues containing papers focused on such topics as the Middle East, channel detection, China, permeability, subseismic fault prediction, the U.S., and Africa.