New Constraints for Petroleum Accumulation Models in the Marine Carbonate Strata and Implications for Frontier Petroleum Exploration in China

Jin, Zhijun

This presentation provides new constraints for geological models of three giant petroleum accumulations in the marine carbonate strata in China, including the Tahe oilfield in the Tarim, Puguang sour gas field in the Sichuan, and Jingbian gas field in the Ordos Basin. It becomes increasingly clear that high-quality marine source rocks are often associated with siliceous or calcareous shales deposited in continental shelf and slope environments. Prolific oil and gas reservoirs are controlled primary depositional environments, burial diagenesis, structural deformations, and deep sourced hot fluids. The presence of thick evaporates appears essential for the formation of large- and medium-sized oil and gas fields in the marine carbonate sequences, particular in the Lower Paleozoic. Evaluation of available geological and geophysical data indicates close association of major oil and gas accumulations with shelf-slope facies and structural hinge zones. The Tahe-Lunnan oil field in the Tarim Basin, for example, is favorably situated in the slope and structural hinge zone, where petroleum has been charged in several pulses from multiple source beds. Therefore, we propose a petroleum exploration concept, that emphasizes source-seal coupling and targets slope-structural hinge zones, for the marine carbonate sequences in China. This concept has been proven highly successful by the recent Yubei 1 discovery in the Bachu region, southwestern Tarim Basin,. Based on the same exploration scenario, future exploration activities in the Chinese marine carbonate sequences should be focused on stratigraphic successions overlain by the Cambrian evaporates in the Tarim and southwestern Sichuan Basin, reef flat zone underneath the Lower Triassic evaporates in the Daba foreland region in the Sichuan Basin, as well as slope and structural hinge zone in the western and southern Ordos Basin.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013