New insight into oil and gas exploration in Miocene and Late Oligocene strata in Qiongdongnan basin

Abstract

Oil and gas exploration prospect for the Miocene and Late Oligocene strata in Qiongdongnan (琼东南) basin are evaluated. The structural-sedimentary and reservoir characteristics are discussed and helpful conclusions are drawn. It was proved that there are mainly two reservoir and capping assemblages in Qiongdongnan basin by drilled wells, i.e., one assemblage of the second and the third members of Lingshui (陵水) Formation, upper Sanya (三亚) and Meishan (梅山) formations. According to hydrocarbon evaluation from burial history and well data, all source rocks in Yacheng (崖城)and Lingshui formations have reached the mature-overmature stage. High temperature and overpressure provide dynamic conditions for oil and gas migration, while the long-term activity of basin controlling faults is adverse to their accumulation in upheaved areas. However, because the secondary faults in the basin ceased their activities at the end of the Sanya Period, and the Sanya Formation was later covered by the regional overlying layer of the Meishan Formation, the blocks and low uplifts near the secondary faults were favorable for oil and gas accumulation. Furthermore, as another important pointed area for gas migration, the highest position of a structural ridge should reasonably be a range that is covered by marine mudstone or sandy mudstone during the whole subsiding period, and therefore, the reservoir bed should not be in that position but at its inferior eminence or adjacent slope zone. Therefore, we can draw a conclusion that the inferior low uplifts and structural ridges rather than the upheavals or the top of a structural ridge, probably, have huge reservoirs, and should be chief exploration targets in the Qiongdongnan basin.

Research on Evaluation of the Carbon Dioxide Sequestration Potential in Saline Aquifers in the Qiongdongnan–Yinggehai Basin

“…The estimated potential at the basin level is 2615 billion tons, while the projected potential at the zone level amounts to 2348 billion tons. The basin is generally in the early stages of natural gas reservoir development [41,42]. As of 2021, there are 84 wells in the basin, with significant variations in water depth, short transportation distances, and locally comprehensive engineering data.…”

Source-to-sink system and sedimentary characteristics of the lower Miocene submarine fans in the eastern deepwater area of the Qiongdongnan Basin, northern South China Sea

“…The tectonic evolution of the Qiongdongnan Basin has been affected by the Pacific-Philippine Sea plate, India-Eurasia plate, South China Sea expansion, and Red River Fault and regional tectonic events that have occurred around Taiwan (Xie Y. H. et al, 2008;Yu et al, 2009;Su et al, 2012;Huang et al, 2014;Xie, 2014;Wang D. W. et al, 2015;Hui et al, 2016). The Tibetan Plateau uplift event led to development of largescale sedimentation and subsidence in the Ledong and Lingshui Sags during the neotectonic period because it is close to the Red River Fault Zone.…”