The style and hydrocarbon prospects of reefs in the Beikang Basin, southern South China Sea

During the Miocene, there were a number of reefs developed in the Beikang Basin, which constitute potential for hydrocarbon exploration. The high-resolution seismic data and numerous well drilling data have provided an opportunity to understand the evolution of reefs in the study area. Six types of reefs were identified, i.e., point reef, platform-edge reef, block reef, bedded reef, pinnacle reef, and atoll reef, and their development could be divided into four stages. In early Miocene, a few point reefs small in size initiated in this basin and they flourished in the early middle Miocene and mainly developed around the Central Uplift and Eastern Uplift. However, the reefs began to wither in the late middle Miocene in response to a rapid relative sea level rise which was caused by the loading subsidence. Since late Miocene, with the continuous rising of the relative sea level, many reefs formerly developed around the Central Uplift and Eastern Uplift have been submerged and only some atoll reefs have survived around the islands on the Eastern Uplift. Additionally, the numerous reefs which are little influenced by later diagenesis are favorable reservoirs for hydrocarbon exploration. The match relation of regional hydrocarbon rock, dredged system and the distribution of reefs indicates that the west of Central Uplift and the east of Eastern Uplift seem to be the favorable exploration zones for the hydrocarbon exploration of reefs in the Beikang Basin.