Paleogeomorphic features and sedimentary facies model of Jurassic strata in Chaoshan sub-basin, northern South China Sea

The Mesozoic strata in the Chaoshan sub-basin of northern South China Sea have rich oil and gas resources. Seismic data and well logging data were used in combination with fine stratigraphic division and denudation calculation to restore paleogeomorphology of the Jurassic sedimentary strata.On the basis of sedimentary facies marker analysis of residual strata, a Jurassic sedimentary model was established. The Jurassic strata suffered denudation alterations at the end of Early Jurassic and Middle Jurassic. Various elements of paleogeomorphology influenced sedimentary system development. Ancient uplift (bulge) indicated the source and direction of sediments. The ancient sea bottom canyon was an important transport passage between source and sedimentation. The slope zone was an important deposition site and had great influence on the quality and size of reservoirs, thus restricting the accommodation space of the basin. The basin bottom (depression) topography controlled the morphology and occurrence of sediments and influenced the quality and size of source rocks. Effective combination of all the elements of paleogeomorphology in time and space seems to be the key to accurate determination of the distribution and range of a sedimentary system, and its control of sedimentary reservoirs and source rocks is very obvious. The conclusion has positive significance for the next exploration and favorable reservoir prediction of the Jurassic strata.