Prediction of favorable reservoir in granite weathering-crust buried-hill type—A case study of the Baoyunting area on Pinghu slope

Pinghu slope is the key exploration area of oil and gas in the Xihu Sag, East China Sea basin. With the deepening of exploration and development, buried-hill-typed reservoirs in deep and basement have become an important target. To promote the exploration, the main controlling factors and favorable reservoir distribution of granite weathering-crust buried-hill reservoirs in the Baoyunting area of Pinghu slope were studied comprehensively using various data including logging, seismic, core, and experimental analysis. Results show that the mineral composition provided material bases for the formation of the granite weathering-crust buried-hill–typed reservoir; leaching controlled the formation of dissolution pores; and tectonic activities generated many fractures. These factors improved the physical properties of the reservoir, and jointly controlled the distribution of reservoirs in the buried-hill type. In addition, using paleogeomorphic restoration and ant body attribute extraction, the weathering and dissolution intensity and fracture development degree were predicted, and finally the granite buried hill reservoirs in the Baoyunting oil-gas area was evaluated in overall.