Abstract
The Lishui Sag is located in the southeastern part of the Taibei Depression, in the East China Sea basin, where the sag is the major hydrocarbon accumulation zone. A three dimensional modelling approach was used to estimate the mass of petroleum generation and accumulated during the evolution of the basin. Calibration of the model, based on measured maturity (vitrinite reflectance) and borehole temperatures, took into consideration two main periods of erosion events: a late Cretaceous to early Paleocene event, and an Oligocene erosion event. The maturation histories of the main source rock formations were reconstructed and show that the peak maturities have been reached in the west central part of the basin. Our study included source rock analysis, measurement of fluid inclusion homogenization temperatures, and basin history modelling to define the source rock properties, the thermal evolution and hydrocarbon generation history, and possible hydrocarbon accumulation processes in the Lishui Sag. The study found that the main hydrocarbon source for the Lishui Sag are argillaceous source rocks in the Yueguifeng Formation. The hydrocarbon generation period lasted from 58 Ma to 32 Ma. The first period of hydrocarbon accumulation lasted from 51.8 Ma to 32 Ma, and the second period lasted from 23 Ma to the present. The accumulation zones mainly located in the structural high and lithologic-fault screened reservoir filling with the hydrocarbon migrated from the deep sag in the south west direction.
Highlights
The Lishui Sag is one of the main exploration hotspots in the Taipei Depression, in the East ChinaSea Shelf Basin
The accumulation zones mainly located in the structural high and lithologic-fault screened reservoir filling with the hydrocarbon migrated from the deep sag in the south west direction
We constructed a detailed 3D model of the basin with several wells and seismic data to get the inner evolutionary process of the basin, which is the key for petroleum exploration
Summary
The Lishui Sag is one of the main exploration hotspots in the Taipei Depression, in the East ChinaSea Shelf Basin. The Lishui Sag is one of the main exploration hotspots in the Taipei Depression, in the East China. The exploration of the Lishui Sag started in the 1980s and six hydrocarbon-bearing structures were discovered far [1,2]. Among these are WZ13, L35-B, and S1, which are oil-bearing structures, whereas LF1, WZ26 are gas-bearing structures. The hydrocarbon bearing structures proved the superior reservoir conditions and source rock core samples showed rich hydrocarbon generation potential in the Lishui Sag. the LS36-A structure, discovered in 1997, is the only commercial field, with potential geological reserves of around 5 billion m3 of gas. Previous studies show that the LS36-A gas field is a complex trap controlled by the tectonic evolution and the low permeability Lower
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