Hydrocarbon accumulation conditions and exploration potential of deep reservoirs in China

With the development of drilling techniques and oil-gas exploration,deep hydrocarbon exploration has gained more and more attention and may become an important fungible field for rising reserves.Analysis on the data of drilling and oil-gas geology of deep wells over 7 000 m in depth shows that the low limit of depth range for generation of deep hydrocarbon is possibly large,and there still exists the hydrocarbon-generation potential for the high mature source rocks.The low limit of preservation depth for the effective reservoir can shift downward,and the fractured reservoir is predominant.The oil-gas pools mainly include the earlier accumulation-later deep burying pattern,the later accumulation pattern after deeply burying and the multi-stage charging pattern.The earlier accumulation pattern can restrain the shrink of rock porosity during the deep burying process.The fractured reservoir is predominant and more developed near the fault belts,when the burial depth is more than 6 000 m.Faults connected with the deep source rocks are usually the important migration pathways for the later oil accumulation.The hydrocarbon enrichment degree near the fault belts is very high.The multi-stage hydrocarbon charging and strong charging processes can often improve the reserve abundance.The hydrocarbon resource in the strata beyond 7 000 m in depth is of considerable potential in the basins in central and western China.