Research Progress in Marine Oil & Gas Reservoirs of the Tarim Basin:A Review of the Conference on "Complex Oil & Gas Pool Formation,Adjustment and Re-accumulation Mechanism of the Typical Superimposed Basin in the West of China" and Discussion on Hydrocarbon Accumulation of the Tarim Basin

Tarim Basin was a typical superimposed basin with large amount of and gas,and lots of hydrocarbon accumulations have been discovered in recent years.As a result of complex hydrocarbon accumulation and transformation of the basin,the studies on its hydrocarbon accumulation are of great challenge.At present,there are some disputes on its sources,reservoir forming stages and process.To meet the need of present exploration,the conference was held in Lanzhou,July 2009,with the subject of Complex Oil Gas Pool Formation,Adjustment and Re-accumulation Mechanism of the Typical Superimposed Basins in the West of China.In the conference,the scholars have discussed the present research situations and open questions of hydrocarbon accumulation of the Tarim basin,and finally reached the agreements as the following:(1)Correct understanding of and gas source was important for resource assessment,the marine and gas are mainly from the Cambrian and Ordovician source rocks in the Tarim basin,and the mixed source oil was obvious,and the Middle-Upper Ordovician source rocks do a greater contribution to the hydrocarbon accumulation.(2)Hydrocarbon accumulation periods are generally related to those significant structural changes.In the Caledonian,the Cambrian source rocks generated and expulsed a large amount of hydrocarbons;in the early Hercynian,the reservoirs were destructed and the Silurian asphaltic sands were formed because of uplifting and exposing;large amount of was filled into reservoirs in the late Hercynian and natural gas in the late Himalayan.(3)To study dynamically on hydrocarbon accumulation processes,it is necessary to restore the ancient structures of important pool-forming periods,and consider the effect of geological events.Only based on comprehensive analysis of some typical reservoirs,the distribution of oil-gas could be summarized.