Reservoir Organic Geochemical Description-An Example from Carboniferous Reserviors on the Tazhong 4 Structure in the Tarim Basin

Key words: 
• reservoir geochemistry /
• reservoir description of organic geochemistry /
• filling history

Abstract: Using the thin layer chromatoraphy /flame ioniertion detector( TLC-FID) coupled with the oil showanaly zer(OSA),the Carboniferous cores from three wells on the Tazhong 4 structure were densely cal-lected and analy sed(about 3 /m),while typical oil samples selected were analysed by GC GC/MS and cardonisotope analysis. The study indicated that thegross composition of residual oils exists an obviousheterogeneities either vertically or laterally. The C group can be divided into three layers CⅢ₁(oillay er)CⅢ₂,CⅢ₃(oil-water lay ers)·It was considered that local layers with high oil saturation within CⅢ₂,CⅢ₃ are of value to test oil and that the primary petroleum reservoir could be destroyed by the Himalayanmovement and petroleum of CⅢ₃ was redistributed again from west to east. then the petroleum of CⅢ₂flowed out along the fault and the oil-water system which has two palaeo-oil-water contacts was formed.According to the lateral maturity variation, it was considered that the filling direction of the main oilsource from the Lower Palaeo zoi c is tentatively from west-north to east-sorth. But data of chromatographic analysis and the valueof carbon isotopes of oils suggested that another type of oil from asubsidiarysou rcein the Upper Palaeozoic fill in the structural high 1on the TZ4 stmcture.