中国海相碳酸盐岩油气储层基本特征

中国在碳酸盐岩油气勘探中相继发现了陕中气田、轮南—塔河油田、塔中油气田、川东北大气区等大型油气田。这些发现揭示了非均质性强的碳酸盐岩储层,主要有4种类型:台缘生物礁(滩)、岩溶风化壳、白云岩和台内颗粒滩四大类储层。中国的台缘礁滩储层主要有两类,一类是面积小的孤立状的塔礁(川东和川东北),另一类是连片分布似层状的台缘礁滩复合体。岩溶风化壳储层依岩溶成熟度和构造型式有三种,即克拉通内岩溶老年期的低幅度地貌层状白云岩储层,岩溶壮年期的高幅度地貌非均质裂缝-洞穴单元储层,以及断块掀斜翘倾的岩溶青年期独立岩溶储层。有油气前景的白云岩储层主要为三类:与蒸发台地相关的准同生白云岩,埋藏成岩作用白云岩和生物成因白云岩。台内颗粒滩主要有两类:即白云石化颗粒滩和裂缝性颗粒滩储层。中国的碳酸盐岩分布广,达300km2,四大类储层发育良好,除已发现油气的四大盆地外,相信不久的将来在中国南方和羌塘地区古特提斯域碳酸盐岩沉积区将取得大的突破。

Characteristics of marine carbonate hydrocarbon reservoirs in China. Earth Science

Great breakthroughs have been made in China's carbonate exploration for oil and gas in recent years with the discoveries of such large-scale oil and gas fields as Shanzhong gas field,Lunnan-Tahe oil field,Tazhong oil and gas field and Northeast Sichuan gas province and so on.These discoveries show that there are mainly four types of highly heterogeneous carbonate reservoirs including reef(bank)on the platform margin,karst,dolomite,and intra-platform grain bank.Firstly,there are mainly two types of organic reef-bank reservoirs on the platform margin in China including small-scale isolated pinnacle reefs(eastern Sichuan and northeastern Sichuan)and widespread semi-laminar reef-bank complex on the platform margin.Secondly,the karst weathered-crust reservoirs consist of three types in terms of the maturation and structural style,namely intra-craton layered dolomite reservoir in the late stage of the karst with gentle topography,heterogeneous fracture-cave reservoir in the prime of the karst with sharp topography,and the independent junior karst reservoir featured by tilting blocks.Thirdly,dolomite reservoirs with hydrocarbon potential are mainly classified into three types including penecontemporaneous dolomite associated with evaporating platforms,burial dolomite and biological dolomite.Fourthly,the intra-platform grain bank includes dolomitized grain bank reservoir and fractured grain bank reservoir.Carbonate is widespread in China with coverage of 300 km2 and four types of reservoirs well developed.It is believed that there will be a great breakthrough in the near future in the South and ancient Tethys in the Qiangtang area,where the carbonate deposited,apart from the four major basins already found.