塔中北斜坡流体复杂区油气富集规律--以中古51井区奥陶系鹰山组为例

Hydrocarbon Accumulation Mechanism of Fluid Complicated Zone in Northern Slope of Tazhong Area,Tarim Basin——An example from the Ordovician Yingshan formation in Zhonggu-51 Wellblock

塔中北斜坡地区鹰山组油气藏具有油气相态多变、油气水分布复杂、无统一油水界面等特征。对横跨塔中Ⅰ号和塔中10号2个次级构造带鹰山组流体分布和性质最为复杂的中古51井区进行了精细解剖。通过原油生物标志化合物对比，以及对沉积、构造、钻井试油等综合研究表明，中古51井区油气富集于距鹰山组顶面30～180m层间岩溶储集层发育带中，以鹰一段下亚段和鹰二段最为有利；油气主要为混源成因，早期油气充注和晚期高成熟天然气沿2条主要走滑断裂气侵，改造早期油藏形成凝析气藏，远离走滑断裂以油藏为主，形成油藏与气藏相间的格局；4条走滑断裂和2排逆冲断裂（塔中10号断裂和塔中Ⅰ号断裂）将中古51井区包围分隔成3个“断块”，“断块”间油气相对封闭，内部呈现低部位含水、高部位富油气的规律。据此，建议研究区下一步钻探以局部“断块”高部位为主。

In recent years, groat success for petroleum exploration of the Ordnvieian Yingshan formatinn in north slope in Tazhong area of Tarim basin has been achieved, and the quasi-layered and large-scale hydrocarbon accumulatinn province has begun to lake shape. The Yingshan karst reservoir is characterized by muhiple phases, complicated oil, gas and water distribution aud nn unique oil-water eontact. This paper presents fine studies of two subsidiary structural zones of Tazhong-I and Tazhong-10, the fluid distribution of Yingshan fnrma- lion and the mosl eomplicaled Zhonggu-51 Wellblnck. The biomarker correlation of the crude oil and the comprehensive analyses of the de- position, structure, drilling and formation testing of Zhonggu-51 Wellblock show that the hydrocarbon accumulation zone is fonnd in the karst reservoir deveelped in 30-180 m apart from the tnp of Yingshan formation, especially al the lower Ying-1 member and the Y ing-2 member, dominated by mixed hydrocarbons in origin; the early charged hydrocarbon and the late high mature gas charging occur along tw. major strike-slip fauhs, making the early oil pool turn into condensate pool, and far apart from the faults appear major oil pools with some gas pools： the Zhnnggu-51 Wellblock is surrounded by four strike-slip faults and two rows of overthrust fauhs （Tazhong-10 and Tazhnng-I faults） and divided into three fault blocks in which water is located in the lower part and oil-gas in the higher part, and relatively sealing of oil and gas among them. Therefore, it is suggested that the next drilling or exploration in this area shouht focus on the higher paris in the fatlt blocks.