准噶尔西北缘中拐凸起石炭系油气地质特征及勘探潜力

Petro-gas Geology Characteristics and Exploration Potential of Zhongguai Uplift in Northwestern Margin of Junggar Basin

针对中拐凸起石炭系裂缝受控因素不明确、圈闭落实难度大、总体勘探程度较低的现状,展开对该地区石油地质特征、油气成藏条件、油气勘探潜力的精细研究。分析认为:中拐凸起经历了一个完整的构造旋回,构造运动较为稳定,具有有利的油气成藏背景。石炭系烃源岩主要为二叠系佳木河组的暗色泥岩和沉凝灰岩,生烃条件优越;火山角砾岩和安山岩孔渗性较好,具有优良的储集性;并具有裂缝-孔隙双重介质的特点。发育上乌尔禾组区域性泥岩盖层和佳木河组局部泥岩盖层,储盖组合较好。在多期构造运动下形成了构造圈闭以及不整合形成的古潜山型、地层剥蚀型、地层超覆型等圈闭,具有良好的油气成藏条件。研究区内断裂、裂缝、不整合十分发育,为油气垂向运移和横向运移提供了很好的通道,油气勘探潜力巨大。研究对进一步的储层综合研究、勘探方向的确定及剩余油挖潜具有指导意义。

According to the phenomenon of uncertainty in fractures controlled factors, difficulty in delineating structural traps and low exploration degree, main geological characteristic of oil, accumulation condition of oil gas, exploration potential of oil gas at Zhongguai uplift is shown. It is indicated that Zhongguai Uplift experienced a com- plete tectonic spinning; the tectonic movement is fairly stable and has the beneficial accumulation condition of oil gas. The hydrocarbon source rocks in carboniferous are mainly dark peat and tuffite of Plj, holding good hydrocar- bon generating conditions. The Porosity and permeability of brecciated lava and andesite are better among the vol- canic rocks, with good reservoir characteristics and the fracture-pore dual media characteristics. Development of re- gional shale cap-rock of P3w and local mudstone cap-rock of Plj, the combination of reservoir and cap-rock is much better. In multi-stage tectonic movements, it has formed structural traps, and because of unconformity, it has formed buried hills traps, eroded strata traps, stratigraphic overlap traps. It has the favorable condition of petrole- um formed. In the study area, faults, fractures and unconformity are extremely developed, and it provides good conditions for the vertical migration and lateral migration of oil and gas, provided with a huge exploration potentiali- ty. Guiding significance is provided for comprehensive reservoir interpretation, determination of exploration direc- tion and remaining oil redevelopment.