塔里木盆地玛扎塔格构造带奥陶系岩溶缝洞体发育特征

Characteristics of Ordovician Fracture-Vuggy Carbonate Reservoir in Mazatage Structure Belt,Tarim Basin

塔里木盆地玛扎塔格构造带奥陶系风化壳基质孔渗差,以次生缝洞体储层为主,非均质性强,缝洞体的分布特征对海相碳酸盐岩储层评价具有重要影响。通过岩心观察并结合测井资料分析,认为该区发育多期岩溶与裂缝。岩溶作用影响深度达400m,单井岩溶孔洞层为3～5层,单层厚10～50m。渗流带岩溶孔洞较发育,潜流带岩溶孔洞欠发育,岩溶强度较小,层段内岩溶孔洞断续分布。洞穴规模较小,机械充填严重。通过构造研究与古地貌恢复建立了研究区岩溶发育模式,和田河气田位于岩溶缓坡—洼地区,岩溶洞穴较少且多充填砂泥;而南部大面积风化壳是3期岩溶作用的叠加区,位于汇流溶蚀的岩溶斜坡区,有利于储层的发育与保存,是缝洞型油气藏勘探的有利方向。

The Ordovician weathering carbonate reservoirs with low matrix porosity,permeability and intensive anisotropy are composed mainly by the secondary dissolution pores and holes and fractures.It is important for marine carbonate reservoir to evaluate the fracture-vuggy distribution in the Mazatage structure belt of Tarim basin.We use the cores and logging date to identity the multi-stages kartification and fracturing.The kartification of the Ordovician carbonate is well developed in the area,which affects the depth up to 400m and the dissolution pore-hole layers about 3-5 layers with individual thickness about 10-50m in the wells.The karst is developed in the vadose zone rather than the phreatic zone.The karst intensity is weak,associated with the straggling distribution of pore-vuggy.The cave scale is small and filled seriously.The karst model is proposed based on structure and palaeogeomorphology recovery.The Hetianhe gas field is located in the karst gentle slope and bottomland,so the caverns filled by argillo arenaceous with ineffective exist is observed.The area of southern crust which was superimposed by three stage karstificaition lies in the favorable karst slope.Therefore,the large area of southern crust as a potential exploration is favorable for the development and preservation of fracture-vuggy reservoir.