厄瓜多尔奥连特盆地白垩系M1油藏沉积储层新认识

在14、17区块古地貌东高西低的区域性认识基础上,根据砂岩厚度分布规律、构造反演、岩心以及录井中高岭石的相对含量,确定了古地貌特征,指出在H油田存在南北向古海岛。结合沉积模式,描述了M1层沉积微相展布。结果表明:H油田位于泥坪和混合坪亚相,N油田位于砂坪亚相和潮道发育区,K—S油田位于潮下带,W油田为潮控三角洲沉积。并对沉积相控制的储层特征和含油性特征进行了分析,指出有利储层为潮道和砂坪砂岩,为中高孔特高渗储层,此类储层分布在目前构造的斜坡部位;混合坪和泥坪中储层分布局限,易形成差油层或干层,此类储层分布在目前构造顶部。由于构造和储层的特殊匹配关系,形成构造岩性复合油藏。

New understanding of sedimentation and reservoir characteristics of M1zone in Cretaceous strata of Oriente Basin,Ecuador

The paleo-geomorphology of Block 14and 17which is high in the east and low in the west in the region is further characterized and an N-S trend paleo-barrier island is identified in H oilfield according to sand thickness,structural inversion,core and kaolinite content in drilled wells.The sedimentary microfacies of M1are described under the guidance of sedimentary model.The results show that H oilfield is mud flat and mixed flat,N oilfield is sand flat and tidal channel,K-S oilfield is located in sub-tidal zone while W oilfield deposits tidal-dominated delta sediments.The analysis of reservoir and oil-bearing characteristics controlled by microfacies indicates that tidal channel and sand flat sandstones are favorable reservoirs with mid-high porosity and extra-high permeability,mainly distributing in the slope.Meanwhile,reservoirs in mixed flat and mud flat with thin sandstone and limited distribution are poor oil layers or dry layers on the top of the structure.Therefore,structural-lithological oil reservoirs are formed due to the special matching relationship between both structure and reservoir.