马朗凹陷芦草沟组储集层特征及有利储集相带

沉积物来源的多源性是造成三塘湖盆地马朗凹陷芦草沟组岩石类型多样性和复杂性的主要原因。储集岩以碳酸盐岩、凝灰岩（沉凝灰岩）为主,主要发育于芦草沟组中段,并具分区发育的特点。黑墩油区以各种灰岩、碎屑岩为主;马中油区以沉凝灰岩为主;牛圈湖油区以砂质白云岩为主。物性特征总体表现为低孔、特低渗;储集空间的成因类型可划分为三类:裂缝型、裂缝-溶孔型和硅化孔缝型;孔隙结构总体表现为中-差分选、中歪度的小孔微喉特征;孔喉连通性普遍较差,微裂缝起连通、储渗的双重作用。裂缝的发育程度最终决定了储集物性优劣。成岩作用中埋藏溶蚀作用、破裂作用和白云岩化作用是主要的建设性作用,裂缝发育纵向分布与其岩性和厚度有直接关系,泥晶灰岩和沉凝灰岩裂缝最为发育。裂缝横向展布及发育受所处构造部位和褶皱强度的控制。

Reservoir Characteristics and Favorable Sedimentary Facies of Lucaogou Formation in Malang Sag, Santanghu Basin

Lucaogou fo rm ation of Malang sag in Santanghu basin is of variety and complexity of rock type s,which were mainly resulted from multiple sources of sediments supply.The res ervoir rocks are dominated by carbonate and tuff developed in the middle section of Lucaogou formation,and possess characteristics of zoned development of dif ferent lithology.Heidun zone is dominated by limestone and clastic rock;Mazho ng zone by tuffite;Niuquanhu zone by sandy dolomite.The petrophysical property assumes low porosity and extra-low permeability.The reservoir space can be cl assified into three types,i.e.,fracture,fracture-denudation pore and silic eous pore-crack.The porosity structure assumes medium-poor sorting,moderate flexure mini-pore and micro throat with poor pore-throat connectivity and micr o fractures that play parts of connection,storage and percolation in the reserv oir.The reservoir quality depends on how fracture developed in it.The diagenes es such as buried denudation,fractured process and dolomitization are the major positive processes.The vertical fracture development and dis-tribution are r elated to in-situ lithology and bed thickness directly.It is shown that the mo st developed fractures are in the micrite and tufffite.The transversal fracture development and distribution are controlled by in-situ structural location an d fold amplitude or intension.