惠民凹陷基山砂体沉积特征及成藏条件

基山砂体是惠民凹陷勘探的主力砂体,前景广阔.通过对基山砂体岩性特征、沉积构造特征及岩石结构特征的综合分析,认为基山砂体为一套混合成因的三角洲-沟道-浊积扇沉积体系,纵向上分为4期.基山砂体粒度较细,以细、粉砂岩为主,受沉积和成岩作用的影响.储层总体上具有中孔低渗、非均质性强、次生孔隙发育的特点.在此基础上,分析了基山砂体的成藏要素,结果表明,丰富的油源、良好的储层、有利的运移条件、良好的生储盖组合及多种圈闭类型的成藏条件,有利于油气聚集成藏.指出基山槽西侧盘河背斜带的构造-岩性圈闭和孟寺低隆起附近的岩性圈闭为下一步重点勘探方向.

SEDIMENTARY FEATURES AND RESERVOIR-FORMING CONDITIONS OF JISHAN SAND BODY IN HUIMIN SAG

The Jishan sand body is the main sand body explored in Huimin Sag, the prospect for the exploration of Jishan sand body is broad. The Jishan sand body is found to be a set of delta-channel-turbidity fan sedimentary system by means of analysis of lithologic characteristics, sedimentary structural characteristics and lithologic texture characteristic. The Jishan sand body is divided into four stages vertically. Grain size of the Jishan sand body is fine, and the rock is mainly composed of fine-grained sandstones and siltstones. Influenced by the sedimentation and diagenesis, reservoir properties are of the characteristics of medium porosity, low permeability , strong heterogeneities and well developed secondary pore. On the basis of recognition, reservoir forming factors of Jishan sand body are analyzed, the results show that the such reservoir forming conditions as rich oil source, good reservoir, favorable migration conditions, good assemblage of generation, reservation and capsulation and various trap types, are favorable for hydrocarbon migration and accumulation. Palaeostructural -lithologic traps of Panhe anticlines in the west Jishan trough and lithologic traps of Mengsi low uplift are the targets for further exploration.