白云凹陷珠海组成岩作用定量表征

Quantitative Characterization of Diagenesis in Zhuhai Formation in Baiyun Sag

成岩作用是储集层发育和形成的必经过程,最终决定储集层的优劣。为满足勘探需要,降低勘探风险,需要正确且全面地认识勘探区成岩作用对储层的影响。以白云凹陷珠海组储层为例,选择成岩综合系数法,以便能较直观地体现成岩作用强度及成岩作用对储层发育带来的影响。但需要进行时间上的校正,在同一时间尺度下计算相关参数。研究区成岩作用主要为颗粒线-凹凸接触,碳酸盐岩类胶结物以及长石溶蚀表现出的压实作用、胶结作用及溶蚀作用,基本以强压实作用为主,储层物性受到的影响较大。研究区成岩相大致可分为致密砂岩强压实相、致密砂岩中压实相、致密砂岩铁白云石胶结相及致密砂岩方解石胶结相,偶有出现致密砂岩杂基充填相。其中因强压实作用而形成的致密砂岩强压实相在研究区大面积分布,是研究区最主要的成岩相,是珠海组储层低孔低渗的主要原因。

Diagenesis is a necessary process for the development and formation of reservoirs,and ultimately determines the quality of reservoirs.In order to meet the needs of exploration and reduce the risk of it,it is to correctly and comprehensively understand the influence of diagenesis on the reservoirs in the exploration area.Zhuhai Formation reservoirs in Baiyun Sag are studied as a case.The comprehensive diagenetic coefficient method is chosen to reflect the intensity of diagenesis and the influence of diagenesis on reservoir develop-ment more intuitively.However,the correction is required to calculate relevant parameters on the same time scale.The diagenesis in the study area is mainly grainline-concave-convex contact,compaction,cementation and dissolution of carbonate rock-type cement and feldspar dissolution dominated by strong compaction,which makes great influence on physical properties of the reservoirs.The diagenetic facies in the study area can be roughly divided into strong compaction facies,moderate compaction facies,ankerite cement facies and calcite cement facies of the tight sandstones and matrix filling facies of the tight sandstones occasionally appeared.A-mong them,the strong compaction facies of the tight sandstone formed by strong compaction distributes in a large area in the study area,which is the most important diagenetic facies in the study area and the main reason for the low porosity and low permeability of Zhuhai Formation reservoirs.