保持性成岩作用与深部碳酸盐岩储层孔隙的保存

Retention Processes and Porosity Preservation in Deep Carbonate Reservoirs

碳酸盐岩储层中的成岩作用一般被分作"建设性的"和"破坏性的"。但常见的如白云岩化和溶蚀作用并非都一定是建设性的,而胶结作用也并非只具破坏性。将那些使碳酸盐岩储层孔隙(主要是部分原生孔隙和早期次生孔隙)得以保持的成岩作用归为"保持性成岩作用"。保持性成岩作用对深部碳酸盐岩储层的发育至关重要。对典型的礁、滩相碳酸盐岩孔隙的研究表明,早期溶蚀、白云岩化均可在早期成岩阶段形成大量次生孔隙,保持性成岩作用可使部分原生孔隙和早期次生孔隙保存下来,并构成现今深部储层的主要储集空间。从岩石结构、地层压力和地层流体对孔隙的保持或改造3个方面,把碳酸盐岩中的保持性成岩作用分为岩石结构改造型、地层压力改造型和过度胶结抑制型3类。

Diageneses in carbonates have long been classified as constructive or destructive. Nevertheless, dolomitization and dissolution, two so-called constructive diageneses, have not constructed much, if any, po- rosities in some cases; and cementation does not only destruct, but also preserve porosities. Retention processes are defined as the diageneses which help to preserve porosities（mainly part of the primary and early secondary porosities）. Those processes are significant for the formation of carbonate reservoirs. Po- rosities of typical reef and shoal carbonates are determined formed by dissolution and dolomitization in ear- ly diagenetic stages. These porosities can be effectively preserved by retention processes and make great contribution to the present deep reservoirs. Therefore,this view of point will provide new insight into the prediction of deep carbonate reservoirs. Retention processes generally retain mechanical compaction, chemi- cal compaction and over cementation by altering or reconstructing rock textures, reservoir pressures, or pore fluids to inhibit porosity loss. Hence, retention processes are subdivided into three types, namely, rock-texture-reconstructing, formation-pressure-reconstructing, and over-cementation-hindering.