黄骅坳陷三马地区中深层储层孔隙发育及主控因素分析

本文根据储集岩样品的显微特征，分析了黄骅坳陷三马地区下第三系中一深部储层中孔隙的成因类型、微观特征及演化规律。研究表明，研究区储层孔隙演化具有明显的阶段性，可划分为原生孔隙、混合孔隙及次生孔隙3个发育带。中一深部储层中原生孔隙所占比例很小，以次生孔隙为主，随埋藏增大，次生孔隙所占比例相应增加。中深部储层中主要分布3个次生孔隙发育带，其深度分别为3200～3500m，3600～4000m，4200～4500m。次生孔隙类型主要为粒间溶孔和粒内溶孔，也可见到铸模孔和微裂缝。导致原始孔隙降低的主要原因为压实和胶结作用，次生孔隙形成机理主要包括长石、方解石的溶解作用和矿物的转化等。本文还讨论了储层岩相、岩性特征、地层水中有机酸浓度的改变、早期方解石的充填、烃类注入、异常高压及微裂缝等地质与地球化学因素对中深部储层成岩作用和次生孔隙形成与分布的控制作用。

Distribution Characteristics of Pores in Medium-Deep Clastic Reservoir Rocks of Sanma Area,Huanghua Depression and Its Controlling Factors

The types, microstructures, distribution and evolutionary characteristics of pores in Paleogene medium-deep clastic reservoir rocks of Sanma area, Huanghua depression, have been discussed in this paper. The result shows that the distribution and evolution of porosity in clastic reservoir rocks vary obviously with the increasing burial depth of the reservoir rock. There exist three evolutionary stages and accordingly the reservoir porosity can be classified into three zones: the zone of primary pores, that of transitional pores and that of secondary pores. The depths of the three zones are shallower than 2 200 m, from 2 200 to 3 400 m and greater than 3 400 respectively. The primary porosity is unimportant in medium-deep reservoir rocks, whereas the secondary pores occupy the main part. There are three secondary pore zones in medium-deep reservoir rocks, with the depth being from 3 200 to 3 500 m, from 3 600 to 4 000 m and from 4 200 to 4 500 m respectively. The secondary pores include mainly intergranular dissolved pores, intra-granular dissolved pores, mould pores and microcracks. The decrease of the primary porosity results mainly from compaction or cementation. The main factors responsible for the development of secondary pores are corrosion of quartz and feldspar or transformation of minerals. This paper also deals with the primary geological and/or geochemical factors controlling diagenesis and pore evolution of reservoir rocks, which include lithofacies, lithology, geochemical charateristics of water in pores (organic acid content), early calcite cementation, early hydrocarbon filling and abnormal high-pressure of fluids in pores.