济阳坳陷古近系储层孔隙类型与次生孔隙成因

济阳坳陷包括东营凹陷、惠民凹陷、沾化凹陷和车镇凹陷,充填的古近系碎屑岩储层埋藏经历了早、中成岩阶段,目前大多沉积储层处于中成岩阶段A期。砂岩储层发育原生和次生孔隙,砂岩次生孔隙的形成主要是烃源岩成熟产生的有机酸对长石颗粒和碳酸盐胶结物溶蚀形成的,但在不同凹陷储层溶蚀对象存在差异。如东营凹陷储层次生孔隙的形成主要为碳酸盐胶结物溶蚀成因,长石溶蚀次之;沾化凹陷和惠民凹陷次生孔隙的形成主要为长石溶蚀成因,碳酸盐胶结物溶蚀次之;车镇凹陷储层的上部次生孔隙为长石溶蚀成因,下部为长石和碳酸盐溶蚀成因。济阳坳陷古近系垂向上2个深度段发育次生孔隙,其发育深度自西向东、由南向北加深,发育位置受控于凹陷内生油中心位置,临近生油中心的砂体内次生孔隙发育。储层综合评价表明,不同沉积凹陷的良好储层发育的地区和深度是不同的。东营凹陷北部坡陡带及中央隆起带储层主要为Ⅰ、Ⅱ类好储层,沾化凹陷孤岛、孤东和孤南层序Ⅲ及Ⅳ、Ⅴ(沙河街组沙三段上亚段至东营组东三段)的储层物性较好,车镇凹陷北部陡坡带、南部缓坡带的层序Ⅲ及Ⅳ(沙河街组沙三段上亚段至沙一段)发育良好储层,惠民凹陷中央隆起带和夏口断裂带层序Ⅰ、Ⅱ、Ⅲ(沙河街组沙三段下亚段至沙二段下亚段)发育较好储层。

Pore Types and Secondary Pore Evolution of Paleogene Reservoir in the Jiyang Sag

The Jiyang sag consists of the Huimin depression, Dongyin depression, Zhanhua and Chezhen depression. Clastic rocks of Paleogene went through early and middle diagenetic stages and now the main reservoir is at a period of the middle stage. Primary and secondary pores were developed in sandstone, the secondary pores were generated from the dissolution of feldspar and calcite cement due to the organic acid from the maturated source rock, but the material dissolved was different in different depressions, for example, the secondary pores of the Dongyin depression were generated from the dissolution of calcite cement, the secondary pores in the Zhanhua and Huimin depression from the dissolution of feldspar, the secondary pores in the Chezhen depression from the dissolution of feldspar in upper section and the dissolution of calcite cement in lower section. The secondary pores were developed at two depths and the depth went down from the west to east, from the south to north in the Jiyang sag. The major controlling factors for secondary pore development were the maturity and location of source rock. Lastly, favorable reservoirs were evaluated according to reservoir depth, sedimentation and diagenesis. The reservoir with good quality was located in the northern and central parts in the Dongyin depression, there was some good reservoir in the Goudao, Goudong and Gounan areas in the Zhanhua depression, and favorable reservoirs were located in the northern steep slope and southern gentle slope of the Chezhen depression and central uplift, south gentle slope of the Huimin depression.