柴西南地区第三系碎屑岩储集层次生孔隙分布及成因

Distribution and genesis of secondary pores in Tertiary clastic reservoir in Southwestern Qaidam Basin

柴达木盆地西南地区的沉积岩石学研究表明，柴西南碎屑岩储集层的储集空间主要为原生孔隙和次生孔隙。次生孔隙发育在1700-3900m深度范围。在红柳泉和跃进地区发育2个次生孔隙带，绿草滩乌南一弯西地区只有1个次生孔隙带。次生孔隙的成因主要是有机质演化过程中释放的有机酸和CO2形成的酸性水对碳酸盐胶结物、长石和岩屑等塑性物质的溶解。次生孔隙的发育和分布纵向上受控于烃源岩成熟时间，平面上受控于酸性水分布范围，此外还与沉积砂体所处的沉积相带和构造断裂的发育程度有关。

The sedimentological and petrologic researches in the southwestern Qaidam Basin indicate that the reservoir spaces in Tertiary clastic rocks are mainly primary pores and secondary pores. Secondary pores exist from 1700 m to 3900 m in the study area. Two secondary pore belts are developed in the Yuejin area, and one in the LUcaotan-Wunan-Wanxi area. The genesis of the secondary pores is the dissolution of carbonate cement, feldspar and lithoclast caused by organic and carbonic acids, which are generated during the evolvement of source rock. The development and distribution of secondary pores are controlled vertically by the maturity time of source rock and horizontally by the location of acidic water. They are also related to the sedimentary facies zone where the sandstones exist and the development of fault zone.