塔中石炭系碎屑岩深埋藏优质储层成因探讨

STUDY ON THE ORIGINE OF QUALITY CLASTIC ROCKS RESERVOIR IN CARBONIFEROUS FROM TAZHONG AREA

塔中地区石炭系碎屑岩为一套次生─原生孔隙型深埋藏优质储层。储集岩为中细粒─细粒石英砂岩，储层形成于古地温梯度低、沉积物浅埋时间长、深埋时间短、孔隙水矿化度高及较早被油气占居的条件下，致使原生孔隙保存较好。同时，塔中地区石炭系目前刚进入８０℃─１２０℃的强溶成岩阶段，次生孔隙正在发育，距离碳酸盐岩沉淀带和后期石英次生加大带尚有较大深度，因而储层的孔渗性维持在最佳状态。

The Carboniferous clastic rocks in Tazhong area is a set of deep burried quality reservoir rocks with both primary and secondary pores. The reservoir rocks are mainly medium fine to fine grain quartz sandstons. The conditions for the primary pores to be preserved in good state are as fellows: the Paleogeothermal gradient should be very low, the shallow burried time should be very long while the deep burried time must be much short than former,the high degree of minera lization and early migration of oil and gas etc. The Carboniferous reservoir rocks are situated in 80℃-120℃ degrees centigrade which is in a highly disolved stage, and is advantage for growing the secondary pores. It does not reach the zone of carbonate precipitation and quartz overgth so as to maintain the reservoir to be in best conditions.