构造对砂岩孔隙演化的控制--以塔里木中部地区东河砂岩为例

塔里木中部地区东河砂岩孔隙大多为原生和次生混合孔隙,次生孔隙的形成与该区南、北两侧坳陷烃源岩成熟排出的酸性水有关,孔隙(包括原生的和次生的)在演化过程中始终受构造作用的控制:早期构造运动形成的塔中Ⅰ号断裂是酸性水从烃源岩注入储集岩的重要通道;古构造格局与演化控制了酸性流体运移路径和方向,最终控制了溶蚀作用和次生孔隙的分布位置;长期继承性的构造高部位比在短时期的构造高部位溶蚀发育物性好;构造高部位捕获烃类致使(原生或次生)孔隙保存下来。后期构造作用破坏油藏,烃类泄漏散失,孔隙重新释放,被晚期碳酸盐胶结而消失。构造在孔隙的形成、保存和消失这一演化过程中始终起着控制作用。

EFFECT OF STRUCTURE ON SANDSTONE'S POROSITY EVOLUTION:A CASE STUDY FROM THE DONGHE SANDSTONES IN CENTRAL TARIM

Most pores of the Donghe sandstones in central Tarim were primary secondary hybrid. The generation of secondary porosities was related to the acid water from the maturation of source rocks in the northern and southern depressions of the Tarim Basin. The porosity evolution was controlled by structure outline and structure evolution throughout the geohistory. The Tazhong No.1 Fault was a main migration channel for acid water from source rocks to reservoirs. The paleostructural outline and evolution restricted the migration path and direction of acid water, and finally determined the positions of dissolution and the distribution of secondary pores. The quality of the reservoirs which situated at the structure high in long period was superior to the quality of the reservoirs in short period structure high. The emplacement of hydrocarbon in the structure high resulted in the porosities (including both the primary and secondary ones) preserved, and the later tectonic events caused the hydrocarbon accumulated in the reservoirs to discharge. At the same time, the porosities were occupied by hydrocarbon before they were released again and filled by later carbonate cements.