南堡凹陷高柳地区深层次生孔隙成因及分布特征

Genesis and distribution of secondary porosity in the deep horizon of Gaoliu area,Nanpu Sag

南堡凹陷高柳地区深层沙河街组在3250-3800m形成1个次生孔隙发育带，次生孔隙类型主要包括粒间溶孔、粒内溶蚀孔、铸模孔、溶解填隙物内孔隙和溶解缝。高柳地区地下水在北部燕山褶皱带接受补给，在重力水头的作用下沿着柏各庄、西南庄等深大断裂下降，尔后沿不整合面侧向运移，直接导致高柳地区深部地层在地表浅埋藏过程中遭受淋滤溶蚀，形成次生孔隙，这些次生孔隙在以后深埋过程中受到异常压力的影响而得以保存。断层和不整合面作为淡水的淋滤通道，与异常高压等因素一起控制着次生孔隙的分布，据此预测，高柳地区高北断层附近、朔河断层下降盘、唐海地区以及紧靠柏各庄断层下降盘的拾场次凹是深层储集层物性较好的地区。

Strong dissolution generates a secondary porosity interval at 3 250-3 800 m in deep sandstones of the Shahejie Formation in the Gaoliu area. The secondary pores include intraparticle pores, interparticle pores, moldic pores, and dissolved cement pores and fractures. The underground water of the Gaoliu area is fed with fresh water in the northern Yanshan folded mountains. The fresh water moves along the deep and big faults such as Baigezhuang, Xi＇nanzhuang etc. under the gravity force, and then moves along with uncomformities. The secondary porosities of deep horizon sandstones are formed by the leaching of ground water along these faults and uncomformities during the shallow burial process, and preserved by the abnormal high pressure during the deep burial process. Faults and uncomformities, served as the leaching path of ground water, alone with the abnormal high pressure, control the secondary porosities distribution. Good reservoirs are possibly at places near the Gaobei fault, the footwall of the Shuohe fault, the Tanghai area, and the Shichang subsag near the footwall of the Baigezhuang faults.