廊固凹陷河西务构造带深部碎屑岩储层特征

CHARACTERS OF DEEP-BURIED CLASTIC RESERVOIR ROCKS IN HEXIWU STRUCTURAL BELT OF LANGGU DEPRESSION

廊固凹陷河西务构造带深部碎屑岩储层以长石砂岩为主，成分成熟度低、结构成熟度中等。深部地层成岩程度较深，已进入晚成岩 Ａ１－Ａ２亚期，受成岩作用的影响，储层总的演化趋势是物性变差。在 ３ ４５０～３ ５５０ｍ段普遍因长石和早、中期碳酸盐胶结物溶解而形成一个次生孔隙发育带，有机酸脱羧而产生的流体溶解是次生孔隙形成的主要机制。次生孔隙以粒内溶孔－粒间溶孔组合为主，孔隙结构以小孔低渗细喉型为主，部分为中孔低渗细喉型和特低孔特低渗微细喉型。碳酸盐含量、沉积相带和成岩作用是影响储层物性的主要因素。平面上廊坊－韩村－北旺一带孔隙度最高，属三角洲相沉积，是河西务构造带深部储层的主要发育区。

Deep-buried clastic rock reservoirs in Hexiwu structureal belt of Langgu Depression mainly consist of feldspathic sandstone with low compositional maturity and middle textural maturity. The deep elastic rocks are in late diage-. nesis stage( AⅠ -AⅡ ) , the physical property of the reservoirs become much more worse. A secondary pore belt developed in the section. From 3 450 m to 3 550 m, intragranular and intergranular solution pores developed well, thus forming available reservoirs, fluid solution caused by decarboxylation of organic acid was the major formation mechanism of secondary pores at the deep section. Pore structure is mainly characterized by small pore-low permeability-fine throat. The content of carbonate, sedimentary fades and diagenesis are the principal factors offecting the physical property of the reservoirs. The porosity of reservoirs in Langfang, Hancun and Beiwang is the highest in Hexiwu structural belt. These places are favourable for the development of the reservoirs.