鄂尔多斯盆地侯北地区三叠系延长组长6储层特征

鄂尔多斯盆地侯北地区三叠系延长组长6储集岩大部分为细粒长石砂岩,少数为细粒岩屑长石砂岩.孔隙度在10%～15%之间,渗透率在(0.1～1.0)×10-3μm2之间,以低孔、低渗、较强的非均质性为特点.长6沉积于三角洲前缘环境,水下分流河道中发育储集砂体.稳定的大地构造条件和沉积环境有利于大面积、较厚的砂体形成.方解石、浊沸石和绿泥石等自生矿物沉淀压实作用,大大降低了原始沉积物孔隙度,长石、中基性火山岩岩屑及浊沸石溶蚀作用产生了相当数量的粒内溶蚀孔和胶结物溶蚀孔.

Reservoir characteristics of the sixth unit of Triassic Yanchang Formation in Houbei area, Eerduosi Basin

In Yangchang Formation in Houbei area, the most of reservoir rock is fine arkose and a little part of reservoir rock is fine lithic arkose. The porosity of it ranges from 10% to 15% , and the permeability ranges from 0.1×10 -3μm to 1 ×10-3μm . The reservoir rock is of low porosity and permeability and serious heterogeneity. The sixth reservoir unit of Triassic Yanchang Formation deposites in lacustrine delta front environment, and the sand bodies of the reservoir develop in subaqueous distributary channel. The stable structural condition and sedimentary environment are beneficial to the formation of large and thick sand bodies. Compaction and the precipitation of authigenec minerals, such as calcite, laumontite and chlorite, greatly reduces the porosity of original sediments. The dissolution of feldspar, intermediate/basic volcanic rock fragments and laumontite creates a large quantity of intragranular and cement dissolution pores.