酒西坳陷青西油田下白垩统储集层裂缝研究

酒西坳陷青西油田下白垩统储集层为裂缝性致密储集层，裂缝以构造斜交缝、层间缝为主，存在北东-南西向和北西-南东向两组方位，以北东-南西向为主。宏观裂缝宽度为0.5～2.0mm，发育程度普遍较高，主要分布在下白垩统下沟组中下部，微裂缝对连通宏观裂缝及溶蚀孔洞起良好的作用，使致密储集层中形成缝-洞网络。有效裂缝主要形成于喜马拉雅期，裂缝最发育地区是青西油田的南部和东部。由于裂缝的形成、发育时期与下白垩统烃源岩的主排烃时期相匹配，裂缝成为油气良好的储集空间和有效的运移通道。图3参12

Fractures in the Lower Cretaceous reservoir of Qingxi Oilfield, Jiuxi Depression, Northwest China

The reservoirs in Qingxi Oilfield of Jiuxi Depression composite compact fracture oil traps. The types of fractures are mainly structural dip fissure and pie-shaped fissure. The fractures' width range between 0.5-2.0mm and development of micro-fissures has the function of connection. Two groups of fractures developed in the Qingxi Oilfield, one strike is NE-SW and another strike is NW-SE. The main strike is NE-SW. Most of the effective fractures are formed in the Himalayan Period. The best development region of fractures is the south and the east parts of Qingxi Oilfield, which are fine reservoir spaces and migration passages since their formation time was matched well with hydrocarbon expelling stage.