惠民凹陷的震积作用及低电阻率油层

Seismic Deposition and Low Contrast Resistivity Oil Layers in Huimin Sag

惠民凹陷沙河街组中存在古地震作用形成的原地扰动层、震浊积岩和震风暴岩,尤以原地扰动层和震浊积岩发育。可见微断层、层内阶梯状断层、震球枕构造、震碎角砾及各种变形构造等震积岩的识别标志。惠民凹陷中央隆起带基山砂体中,震积作用及震积岩分布与火山作用、火成岩分布具有同时间性与同空间性。震积岩,特别是震裂岩和震碎角砾岩中的孔、缝形成早,改善储集层渗透性,可成为一种非均质性很强的储层。该储层具有裂缝-孔隙双重孔隙网络,常形成相对低电阻率油层。

Ancient earthquakes formed seismites, seismoturbidites and tempestites in Shahejie Formatiom in Huimin sag. Many kinds of soft identified structures have been found in seismites, such as micro - faults, step micro - faults, seism pillows, seismic breccias and deformation structures. Seismic deposition and seismite distribution have the same time and space with volcanism and igneous in Jishan sandstone body. Pores and fractures formed in early time and they improve the permeability in seismites, especially, in seismic shattering rocks and seismic breccias. Seismites will become the reservoirs that have the strong heterogeneity. The reservoirs often form the low contrast resistivity oil layers because they have the dual pore networks, that is, fractures and pores.