延川南地区下石盒子组致密砂岩气储层特征及成藏条件

Xiashihezi Formation Compact Sandstone Reservoir Features and Reservoiring Condition Analysis in Southern Yanchuan Area

延川南地区位于鄂尔多斯盆地东南缘晋西挠褶带与渭北隆起交汇处,区内2口钻井在盒6、盒8段试气获得中—高产气流。在前人研究的基础上,对下石盒子组致密砂岩气储层的沉积相类型、储集空间特征、储层物性以及影响气藏发育的主控因素进行分析,认为下石盒子组产气层位一般发育在河道的砂体富集带的心滩微相,储层岩石类型以长石岩屑质石英砂岩为主,岩屑砂岩、岩屑质石英砂岩次之。研究区河道砂体富集带在上部受泥岩封盖,侧向上受逆断层遮挡,形成岩性-地层复合型气藏。

The southern Yanchuan area is situated at the junction of Jinxi flexural folded zone and Weibei uplift, southeast margin of the Ordos Basin. During the gas tests of two wells in the area have obtained medium to high yield gas flow in the sixth and eighth mem- bers of the Xiashihezi Formation. Based on previous studies, analyzed the formation＇ s compact sandstone reservoir sedimentaD7 facies type, accumulating spatial characteristics, reservoir physical property and main controlling factors to impact gas reservoir development, considered that the gas producing horizon in the formation is generally developed in the channel bar mierofaeies of river sand mass en- richment zone, reservoir rock type is mainly feldsparlithic quartz sandatone, lithic sandstone and lithic quartz sandstone the second. The channel sand mass enrichment zone in the area is covered by mudstone on top and blocked by reversed faults laterally, thus formed the lithologic-stratigraphic composite gas reservoir.