鄂尔多斯盆地安塞油田长10优质储层特征

鄂尔多斯盆地安塞油田长10期发育以细砂岩和中砂岩为主的长石砂岩,胶结物主要有浊沸石、石英加大等硅质胶结物、绿泥石和方解石；在早成岩早期酸性地层水大量溶蚀颗粒间胶结物,压实作用强烈,在中成岩早期,湖相泥岩中生成的酸性介质溶蚀砂岩颗粒间的胶结物及长石和岩屑颗粒碎屑,形成次生溶蚀孔隙,从而形成优质储层.纵向上,在不整合面和层序界面附近,储层溶蚀作用强烈,次生孔隙发育,是优质储层发育部位,向上溶蚀作用逐渐变弱;在平面上,越靠近湖盆中心溶蚀作用越强,越远离湖盆中心溶蚀作用越弱.鄂尔多斯盆地安塞油田长10优质储层主要发育在三角洲平原高能分流河道发育带,溶蚀作用形成的浊沸石溶蚀孔隙、方解石溶蚀孔隙、长石溶蚀孔隙等次生孔隙成为优质储层形成的有利相带.

An analysis of favorable reservoir characteristics of Chang 10 Formation in the Ansai oilfield, Ordos Basin

The cements of feldspathic sandstone in Chang 10 formation mainly include such types as laumontite, quartz overgrowth, chlorite and calcite. Compaction was intense in early diagenesis because the formation water changed into acidic media and particles lacked the support of cement. Secondary pores were formed in Middle diagenesis because the acidic water derived from the mudstone of lake facies dissolved cements, feldspar, and lithic grains during the migration process from source rocks to sandstones, thus forming the favorable reservoir. In the vertical direction, the reservoir dissolution in unconformity and sequence boundary was intense, and secondary pores were developed. Upwards, the dissolution gradually became weaker, and hence secondary pores were not developed. In the plane, the dissolution became gradually weaker from the hydrocarbon center to the shore. The favorable reservoirs of Chang 10 formation in the Ansai oilfield are mainly distributed in high-energy distributary channel of the delta plain, and a large number of secondary pores formed by dissolution become beneficial facies of the favorable reservoir.