旬–宜区块长3段沉积特征及有利勘探相带

Sedimentary characteristics and favorable exploration facies belts of Yanchang formation Chang-3 member of Xun-Yi block area

旬–宜区块延长组长3段沉积相带的分布是控制长3段致密砂岩油藏分布的关键因素。在岩心、钻测井、地震等资料分析的基础上,结合鄂尔多斯盆地延长组沉积背景,认为旬–宜区块延长组长3段主要发育辫状河三角洲、滨浅湖沉积体系,识别出水下分流河道、分流间湾、河口坝等沉积微相,其中,水下分流河道发育规模广、砂体厚度大(单砂体厚度8.0~18.0m)、物性好(平均孔隙度11.3%、平均渗透率0.7×10–3μm2),对油气的富集程度起重要的控制作用,是有利的勘探相带。

The distribution of sedimentary facies belt in Chang-3 member of Yanchang formation is the key factor to control the distribution of tight sandstone reservoir. Based on the analysis of core, drilling, logging and seismic data, combined with the sedimentary background of Yanchang formation in Ordos basin, it is considered that the braided river delta and shore shallow lacustrine sedimentary system are mainly developed in Xun-Yi block area of Chang 3 member. The sedimentary microfacies such as underwater distributary channel, distributary bay and mouth bar are identified. Among them, the underwater distributary channel has wide development scale, large sand body thickness(single sand body thickness of 8.0~18.0 m), and good physical properties(average porosity of 11.3%, average permeability of 0.7×10–3μm2), which plays an important role in controlling the enrichment degree of oil and gas, and are favorable exploration facies zones.