鄂尔多斯盆地坪北地区延长组长8、长9油层沉积特征研究

STUDY ON THE SEDIMENTARY CHARACTERISTICS OF THE OIL-BEARING LAYERS C-8 AND C-9 OF YANCHANG FORMATION IN PINGBEI AREA,ORDOS BASIN

在对坪北地区深层延长组长8、长9油层组的油气勘探中,发现了较好的含油显示.综合测井、录井、岩心及其分析化验资料等,对坪北地区延长组长8、长9油层组岩石学、古生物学及地球物理特征进行综合研究,结果表明:长8、长9油层组沉积时期坪北地区发育湖泊-三角洲沉积体系,主要发育三角洲前缘沉积以及滨浅湖或前三角洲沉积;进一步可划分为水下分流河道微相、水下分流河道间微相、远砂坝微相、滨浅湖泥岩及前三角洲泥岩,其中水下分流河道砂体比较发育,是油气聚集的主要场所.

Good oil and gas shows are discovered in the exploration of oil-bearing layers C-8 and C-9 in Yanchang Formation, Pingbei area. Combining the data of well logging, geological logging, drill core and chemical analysis, a comprehensive study is conducted on the petrological, paleontological and geophysical characteristics of C-8 and C-9. The results show that the lacustrine-delta depositional systems, mainly delta front facies and shore-shallow lacustrine or prodeha sedimentary facies, are developed in the Pingbei area during the sedimentary period of C-8 and C-9, which can be subdivided into underwater distributary channel, underwater distributary interchannel, distant sandbar, shore- shallow lacustrine mudstone and prodelta mudstone microfacies. Among the facies above, the sand body of underwater distributary channel is relatively developed, serving as the main oil-gas accumulation place.