塔里木盆地轮南油田2、3井区三叠系沉积微相研究

三叠系作为塔里木盆地的主要含油气层系已逐渐被近几年来的油气勘探实践所证实.本文采取综合研究的技术思路和方法,通过取心分析、测井划相,结合开发动态资料,精细刻划各单油砂体在平面及空间上的微相展布.研究表明轮南油田三叠系砂岩,以含砾中粗粒砂岩为主,粒度较粗,重力流沉积特征较突出,以河湖相为主的碎屑岩沉积,其烃源岩主要发育于深湖-半深湖、浅湖和三角洲亚相,从大的韵律到小的层理都显示粒序递变的构造特征,为重力流悬浮搬运沉积的主要标志,存在辫状分支河道微相砂体,分支河道侧缘微相砂体和分支间湾微相砂体三种类型.中上三叠统粗碎屑岩,以及泥岩、粉砂岩,是以半深湖、浅湖至滨岸相环境为主的沉积,自下而上沉积环境分别发育有扇三角洲平原亚相、扇三角洲前缘亚相和前扇三角洲亚相.

Triassic sedimentary microfacies in the second and third well fields in the Lunnan Oil Field,Tarim Basin

The Triassic strata occur as the main oil reservoirs in the Tarim Basin.The planar and spatial distribution of sedimentary microfacies in individual oil reservoirs of reservoir sandstones is explored on the basis of the analysis of cores and well logs,in combination with the petroleum exploration in recent years.The Triassic sandstones in the Lunnan Oil Field are composed of gravelly medium-to coarse-grained sandstones with coarser grain sizes,indicating typical gravity flow deposits,and fluvial-and lacustrine-dominated clastic deposits.The source rocks are developed in the deep lake and bathyal lake,shallow lake and delta subfacies,and typical of the gravity flow deposits by suspension transport.Three types of sandstones have been recognized,including braided distributary channel microfacies,distributary channel flank microfacies and interdistributary way microfacies sandstones.The Middle and Upper Triassic coarse-grained clastic rocks,mudstone and siltstone are assigned to the bathyal lake,shallow lake and littoral deposits in the fan-delta plain,fan-delta front and prodelta subfacies from the base upwards.