川东卧龙河—洋渡溪区带长兴组台内礁滩沉积格局及有利储集体展布

Depositional Pattern and Reservoir Distribution of Changxing Formation Intra-platform Reef and Shoal in Wolonghe-Yangduxi Zone of eastern Sichuan Basin

随着川东碳酸盐岩礁滩储层勘探的大力推进,台内礁滩储层成为该区关注的重点之一,但其研究程度较低。本文以岩芯、野外剖面、薄片鉴定资料为基础,确定研究区长兴组早期发育碳酸盐岩缓坡沉积体系;中—晚期发育碳酸盐岩台地沉积体系,开阔台地相构成该区主要沉积类型。层序地层研究表明:长兴组划分为两个三级层序,台内礁滩主要发育于Sq1和Sq2的高位体系域,横向上分布不连续,纵向上发育期次有变化,其中西部构造区带主要发育于Sq2-HST,而在东部Sq1和Sq2高位体系域均有分布,且以Sq1-HST更为发育。物性分析资料表明颗粒白云岩、粉晶白云岩为主要的储集岩类,台内礁滩沉积为主要储集相带,台内礁滩的沉积格局控制着有利储集体的分布,而台内地貌高地对于控制礁滩分布具有关键作用。地质和地震预测结果表明研究区有利台内礁滩储集体的发育主要沿遂宁和广安两个台内高地展布,卧龙河构造带是已经揭示的有利储层发育带,南部高带可能是该区未来台内礁滩储集体勘探的重要方向。

With vigorous promotion on the exploration for carbonate reel and shoal reservoirs in eastern Sichuan basin, the intra-platiorm reel shoal reservoir has become one focus in this area,but the study extent is lower . In this paper, based on the study on cores,field profiles and thin section data,it is ascertained that the principal sedimentation type of the study area mainly consists of Changxing Formation carbonate ramp sedimentation developed at early stage,and carbonate platform sedimentation developed at middle and late stages,open platform facies is the main sedimentation. The Changxing Formation can be divided into two third order sequences’the intra-platform reef and shoal bodies are mainly developed in Sq1-HST and Sq2-HST,and lateral distribution is not continuous, longitudinal development of phase changes’ the west tectonic zone is mainly developed by Sq2-HST,whereas the east tectonic zone is developed by both Sq1-HST and Sq2-HST,and Sq1-HST is more developed. Physical analytic data show that grain dolomite and powder dolomite are the main reservoir rocks ’ the intra-platform is the main reservoir facies ’ sedimentary structure within reefs station controls the distribution of favorable reservoir. But the intra-platform highland plays a vital role in controlling the distribution of reef shoal. The vast majority of reef shoals recognized by geologic and seismic data are distributed along the Sui’ning and Guang’an intra-platform highlands’ Wolonghe tectonic zone is already disclosed favorable reservoir zone ’ and the high zone in the south of the study area may be the important exploration direction of the intra-platform reef shoal reservoirs in this area in the future.