潜江凹陷马王庙地区新沟咀组下段重要层段沉积相特征

摘要

The lower part of Xingouzui Formation of Mawangmiao area is an important producing pay and profitable range to find lithologic hydrocarbon reservoir in the future.Based on the synthetical analysis of cores description,thin section analysis and logs,and combined with sedimentary marks of lithology,paleoclimate,sedimentary structure,and so on, the lower segment of Xingouzui Formation is ascertained shallow water delta-shore-shallow lacus depositional system,and is further divided into subfacies as follows：delta front,prodelta,shore-shallow lacus,etc.and several microfacies.Provenance analysis results indicate that the study area is controlled by northeastern Hanchuan provenance and northwestern Hanshui provenance,the study area develops two lobate deltas of NE-SW and NW-ES distribution,especially the NE-SW delta develop more widely.During the Ⅱ-oil group depositional stage,depositional water depth is the most deep,and the delta develop most widely,Ⅲ-oil group takes second place.And during the Ⅰ-oil group depositional stage,depositional water depth is the most shallow and the delta develop most shallowly.Most of all,the underwater distributary channel microfacies develop most widely.Through analyzing sedimentary facies distribution and reservoir sands distributing rule of three oil groups and important sections of Xia31,Xia25 and Xia13,indicate that the underwater distributary channel microfacies of Xia25 has most wide scale and most thick sand,the sand distribution rule according to underwater distributary channel distribution.The sedimentary facies distribution of Xia31 and Xia13 coincide with the Xia25 and northwestern delta front sand of Xia31 develop more wide.The result of analyzing every microfacies reservoir physical property indicates that underwater distributary channel has highest porosity.Thus underwater distributary channel microfacies and thicker sand distribution region of each section should be optimum reservoir facies and beneficial region to seek for lithologic hydrocarbon reservoirs.%马王庙地区新沟咀组下段为江汉盆地重要的产层之一,也是今后寻找岩性油气藏的有利区域。通过岩芯观察、室内镜下薄片鉴定分析、测井曲线等资料的综合分析,并结合岩石学、古气候、沉积构造等沉积相标志研究,确定该区新沟咀组下段发育浅水三角洲—滨浅湖沉积体系,进一步细分为三角洲前缘、前三角洲、滨、浅湖等沉积亚相和若干微相类型。物源分析结果表明,研究区受控于东北方向汉川物源和西北方向汉水物源影响,分别发育东北—西南向和西北—南东向展布的三角洲朵体,尤以前者发育更广。其中Ⅱ油组沉积期沉积水体相对更深,三角洲沉积分布范围最广,