塔里木盆地塔西南坳陷和田凹陷普司格组烃源岩沉积环境及有机地球化学特征

二叠系是叶城_和田凹陷最为重要的烃源岩层系之一。通过和田凹陷杜瓦地区野外露头剖面及最新钻井分析，并结合有机地球化学测试数据，对二叠系普司格组烃源岩沉积特征、古环境及有机地球化学特征进行研究。结果表明：普司格组烃源岩发育在滨湖、浅湖及半深湖亚相中，乌鲁吾斯塘地区和杜瓦地区为烃源岩沉降中心，以低Pr/Ph值、较高伽马蜡烷指数等为特征，表现出较强还原性、较高盐度下具有一定水体分层的湖相沉积产物。普司格组烃源岩有机碳(TOC)值为0.12%~5.68%，为“差-中等”烃源岩，有机质类型以Ⅱ型、Ⅲ型为主，镜质体反射率R_O值为0.72%~1.385%，主体已进入成熟-高成熟阶段。结合地震资料、生储盖条件分析认为，杜瓦地区普司格组烃源岩生烃潜力较好，逆冲推覆体为油气勘探的可能有利区域，准原地质体为塔西南坳陷山前带最为有利的油气勘探区域，原地质体埋深很大，是目前勘探工作面临的主要挑战之一。

The sedimentary environment and geochemical characteristics of the source rocks in the Pusige Formation in Hetian Sag,southwestern Tarim Basin,China

Based on the outcrop section and new well drilling data and organic geochemical analysis results in the Duwa region,a detailed comparative study about hydrocarbon source rocks was conducted.The results suggested that the hydrocarbon source rocks developed in the sub facies of lakeside,shallow lake and semi-deep lake sub.And it had lower Pr/Ph ratio,higher gammacerane ratio,which reflected the source rocks were the products of lake facies and had a stronger reducibility,higher salty sedimentary environment and a certain water column.The Wuluwusitang and Duwa region were the subsidence center of the source rocks.The OM (organic matter) was between 0.12% and 5.68%,which was in the “poor to medium” level.The type of OM was mainly typeⅡ and Ⅲ.The vitrinite reflectance was between 0.72% and 1.385%,which suggested most of hydrocarbon source rocks had entered the mature to high-mature stage.A comprehensive analysis which included the seismic data and the condition of the source rocks,reservoir and cap was conducted.The source rocks of the Pusige Formation still have a certain potential for generating hydrocarbon.And the nappe system is the potential good exploration area which generates oil and gas,and the quasi in situ is the most favorable oil and gas exploration area in the front of Duwa region mount,and because of the deeper burial depth,the in situ system is one of the most difficult challenges for the exploration work. Hetian Sag;Pusige Formation;Hydrocarbon source rocks;Sedimentary environment;Geochemical characteristics