鄂尔多斯盆地甘泉—富县地区长7烃源岩地球化学特征

摘要

Ganquan-Fuxian area is a main enrichment area of tight oil in Yanchang Oilfield,Ordos Basin,however, the resource potential and enrichment law are unclear,and the exploitation risk is large. The data of cores and log-ging were used to study the distribution of Chang 7 source rocks,and the total organic carbon,pyrolysis,chloro-form bitumen"A"and vitrinite reflectance(Ro)were analyzed to evaluate the hydrocarbon-generating potentials of Chang 7 source rocks. The results show that the organic matter is mainly of Ⅰ and Ⅱ1 type and in a matu-rate oil generation stage,with great hydrocarbon-generating potential,which is determined to be relatively good source rocks. The thickness and organic matter abundance of Chang 7 source rocks are controlled by sedimentary environment. The Chang 7 source rocks are mainly distributed in northwestern deep to semi-deep lake sedimentary area near the center of the lake basin,with the thickness of 50-70 m,which can be the key area for the next tight oil exploration. The research result is helpful for guiding the evaluation of hydrocarbon geochemical characteris-tics and hydrocarbon generation potential and the prediction of favorable oil and gas areas.%鄂尔多斯盆地甘泉—富县地区是延长油田致密油主要发育区,为了解决延长组长7油层组致密油资源潜力不清、富集规律不明、勘探开发风险大等问题,利用岩心和测井资料,研究了长7暗色泥岩的分布特征,并通过烃源岩总有机碳、烃源岩热解参数、氯仿沥青"A"族组成、镜质体反射率(Ro)等的分析测试,评价了长7烃源岩的生烃潜力.结果表明:烃源岩有机质丰度高,主要为Ⅰ和Ⅱ1型,有机质热演化程度普遍达到成熟生油阶段,生油潜力大,总体评价为较好—好烃源岩;烃源岩的分布明显受沉积格局控制,靠近湖盆中心的深湖—半深湖沉积区的西北部是长7烃源岩的主要发育区,厚度为50～70 m,可作为下一步致密油勘探的重点区域.该研究成果对类似地区的烃源岩地球化学特征、生烃潜力评价、预测油气有利区具有指导作用.