柴北缘鱼卡地区中侏罗统油页岩类型及成矿差异

柴达木盆地鱼卡地区中侏罗统石门沟组发育多层油页岩,通过对YYY-1井全井岩心观察和地化分析,在页岩段和含煤段识别出两种类型油页岩。上部页岩段油页岩发育于深湖—半深湖环境中,含油率中等,单层和累计厚度均较大,w(TOC)为5.97%~15.35%,S_1+S_2为29.71~118.62 mg/g,有机质类型主要为Ⅰ型、Ⅱ1型,有机质来源主要以藻类体湖泊生物为主;下部含煤段油页岩发育于湖沼环境中,含油率较高,单层和累计厚度均较小,且与煤和炭质泥岩互层,w(TOC)为13.80%~48.80%,S_1+S_2为39.31~162.12mg/g,有机质类型主要为Ⅱ2型,有机质来源以陆源高等植物为主。沉积环境和有机质来源是影响这两种油页岩矿床差异的关键因素。

TYPES AND MINERALIZING DIFFERENCES FOR MIDDLE JURASSIC OIL SHALE IN YUQIA REGION OF NORTH MARGIN IN QAIDAM BASIN

Multilayered oil shales are developed in Shimengou Formationof Middle Jurassic Epoch in Yuqia area of Qaidam Basin,with the help of the core observation and geochemical analyses of the whole cores of Well YYY-1,two types of the oil shale were identified in the shale and coal bearing intervals.The upper-interval oil shale was developed in the deep lake-semi deep lake environments,the oil-bearing rate is medium,the single layer and accumulative thicknesses are pretty larger,the organic carbon content w (TOC) is between 5.97％ to 15.35 ％,and hydrocarbon generating potential (S1 +S2) is between 29.71 to 118.62 mg/g,the types of the organic matter are mainly Type Ⅰ and Type Ⅱ 1,the main source of the organic matter is the lacustrine algae organism;the lower coalbearing oil shale was developed in the lacustrine environment with pretty higher oil-bearing rate,but the single and cumulative thicknesses were rather smaller,and moreover was interbeddedly buried with the coal and carbonaceous mudstone,w (TOC) is 13.80％-48.80％ and S1+S2 is 39.31-162.12 mg/g,the types of the organic matter are mainly Type Ⅱ 2,the source of the organic matter is mainly terrigenous higher plants.The sedimentary environments and sources of the organic matter are the key factors influencing the mineralizing differences between the two types of the oil shale.