柴达木盆地胜利区块中下侏罗统烃源岩控制因素与发育特征

Study on control factors and development features of middle-lower Jurassic hydrocarbon source rocks, Shengli Area, Qaidam Basin

烃源岩是新区油气勘探面对的首要问题,中下侏罗统是柴达木盆地东部胜利区块发育的主力烃源岩层系之一。野外地质调查发现,研究区主要发育深湖—半深湖相油页岩以及湖沼相煤系烃源岩2种类型烃源岩。烃源岩分布较广,但横向残留厚度及埋藏深度差异较大,主要受侏罗纪原型盆地发育与后期构造运动的双重影响。地化分析结果表明,深湖—半深湖相油页岩为好烃源岩,湖沼相煤系烃源岩为中等—好烃源岩。在研究区东部烃源岩厚度较大且已进入成熟阶段,是成熟油气有利勘探区;在中西部厚度较薄且只进入低熟阶段,是低熟油气勘探区。

Hydrocarbon source rocks are the primary problem for oil and gas exploration of new area. Middle-lower Jurassic in Shengli area of Qaidam basin is one of the main blocks developed abundant hydrocarbon source rocks. There are two kinds of hydrocarbon source rocks developed in the study area, including limnetic facies bituminite, shale and limnetic facies coal (dark mud rock, battie, valengongite, coal) according to field geologic research. These two kinds of hydrocarbon source rocks are distributed widely. But, the lateral residue thickness and burial depth are quite different, which is largely controlled by the double influence of the Jurassic prototype basin development and the late tectonic movement. Based on geochemical analysis, limnetic facies bituminite is good hydrocarbon source rock, and limnetic facies coal hydrocarbon source rock is medium to good hydrocarbon source rock. The thick hydrocarbon source rock in eastern area entered mature phase with mature oil and gas for exploration. The thin hydrocarbon source rock in middle-western area entered low-mature phase with low-mature oil and gas for exploration.