塔里木东部满东1井志留系天然气成因与成藏期初步分析

满东1气藏的发现是塔里木盆地东部地区油气勘探获得新突破的重要标志。本文充分利用目前所获得的大量地质和地球化学资料,从天然气的组份特征、成因类型、成熟度和气源对比等方面对该井天然气的成因进行了分析,认为满东1井天然气属于海相腐泥型天然气,来源于寒武系-下奥陶统海相过成熟烃源岩,烃类气体组成具有油裂解气的特征。海相泥质烃源岩中氨基粘土矿物在过成熟阶段分解并氧化,形成大量的氮气,导致满东1气藏高含氮气。包裹体和埋藏史研究结果表明满东1气藏成藏过程复杂,主要成藏期为燕山喜马拉雅期。

A PRELIMINARY STUDY ON NATURAL GAS GENESIS AND POOL-FORMING PERIOD IN THE SILURIAN OF WELL MANDONG 1, EAST TARIM BASIN

The advances on exploring natural gas reservoir in the Silurian of the Well Mandong 1 in eastern Tarim Basin must be an important symbolic breakthrough on oil and gas exploration. Taking full advantages of the substantially existing geological and geochemical data, the paper analyzed the genesis of natural gas in the Silurian of the Well Mandong 1, dealing with the aspects of component characteristics, genetic-types of the gases, organic matters maturities and correlation of gas sources. It was the evidence that indicated the natural gas in the Well Mandong 1 derived from marine sapropel-type kerogen, possessed the compositional characteristics of oil-splited gas and originated from marine post-mature source rocks of the Cambrian-Lower Ordovician’s. A mass of nitrogen formed in the process of marine amino-clay minerals degradation and oxidization in the post-mature phase and resulted in a highly content of nitrogen in the gas pool of the Well Mandong 1. Based on studies of inclusion and burial history, it was thought that the pool-forming process of the gas pool in the Well Mandong 1 was complicated, with its major pool-forming period being the Yanshanian-Himalayan period. Combined with the fruits of the Well Yingnan 1, the exploration direction in the eastern part of the Tarim Basin was discussed.