中国中新生代咸化湖盆烃源岩沉积的问题及相关进展

我国东部断陷湖盆和西部坳陷湖盆第三系均有蒸发岩与烃源岩共生现象。前者水体深、咸化范围小，在氯化盐和碳酸盐沉积环境中形成了优质烃源岩，后者水体浅、咸化范围大，在氯化盐和硫酸盐沉积环境中发育了优质烃源岩，作者认为两种湖盆出现的水体分层是有机质堆积和保存的重要条件。济阳坳陷和柴达木盆地为两类咸化湖盆的典型代表，对它们的研究可以深化蒸发岩-烃源岩共生区油气地质的认识、促进勘探发展。

Progress in Research of Deposition of Oil Source Rocks in Saline Lakes and Their Hydrocarbon Generation

If evaporization of the lake-water is stronger than influxion of fresh-water, the lake becomes a saline deposition environment, where carbonates, sulfates and chlorates as well as sand and mud can be deposited. Having been investigating for over 20 years, the authors belive that the saline lakes are good places for excellent hydrocarbon source rocks deposition. The water column in the saline lakes is stratified by gravitation, so that the surface water is of lower salinity and is suitable for aquatic organisms; in contrast, the base water of the lakes is of higher or super-high salinity and in anoxic condition, and is the best place for organic matter accumulation. Therefore, in the lakes the hydrocarbon source rocks and evaporites are deposited together. The Tertiary sediments in the Qaidam basin and Eocene sediments in the Dongying Depression are important deposits of saline lakes. The deposition models of the evaporites and hydrocarbon source rocks outlined by the authors are a guide to better understand the evolution of saline lacustrine basins and distribution of high potential hydrocarbon source rocks. In burial history of the saline deposits, some of evaporite minerals interacted with organic matter in the hydrocarbon source rocks including catalysis on thermal degradation of organic matter into hydrocarbons, which results in immature oil generation from the hydrocarbon source rocks. This paper presents a series of experiments conducted on the interaction between evaporites and hydrocarbon source rocks to examine mechanism of oil and gas generation in the saline deposits. The study may provide new ideas for petroleum exploration in saline lacustrine basins.