盐湖生物发育特征及其烃源意义

Development Characteristics of Biologies in Saline Lake Environments and Their Implications for Hydrocarbon Source

盐湖类盆地(咸化湖盆)发育了许多陆相大油气田,但其生物发育特征却因组成复杂与种类独特而认识较模糊,是石油地质地球化学和湖相沉积学领域的重要科学问题。为加深对其理解,本文综述了盐湖(咸化湖盆)环境中生物发育的特征,并讨论了其烃源意义。结果表明,盐湖(咸化湖盆)并不是传统认为的"生物荒漠",而是随盐度增加生物种类减少但生物量并不减少,可以有较高生产力,形成优质烃源岩。盐湖(咸化湖盆)中的生物系统组成异常复杂,包括高等植物、藻类、缺氧光合细菌、厌氧化能自养细菌、脊椎动物、无脊椎动物、古菌等,且生物不是均匀而是呈层分布,不同种类生物的耐盐度也各不相同。盐湖(咸化湖盆)生物的生物标记物及其数量关系对环境具有指示意义,生物及其盐度变化影响着与烃源岩有机质丰度相关的生产量、破坏量和稀释量等,进而影响油气生烃。未来仍有许多科学问题有待进一步深化研究,如盐湖(咸化湖盆)生物种类及数量、各生物生烃贡献比例、生物生产量、破坏量和稀释量的影响机制、成烃模式和机制、盐湖(咸化湖盆)形成的机制等。

Saline lakes of continental environments host many giant oil and gas fields. However, the biologies within these environments have not been well constrained due to the complexity and speciality, which are important scientific issues in the fields of petroleum geochemistry and lacustrine sedimentology. To better understand these issues, this paper reviews the development characteristics of biology in saline lacustrine facies and discusses their implications for hydrocarbon source. Results show that the salinelakes are not the traditionally thought “biological deserts”. Instead, along with the increase of salinity, biological species decrease but the biomass does not reduce, and thus saline lakes can have high productivities, further forming high quality hydrocarbon source rocks. Composition of the biological system in saline lakes is rather complex, including higher plants, algae, hypoxia photosynthetic bacteria, anaerobic autotrophic bacteria, vertebrates, invertebrates, and archaea. Moreover, the organisms in saline lakes are not uniform but hierarchically distributed, and salt tolerances of species are different. Biomarkers and their quantitative relationships of saline lacustrineorganisms have implications for the environments. The change of the organisms and the salinity influence the production, destruction and dilution related to the abundance of organic matter in source rocks, which further hasgeological significance on petroleum formation. In the future, there are still many scientific issues to be further studied, such as the species and quantity of saline lacustrine organisms, the proportion of contribution to hydrocarbon generation for each species, the influencing mechanisms of the amount of biological production, destruction and dilution, hydrocarbon generation model and mechanism, and the formation mechanism of saline lakes.