GEOCHEMICAL CHARACTERISTICS AND GENESIS OF DEEP MARINE CARBONATE NATURAL GAS IN CHINA
Jian Li1,2, Jin Li1,2, Jianglong Shi3, Zhisheng Li1,2, Zengye Xie1,2, Xuening Qi1,2
1Research Institute of Petroleum Exploration and Development, Langfang, Hebei Province, 065007, China
2Key Laboratory of Gas Reservoir Formation and Development, CNPC, Langfang, Hebei Province, 065007, China
3Institute of Porous Flow Fluid Mechanics, University of Chinese Academy of Sciences, Langfang, Hebei Province, 065007, China
Keywords: Natural-gas, genesis, marine carbonate, Chinese sedimentary basins
Abstract
Deep and ultradeep oil and gas have been the prominent direction of international exploration in recent years. The deep oil and gas resources are distributed predominantly in three domains of carbonate, clastic, and igneous rocks. The carbonate rock reservoirs contain about 40 % of global oil and gas reserves owing to their superior reservoir properties. In recent years, a number of large oil and gas fields have been discovered in deep marine carbonate rocks in China, especially in the Sichuan and Tarim basins, which shows a vast oil and gas exploration potential in these rocks. In this paper, the genesis and source of deep natural gas in the Tarim and Sichuan basins have been systematically studied. The results show that the natural gas in deep marine carbonate rock reservoirs is generated not only from the later deep-source rocks. The substantial cracking of crude oil and pyrobitumen in the reservoir under conditions of great burial depth and high geotemperature can also provide abundant natural gas sources for deep reservoir. Accordingly, the contribution of gas from oil cracking should be considered in the evaluation of deep natural gas resources.
DOI: 10.15372/RGG2019129
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