Hydrocarbon accumulation rules and inspiration for the exploration of sub-salt carbonate reservoirs in the Great Campos Basin, Brazil

doi:10.3969/j.issn.1672-7703.2020.04.008

Abstract

Abstract: Since the discovery of the giant Lula oil field in 2006, a number of large oil and gas fields have been discovered in deep-water sub-salt strata in the Great Campos Basin in Brazil, which has become one of the ‘hotspots’ of global exploration. This study examines the hydrocarbon accumulation conditions of sub-salt oil and gas systems by analyzing these exploration discoveries and their oil and gas characteristics. The results show that the hydrocarbon generation conditions of sub-salt lacustrine shales are excellent, forming multiple hydrocarbon generation centers and strong oil and gas charging systems. Extremely thick gypsum-salt strata delayed the evolution of source rocks and effectively preserved oil and gas. Large-scale development of lacustrine microbial reservoirs provided the conditions for oil and gas enrichment. Sub-salt oil and gas resource potential was re-evaluated for this study using the scale sequence method, revealing the yet-to-be-discovered recoverable oil and gas resources of around 331×108 bbl. Systematic analysis of exploration history and experience suggest that the key factors in the discovery of large sub-salt oil and gas fields are the transformation of exploration ideas, continuous investment, and technological progress. Risk in commercial oil and gas discovery is principally affected by the scale of high-quality reservoirs, the types of oil and gas reservoirs, and the scale of economic reserves. Structural traps which developed in uplifted areas during rift-periods are the most important exploration targets, followed by stratigraphic-lithologic traps. High positions in ultra-deep ocean have particular exploration potential.

CLC Number:

Zhang Zhongmin, Zhu Yixuan, Zhang Demin, Su Yushan, Yao Wei, Bao Zhidong, Song Jian, Shen Weihong. Hydrocarbon accumulation rules and inspiration for the exploration of sub-salt carbonate reservoirs in the Great Campos Basin, Brazil[J]. China Petroleum Exploration, 2020, 25(4): 75-85.

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