【摘要】 针对白云凹陷烃源岩的类型和分布特征争议大,主力烃源岩及成藏贡献不明,不同区带油气分布差异性极大的问题,本研究通过对该区文昌及恩平期沉降速率分析,结合已钻井油-气-岩有机地球化学特征与不同母质类型源岩黄金管高温高压生成天然气模拟实验产物特征,认为白云凹陷发育半深湖、浅湖及海相/海侵3类烃源岩,白云主洼及白云西洼的洼陷区(沉降速率>200 m/Ma)可能发育规模性半深湖-深湖相源岩,斜坡-隆起区低沉降速率区(<200 m/Ma)文昌组及恩平组发育浅湖相源岩;白云主洼东部恩平组晚期发育海相/海侵泥岩。文昌组浅湖-半深湖相源岩为该区主力气源岩,而斜坡带中-低沉降速率区文昌组及恩平组浅湖相源岩为主力油源岩,海相/海侵源岩未见成藏贡献,呈现"二源供烃"格局。另外,根据烃源岩生排烃史、断裂体系发育等成藏要素及天然气生烃动力学建模,探讨了白云凹陷中浅层及洼陷内中深层气源及成藏特征差异性;认为隆起区已发现的中浅层气藏隶属于凝析油伴生气含气系统,为干酪根裂解气成藏;洼陷内深层气藏隶属于油裂解气含气系统,为洼陷内因缺乏油源断裂沟通疏导未经排出的原油裂解生气,为超压驱动、致密层阻隔的油裂解气成藏。更多还原

【Abstract】 In view of the great controversy on the types and distribution characteristics of source rocks in Baiyun Sag, the unknown contribution of main source rocks to hydrocarbon accumulation and the great difference in the distribution of oil and gas in different zones, this paper first studied the organic geochemical characteristics of drilled oil-gas-rocks and the characteristics of the simulated experimental products of natural gas generation from different types of source rocks by analyzing the settlement rate of Wenchang and Enping periods. It has been found that there are three types of source rocks in Baiyun Sag: semi-deep lake, shallow lacustrine and marine or transgressive source rocks. Large-scale semi-deep lake to deep lacustrine source rocks might be developed in the depression area of Baiyun Main Sag and Western Baiyun Sag with high settlement rate(above 200 m/Ma), while shallow lacustrine source rocks were mainly developed in Wenchang Formation and Enping Formation in slope uplift area with low settlement rate(below 200 m/Ma). Marine or transgressive source rocks were developed in Upper Enping Formation in Eastern area of Baiyun Main Sag. The oil-gas accumulation takes a pattern of “two hydrocarbon sources”, with the shallow lacustrine to semi-deep lake source rocks of Wenchang Formation as the main gas source rocks in this area, the shallow lacustrine source rocks of Wenchang Formation and Enping Formation as the main oil source rocks in the slope zone with medium-low settlement rate, and the marine or transgressive source rocks having no contribution to hydrocarbon accumulation. Then, the paper discussed the differences of gas source and reservoir forming characteristics between the middle and shallow layers and the middle and deep layers in Baiyun Sag according to the hydrocarbon generation and expulsion history of source rocks, the fault system development and other reservoir forming factors, and the dynamic modeling of natural gas hydrocarbon generation. It has been found that the middle shallow gas reservoirs discovered in the uplift area belong to the gas bearing system of condensate associated gas and are formed by kerogen cracking gas. Gas discovered in the deep layer in the sag belongs to the oil cracking gas bearing system, which is the oil cracking gas accumulation in the sag due to the lack of oil source fault communication, unclassified crude oil cracking gas, overpressure drive and tight layer barrier.更多还原