古油藏及其对天然气藏的控制作用研究进展

Progresses on Primary Study of the Paleo Oil Reservoirs and Its Control on Natural Gas Accumulation

综述了古油藏的相关概念、发展历史与进程,古油藏研究进展表现在早期的古油藏的发现与证实,中期的储层固体沥青-成藏成矿流体关系研究,晚期的古油藏与现今气藏研究3个方面;刻画了古油藏研究今后的重点,主要包括未有钻井资料地区古油藏规模的确定、古油藏成藏—金属成矿耦合动力学机制、古油藏成藏—破坏过程的动态恢复,以及古油藏研究方法的系统化与信息化等方面的研究。同时,探讨了古油藏对现今天然气藏的控制作用:古油藏原油是优质气源岩,沥青质是天然气藏的良好封堵层;油藏原油裂解时圈闭开放度与现今气藏成藏率成正比;油藏与现今气藏在位置上的继承性更加有利于裂解气藏的保存。

A paleo oil reservoir is an oil reservoir which was accumulated in the geological history, but is damaged now. Abundant bitumen and hydrocarbon inclusions in the reservoir rocks are the key identification marks recording all the information of the oil from its generation to accumulation-bitumization-damage. About forty paleo oil reservoirs are found to be mainly distributed in South China, from Sinian to Triassic. The overview of paleo oil reservoir concept and its development and progress shows that the study on paleo oil reservoirs has experienced several stages, identification process in the early stage, the study of solid bitumen of reservoirs and coupling studies of ore-hydrocarbon accumulation in the middle stage, and the correlation study of paleo Oil reservoirs and present-day gas reservoirs in the late stage. It is expected that the future study of paleo oil reservoirs will focus on the scale of the oil pools in the region without drilling, the dynamic recovering of the play and destruction process of the ancient oil pools, and the systemization and digitalization of the approach. The discussion of the control of the paleo reservoirs over the present natural gas reservoirs confirms that the oil in the paleo reservoirs is the gas source rock of good quality and its bitumen belt serves as a good seal for the natural gas. It is also found that the trap openness of the gas reservoir is proportional to the gas rate of accumulation during the oil cracking and that the inheritance of the present reservoir to the paleo reservoir in position is more favorable for the conservation of oil-cracking gas reservoirs.