超深层油气藏石油地质特征及其成藏主控因素分析

由于区域地质背景的不同，根据前人的研究成果，确定了超深层油气藏为大于6km的埋深。对超深层油气藏的烃源岩、储集层、盖层和圈闭等的研究发现:与一般烃源岩相比，超深层油气藏的烃源岩成熟期晚、成熟度较高，生烃作用除了受温度和时间的控制外，还受压力作用的影响，超压对有机质热演化和生烃过程有着强烈的抑制作用；储集层主要以次生孔隙为主，年代偏老，储集层岩性中，碳酸盐岩所占比例达33%；盖层主要为盐岩、泥质岩；圈闭类型主要为构造圈闭、岩性圈闭、礁和复合圈闭。超深层油气藏主要受地层异常压力分布和温度等因素的控制。对我国超深层油气藏的勘探，可集中于地温梯度较小的地区、超高压体系内的次生孔隙和裂缝发育带、深层海相碳酸盐岩区、盐下地层和东部海域的深水区等。 

Petoleum geology features and accumulation controls for ultra-deep oil and gas reservoirs

According to previous studies and specific geological settings of different regions, ultra-deep reservoirs have been defined as being 6 km. Petroleum geology studies of ultra-deep reservoirs have been made, including considerations of source rock, reservoir, cap rock and trap. Compared to conventional source rocks, the source rocks in ultra-deep reservoirs entered the mature stage later and have a higher maturity. Hydrocarbon generation was controlled by temperature, time and pressure. Overpressure strongly restricted the thermal evolution of orga-nic matter and hydrocarbon generation. Secondary pores with an older age worked as the main reservoir space. Carbonate rocks account for 33% of reservoir. Cap rocks are dominated by evaporites and mudrocks. The major traps are structural, lithological, reef and combination traps. The formation of ultra-deep reservoirs was controlled by abnormal pressure and temperature. It is suggested that ultra-deep oil and gas exploration in China should focus on the areas with lower geothermal gradients, stratigraphic intervals with secondary porosity and well-developed overpressures, deeply-buried carbonate rocks, sub-salt sequences and East China's deep offshore areas.