歧口凹陷马东地区深层油气藏特征及成藏主控因素

Characteristics and main accumulation controlling factors for deep hydrocarbon reservoirs in Madong area of Qikou Sag

歧口凹陷马东地区油气勘探已经向凹陷深部进发,但凹陷深部油气成藏的主控因素不明确,勘探风险较大。利用钻井资料、油藏流体分析测试资料、三维地震资料等,通过油气藏流体特征分析、油气藏解剖、三维地震属性提取和地层切片等研究手段,对歧口凹陷马东地区深层油气藏形成的主控因素进行研究,并预测了凹陷深部油气成藏潜力区。结果表明:研究区为超深、高温、异常高压油气藏,原油性质为挥发油;油气藏类型为岩性-构造或岩性油气藏,高部位为岩性-构造油气藏、低部位为岩性油气藏,储层呈现为层状,构造低部位油水系统相对复杂,具有多套油水系统,构造高部位未见统一油水界面;沙三段和沙一段烃源岩油气供给较好,后期断裂活动相对较弱,油气保存条件较好,凹陷深部油气藏受控于砂体的展布。凹陷深部有利砂体分布在扇体主体部位边缘的滑塌透镜体,主要发育在板Ⅱ和滨Ⅰ油组内,是歧口凹陷马东地区下一步勘探的有利部位。

The oil and gas exploration has been advanced to the deep formations in Madong area of Qikou Sag, but the main controlling factors of the hydrocarbon accumulation in the deep part of the sag are not clear, and the exploration risk is rather great. Using drilling data,reservoir fluid analyzed and tested data, 3 D seismic data, etc., the main controlling factors of the hydrocarbon accumulation in deep formations of Madong area in Qikou Sag were studied by the following researching methods: the analyses of the reservoir fluid characteristics, oil and gas reservoirs analysis, 3 D seismic attribute extraction, stratigraphic slice and so on, and moreover the deep potential areas of the hydrocarbon accumulation in the sag were predicted. The results show that the oil reservoirs in the study area can be divided into ultra deep, high temperature, abnormal high pressure oil and gas reservoirs, and the crude oil is the volatile oil;the hydrocarbon reservoir types contain lithologic-structural and lithologic ones, the former is in the higher structure areas, while the latter is in the low part. The reservoirs present layered forms, the oil-water systems in the lower part are relatively complex and furthermore show multi-set of the systems, there is no unified oil-water interface in the high part;the oil supplies in Member Es3 and Es1 source rocks are much better, and the late fault activities are relatively weak but the hydrocarbon preservation conditions are better,the hydrocarbon reservoir in deep sag is controlled by the distribution of the sandbody. The favorable sandbodies in the deep part are distributed in the slump lens beside the principal part of the fans and mainly developed in Oil Group BanⅡand BinⅠ,and furthermore are the favorable areas of the next exploration in Madong area of Qikou Sag.