渤海海域石臼坨凸起两个亿吨级隐蔽油气藏勘探实践与启示

Two 100 million-ton class subtle reservoirs in Shijiutuo uplift, Bohai Sea-exploration practices and enlightenments

近年来,渤海海域石臼坨凸起发现了两个亿吨级隐蔽油气藏,勘探实践证实:地质新认识为油气勘探发现提供了理论指导和科学部署。石臼坨凸起低幅构造背景下"脊—圈—砂"三元耦合控藏机理,指导了凸起区新近系极浅水三角洲构造—岩性复合油气藏的重大发现;陡坡带盆缘断裂转换带隐蔽油气藏差异成藏模式,指导发现了渤海油田首个古近系中深层地层—岩性亿吨级油气藏。这些地质新认识进一步推动了技术攻关与创新,形成了浅层低幅构造背景下变速成图技术、"富砂型"极浅水三角洲岩性圈闭描述技术、断—砂耦合半定量分析技术、中深层构造—沉积模拟下精细古地貌恢复技术、中深层地层—岩性复合圈闭识别技术和中深层复杂岩性测试技术6项关键技术,为渤海海域规模型隐蔽油气藏的发现提供技术支撑和保障,具有很好的推广意义。

In recent years, two 100 million-ton class subtle reservoirs were found in the Shijiutuo uplift within the Bohai Sea. Exploration practices have proved that new geological understandings provide theoretical guidance and scientific deployment for hydrocarbon exploration discoveries. The mechanism of ternary-factor （ridge-trap-sand） coupling for controlling reservoir in low-amplitude structure guided the significant discovery of the Neogene structural-lithologic reservoir in extra-shallow water delta in the Shijiutuo uplift. The differential hydrocarbon accumulation mode of subtle reservoirs in basin-margin fault transfer zone in steep slope belt facilitated the discovery of the first 100 million-ton class the Palaeogene stratigraphic-lithologic reservoir in the medium-deep layers in the Bohai oilfield. These new geological understandings further promoted technical researches and innovations. As a result, six key technologies have been developed, including the variable-velocity mapping for shallow low-amplitude structure, the description of lithologic traps in sand-rich extra-shallow water delta, the semi-quantitative fault-sand coupling analysis, the exquisite palaeogeomorphic restoration under the tectonic-sedimentary simulation in medium-deep layers, the identification of stratigraphic-lithologic traps in medium-deep layers, and the testing of complex lithologies in medium-deep layers. These technologies provide technical support and assurance for discovering large subtle reservoirs in the Bohai Sea, playing a prospective role for future promotion and application.