苏丹红海中部深海区油气成藏地质条件与勘探策略

Petroleum Geological Conditions & Exploration Strategy in Deep Offshore Area, Middle Sudanese Red Sea

深海油气资源丰富,是世界未来油气新增储量的重要接替区,但勘探投资大、作业风险高,因此制订合理的勘探策略对石油公司降低作业风险、减少勘探成本及尽快获得油气发现等都极为重要。以苏丹红海中部深海勘探区为例,系统分析了该区的地质结构、石油地质条件及有利勘探领域,探讨了制约该区油气勘探的主要因素。研究认为:苏丹红海中部深海区总体具有"两凹一凸"的构造格局;基底为前寒武系火山岩、变质岩,沉积地层主要为中、上新世红海同裂谷—后裂谷活动时期沉积的碎屑岩、碳酸盐岩和蒸发岩;纵向上发育盐上、盐下两套潜在的油气成藏组合,北部凹陷盐下油气成藏条件相对较好,具备大规模烃类生成、聚集的地质条件,是该区开展圈闭评价与钻探目标优选的最有利地区;由于盐层厚度大、地震资料品质差,导致盐下圈闭的落实程度普遍较低,钻前地质及作业风险难以准确预测,因此改善地震成像质量,评价、优选有利的钻探目标,并针对性地进行钻前准备仍将是该区下步勘探工作的重点。

Owing to its abundant hydrocarbon resource, deep offshore region will become the important replaced area for future oil & gas reserves increment. Enacting appropriate exploration strategy is vital for the oil companies to decrease exploration investment, avoid drilling risks, and attain oil & gas discoveries ASAP. This paper took the deep offshore exploration region of the Middle Sudanese Red Sea as an example to make a systemic analysis to its geological configuration, petroleum geology conditions and influence factors for exploration activities. The results indicated that there were two sags and one salient in the deep offshore area; basement was pre-Cambrian igneous and metamorphic rocks and main sedimentary strata were clastics, carbonate and evaporates deposited during Miocene-Pliocene Red Sea rifting and drafting period. Two sets of source-reservoir-cap assemblages, i.e. above-salt and sub-salt, were formed in the region and Belayim Formation reservoir in the north sag was the most favorable potential target because of its good hydrocarbon generation & accumulation condition. The identification & reliability of sub-salt drilling prospects and the accurate geological & engineering risks prediction before drilling were key factors for offshore drilling. Improving the seismic imaging quality, re-interpreting and re-evaluating the sub-salt prospect configuration and finalizing the offshore drilling preparation were still the primary jobs for next exploration period.