苏丹红海中部地区盐构造特征及油气勘探潜力分析

Salt tectonic characteristics and analysis of hydrocarbon exploration potential in the middle area of the Sudanese Red Sea

基于区域地质、钻井及地震资料,分析苏丹红海中部地区的盐层分布、盐构造特征及油气勘探潜力.结果表明:中新统Dungunab组盐层在该区分布广泛、厚度大,发育盐席、盐脊、盐背斜、块状盐体等盐构造形态,差异负载作用是造成盐层厚度及盐构造形态平面差异的主要原因;盐上主要沉积Zeit组砂、泥岩地层,具有自生自储的油气成藏条件,但分布范围受物源及盐丘形态控制,有利勘探区仅局限于评价区西部被盐丘分隔的小的沉积凹陷之内,范围有限;盐上圈闭的形成也主要与盐构造活动有关,发育滚动背斜、穹隆状背斜、盐层侧向封堵形成的地层圈闭及盐披覆构造等4种圈闭类型,其中穹隆背斜位于Zeit组沉积凹陷内,油气成藏条件较好;目前识别的有利圈闭均位于深水区,虽具有一定的资源规模,但海上作业费用昂贵,勘探潜力总体较为有限.

The paper makes an integrated study of the salt distribution,salt tectonics features and exploration potential in the Middle area of the Sudanese Red Sea based on regional geology,wildcats and seismic data.The results indicate that the Mid-Miocene Dungunab Formation has extensive distribution in the Middle of the Sudanese Red Sea and the main salt structure styles include salt sheet,salt ridge,salt anticline and bulk salt body etc;the depositional differential loading of above-salt successions caused the salt thickness and salt structure styles to bring about diverse distribution characteristics.Zeit Fm.is predominately clastics sediments of the above salt successions and its distribution is controlled by the source and salt dome location.There exist several minor deposit sags with thick Zeit formation and having basic petroleum geology conditions,which will become the potential area for salt structure exploration.The formation of local traps of the above salt is related to the salt tectonism and four kinds of prospects,i.e.,roller anticline,anticlines between salt dome,diaper structures on salt dome & statigraphical traps sealed by salt dome laterally,were identified.The domed anticlines which form early and are located in the Zeit Fm.depocenter area are the most favorable exploration target,but the deep water and the great amount of drilling costs will lower their exploration potential.