珠江口盆地惠西南地区转换斜坡类型及其控藏作用

Types of the Transfer Ramp and Its Controlling Hydrocarbon in the Southwest of Huizhou Depression,Pearl River Mouth Basin

综合利用地震、钻井、油藏及地球化学资料,对珠江口盆地惠西南地区转换斜坡特征及其对油气的垂向输导作用开展了研究。研究揭示研究区发育了开放型、连接型和破坏型3类转换斜坡,已探明的油藏主要分布在转换斜坡附近或与其相连构造脊的圈闭内。3类转换斜坡对油气的垂向输导能力存在差异,破坏型转换斜坡的垂向输导性最强,与其相关的中浅层油藏储量大、充满度高;开放型转换斜坡的垂向输导性最弱,与其相关的中浅层油藏几乎不发育;连接型转换斜坡的垂向输导性则介于前两者之间。转换斜坡内微裂隙发育程度的差异决定了其垂向输导油气能力的强弱,利用位移-距离法分析认为形成破坏型转换斜坡的应力最强,微裂隙最发育,导致其垂向输导能力最强。转换斜坡输导油气差异性的认识可为珠江口盆地的油气勘探提供指导。

Based on the comprehensive utilization of seismic data,drilling data,oil reservoirs and geochemical data,this paper studies the characteristics of the transforming slope for the vertical transporting of oil and gas in the southwest region of Huizhou in the Pearl River Mouth Basin.The study results show that three types of transforming slope exist in the study area,open mechanism,connected mechanism and destructed mechanism.The proven reservoirs are mainly distributed in the traps near the transforming slope or the trap in the connected structural ridge.Differences are found in the vertical transporting capability of the three kinds of transforming slopes.The destructed mechanism transforming slope possesses the strongest vertical transporting capability,due to high reserves and high filling capacity in the middle and shallow reservoirs,while the open mechanism transforming slope has the weakest vertical transporting capability,with the associated shallow reservoirs almost undeveloped.The connected mechanism transforming slope has the capability between the former and the latter.The difference of the development degree of micro fissures in the transforming slope determines the strength of the vertical transporting of oil and gas.The analysis by the displacement-distance method shows that the strongest stress inside the destructed mechanism transforming slope with the well developed fissures makes the vertical transporting capability stronger.The understanding of the difference of hydrocarbon transfer can provide guidance for oil and gas exploration in the Pearl River Mouth Basin.