莱州湾凹陷油气成藏动力学特征

Dynamic characteristics of the hydrocarbon accumulation in Laizhouwan Sag

莱州湾凹陷是渤海海域勘探的新区.通过对莱州湾凹陷温压场、应力场、流体势分析,结合该区油气成藏地质条件,莱州湾凹陷明下至沙四段成藏动力学系统可划分为自源高压封闭、混源常压半封闭、他源常压开放3类成藏动力学系统;成藏动力特征决定了莱州湾凹陷油气以断层运移、垂向运聚为主.北部陡坡带和中央构造带自源高压封闭、混源常压半封闭成藏动力学系统为下阶段勘探的主要目的层系,次之为东部走滑带他源常压开放成藏动力学系统.

Laizhouwan Sag is a new exploration area in Bohai sea area.The study on the hydrocarbon accumulation dynamics of the area is an effective method for determining hydrocarbon migration direction and predicting favorable hydrocarbon traps.Based on the geologic conditions of petroleum accumulation and according to the analyses of the temperature--pressure field,stress field and fluid potential in the studied region,it is held that there are three types of hydrocarbon accumulation dynamic systems in Laizhouwan Sag,including self-source high-pressure closed dynamic system,mix-source normal-pressure semi-closed dynamic system and out-source normal-pressure open dynamic system.The dynamic features determines the fact that faults become the dominant pathway for vertical hydrocarbon migration and accumulation in the area.The study results show the self-source high-pressure closed dynamic system and the mix-source normal-pressure semi-closed dynamic system in the northern steep-slope zone and the central structural zone are the most favorable exploration targets and the eastern out-source normal-pressure open dynamic system is the secondary exploration target.