莺-琼盆地三维压力场和油气运移

莺歌海和琼东南盆地具有高温高压地层特征.莺歌海盆地的异常压力分布显示,平面上异常高压自中央坳陷带向盆地两侧斜坡带逐渐减小并过渡为静水压力,纵向上中央坳陷带受底辟活动的影响,压力系数自上新统下部地层往下逐渐增大,向两侧斜坡带逐渐减小,呈现"圣诞树"的展布特征.底辟带中浅层及底辟带周缘压力过渡带、中深层压力回倾带均是油气运移的指向,是重要的天然气勘探区域.琼东南盆地的崖南凹陷和乐东凹陷的超压最高,宝岛凹陷的超压较低,地层压力的纵向分布揭示由浅至深地层压力系数逐渐增大,但存在着中新统三亚组和中新统陵水组三段2个明显的泄压带,这2个带也是重要的天然气聚集带.

3D Geopressure Field and Hydrocarbon Migration in Yinggehai and Qiongdongnan Basins

Yinggehai and Qiongdongnan basins are characterized by high geotemperature and overpressure. The lateral distribution of geopressure in Yinggehai Basin shows that the abnormal overpressure in the central sag is decreasing slopeward to hydrostatic pressure. Affected by the activities of mud diapirs,geopressure coefficient increases vertically from Lower Plioence downward and decreases slopeward,distributed in a Christmas tree-like shape. Shallow layers above mud diapirs, normal-pressure belts and pressure-transition belts around mud diapirs,are favorable for hydrocarbon migration and important for natural gas exploration. While in Qiongdongnan Basin,Yanan and Ledong depressions have highest overpressures. Thewhile Baodao Depression has comparatively lower overpressure. The distribution of formation pressure indicates downward increase of the pressure coefficient, but two obvious pressure-releasing zones occur in the Sanya Formation and Lower Linghsui Formation,which are important areas for gas accumulation.