【摘要】 对歧口凹陷单井压实曲线的分析表明 ,歧口凹陷的压力体系在纵向上可以划分为 3个压力系统 ,即静水压力带、上超压带和下超压带。静水压力带的底界深度为 2 0 0 0m左右。上超压带主要分布在盆地中心部位 ,深度范围较窄 ,仅几百米 ,超压幅度不高 ,压力系数相对较低 ,一般为 1 .3～ 1 .4。下超压带分布在整个凹陷范围内 ,起始深度为 2 0 0 0～ 3 0 0 0m ,在凹陷中心较深 ,边缘较浅 ;下超压带超压值高 ,压力系数大 ,可达 1 .5～ 1 .6。在层位上 ,沙一中、上亚段地层压力系数最大 ,沙一下亚段次之 ,沙二段和沙三段压力系数较低 ,各层位的压力系数平面分布趋势基本一致 ,均表现为从凹陷中心 (海岸线位置 )向西南方向压力系数逐渐降低 ,最后变为正常的静水压力。异常压力的分布主要受深度和层位的控制 ,并与成岩作用有密切关系。图 3参 1 0更多还原

【Abstract】 Three pressure zones were identified by pressure data derived from sonic log in Qikou sag, Huanghua depression. These three pressure zones were the hydrostatic zone, the upper overpressured zone and lower overpressured zone. The bottom depth of the hydrostatic zone is approximately 2,000m. The upper overpressured zone mainly occurred in the central part of the sag, while the lower overpressured zone developed all over the sag. The thickness of the upper overpressured zone is only several hundred meters and the pressure coefficient is 1.3-1.4. The top depth of lower overpressured zone is 2,000-2,500m in marginal area and 3,000m in the central part. With the value of 1.5-1.6, the pressure coefficient is higher in the lower overpressured zone than in the upper one. The pressure coefficient is vertically higher in the first member of Shahejie Formation, as compared with that in the second and the third members of Shahejie Formation, and is horizontally higher in the central part of the sag, as compared with that in the marginal area. The distribution of abnormal pressure is mainly controlled by the burial depth and strata, and is also closely related to diagenesis.更多还原