海洋复杂陆坡深水区速度场建立方法探讨

海洋深水探区多在陆坡区,水深变化大,最深超千米,地质条件复杂,探井稀少,难以得到准确的速度场,直接用叠加速度转换深度会导致沉积层构造畸变,若仅用钻井速度预测深水区深度也将导致巨大误差。这里在分析深水速度结构特征和影响因素基础上,通过理论模型正演方法研究优选最佳速度反演的方法;利用钻井速度、叠前相干反演速度及地震叠加速度相互制约,形成了适合白云凹陷深水区的时深转换方法,较好地解决了深水区崎岖海底造成的构造畸变,深度预测精度得到大幅提高。

THE METHOD RESEARCH FOR VELOCITY FIELD ESTABLISHING IN THE COMPLEX DEEPWATER AREA

In the deepwater exploration,it is difficult to get the accurate velocity as there is varying water-depth(most over several kilometers),fewer wells and complex geologic condition in the continental slope area.Depth conversion of the direct use of stack velocity will lead to distortion of sedimentary layer structure.Only use drilling speed for the depth prediction of deepwater area will also lead to large errors.Based on the analysis of velocity structure characteristics and influencing factors,authors select the best velocity-inversion method due to the research of forward modeling.Then buildup the depth conversion method suitable for the deepwater area of baiyun sag,by use of the mutual restraint of drilling speed,velocity of coherent inversion and seismic stacking speed.This method resolves tectonic distortion owing to rough subsea preferably,and improves depth-prediction accuracy consumedly.