马头营地区低幅度构造速度建模方法

冀东马头营地区馆陶组低幅度构造具有很大的油气勘探潜力。该区地表结构复杂、断层发育，一直受深度域速度模型精度限制，低幅度构造圈闭难以识别。为此，提出一套新的综合速度建模方案：首先，考虑断层的影响，在时间偏移域建立准确的层位解释模型，采用基于地质层位解释的横向速度建模方法，有效消除断层导致的横向速度剧烈变化带来的影响；其次，考虑在叠前深度域偏移中浅层速度模型的误差累积会影响深层目的层成像质量，浅层采用回转波层析成像反演出精确的近地表速度场，中深层采用反射波层析成像速度建模，二者结合获得融合速度场；最后，在融合速度场基础上，采用以地质层位为约束、基于模型的高精度网格层析进行速度优化，提高速度模型精度。应用上述方案建立的高精度层速度模型，明显提高了冀东马头营低幅度构造的成像精度及与钻井资料的吻合度，该建模方案可为相似地质条件下低幅度构造成像提供借鉴。

Velocity modeling of the low-relief structure in the Matouying area of Jidong Oilfield

The low-relief structure of the Guantao Formation in the Matouying area of Jidong Oilfield is very potential in exploration. However,with complex terrains and developed faults,and limited by less accurate depth-domain velocity models,it is difficult to identify the low-relief structural traps. To this end,a new and comprehensive velocity modeling scheme is proposed as follows:Considering the influence of faults,first establish an accurate horizon interpretation model in time domain,and based on the model,effectively eliminate the impact of dramatic changes in lateral velocity caused by faults;second,considering that error accumulation of the shallow velocity model in prestack depth migration affects the imaging quality of deep target layers,invert the accurate near-surface velocity field by diving wave tomography for shallow layers,build the velocity model by reflected wave tomography for middle layers,and combine the two parts to obtain a merged velocity field;finally improve the velocity model on the basis of the merged velocity field and model-based high-precision grid tomography under the constraint of geological horizons. The high-precision velocity model established by the above scheme has significantly improved the i-maging accuracy of the low-relief structure in the Matouying area in the Jidong Depression,and the result is consistent with drilling data. This modeling scheme is a reference to imaging low-relief structures with similar geological conditions.