基于各向异性深度偏移成像技术在A气田的应用

A气田构造南部和北部地震速度横向变化较大,需要利用变速成图来分析地层真实构造形态。通过各向异性的深度域速度建模和基于深变子波的深度域井震标定得到深度地震数据体,再进行构造解释、井点深度校正,最终得到变速构造图。相比于常速成图,变速成图对应气、水边界与强振幅匹配度更好,井点校正误差更小,计算的动、静储量更匹配。新钻A–B7井钻后证实,变速成图可靠性高,钻前深度预测误差在4 m以内。A气田变速成图较常速成图能更加客观地描述地下真实的构造形态,更好地进行深度预测,指导调整井钻前深度预测。

Application of anisotropic depth migration imaging technology in A gas field

The velocity in the south and north of the structure of A gas field varies greatly, so it is necessary to use variable velocity mapping to analyze the real structural morphology of the strata. The depth seismic data were obtained through anisotropic depth domain velocity modeling and well seismic calibration in depth domain based on deep variable wavelet, and the structural interpretation and well point depth correction were performed to obtain the final variable velocity structural map. Compared with the normal rapid mapping, the gas-water boundary and strong amplitude match better in the variable velocity mapping, with smaller well point correction errors, more matched calculated dynamic and static reserves. The reliability of variable velocity mapping was proved after drilling the newly drilled A-B7 well, and the prediction error of pre-drilling depth was less than 4 m. Compared with the normal rapid mapping, the variable velocity mapping of A gas field is more objective to describe the real underground structural morphology, and can better predict the depth and guide the adjustment of the depth prediction before drilling.