动态速度迭代技术在复杂构造区随钻导向中的应用

Application of Dynamic Velocity Iterative Technique to Steering While Drilling in Complex Tectonic Zones

由于四川盆地边缘页岩气开发区域受到多期构造的叠加改造,构造复杂,导致地层速度变化大,难以精确构建速度模型,井震匹配性差,影响了水平井的钻遇率。为此,结合常规三维地震井位标定,建立标准层,分析地层的各向异性,明确了地层速度纵横向的变化特征,通过对埋深系数与产状进行矫正,并采取纵向速度、横向速度叠加计算建立速度场,不断应用井的层位信息动态更新速度场,确保随钻模型的精度,提高了地震预测靶点深度、判断产状变化规律的准确性。该方法在实际应用中,靶点预测与实钻误差降低至7.7 m,远高于地震分辨率,证实该技术方法的合理性和适应性,可广泛应用于水平井随钻地质导向中。

Since the shale gas development area at the edge of the Sichuan Basin is subject to superimposed transformation of multi-stage tectonics and tectonic complexity,it results in large changes in formation velocity,makes difficult to accurately build a velocity model with poor well-seismic matching,and affects the drilling catching rate of horizontal wells.To this end,we combined conventional 3D seismic well calibration,established a standard formation,analyzed the anisotropy of the formation,clarified the longitudinal and transverse variation characteristics of the formation velocity,corrected the burial depth coefficient and the occurrence,and took the longitudinal velocity and transverse velocity superposition calculation to establish the velocity field;dynamically update the velocity field by applying the formation information of the wells to ensure the accuracy of the drill-following models,improving the accuracy of seismic prediction target depth and the judgement of the occurrence variation pattern.In the practical application of this method,the error between target prediction and actual drilling is reduced to 7.7 m,which is much higher than the seismic resolution,which proves the rationality and adaptability of this technical method,and can be widely used in geosteering of horizontal wells.