基于随钻方位伽马和电磁波电阻率的井下可视化地质导向技术

Downhole Visualized Geosteering Technology Based on Azimuth Gamma and Electromagnetic Wave Resistivity Logging While Drilling

水平井钻井过程中不能直接观测地层的地质结构,常常造成轨迹调整不及时而脱离钻井目标。提出一种地层实时可视化井眼轨迹导向技术,提高水平井钻遇率。借助已钻井的测井数据和随钻实时数据,基于随钻方位伽马和电磁波电阻率测井,整合井周三维建模地层预测、井下导向可视化、随钻实时地层走向自动分析及边界自动预测,实现地层可视化精准预测。地层初始模型采用地震层面约束下的多井井周地层反演技术构建;地层走向采用近钻头伽马确定;地层边界位置利用远探测电阻率确定。充分发挥各类型仪器探测优势,综合多类型测井数据,保证技术目标实现。该技术已进行现场应用,精确预测了地层的地质特征,保证了高时效优质钻井,为提高优质储层钻遇率提供了新的技术手段。

The purpose of drilling a horizontal well is to drill as more reservoirs as possible to increase recovery.In complex strata,it is difficult to adjust the trajectory in time because the geological structure before the bit cann’t be seen while drilling.A real-time visualization technique is proposed to guide drilling operation and improve drill-in rate.Based on logging and drilling data of drilled wells,and the real-time LWD data of the well being drilled,i.e.azimuth gamma and electromagnetic wave resistivity,the technique realizes formation visualization and accurate target prediction by building a near-wellbore 3D model,visualized downhole navigation,real-time formation strike analysis and automatic boundary prediction while drilling.The initial formation model is constructed by multi-well formation inversion with seismic constraints,formation strike is determined by near-bit gamma data,and formation boundary is determined by remote detected resistivity.The technology takes full advantages of logging tools and full use of logging data.Field application has proved that it can accurately predict gelogical characteristics and ensure accurate and fast drilling.It provide a new technical means to improve the drill-in rate of good reservoirs.