基于拟合随钻声波时差曲线的地震导向水平井技术

Seismic steering method for horizontal well based on acoustic log reconstruction while drilling

松辽盆地北部扶余油层是近几年致密油勘探的热点领域.针对平面展布窄小、厚度超薄储层的地震导向水平井问题,提出了基于拟合随钻声波时差曲线的地震导向水平井技术.其实现过程可概括为:(1)钻前利用已知直井拟合声波时差曲线,在此基础上开展纵波阻抗地质统计学反演,提高储层预测精度,优化井位轨迹设计;(2)钻探过程中目的层上方钻遇标志层(青山口组三套油页岩)时,调整时深转换参数,重新设计井轨迹;(3)钻头进入扶余油层,利用随钻伽马曲线阶段性拟合声波时差曲线,在此基础上开展动态拟纵波阻抗地质统计学反演储层及深度预测,指导井轨迹调整.通过对水平井Z的模拟分析,证明该方法可以有效导向水平井入靶、指导水平井钻进的同时,也能满足钻井现场的时效性要求.

Fuyu reservoir is one of the hottest fields of tight oil exploration in recent years. High precision depth and reservoir prediction of target ＂sweet point ＂ is helpful for the high sand drilling rate of horizontal well in thin-bed reservoir. To improve the precision,a seismic steering method for horizontal well based on acoustic log curve reconstruction while drilling is carried out. Three steps are taken in this method. Firstly,MRGC（Multi-Resolution Graph Based Clustering） method is used to reconstruct Gamma ray log curve to quasi acoustic log curve which can distinguish between sand and shale better than the practical acoustic log curve. Before drilling,Quasi P-wave impedance geostatistical inversion is carried out to improve the accuracy of reservoir prediction and to optimize well trajectory design; Secondly,in the process of drilling,well trajectory is redesigned based on time-depth conversion parameters adjustment when the bit meets some key beds above the target＂sweet point＂; Lastly,when the bit goes into Fuyu reservoir,acoustic log curve is reconstructed by using Gamma ray log curve of LWD. Based on the reconstructed acoustic log curve, dynamic quasi P-wave impedance geostatistical inversion could be carried out to predict reservoir dynamically in drilling process. This method can not only provide high precision seismic steering for horizontal well landing,but also provide guiding help when geosteering horizontal section. Through the simulation analysis of horizontal well Z,it is proved that the method is not only helpful for target point landing and horizontal section drilling,but can meet the requirements of the efficiency while drilling on the drilling site.