储层界面预测模型在水平井地质导向中的应用

目前地质导向前导模型中储层界面预测方法只适用于较稳定的地层，对于构造变化大的储层预测结果与实际情况存在较大误差，需要对其进行完善。选择适当的邻井，以正北方向为y轴建立直角坐标系，在直角坐标系下计算出待钻水平井的多处水平位移和对应储层界面垂深点，将得到的这些点利用曲线拟合的数学方法建立二维储层界面预测模型，它是水平位移与储层界面垂深的二元函数。利用储层界面预测模型判断储层上下倾、计算储层的视倾角并判断钻头与储层界面的相对位置。应用储层界面预测模型对JL区块的一口水平井进行了现场预测，结果表明最终的储层界面预测模型为拟合效果最好的二次函数，拟合度达到了68%；预测出的储层界面垂深与实际垂深基本相吻合；在横向展布上预测的储层界面起伏变化与实际完全一致。研究表明，选择6口邻井数据得到拟合度为68%储层界面预测模型可以满足着陆和导向需要；预测结果的准确度与选择的邻井数呈正相关。研究结果为水平井地质导向钻进提供指导依据，提高钻遇率。

Application of the reservoir interface prediction model in geosteering of horizontal wells

Current reservoir interface prediction method of pre-drilling geosteering models works well in prediction of stabile formations,but it gives a relatively big error when predicting reservoir interfaces in a complex structural setting.Selecting appropriate adjacent wells and establishing a rectangular coordinate system with north direction as the y axis we calculated the horizontal displacement of the horizontal wells and the corresponding depth of the reservoir interface in the rectangular coordinate system,and built a 2D reservoir interface prediction model by using the mathematical method of curve fitting.This model is a binary function of horizontal displacement and reservoir interface.The reservoir interface prediction model is used to determine reservoir dips and calculate apparent dip angles and the relative displacement between bit and reservoir boundaries.The model is applied to predict a horizontal well in JL block,and the results show that the final reservoir interface prediction model is a quadratic function with a fitting degree of 68%.The predicted vertical depth of reservoir interface basically coincides with the actual vertical depth,and the predicted relief of reservoir interface is consistent with the actual relief on map view.The results show that the reservoir interface prediction model with a fitting degree of 68% built based on the data of 6 adjacent wells can meet the needs of landing and geosteering.The accuracy of the prediction results is positively correlated with the number of adjacent wells chosen.The results can provide guidance for geosteering of horizontal well and effectively keep the horizontal well within the target interval.