基于小尺度网格层析速度反演的孔隙压力预测方法  

Pore Pressure Prediction Method Based on Small Scale Grid Tomographic Velocity Inversion

作　　者：王智瑞 Wang Zhirui(Geophysical Department of China Oil-field Services Limited,Tianjin 300451,China)

机构地区：[1]中海油田服务股份有限公司物探事业部,天津300451

出　　处：《工程地球物理学报》2022年第4期483-489,共7页Chinese Journal of Engineering Geophysics

基　　金：国家自然科学基金(编号:42004094,42004095)。

摘　　要：深度域层速度场参数是孔隙压力预测方法中最为重要的参数之一,但由于层析成像建模方法受地震资料品质的依赖程度较高,针对复杂构造地层或薄层目标地层,常规层析成像方法的模型建立精度难以得到保障,进而影响孔隙压力预测的精度。针对上述问题,本文提出一种基于小尺度网格层析成像的速度场建立方法,该方法对泥岩欠压实地层目标域构造进行网格剖分,通过解析共偏移距域道集的剩余曲率为自变量的三维矩阵方程以得到每个剖分网格点的剩余速度校正量,进而利用剩余速度校正量进行模型更新迭代,以提高速度场及孔隙压力预测的精度。剩余速度场的分辨率及精度由网格步长大小决定,减小网格步长间距能够提高剩余速度场模型建立的精度及分辨率,但会大幅降低建模效率。运用该方法对泥岩欠压实地层广泛发育的渤海A油田进行了方法测试,由实际资料测试结果分析可知,与常规方法相比,利用小尺度网格层析速度反演方法建立的速度场,能够大幅提高速度场建模的分辨率及精度,进而提高孔隙压力预测的精度,该方法有望在实际生产当中得到广泛的应用。The interval velocity in depth domain is one of the most important parameters in pore pressure prediction methods.However,due to the high dependence of tomography modeling method on the quality of seismic data,it is difficult to guarantee the modeling accuracy of conventional tomography method for complex structural strata or thin-layer target strata,thus affecting the accuracy of pore pressure prediction.To solve the above problems,this paper proposes a method to establish the velocity field based on small scale grid tomography,which meshes the target domain structure of mudstone under compacted formation,and obtains the residual velocity correction of each mesh point by analyzing the three-dimensional matrix equation with the residual curvature of the common offset domain gathers as the independent variable.Then the residual velocity correction is used for model updating iteration to improve the accuracy of velocity field and pore pressure prediction.The resolution and accuracy of the residual velocity field are determined by the grid step size.Reducing the grid spacing step can improve the accuracy and resolution of the residual velocity model,but it will greatly reduce the modeling efficiency.The method proposed in this paper is applied to check on Bohai A oilfield,an area widely developed in mudstone under compacted strata.The actual data show that the velocity field established by the small scale grid tomography velocity inversion method can more greatly improve the resolution and accuracy of the high-speed field modeling compared with the conventional method,and then improve the accuracy of pore pressure prediction.This method is therefore expected to be widely used in similar practical production.

关 键 词：油气勘探 孔隙压力预测 小尺度网格 速度场模型 

分 类 号：P631.4[天文地球—地质矿产勘探]