A novel algorithm for evaluating cement azimuthal density based on perturbation theory in horizontal well  

作　　者：Ji-Lin Fan Feng Zhang Qian Chen Hao-Chen Song Lu-Yu Zhong Yue-Xiang Dai 

机构地区：[1]National Key Laboratory of Deep Oil and Gas,School of Geosciences,China University of Petroleum(East China),Qingdao 266580,Shandong,China [2]China National Logging Corporation,Xi'an 710076,Shaanxi,China [3]Sinopec Matrix Corporation,Qingdao 266001,Shandong,China

出　　处：《Petroleum Science》2024年第1期244-251,共8页石油科学（英文版）

基　　金：The authors would like to acknowledge the support of the National Natural Science Foundation of China(41974127,42174147).References。

摘　　要：Cement density monitoring plays a vital role in evaluating the quality of cementing projects,which is of great significance to the development of oil and gas.However,the presence of inhomogeneous cement distribution and casing eccentricity in horizontal wells often complicates the accurate evaluation of cement azimuthal density.In this regard,this paper proposes an algorithm to calculate the cement azimuthal density in horizontal wells using a multi-detector gamma-ray detection system.The spatial dynamic response functions are simulated to obtain the influence of cement density on gamma-ray counts by the perturbation theory,and the contribution of cement density in six sectors to the gamma-ray recorded by different detectors is obtained by integrating the spatial dynamic response functions.Combined with the relationship between gamma-ray counts and cement density,a multi-parameter calculation equation system is established,and the regularized Newton iteration method is employed to invert casing eccentricity and cement azimuthal density.This approach ensures the stability of the inversion process while simultaneously achieving an accuracy of 0.05 g/cm^(3) for the cement azimuthal density.This accuracy level is ten times higher compared to density accuracy calculated using calibration equations.Overall,this algorithm enhances the accuracy of cement azimuthal density evaluation,provides valuable technical support for the monitoring of cement azimuthal density in the oil and gas industry.

关 键 词：Cement azimuthal density Perturbation theory Casing eccentricity Spatial dynamic response function Regularized Newton iteration 

分 类 号：P618.13[天文地球—矿床学]