同时反演泥浆与环空介质声阻抗的超声脉冲回波固井质量评价方法  

An algorithm to simultaneously inverse the mud and cement acoustic impedances from the ultrasonic pulse-echo measurement in a cased-hole

作　　者：杨耿骁 王华 YANG GengXiao;WANG Hua(University of Electronic Science and Technology of China,School of Resources and Environment,Chengdu 611731,China;Shenzhen Institute for Advanced Study,University of Electronic Science and Technology of China,Shenzhen Guangdong 518110,China)

机构地区：[1]电子科技大学资源与环境学院,成都611731 [2]电子科技大学(深圳)高等研究院,广东深圳518110

出　　处：《地球物理学报》2023年第10期4370-4385,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41974150,42174158);中央高校基本科研业务费项目(ZYGX2019J071,ZYGX2020J013)资助。

摘　　要：固井质量评价是石油勘探开发过程中极为重要的一个环节,对油气资源勘探开发效益以及油气资源安全生产和环境保护都有十分重要的意义.超声脉冲回波技术可以计算套管和地层间环空介质(水泥)声阻抗,从而判断环空材料的种类以评价固井质量.传统的水泥声阻抗计算方法将井筒内的泥浆声阻抗看作是在环向上和轴向上均匀不变的值,会导致计算的水泥声阻抗不准.为了解决这一问题,本文利用多层介质模型的模拟数据研究了水泥声阻抗、泥浆声阻抗与脉冲回波波形在时域共振波区间内变换后的拟合直线的特征斜率与特征截距的变化规律,提出了同时反演水泥声阻抗和泥浆声阻抗的方案.通过比较模拟数据、刻度井测量数据中的特征斜率和截距,并构造迭代公式不断迭代水泥声阻抗、泥浆声阻抗,形成了同时得到水泥声阻抗和泥浆声阻抗值的数据处理流程.数据处理流程经过等比刻度井数据测试,反演结果与模型井实际情况一致,证明了本文提出的数据处理流程的正确性.最后将本文的数据处理方法应用在某油田实测数据中,并与传统数据处理结果进行了对比.Cement bond evaluation is extremely important in oil/gas exploration and development,which is of great significance to the efficiency of oil and gas development,as well as the safe production and environmental protection.The ultrasonic pulse-echo technology can calculate the acoustic impedance of the annular medium(cement)between the casing and formation,so as to determine the material type in the annulus for cement bond evaluation.The traditional cement acoustic impedance inversion method regards the borehole mud acoustic impedance as a constant in the azimuth and axis,which is inconsistent with the field situation and will lead to inaccurate cement acoustic impedance in the calculation.Aiming to solve this problem,this paper uses the simulation data from a multilayered model to study the influence of the acoustic impedances of borehole mud and cement on the extracted characteristic slope and intercept from a fitting line on the waveforms in a semi-logarithmic coordinate.Then a scheme to simultaneously inverse the mud and cement acoustic impedances is proposed.We construct the iterative formula to continuously iterate the borehole mud and cement acoustic impedances after comparing the characteristic slope and intercept in both the simulation data and the full-scaled calibration well measurement data.Then we form a data processing process to determine the cement and borehole mud acoustic impedances at the same time.The data processing process is tested by the data from a full-scaled calibration well,and the inversion result is consistent with the actual situation of the model well,which proves the correctness of the proposed data processing process.Finally,the proposed data processing method is applied to a field data set in a well from an oilfield.

关 键 词：固井质量评价 超声脉冲回波 声阻抗反演 

分 类 号：P631[天文地球—地质矿产勘探]