陈雪莲^1,2,,
唐晓明^1,2,,
1. 中国石油大学(华东)地球科学与技术学院, 青岛 266580
2. 中国石油大学(华东)深层油气重点实验室, 青岛 266580

基金项目: 国家自然科学基金（41774141，41804124，41821002）和中石油重大科技项目（ZD2019-183-004）联合资助


详细信息

作者简介: 陈雪莲, 1976年生, 女, 副教授, 2006年获中国石油大学(华东)地质资源与地质工程专业博士学位, 主要从事声波测井方法及岩石物理的教学和科研工作.E-mail:chenxl@upc.edu.cn

通讯作者: 唐晓明, 1955年生, 男, 现中国石油大学(华东)工作, 教授, 博士生导师, 主要从事地球物理(特别是声波)测井、岩石物理学、地震波传播及测量等方面的研究和技术开发工作.E-mail:tangxiam@aliyun.com

中图分类号: P631

收稿日期:2020-04-30
修回日期:2020-09-30
上线日期:2021-01-10

The wavefield characteristics of dipole acoustic logging in a double-casing well

CHEN XueLian^1,2,,
TANG XiaoMing^1,2,,
1. School of Geosciences, China University of Petroleum, Qingdao 266580, China
2. Key Laboratory of Deep Oil and Gas, China University of Petroleum, Qingdao 266580, China


More Information

Corresponding author: TANG XiaoMing,E-mail:tangxiam@aliyun.com

MSC: P631

--> Received Date: 30 April 2020
Revised Date: 30 September 2020
Available Online: 10 January 2021


摘要
摘要:多层套管井中的套管-水泥以及水泥-地层在径向上的分布较单层套管井界面多且径向分布范围更深.目前还未有针对多层套管井固井质量评价的有效方法，偶极子阵列声波测井具有工作频率低径向探测深的优势，本文通过实轴积分和三维有限差分计算了偶极子声源在不同胶结状况的双层套管井中激发的声场，旨在探讨偶极子阵列声波在双层套管井中评价外层套管和地层之间胶结状况的可行性.计算结果表明，在两层套管之间充填泥浆时，全波波形中可明显观测到地层弯曲波和套管弯曲波，若外层套管和地层之间充填水泥套管弯曲波的慢度明显高于充填泥浆时的慢度值；在外层套管和地层之间胶结的水泥出现缺失，套管弯曲波的频散曲线会处于完全胶结与完全无胶结之间，其变化量与水泥在外层环空的占比近似成线性关系，几乎不受水泥缺失的径向位置影响.由于偶极子声源的指向性，套管弯曲波的响应特征主要受与声源振动指向的方位扇区胶结状况的影响；在两层套管之间充填水泥时，若外层套管和地层之间充填泥浆，仍可观测到套管弯曲波，模拟波列提取的套管弯曲波的频散曲线与解析解计算的频散曲线吻合，两层套管通过水泥胶结在一起，其弯曲振动的传播速度稍有增加，类似单层套管厚度加厚的响应特征.两种模拟方法得到的结果均表明套管弯曲波对外层套管和地层之间的充填介质敏感，验证了偶极子阵列声波测井在双层套管井固井质量评价中应用的可行性.
关键词: 双层套管井/
偶极子声源/
套管弯曲波/
频散/
水泥胶结

Abstract:Compared with the conventional single-casing well, the multi-casing well has more layered interfaces and a deeper radial distribution of the interfaces. At present, the industry needs a method for evaluating the cement quality of multi-layer casing wells. The dipole array acoustic logging has the advantage of low operation frequency and deep radial depth of penetration. In this paper, the dipole acoustic wavefield is calculated respectively using the real axis wavenumber integration and the three-dimensional finite difference waveform modeling methods. The wavefield excited in the double-casing wells with different cementation conditions was analyzed to explore the feasibility of using dipole array acoustic logging for evaluating the cementation quality between the outer casing and the formation in the double-casing wells. The calculation results show that, when the mud fills the annulus between the inner and outer casing layers, the formation- and casing-flexural waves can be clearly observed in the full-wave data; in addition, the slowness of the casing flexural wave is significantly higher when the outer casing and the formation are filled with cement than filling with the mud; by proportionally decreasing the amount of cement between the outer casing and the formation from fully cemented to no-cement conditions, the casing flexural-wave dispersion curve varies between the two extreme conditions, and its variation is approximately linearly proportional to the cement portion of the annulus, and is insensitive to the radial position of the cement. Due to the directionality of the dipole source, the response characteristics of the casing flexural-wave are mainly affected by the cementation condition in the azimuthal sector in the source vibration direction. In the case that the two layers of casing are well cemented but the outer casing and the formation are filled with the mud, the casing flexural wave can still be observed. The wave dispersion characteristics extracted from the simulated wave data and those calculated from the analytical solution are in good agreement. Cementing the two layers of casing appreciably increases the casing flexural-wave speed, a response characteristic similar to that of a thickened single-layer casing. The results obtained by the two simulation methods indicate that the casing flexural-wave is sensitive to the filling material between the outer casing and the formation, verifying the feasibility of using dipole acoustic logging for cement evaluation in double-casing wells.
Key words:Double-casing well/
Dipole acoustic source/
Casing flexural wave/
Dispersion/
Cement



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