CHEN Dehua1,2 WANG Xiuming1 ZHANG Hailan1 WANG Dong1 WEI Tao3 LIU Liping3

(1 State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences Beijing 100190)

(2 Department of Geophysics, Daqing Petroleum Institute Daqing 163318)

(3 Logging Center of COSL Yanjiao 101149)

Received Mar. 20, 2009

Revised Jun. 25,2009

Abstract The acoustic field in a cased hole is studied through numerical modeling by combining experiment measurement when the first and scond interfaces are bonded well. The effects of the density of the cement, the diameter and thickness of the steel pipe on the amplitude of casing arrival (ACA) are investigated, and a part of the numerical results are compared with the experimental results. These results show that the ACA decreases with the increasing density of the cement. There exists a large difference between the ACAs for the low- and normal-density cements. Therefore, the different standard should be taken in the bonding evaluation for cements with different densities. As the thickness of the steel pipe increases while its diameter keeps as a constant, the arrival time of the casing wave remains unvaried, while the ACA increases. But, when the diameter of the pipe with a constant thickness increases, the arrival time of the casing wave is delayed, and the ACA decreases. As for three kinds of the steel pipe commonly used in oilfields, the relative amplitude of the casing arrival is larger in the big pipe. In addition, the numerical results of the varying trend of the relative amplitude of the casing arrival with the density of cements, on the whole, are in agreement with the experimental ones.

PACS numbers: 43.35, 43.40, 91.60