Changes

Cement evaluations are primarily done with cement bond logs or pulse-echo cement evaluation tools. These are acoustic devices whose main objectives are the measurement of cement annular fill around the casing.

Cement evaluations are primarily done with cement bond logs or pulse-echo cement evaluation tools. These are acoustic devices whose main objectives are the measurement of cement annular fill around the casing.

The ''cement bond log'' (CBL) measures the degree to which cement contacting the pipe on the outside attenuates an acoustic signal traveling along the pipe.<ref name=pt09r21>Pardue, G. H., Morris, R. L., Gollwitzer, L. H., Moran, J. H., 1963, Cement bond log—a study of cement and casing variables: Journal of Petroleum Technology, May.</ref><ref name=pt09r9>Fitzgerald, D. D., McGhee, B. F., McGuire, J. A., 1983, Guidelines for 90% accuracy in zone isolation decisions: Richardson, TX, Society of Petroleum Engineers, SPE 12141.</ref><ref name=pt09r25>Western Atlas International, 1985, Acoustic Cement Bond Log and Prolog CBL: Houston, TX, n. 2206.</ref> [[:file:production-logging_fig6.png|Figure 6]] illustrates how the acoustic signal is affected by the presence of cement. The initial portion of the acoustic signal or signature indicates the amplitute of the signal traveling along the pipe. The a mplitude curve records the amplitude of this initial portion or pipe signal. A low amplitude indicates good bond, while a very high signal amplitude shows free pipe. This amplitude measurement can be converted to percent annular fill of cement. The ''variable density log'' (VDL) at the far right of [[:file:production-logging_fig6.png|Figure 6]] is a contour map of the received wavetrain signature as it changes with depth.

The ''cement bond log'' (CBL) measures the degree to which cement contacting the pipe on the outside attenuates an acoustic signal traveling along the pipe.<ref name=pt09r21>Pardue, G. H., R. L. Morris, L. H. Gollwitzer, and J. H. Moran, 1963, Cement bond log—a study of cement and casing variables: Journal of Petroleum Technology, May.</ref><ref name=pt09r9>Fitzgerald, D. D., B. F. McGhee, and J. A. McGuire, 1983, Guidelines for 90% accuracy in zone isolation decisions: Richardson, TX, Society of Petroleum Engineers, SPE 12141.</ref><ref name=pt09r25>Western Atlas International, 1985, Acoustic Cement Bond Log and Prolog CBL: Houston, TX, n. 2206.</ref> [[:file:production-logging_fig6.png|Figure 6]] illustrates how the acoustic signal is affected by the presence of cement. The initial portion of the acoustic signal or signature indicates the amplitute of the signal traveling along the pipe. The a mplitude curve records the amplitude of this initial portion or pipe signal. A low amplitude indicates good bond, while a very high signal amplitude shows free pipe. This amplitude measurement can be converted to percent annular fill of cement. The ''variable density log'' (VDL) at the far right of [[:file:production-logging_fig6.png|Figure 6]] is a contour map of the received wavetrain signature as it changes with depth.

The ''pulse-echo cement bond log'' (CET) operates in an entirely different acoustic mode than does the CBL.<ref name=pt09r10>Froelich, B., Dumont, A., Pittman, D., Seeman, B., 1982, Cement evaluation tool—a new approach to cement evaluation: Journal of Petroleum Technology, August.</ref> The pulse-echo tool is effective at measuring the compressive strength of cement behind pipe, as well as detecting the presence of liquid or gas behind pipe. The main presentation of the pulse-echo tool is the cement map shown on the right of [[:file:production-logging_fig7.png|Figure 7]]. The dark areas correspond to cement, and the white areas indicate the lack of it. With such a cement map, likely channels can be readily detected.

The ''pulse-echo cement bond log'' (CET) operates in an entirely different acoustic mode than does the CBL.<ref name=pt09r10>Froelich, B., A. Dumont, D. Pittman, and B. Seeman, 1982, Cement evaluation tool—a new approach to cement evaluation: Journal of Petroleum Technology, August.</ref> The pulse-echo tool is effective at measuring the compressive strength of cement behind pipe, as well as detecting the presence of liquid or gas behind pipe. The main presentation of the pulse-echo tool is the cement map shown on the right of [[:file:production-logging_fig7.png|Figure 7]]. The dark areas correspond to cement, and the white areas indicate the lack of it. With such a cement map, likely channels can be readily detected.

===Casing inspection===

===Casing inspection===