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This paper is to be presented at the Mechanical Engineering Aspects of Drilling Production Symposium in Fort Worth, Tex., on March 23–24, 1964, and is considered the property of Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Engineers or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.
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The importance of effective isolation of the producing formations has led to the development of tools to evaluate the bonding of the cement to both the pipe and the formation. In order to record all of these acoustic properties of the cased hole, the Micro-Seismogram Log has been combined with the Acoustic Cement Bond Log.
Properly used, these logs can be used to evaluate cementing techniques early in the development of fields in various areas, thus reducing recompletion and remedial costs. The Micro-Seismogram and Acoustic Cement Bond Logs run before and after cement squeezing verify interpretation of the initial runs by effectively recording changes resulting from the additional cement. Since pressure changed inside the casing will cause the pipe to expand or contract, well studies are included to aid in evaluating this factor.
The purpose of the primary cementing job of the precaution casing is to effectively isolate production zones and to eliminate the production of undesirable fluids. Variations in formations, drilling techniques, and mud programs necessitate a suitable cementing program.
Many time in the case of multiple pay field, the effective isolation of only one or two zones is evaluated by actual test upon initial completion. Information on the hydraulic isolation of other producing zones usually awaits recompletion at some future date in the life of the field. Under these circumstances it is very likely that a decision of whether or not to block squeeze must be made on every well that is to be recompleted. In formations, where some form of well stimulation is performed for commercial production, the necessity for effective isolation is obvious, since cement squeezing of fracture-stimulated formations can possibly damage well productivity by cementing the fractures. Through the proper use of acoustics the entire cemented interval can be evaluated. Thus, the well operator can be aided in adapting a suitable cementing program to meet the specific problem.
The Acoustic Cement Bond Log (ACBL) is an outgrowth of acoustic velocity logging, and it has been in field use for more than three years. The ACBL has had wide spread use in evaluating the cement bonding in individual wells; however, until recently it has not been used to its full potential. The cased hole presents a number of travel paths for the acoustic signal from transmitter to receiver.