The Fluid-Compensated Cement Bond Log

Nayfeh, T.H.; Wheelis, W.B.; Leslie, H. D.

doi:10.2118/13044-pa

Cited by 7 publications

(4 citation statements)

References 2 publications

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“…Despite the careful fluids and cement slurry design this could not be anticipated. [3][4][5][6][7][8][9] . Although the typical CBL interpretation charts and many of the guidelines for cement evaluation logs interpretation are based on cement compressive strength, the acoustic impedance is a better parameter to use for CSE.…”

Section: Sonic and Ultrasonic Logs Refreshmentmentioning

confidence: 99%

Cement Sheath Evaluation in Nonconventional Environment—Case History

Paula

Rodrigues

Vicente³

2007

SPE Annual Technical Conference and Exhibition

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fax 01-972-952-9435. AbstractSonic and ultrasonic tools have been widely used for cement sheath evaluation along the last decades. The evaluation main goal is the definition of the presence of cement in the annulus and its ability of promoting hydraulic isolation among different permeable zones, regardless of its density, compressive strength or even quality of the slurry. The challenges interpreting those logs are enormous because the influence of many variables in the acoustic signal. The difficulties increase dramatically if the well configuration is not conventional. In those cases, huge mistakes can occur requiring from the interpreter experience, understanding of the tools and acoustic principles, and detailed information about the well, casing, cement, and so on. The paper describes in detail three well documented cases histories where nonconventional conditions in the wellbore prevailed and required extreme care and experience to obtain the correct log interpretation. The first case reports the evaluation of an annulus with cement between two concentric casings; the disturbances caused by reflections from the second interface in the CBL signal are discussed and recommendations presented to bypass this obstacle. In the second case, the challenges to evaluate the cement sheath in a fiber glass casing are presented; usually in this case, the first signals arriving at the receiver do not come from the casing. Finally, the last case history describes the difficulties to come up with the right evaluation logging a liner cemented with lightweight slurry. For all cases, guidelines and recommendations are suggested to avoid misinterpretations and assure correct decisions about cement sheath evaluation.

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Section: Sonic and Ultrasonic Logs Refreshmentmentioning

confidence: 99%

Cement Sheath Evaluation in Nonconventional Environment—Case History

Paula

Rodrigues

Vicente³

2007

SPE Annual Technical Conference and Exhibition

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“…Downhole conditions are known to have an effect on the CBL signal. In 1981, Nayfeh et al 6 presented charts showing the influence of temperature, wellbore fluid density and wellbore fluid type on the CBL amplitude in free pipe. One of the most striking results presented was that CBL amplitude in a 7" casing increases by 70% if the casing is filled-up with a 11.5 lb/gal CaCl2 brine instead of water.…”

Section: Known Limitations Of Cbl Interpretationmentioning

confidence: 99%

Integration of Cement Job Data for Better Bond Index Interpretation

Jutten¹,

Toma²,

Morel³

et al. 1991

SPE Production Operations Symposium

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Cement job evaluation has always been a major problem. Acoustic and ultrasonic logs are widely used to assess the quality of the cement job but even experts experience difficulties in locating cement on a bond log. Bond Index (BI) has been the only interpretation method to make quantitative evaluation of the cement job. Unfortunately, BI is far from being an exact figure and in many cases it will not be a valid method to use. Moreover, whenever BI is valid, it is very difficult at present to choose the right references for doing the interpretation. This paper demonstrates that the evaluation of cement jobs can be significantly improved when the design and actual cement job data are taken into consideration. Integration of this data, linked to characterizing the cement by its acoustic properties rather than its compressive strength, allows a calculation of all reference values for a . better BI interpretation, and prevents misinterpretation in many cases. Field cases are also discussed which show the validity and the added benefits of the new integrated approach. 1

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“…243 borehole fluid properties and the temperature or pressure characteristics of the measuring apparatus. 3 Gollwitzer and Masson 2 have disclosed a means of computing a compensated spatial attenuation rate from muitispacing data that is relatively independent of these environmental factors.…”

Section: Introductionmentioning

confidence: 99%