Density Measurements Of Cement Sheaths Provide Accurate Evaluation Of Oil Well Cementing Operations

Publication Rights Reserved This paper was prepared for the 38th Annual Fall Meeting of the Society of Petroleum Engineers of AIME in New Orleans, La., on October 6–9, 1963, and is considered the property of the Society of Petroleum Engineers. Permission to published 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 Technology or the Executive Secretary. Such abstract should contain conspicuous acknowledgement of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request providing proper credit is given that publication and the original presentation of the paper. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Laboratory and field results have proven the use of density measurements of the cement sheath to provide more information than other methods to evaluate oil well cementing in relation to the well program. Skips, channels, voids, and low density slurries are accurately detected from density measurements. This knowledge compared to the type of completion or rework program desired will assure the engineer of a successful program. A flux of collimated gamma rays directed into pre-set weights of solids and solutions, adjacent to casing, has produced an adequate spread of points that is relative to the bulk density of these materials. The phenomenon of backscattering affected by compton scattering, photoelectric absorption and the mechanics of the sonde has made this possible. Test pit and field data revealed the required mechanics to narrow the zone of inspection to borehole dimensions only. Since the amplitude of the recorder response is subject to bulk density changes of the mass adjacent to the casing, then the result will show the uniformity or the non-uniformity of the solids or solutions in this area. Contamination by a foreign material decreases the cohesiveness of the cement slurry, therefore it reduces the adhesiveness of the cement to casing and adherence of cement to formations. Interpretation of the density curves is easily made by engineers or operators. Typical logs from various areas are shown to support the laboratory development data. The information obtained is a valuable aid lo interpreting neutron logs and chlorine logs as shown by case histories.