A New and Innovative Technology for Cement Evaluation

Abstract

Abstract The Segmented Bond Too] is a new, innovative acoustic logging device that utilizes six pads and twelve high-frequency, steered transducers to accurately evaluate cement integrity both longitudinally and radially around the entire casing periphery Two comprehensive presentations are available, both of which are easily interpreted. Several examples from commercial and test wells emphasize the versatility of this new high-tech too] design. Introduction The Segmented Bond Tool (SBT) is an acoustic logging device that employs six pads and twelve high-frequency, steered transducers to accurately evaluate cement integrity. The high-tech tool design, innovative user-friendly presentation schemes, and example cases will demonstrate the SBT's versatility. The fully compensated SBT attenuation measurements are made on the internal wall of the casing, essentially eliminating most centering problems associated with other bond log devices. Tool design and problems associated with other bond log devices. Tool design and surface instrumentation effectively segment the wellbore into six 600 segments providing complete 3601 evaluation of the pipe circumference. The SBT is capable of logging casing sizes from 4.5 in. (114.3 mm) to 16 in. (406.4 mm), is tolerant of slight eccentering due to the pad configuration, and because there is no mud path, the SBT is insensitive to borehole fluid content. The system is essentially independent of fast formation arrivals because of the short transducer spacing and early gate selection. A 5-ft [1.52-m] omnidirectional transmitter-receiver pair is also provided for full wave acoustic Signature or Variable Density [VDL] presentation to evaluate acoustic coupling to the formation, thus providing a stand-alone system. Surface systems generate two comprehensive well-site presentations. For the well-versed bond log analyst, a Primary presentation is displayed in conventional cement bond log (CBL) or Bond Attenuation Log (BAL) format, with some added features. A new and innovative Segmented Array, presentation displays a comprehensive user-friendly cement map, attenuation rates for each of the six segments, and an orientation trace that identifies the low side of the instrument in a deviated borehole. The cement map is shaded in five tones varying from black (excellent cement quality through three diminishing shades of gray to white (essentially uncemented), and is presented and scaled in a manner that quickly identifies the vertical and radial distribution of cement integrity. Implementation of this new cement evaluation technology will ultimately simplify many economic and technical decisions affected by well cementing conditions. p. 579