Obtaining Successful Shoe Tests in the Gulf of Mexico: Critical Cementing Factors

Author:

Harris Kirk1,Grayson Gary1,Langlinais Joey1

Affiliation:

1. Halliburton Energy Services, Inc.

Abstract

Abstract Approximately one out of six casing shoes in the Gulf of Mexico (GOM) require a cement squeeze job after primary cementing. Numerous theories exist regarding the causes of high shoe-test failure rates, but failure is often attributed to problems associated with the primary cementing job. A GOM database containing information about more than 4,000 shoe-cementing operations was reviewed to find correlations between the success/failure rate and industry-accepted best cementing practices. The results confirm some correlations between the cementing process and shoe-test success; however, no single cementing parameter has an overwhelming effect on shoe failure. Of the industry-accepted best cementing practices, the GOM database shows the following factors to be most important for shoe-test success:pipe movement,maintenance of circulation during cementing,accurate displacement volumes,centralization, andapplication of foam cementing. The cementing parameters that appear to have less effect on shoe-test outcomes weremud properties,displacement rates,spacer volumes, andapplication of a hesitation squeeze at the end of the primary cement job. The review of the GOM database also showed that deeper casings are more susceptible to shoe-test failure, as are wells in deeper water. The data shows a constant rate in shoe-test failures since 1993 and a large variation in success between operators. Introduction After a primary cementing job and before drilling the next hole section, operators usually perform a leakoff test (LOT). Cement is drilled from the shoe track, and a small length of new formation (usually 10 ft) is opened. When pressure is applied to the new formation, the pressure-volume curve simultaneously evaluates the quality of the primary cementing job and the strength of the newly drilled formation. If the pump-in pressure is lower than the expected formation strength, or if the leakoff test exhibits unusual pressure declines, it is usually assumed that there is a cement channel.1 However, debates continue regarding the reasons for the relatively high number of shoe-squeeze failures in the GOM. Is the problem related to poor cementing practices, weak formations, or a combination of both? A database containing information about 4,099 shoe-cementing operations was reviewed to help determine the extent to which cementing practices influence successful leakoff tests. Since 1993, data have been collected by onsite cementing operators and forwarded to a database manager. Almost every aspect of a cementing job is kept in the database, ranging from cement-slurry type to casing-thread specifications. Much of the data were collected through monitoring of industry-accepted cementing practices that achieve good production-casing cementing results, such as the use of pipe movement, large spacer volumes, and centralization. The study described in this paper used the database to help determine whether industry-accepted production-cementing practices are critical to the success of shoe-cementing operations. Shoe Tests and Casing-String Type Four types of casing strings (conductor, surface, intermediate, and drilling liner) were reviewed to help determine success-rate differences. The results show greater success in the shallower casings (Tables 1 through 4). Conductors and surface casings exhibited 13 and 11% failure rates, respectively. However, the database revealed 19% failure rates for both intermediate casings and drilling liners, which is an approximately 60% increase in the failure rate among deeper casings.

Publisher

SPE

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Numerical Modelling of Extended Leak-Off Test with a Pre-Existing Fracture;Rock Mechanics and Rock Engineering;2015-08-07

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