The Prediction and Control of Casing Wear (includes associated papers 6398 and 6399 )
- William B. Bradley | John E. Fontenot
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- February 1975
- Document Type
- Journal Paper
- 233 - 245
- 1975. Society of Petroleum Engineers
- 7 in the last 30 days
- 728 since 2007
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Casing wear is a problem in many wells and can cause abandonment of a well before reaching total depth, or can lead to a blowout. Procedures for estimating casing wear caused by rotating, tripping, and running wireline have been developed. Based on results of extensive laboratory study, they allow consideration of, among other things, dog-leg severity, coupled with drillstring tension, mud solids, and drillpipe protectors.
Casing wear is a problem in many wells. In directional holes, very deep holes, and medium-depth abnormally pressured holes, it can become a critical problem. It can cause the abandonment of a well before reaching total depth or, in certain cases, it can lead to a blowout. The objective of the work reported here was to develop better methods for the prediction and control of casing wear. To develop better predictive methods, casing wear rates were measured under controlled conditions. Laboratory measurements were made to define the major factors in rotating, tripping, and wireline wear. This paper compares the various modes of casing wear and develops procedures for estimating field wear rates.
Although casing wear has been a problem for many years, published literature on the subject is meager. In the United States, tests have shown the value of fine-particle tungsten carbide hardbanding on the reduction of casing wear by rotating tool joints. The remaining body of literature on casing wear comes primarily from Russia. Laboratory tests have been run there to determine casing wear rates by drillpipe rotation. Unfortunately, they were run in drilling muds without abrasives. Russian investigators have also studied the wearing mechanisms of abrasives, but their studies were not done with casing. The effects of other variables on the casing wear process have also been studied by Russian investigators. Theoretical calculations of wear because of drilling, tripping, and connecting were made. But, without experimentally determined wear rates, these calculations are of little value. Test results also show that the hardness of the casing does not greatly affect its wear resistance. Analysis of recovered casing has indicated that, in many instances, temperatures of the wear surfaces reach 900 to 1,000 degrees C. Wearing under these conditions can produce significant cracking of the casing wall and a substantial reduction in casing strength. Casing damage by drill bits during tripping has also been reported by the Russian investigators. The ability of drillpipe rubbers to prevent contact between the drillstring and casing is discussed in Ref. 15. Tests to determine the deflection of the protectors under various conditions of load, mud, and temperature are reported. These results are similar to the results reported in Ref. 1. Physical damage to the protectors from casing joints during tripping is also discussed. Calculations and casing-design considerations to minimize failure of casing because of wear are reported in Refs. 5, 10, 16, and 17. Measurement of drag forces at points of contact in wells is reported in Ref. 16.
|File Size||873 KB||Number of Pages||13|