Abstract
Coiled tubing abrasion from well completion interference is a prominent failure mode in the industry. Variables influencing the severity of the abrasion include string design, completion design, well tortuosity and the well environment. The complexity of wells has increased which has required the industry to use higher strength coiled tubing materials and, larger diameters of coiled tubing. In doing so, the tubing force analyses suggest higher normal forces against the casing has become standard.
SPE 81724 (Larsen, Reichert 2003) studied the wet and dry abrasion relationship of 90ksi yield coiled tubing against L80 and L80-13Cr completion materials and found dry abrasion to be 250 times more aggressive compared to wet abrasion in those tests. Furthermore, despite the impression that abrasion occurs more often in chrome completions, the results showed chrome completion abraded the coiled tubing at approximately the same rate as the standard L80 in those tests.
Since then, the use of quench and tempered coiled tubing typically in the range of 110-140 ksi. minimum yield strength is mainstream to navigate the increased length and tortuosity of the wells currently being drilled. As a result, abrasion appears to be more frequent, though intermittently reported because failures near the whip end and bottom hole assembly are commonly dismissed in the field near as normal for operations. In instances where the abrasion occurs in the middle of the string, the results can be more challenging for well control.
The purpose of this paper is to further explore the abrasion relationship between conventional 90 grade coiled tubing and some of the newer high strength quench and tempered materials in the 110-140ksi yield range. These coiled tubing materials were mated with various well completion materials including L80, L80-13Cr, P110 and P110-13Cr. Only dry abrasion was investigated at this time to carefully examine the abrasion relationship of each material. In summary, the data further supports the conclusions in SPE 81724 (Larsen, Reichert 2003) where coiled tubing materials showed similar abrasion rates against the various casing materials with and without chrome additions. Furthermore, the casing abrasion rates could be shown to be consistent with their relative hardness: the harder the material, the lower the abrasion rate. Additional future work will also consider friction reducers and varying normal forces.
