The Study and Application of High Temperature ‑ Resistant Solid Expandable Tubular Technology

The introduction of solid expandable tubular has been successful in the oil and gas industry, normally nitrile-butadiene rubber was vulcanized outside the tubular in order to seal off the annulus between the tubular and the wellbore, and the rubber may fail at about 400K temperature, making the tubular incapable while applied in high-temperature wells. To solve this problem, two kinds of materials aimed at replacing the rubber were considered, one is copper which could be welded upon the tubular, and the other is the steel which is the protruding part of the SET body and can be obtained through machining process. Firstly full-scale expansion tests were performed to compare the impact of copper and steel on the expansion force, given the same length and post expansion interference; secondly the experiments aimed at understanding the sealing ability of the two new materials were carried out in the simulative environment of 673K. The results showed that the use of copper and steel witnessed increased expansion pressure about 10% and 20% respectively compared to rubber, when the two materials were put into 673K environment for pressure testing, both copper and steel demonstrated instable results due to the irregular shape of the casing, therefore the right strategy was to set up sealing components at different part of the SET to increase the chance of success. The test results demonstrated that generally 0.5mm post expansion interference was enough for both to function well at 25MPa. The steel was more reliable than the copper since the latter demands additional process to be integrated with the SET and the field application of the casing patching in the high temperature well selected steel as the sealing material, two months after the operation, the steel passed the test of 15MPa without any leak. We expect this research will contribute to improving the high-temperature resistant ability of expandable tubular, and will help form the technical basis for the future application in some extreme conditions.