Criterion for Gas Seal Tightness of Premium Connection of Oil Country Tubular Goods

摘要

The application of casing in a high pressure well increasingly exposes various problems in the performance of casings. One of the biggest concerns is seal tightness connection, since an available criterion for seal tightness is not fully determined. In general, not only premium connection (PJ) but also API connection have a high seal tightness and there are few troubles of leakage. A tentative criterion for seal tightness of the radial seal surface of PJ has been proposed. The criterion is derived from experimental leak test results and Finite Element Analysis. It is also composed of sealing contact pressure and contacting width on the radial seal surface. However, the criterion is not yet formulated.In this paper, the criterion is evaluated by approximate application of the thin cylindrical shell theory and is formulated. The results are summarized as follows:1)A criterion for seal tightness of the radial seal surface is formulated by two factors, i.e., sealing contact pressure and contacting width.2)The criterion is formulated using the function type derived from the thin cylindrical shell theory, i.e., it is represented by a multiplier of sealing pressure and 2-order polynomial of contacting width.