BJC-FJ直连型特殊螺纹套管开发OA

Aiming at the challenges of limited drift diameter,high running friction,low tensile efficiency,and insufficient sealing reliability under cyclic loading associated with traditional coupling-type casings in the casing-in-casing wellbore reconstruction process for old wells,this paper develops the BJC-FJ flush joint connection two-stage metal-sealed premium casing.This product is specifically designed for ultra-narrow gap working conditions such as old well repair and wellbore reconstruction.An innovative connection structure featuring a hook-type buttress thread+two-stage metal seal+reverse double positioning shoulderwas designed to achieve the unification of maximized inner drift diameter and superior gas sealing performance within the same specification.Through numerical simulation and full-scale physical performance evaluation,the gas sealing reliability of the joint under combined loads of tension/compression,internal/external collapse pressure was verified.Experimental data demonstrate that the Φ88.9 mm×6.45 mm 125V BJC-FJ connection possesses excellent connection strength and anti-leakage capabilities.Field application results confirm that the BJC-FJ flush joint connection casing successfully meets the rigorous requirements for casing running,cementing operations,and large-scale repeated fracturing treatments.This study verifies that the BJC-FJ flush joint connection premium casing effectively resolves the contradiction between drift diameter and sealing performance in wellbore reconstruction,providing reliable key equipment support for the efficient potential tapping of old wells in unconventional oil and gas reservoirs.