Advancement of wellhead sealing technologies during production well servicing

UDK: 622.245.73

DOI: 10.24887/0028-2448-2026-7-58-61

Key words: blowout preventer, wellhead assembly, well equipped with two-tubing-string assembly, dual completion for production, dual completion for injection, risk of gas, oil, water blowout

Authors: S.А. Mokeev (TatNIPIneft, RF, Almetyevsk); R.Z. Ziyatdinov (TatNIPIneft, RF, Almetyevsk); K.M. Garifov (TatNIPIneft, RF, Almetyevsk); D.N. Makarov (Well Servicing Department, Tatneft PJSC, RF, Almetyevsk)

This research aims to examine the disadvantages of existing equipment and consider the features of designed blowout preventer installed at wellhead of production well equipped with two-tubing-string dual completion system. Well servicing of hazard class I and II wells necessitates reliable industrial safety control. Existing preventers are incompatible with dual-string wellhead assemblies, thus posing a risk of uncontrolled release of gas, oil, and water and resulting in failure to meet the requirements of Blowout Prevention Service of the Ministry of Emergency Situations of Russia regarding the obligatory use of blowout prevention equipment. To address the above challenges, engineers of Well Servicing Technology Sector of TatNIPIneft’s Well Operation and Workover Department improved existing preventer designs and developed wellhead sealing technologies for wells equipped with two-tubing-string downhole assembly depending on wellhead equipment type. At wellhead assembly 2ANK-50/40x2, 2ANK-40x21, 2ASHK-50/40x21 or 2ASHK-40x21, advanced double-ram blowout preventer PPS-2F-180x21-2K is used which has two levels of pipe rams, where the opening formed by the upper ram level is offset relative to the bore of blowout preventer. Modified PPShR-2F-152x21 preventer with accessories is used with AUD 50x14 or AUD 40x14 wellhead assemblies. The equipment and technology were successfully field tested in seven wells with two-tubing-string downhole assemblies. The work was presented to Technology Innovation Board and included in TATNEFT PJSC best corporate practices. The developed solutions enable compliance with industrial safety regulations and efficient servicing of dual-tubing-string dual completion wells, minimizing the risk of gas, oil, and water blowouts.

References

1. On approval of the federal norms and regulations in the field of industrial safety “Safety Rules in the Oil and Gas Industry”: Order of Rostechnadzor dated December 15, 2020, no. 534

2. Patent RU2808812C1, Bop for a well with a double-row pipe string, Inventors: Mokeev S.A., Ziyatdinov R.Z.

3. Patent RU2805701C1, Method for installing preventer on support flange of wellhead assembly and constant tripping out two-lift arrangement of downhole equipment from well and device for its implementation, Inventors: Mokeev S.A., Ziyatdinov R.Z., Makarov D.N.