5 1/2 in. Subsurface Safety Valve Development and Qualification for CCS/CCUS Wells

Abstract This paper discusses the development and qualification of a 5 ½ in. tubing mounted surface controlled subsurface safety valve for Carbon Capture and Storage (CCS)/Carbon Capture, Utilization, and Storage (CCUS) well environments where the design and qualification program specifically addresses the challenging operating and survival well temperature conditions reaching extremes of −35°C and −78.5°C respectively. The 5 ½ in. CCS/CCUS safety valve was based on an existing field-proven and reliable platform that has, and continues to serve, the oil and gas industry. A FMECA performed on the existing platform highlighted the prudent focus areas, enabling early derisking and contingency planning to take place. Post-FMECA derisking activity included an extensive metallic and non-metallic material evaluation, identifying suitable materials for extreme low temperature applications and exposure to high concentration CO2. Additionally small-scale testing was performed on the non-elastomeric high performance rod piston seal assembly which demonstrated dynamic operation at −35°C and static survivability at temperatures down to −78.5°C, even under low- and high- differential pressure conditions. The small-scale testing also examined functionality of the flapper and seat assembly, as well as the body connections, at the mentioned CCS/CCUS operating and survival well conditions providing a high degree of confidence ahead of full-scale testing. Full scale testing followed an adapted version of API 14A annex G.3 where over 550 operating cycles were performed on a full-scale valve at various temperatures, down to −35°C, both before and after exposure to a survival condition at −78.5°C. Pressure sealing integrity of all critical components was proven at low and high pressures of up to 10,000 psi even at the survival condition of −78.5°C. A differential opening test, following an adapted version of API 14A annex G.4, was conducted at −35°C to prove continued functionality after a slam-open event at extreme temperatures. All testing used a gas medium where zero leakage across the sealing components was identified through the entire test sequence. Small- and full-scale testing was performed with different control line fluids, including oil and water based, without incident. Additional API prescribed testing was conducted to enable API 14A 13th edition monogramming per a V1-R validation grade. The development and qualification protocol were propagated across a range of common safety valve sizes for the wider CCS/CCUS market: 3 ½-in., 4 ½-in, 5 ½-in. and 7-in resulting in the release of a new portfolio of Tubing Retrievable Surface Controlled Subsurface Safety Valve Technologies.