Case Study: Performance Analysis of Sub-Surface Safety Valve in Steam Injection Wells for Thermally Assisted GOGD Heavy Oil Field
Authors: Nofali N. , Riyami M. , Amri M. , Shaibani M. , Salama S. 
Published: December 2024

Field-Q is a heavy and sour oil field characterized by a naturally fractured, dome-shaped carbonate reservoir with a compact structure. The recovery mechanism implemented is thermally assisted gas oil gravity drainage (TA-GOGD), where steam is injected at the crest and oil is produced from the base, utilizing fractures for steam distribution and oil collection. The steam injectors are shallow, deviated, open-hole wells drilled at the top crest of the reservoir, penetrating a gas cap containing 3% H2S, which allows for the self-flow of sour gas when steam injection ceases. This paper aims to thoroughly present the application of Sub-Surface Safety Injection Valves (SSSIV) in extremely high-temperature environment. It will address well integrity compliance requirements, well completions and SSSIV design, operational challenges of SSSIV, well intervention case studies, and recent improvements made.

The well integrity requirements for Sub-Surface Safety Valve installation in Field-Q steam injection wells are analyzed through various dispersion model scenarios. The design considerations for well completion to comply with the required well integrity barriers are illustrated, specifically addressing the issue of high temperatures that limits the use of Surface Controlled SSIV (SC-SSIV). The impact of SSSIV installation on steam injection rates, quality, pressure drop, and heat loss is modeled using WellCAT software for different completion sizes, presenting multiple scenarios. Additionally, real case studies are included, highlighting operational challenges, well intervention issues, and the inspection analysis of retrieved SSSIV. The paper also discusses ongoing design improvements and operational practices aimed at enhancing SSSIV performance.

The well integrity requirement to prevent self-flow capability has been successfully met by installing a mechanical SSSIV capable of withstanding high temperatures, with additional barriers incorporated into the Christmas tree. However, the installation of the SSSIV has resulted in varying impacts on steam injection parameters depending on completion size and operational scenarios. Lessons learnt and improvements have been captured from several observations during the injection phase, well interventions, and findings from the inspection analysis of retrieved SSSIV. Consequently, efforts have been made to ensure reliable SSSIV performance and optimized well completion design, along with proper operational procedures. These measures aim to ensure well integrity barriers, avoid complex well interventions, sustain steam injection, and ultimately enhance oil production from Field-Q.

The implementation of SSSIV in high-temperature environments is unique in the industry. This paper presents numerical analysis and real case studies, detailing both challenges and improvements. These insights contribute to the understanding of optimizing steam injection wells in similar thermal enhanced oil recovery projects.