Sustained annulus pressure is an increasingly common well integrity issue encountered particularly in aging platforms. The issue is normally discovered via periodic wellhead maintenance programs or during monitoring by the production team. Subsequently, the wells integrity team will pursue well diagnostic via annular pressure diagnostic by manipulating and creating specific conditions to acquire information on the potential leak rate, leak path, and source of the leak. The probable culprit of the tubular integrity issues is due to completion or casing leakages, or failed cement conditions. The generic rectification technique available varies from rig to rigless method. Considering the low economic of the field & remote jacket location with a small footprint and limited crane capacity in Sabah waters, either the rig or workover option can be unfavorable. Therefore, the options available to remediate the sustained annulus pressure are limited considering the platform's design and operational setup. Historically, the team has attempted with a conventional pump and lubricate the annulus to mitigate the symptoms. However, the effectiveness was questionable as the pressure kept creeping up within a short period which urged the team to look into better technology solutions. With the limitations above, the team warrants a new holistic approach to resolve the sustained annulus issue. Annulus Intervention System (AIS) provides better fluid conveyance and circulation for better fluid displacement at the targeted depth. The AIS system has a smaller footprint as compared to a pumping or workover unit which is a major advantage for a small and remote platform directly applicable to the target Sabah asset. This paper will table out the step-by-step method that has been taken by the team to ensure the AIS system is engineered and tailored to rectify the sustained annulus pressure in a less than 500-meter square deck space.
Through recent years, there have been an increase of well integrity issues arising from the build-up of pressure in a well's casing annulus, or Sustained Annulus Pressure (SAP). The casing annulus (the volume between 2 concentric casings) are typically not designed for intervention and are only accessible from the casing valves at surface. While the A-annulus (the volume immediately next to the production tubing) may have limited accessibility from the tubing itself, for B- and C- annulus, this access is non-existent. Up until now, this has been the primary challenge in rectifying SAP issue in casings. Current well intervention technologies or methodologies are unable to rectify SAP issues and the wells had to be shut-in (production deferment) or required bleed-off facilities installed (additional CAPEX and OPEX). A breakthrough technology and methodology is required to resolve SAP issues and prevent risk escalation and production deferment. The desired solution should have the following characteristics: Ability to enter casing annulus, effectively lubricate the annulus, practicable at offshore and cost effective. Based on the objectives, a technology selection process was performed concurrently with development of the execution methodology. This resulted in the selection and vetting of the Annulus Intervention System (AIS) Wellspring which utilizes a compact and flexible conveyance system known as ‘wellspring’ to be installed at the casing gate valve, ability to deliver fluid up to 400m away from pumping point and have integrated well control barrier for safe intervention into a live condition well. In addition, a suppression fluid placement methodology was designed using a heavy (14.8 ppg) brine system to replace the existing (lighter) casing annulus fluid. This was calculated to have a net pressure downwards and therefore suppressing the SAP. With systematic process and procedure in place, team managed to prove the AIS can be conveyed through the casing head valve, passthrough the casing hanger and entered the B-annulus. The suppression fluid which is 14.8ppg brine also was able to be pump into the annulus to replace the degraded water-based mud with an optimum pumping rate and operating pressure. By achieving that, the team manage to suppress the SAP which ultimately safeguard the production from the well. This paper shall discuss the process of identification, diagnostic and subsequently the step-by-step method that has been taken by the team to ensure the AIS system is well suited to rectify the sustained annulus pressure. It will also discuss the execution strategy, technical challenges faced and lesson learnt during the execution of the project.
The loss of functionality of the surface controlled subsurface safety valve (SCSSV) due to blockage of, or damage to, the hydraulic control line can present a major problem to Operators. The subsequent loss of hydraulic pressure to the valve means the valve will close resulting in loss of production and hence alternative methods for re-establishing control of the SCSSV are required. Performing a full scale work-over to replace the inoperable control line can require major expense and may not be justifiable in a mature well, while installation of a velocity or dome charged subsurface controlled safety valve may not meet well integrity or production requirements. Hence the preferred alternative is to install a System to Restore Full Safety Valve Functionality that is cost effective, restores production, and maintains well integrity requirements. The Tubing Retrievable SCSSV on well C-02 in the Sabah water of East Malaysia lost its functionality due to a leak in the control line. The SCSSV body was also found to be leaking from tubing to annulus which resulted in the failure to successfully lock open the SCSSV. Initially a major rig work-over had been anticipated to pull the tubing and replace the safety valve and control line. This operation would have required the use of a Hydraulic Work-over Unit (HWU) to perform the work which would have incurred a major expense. An alternative method was proposed that would allow replacement of the safety valve and control line, and to straddle the leak in the SCSSV body without pulling the production tubing or making changes to the wellhead configuration. This alternative method was a unique concept not previously attempted by any operator in Asia Pacific. This innovative approach would involve four elements: Installation of a Lock Mandrel and Separation Sleeve to straddle the leak in the SCSSV body & hold open the SCSSV flapper. Installation of a Wireline Retrievable Subsurface controlled safety valve with wet connector to connect to a new control line installed through the tubing (WDCL Safety Valve) which is anchored and located in the Tubing above the Tubing Retrievable SCSSV by means of a packer system. A new control line and special control line connector installed from the wellhead to the WRSCSSV through the production tubing. A new penetration in the Wellhead Lower Master Valve for the injection of hydraulic power fluid to control the WRSCSSV. These 4 elements provided a unique solution and the installation was successfully completed under a severe deadline. This was achieved by a high level of cooperation and collaboration between all parties throughout all phases of the project including and not limited to the planning, design and installation. This paper will describe in detail the system components and the decision processes and evaluations that led to the selection of this alternative solution. The collaborative efforts between the operator and two major service providers will be examined and discussed and the installation procedure described in detail. The paper will describe why the successful completion of this project marks a significant milestone in the remediation of older producing wells.
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