Challenges & Mitigations in a Matured Gas Field in the Sultanate of Oman

Abstract

The SN-Deep field is located in the central area of the Sultanate of Oman, 20 km west of the Qarn Alam (QA) station and is operated by the Gas Directorate. The field consists of three deep sandstone reservoirs with rich and lean gas fluids. 50% of GIIP has been produced resulting in significant pressure depletion. This paper will: Illustrate the WRFM approaches used to manage some of the late life of the field challenges such as sand production, water breakthrough, and scale formation, which were not predicted during the fields’ development phase. Enhanced field production recovery through new technologies to unlock additional reserves. Extensive well, reservoir, and field management (WRFM) interventions have reduced the field's production decline and sustained the production performance through the following: Water producing wells – analytical techniques are used to predict water production and forecast which wells are expected to reach critical rates. Resources are therefore allocated yearly for wells expected to show significant water production, limiting well down time. In addition, velocity strings with water shut-off are deployed to minimize deferment and cost. During interventions, wells with additional behind casing reserves volumes are also produced. Foam assisted lift (FAL) and permanent installation has been used as secondary means to reduce additional hydrostatic heads for wells with high water production. A trial with FAL on some wells showed sustainable gas rate with high WGR after foam injection. Scaling and salting – to prevent declining production potentials, proactive fresh water bull heading is used to treat symptomatic wells. The technique and the frequent well interventions were able to reduce the deferment and the need for other expensive resources. Solids production – sand production in the field is managed via implementing an integrated sand management strategy that covered all aspects related to required investigation, arresting, and control monitoring.