Production Optimization of Unstable Wells
To debottleneck flow restrictions of unstable production wells to maximize and maintain production rates
The operator had tied-in a new satellite field to an existing production facility. Upon production start-up, it was identified that the production from the satellites showed significant instabilities with pressure and flow rate oscillations.
Some of the wells also ceased to flow after a period of unstable production and were subsequently shut down. This production environment caused huge challenges at the process facility topside and it was decided to kick off a debottlenecking project with the mandate of evaluating the cause of this behavior and propose mitigating options.
With an expected production in the excess of 50,000 bbls of oil per day from the satellites - it was crucial to solve this problem quickly and effectively.
What we did
Add Energy's flow assurance experts were contacted to assist the debottlenecking task force.
During this project, our engineers:
- Built a network model of the production system (the initial simulations aligned well with the actual production data taken from the online flow monitoring system)
- Conducted transient simulations
- Identified solutions to maximize and maintain production rates
Initially, it was believed the unstable production was caused by water entrainment from the reservoir, however, Add Energy demonstrated that this in fact, was not the case, through transient simulations.
Through these simulations, it was identified:
- That the wells experienced slug flow due to low gas velocities and consequently liquid accumulation in the tubulars
- The pressure behind the liquid plug containing mostly oil and condensate (with a very small amount of water) built until it was sufficient to blow the liquid slug to the seabed
- This oscillating behaviour continued until some of the wells ceased to flow
- It was obvious that the completion size used for these wells were not optimized based on the reservoir and fluid conditions.
The short-term solution:
The long-term solution:
The operator opted for both long and short term options, which achieved the following results:
- The field is currently producing according to the initial delivery plan using lifting techniques designed by Add Energy
- This project reiterated the requirement and advantages of running transient simulations in the design phase of a project of this type
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