PETRONAS and OVS Group team up to optimize gas-lift process in offshore dual string oil wells in Baram field, Malaysia. This paper outlines how the real-time production data and well model approach help to overcome the challenges faced in dual string gaslift wells and improve their performance.

Challenges

  • To determine the injected gas allocation factor in dual-string wells when both strings are producing.

  • To determine the well inflow performance with limited or no reservoir information such as permeability, drainage area, skin etc. for multiple completions.

  • To improve the well and field performance in absence of daily measured flow rates.

  • To diagnose high producing GOR wells to improve the gaslift performance.

Methodology

  • Gas Allocation method is developed to compute gas injection rate in each string based on welltests.

  • Composite IPR is built at the solution node (Figure: 1.0) where fluids from all producing completions are commingled in tubing and nodal analysis is performed.

  • Well-model-based Virtual Meter (VM) approach is used to estimate the flow rates and improve the well and field performance.

  • Gas lift diagnostic is used to identify gas-lift performance issues.

Results, Observations, and Conclusions:

  • Integration of databases helped to find out missing/wrong data in well tests and prioritize well tests which are overdue.

  • Ensuring the consistency of Total GOR at reservoir and well level improved the inflow performance for production surveillance, optimization and forecast.

  • VM enhanced the surveillance and understanding of wells, highlighted opportunities and improved the allocation method.

  • Recommendations were made to review production strategy due to gas conning or gaslift design to improve the production and gaslift performance in high producing GOR wells.

Significance of Subject Matter:

  • When limited or no downhole information is available, pressure gradients analysis in both casing and tubing helps to estimate the gas injection rate using surface measurements.

  • In case of multipoint injection (Figure: 2.0), well performance is carried out based on deepest injection point if it is possible. Necessary recommendations are made to avoid multipoint injection for efficient gas lift operation.

Application

  • It can be applied to any single or dual string gas lift well.

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