Abstract
This paper presents an advanced gas lift facility design that utilizes electric compression coupled with innovative process controls both on- and off-skid to improve system uptime, allow for scalable distributed and remote operations, enhance process safety, and reduce emissions. Real-time on-skid compressor data is communicated wirelessly for unit surveillance and downtime diagnosis.
This new approach to gas lift compression was collaboratively developed with a compression services provider and relies primarily on an electric motor prime mover coupled with a variable frequency drive (VFD). A compressor panel with digital pressure and temperature inputs is tied back to the well pad facility PLC and SCADA systems for data communication and flow control adjusTMent. Automated blowdown valves and audible alarms enable safe compressor auto- and remote-starts.
This advanced motor-driven gas lift system is compared to typical engine-driven setups operating in similar rich, wet-gas applications at distributed and remote well pad facilities. Before and after comparisons demonstrate the value of electronically actuated (versus pneumatic) control valves supplied with instrument air. A unique methanol conveyance system is described which provides effective protection when operating below the hydrate formation temperature at compressor suction, interstages, and discharge.
Successful auto-restarts enable smooth operation during line power fluctuations and momentary suction/discharge pressure abnormalities which previously constituted the majority of compressor downtime. As a result, the auto-restart functionality improves unit runtime and therefore well productivity while reducing operator callouts. Motor drives eliminate fuel/start gas requirements and downtime while simplifying the auto-start sequence. They also require less frequent planned maintenance and shorter maintenance duration as compared to engine drives. Additional benefits are the elimination of engine emissions, minimal impact to facility air permits, reduction of shutdowns on the driver, and greater mechanical availability due to fewer moving parts. Streamlined optimization is provided via flow rate control on location at the PLC/HMI or remotely via SCADA enabling greater flexibility for both engineers and operators. Real-time on-skid data communicated wirelessly for remote surveillance enables unit downtime root cause analyses and prescriptive improvements that otherwise would be difficult to diagnose.
Coupled with advanced process controls, remote monitoring, and an electric drive compressor, this novel gas lift facility enables scalability at distributed locations across a large acreage position. Operators and engineers are able to deploy a more robust and reliable artificial lift system to support dynamic and rapidly growing field development plans where remote operations and real-time monitoring are highly desirable and gas lift optimization ability is uncompromised.
