Gas lift (GL) has regularly been cited as an exemplar of the ‘digital oilfield.’ For the digital brigade, GL is seen as an opportunity for digital optimization. Presentations from the ALRDC/ASME 34th Gas-Lift Workshop held earlier this year in Singapore appear to support the idea that GL optimization (GLO) is an under utilized technology with huge potential, but that the impact of ‘digital’ is perhaps secondary to the organizational, engineering and people challenges.
Two presentations described how ExxonMobil ‘s global artificial lift group (GALG) was created to ‘focus key resources on evaluation and optimization of artificial lift systems.’ The business case is rather compelling. ExxonMobil has around 1,000 operated gas lift wells world wide. These represent some 10% of its total well count but make up around 1/3 of overall production. Gas lift deployment is expected to rise significantly in next few years. The GALG is made up of a body of qualified technicians. A structured process has been put into place for review and prioritization of interventions. A standard toolkit comprises Echometer’s WellAnalyzer, digital thermal monitoring, clamp on flowmeters and AppSmith’s WellTracer surveillance tool. Early tests in a SE Asia offshore GLO project evaluated 29 wells, coming up with 12 optimization recommendations. This resulted in a 24% hike in production—and pointed the way to considerable upside from further work. The process is one of continuous learning—hence the use of rotating technicians to share technology and best practices.
A Shell presentation leveraged Petex’ IPM open server macros to connect Prosper and Gap simulators with AppSmith’s WinGlue gas lift software, Shell’s tool of choice. Open server macros developed in Excel VBA code have allowed the tools to interoperate on tasks such as an equilibrium curve module, that determines the maximum depth of injection in gas lift design and analysis. Another use case involves combining many individual well optimizations in WinGlue in GAP for global, field wide optimization. Petex is now considering adding these extensions to Prosper.
A break-out session debated new technology, noting that although world has changed a lot of the last 40 years, gas lift remains the same. In fact, some technology ‘tweaks’ (electric, hydraulic or wireless gaslift) have mostly died quietly. The group outlined the attributes of an ideal gas-lift system as follows, a ‘dynamic’ system that continuously optimizes gas-lifted production, both down-hole and at surface without the need for workover interventions, a system that can inject at any rate at any depth, software driven field-wide optimization and virtual metering. For green field developments, the added cost of a smart gas-lift string should be a no brainer when the prize is a 5% production hike. Presentations available on www.oilit.com/links/1104_47.
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