Dual-string completions limit optimization choices
Producing from mature oil fields in Ecuador introduces many reservoir challenges, including multizone oil production and high water-handling costs. Traditionally, operators deploy dual-string completions with sliding sleeves and dual ESPs to access the different layers and obtain back allocation with standard surface well testing.
Although these dual-completion wells are functional, they are far from ideal. Production logging is uneconomical because it requires pulling the ESP. So, to estimate oil, water, and gas production, operators schedule periodic surface well tests. From the total (commingled) production, they back allocate oil and water rates based on oil API and water salinity. The process prevents frequent analysis, making it extremely challenging to optimize the wells for maximum production.
For a pilot project studying the value of intelligent completions, an operator wanted to monitor production parameters (flow rates, water cut, and productivity index for each reservoir layer) and maximize oil production by optimizing downhole valve settings in three wells.
Intelligent software adds real-time flexibility
Schlumberger recommended using the WellWatcher Advisor software to manage an intelligent well completion incorporating gauges and multiposition flow control valves. The software analyzes downhole data from the completion system in real time to estimate flow allocation, productivity index, and average reservoir pressure of each zone. It then uses those calculations to optimize production for system constraints, such as drawdown, bubblepoint, or rate limitations.
Guided by the software analysis, engineers adjust each flow control valve to manage production from individual layers, and production is then commingled. The completion system enables single-string configurations, reducing the number of ESPs required for lifting. Unlike traditional dual completions, the intelligent completion is versatile and simplifies workovers, precluding the need to pull a lower completion.