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
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 then 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 IntelliZone Compact system with multiposition flow control valves and
gauges. 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. The software then uses those calculations to optimize
production for system constraints, such as drawdown, bubble point, or rate
Guided by the software analysis, engineers adjust each flow control
valve to manage production from each layer, and then production is 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.