The value added by intelligent wells (I-wells) derives from real-time, reservoir and production performance monitoring together with zonal, downhole flow control. Unfortunately, downhole sensors that directly measure the flow rates and phase cuts required for optimal control of the well's producing zones are not normally installed. Instead, Multi-zone, Multi-phase Flow Metering (MFM) parameters are calculated from indirect measurements (e.g. from zonal pressures, temperatures, and well flow rates).
To-date all published techniques of zonal flow rate allocation in multi-zone I-wells are “passive” in that they calculate the MFM parameters for a fixed given configuration of the completion. These techniques are subject to model error, but also to errors stemming from measurement noise when there is insufficient data duplication for accurate parameter estimation. This paper describes an “active” monitoring technique which uses a direct search method based on Deformed Configurations to optimise the sequence of Interval Control Valve (ICV) positions during a routine multi-rate test in a “intelligent” well. This novel approach maximises the accuracy of the calculated reservoir properties and MFM parameters.
Four “active monitoring” levels are available. Each one uses a particular combination of down-hole and surface measurements depending on the available well performance monitoring systems. Level one is the simplest, requiring a minimal amount of well data. The higher levels require more data; but provide, in return, a greater understanding of the in-flow performance, the volumes of produced fluids and the reservoir's properties at both a well and a zonal level.
Our “active monitoring” workflow can be extended to a wide range of production and injection allocation problems for any well completion type. The workflow may also be used to improve the accuracy of production flow rate measurements and, ultimately, to maximise oil production rate and recovery.