A Dynamic Optimisation Technique for Simulation of Multi-Zone Intelligent Well Systems in a Reservoir Development

Abstract

Abstract Intelligent well technology provides an operator the capability to remotely control, monitor and manage multiple horizons in a given well. Application of the technology has provided significant value, through the ability to control multiple zones independently, reduce total number of wells, reduce future costly well intervention, accelerate production between zones to maintain a plateau for extended period of time. Common reservoir simulation tools are not well suited to model the performance of wells with downhole flow control devices, and specifically have difficulty automatically optimising the configuration of intelligent well control valves in the time domain, to maximise objective functions such as discounted production or hydrocarbon reserves recovered. This paper reviews the process and results of reservoir simulation and modelling of a multi-layer, compartmentalized clastic oil reservoir with strong aquifer drive, developed using intelligent well technology. The paper describes the process by which an optimisation technique was incorporated in the simulator, with the ability to model binary and multi-position downhole intelligent well [L1]Interval Control Valves (ICVs). The optimisation technique described was used to simulate the performance of a multi-layered commingled reservoir developed with intelligent wells. The production forecasts quantify the benefit of multi-position interval control valves over base case conventional development scenarios. For the typical reservoir studied, intelligent well systems accelerate production and maintain a longer plateau period when compared to conventional completion techniques. Introduction An intelligent well is a system capable of monitoring production and reservoir data, with the ability to control downhole production (and injection) processes without interavention, in order to maximise asset value. The monitoring aspect consists of permanent down-hole pressure and temperature sensors or fibre optics that feed reservoir information to a surface data gathering system. The controlling capability is achieved by using hydraulic, electric or electro-hydraulic controlled Interval Control Valves (ICVs). The ICV can either be a binary on/off system or have variable choking capability. Several authors1–5 have presented field applications of Intelligent Well Technology (IWT) and demonstrated the ability of this technology to improve recovery and maximise oil production. Some of the benefits of IWT are derived from adopting a commingled production scenario for multiple reservoirs. In this application, control devices are installed in each zone to independently control flow in to or out of the reservoir. The required control is triggered by the interpretation of the information gathered from the downhole sensors and surface (or sub-surface) measurement system. In the conventional approach, the engineer waits for problems to occur and then uses the technology to mitigate them. A more proactive approach is to couple IWT control devices with a reliable predictive reservoir model. This enables dynamic optimisation of zonal performance to enhance overall reservoir management.