Abstract

We focus upon the use of Intelligent Well Technology (IWT) to monitor and optimize production from wells containing a single tubing string completed in multiple pay zones. Wells producing under a water injection programme are inevitably susceptible to water breakthrough. Once breakthrough occurs, the operator of the well is faced with a choice between continuing recovery at a reduced rate, or sacrificing recoverable oil. If the well is producing from multiple pay zones then the situation is more complicated, as breakthrough may occur at different times in different layers. IWT allows the operator to regulate production from each zone using Interval Control Valves (ICV's).

We begin by investigating the application of IWT to a simple conceptual model: a single well producing from two isolated pay zones of contrasting permeability. This enables the factors influencing water breakthrough in a multi-layered reservoir to be investigated in isolation, providing fundamental insight into the impact of reservoir characteristics, fluid properties and well architecture. We find that the optimum method of producing from multiple pay zones is to employ IWT to choke back the high permeability zones, which results n the synchronised breakthrough of water along the wellbore. This serves to accelerate and/or increase production, and to optimise the displacement efficiency. We also find that IWT yields optimum benefit in fields with an adverse mobility ratio, and either limited field life or limited well productivity.

We then apply this knowledge to a full field model of the Maureen Field, UKCS. The Maureen Field was deposited in the deep marine environment, and is made up of submarine channels, fans, and poorer quality interchannel sands, separated by shales of varying lateral extent. We find that IWT does not accelerate or increase production from either of the target wells, because oil is simply displaced into the catchment area of other nearby producers. This suggests that IWT is best employed to choke production from wells which are isolated, or far from, other producers. Caution is therefore required when identifying candidate wells for IWT, as production may be reduced rather than enhanced.

Introduction

Intelligent Well Technology (IWT) has the potential to improve reservoir and well management. An intelligent well system is a combination of: 1

  1. Downhole sensors to sample environmental parameters;

  2. Downhole actuators to change the operating conditions of the well; and

  3. Interpretation and processing algorithms to optimise reservoir/well performance.

IWT provides the operator with ‘real time’ data from the wellbore, and enables the wellbore architecture to be reconfigured remotely by the operator in response to this data without shutting in the well and introducing a workover rig. Candidates for IWT are remotely located wells where interventions are difficult, and wells with complex wellbore architectures where frequent interventions are required to optimise production.

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