Iain Lees and John Hunter, Tendeka

Reservoir monitoring has come a long way from early variations, where technology, data quality and run-life left a lot to be desired.

Current systems have brought together the very latest developments in electronics, materials and technology to provide reservoir engineers with a highly detailed assessment of what’s going on downhole.

It’s widely accepted today that an effective reservoir monitoring system can deliver significant benefits including reduced uncertainty, improved understanding of reservoir changes, monitoring of pressure draw-down over time, improved pressure build-up recording and understanding of cross-reservoir communication.

Understanding fully what’s happening down below, reacting to changes or even planning ahead to avoid or mitigate them adds to field life and can avoid costly intervention.

So, it’s critical to make sure the reservoir monitoring system you adopt matches your needs exactly. In this current low oil price market, and with ever more challenging high pressure and harsh environments to combat, getting that decision right is more important than ever and could ultimately save millions of dollars.

Firstly, we need to understand what the operator wants to achieve from the reservoir. Are they looking for maximum production in a short period of time, or is the requirement more for sustained, longer-term production levels, with the focus on enhanced life, possibly changing functionality such as from oil to gas production, or from producer to injector over their lifetime?

Is the up front cost of the system the critical factor, or is it the potential to enhance value over time that an efficient system can bring?

What data does the operator require from the reservoir and how will this information be used? What’s the end goal for the reservoir? How can your reservoir monitoring system be used to make a difference to your company’s bottom line?

Reservoir monitoring solutions can be divided into the widely established conventional cabled system or the increasingly popular wireless alternative.

In permanent monitoring, we’ve developed our Guardian range, incorporating a distributed temperature sensing fibre optic cable. It provides the fastest measurement speeds available and coverage of up to 50km from a single channel, while the surface acquisition unit delivers the data you want to see in real time. Guardian can provide detailed analysis of a well or an instant snapshot of activity, depending on the degree of information required.

In more challenging monitoring situations, where information is required from further parts of the reservoir, multi lateral wells are planned or where reducing the number of control lines is crucial, then our SigNet wireless solution is the right option.

SigNet is a fully wireless, modular intelligent completion system, made up of any combination of the two key components; wireless PT gauges, and wireless inflow control valves (ICV). Either component can be permanently installed as part of the completion, or can be retro-fitted using conventional intervention tools.

SigNet systems use wireless pulse telemetry to enable the ongoing monitoring, control and optimisation of both production and injection wells.

The tool function requires very little power, and data is transmitted to the surface using the well’s own energy so it has a long operating life. Furthermore, life of well operation is made possible by using the Tendeka Downhole Power Generator.
Since no additional hardware or surface modification is required the wireless gauge can be installed as close to the production zone as necessary and will start transmitting well data instantly.

A key advantage over conventional monitoring and intelligent well systems is that SigNet does not require the use of control lines. Therefore upfront costs are lower, control line reliability concerns are fully removed, and when the time comes, well abandonment costs are significantly reduced as the production tubing and control lines do not need to be removed to secure a cement barrier that can be validated against regulatory requirements.

In both systems what can be done with the data is almost as important as the data acquisition itself. It’s important to consider trend analysis, event detection and alarm activity so that we can ultimately create a system which is effectively developing its own intelligence and suggesting solutions.

Whatever your monitoring focus, it’s important that the system you choose enables you to make far-reaching decisions that help manage reservoir performance, enhance production and increase your overall recovery.