Active feedback control of unstable wells at the Brage field

Stabilization of horizontal wells with gas lift is achieved by a novel dynamic feedback control solution using the production choke at the wellhead. The production choke is controlled by an AC 800M ABB controller via the Siemens DCS system at Brage.

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Norsk Hydro has implemented numerous measures to prolong the field’s production lifetime. The goal was to further reduce operational costs, and together with finding additional ways to increase oil recovery. An issue of concern has been slugging wells. In some cases, slugging has been so severe, that the well has had to be shut down.

The installation of Active Well Control has brought these wells back on stream and in some cases even increased production. A day-to-day service and follow up scheme was included to ensure optimal use of the tool.

Main facts

Industry Oil, gas and petrochemicals
Customer Norsk Hydro
Country Norway

Advanced Process Control
- Active Well Control
- Remote service and tuning

 2000 - 2004

Feedback control fundamentals

Feedback control means that the settings of one or more controls in a system, e.g. valve openings or set points for pressures, temperatures, levels or flows, are based on readings of one or more measurements in the same system. Feedback control can be automatic or manual. Manual feedback control means that the decision on the setting of the controls is done by a human, while automatic feedback control means that the decision is made by some device. The device could be mechanically based, electrically based, electronically based, hydraulically based or a combination thereof. Of course, there is an abundance of examples of both manual and automatic feedback control related to oil production.
ABB has achieved promising field results with a novel concept for stabilization of unstable production from an oil well. The main ingredient in this concept is the application of active feedback control to the production choke, relying on a measurement of the downhole pressure as well as measurements of the pressures at the wellhead. On the test well, which was impossible to operate manually, the variations in the wellhead pressure were decreased by 75-100% when active feedback control was in operation. In contrast to the situation with manual operation, it was not necessary to shut in the well for shorter or longer periods of time to build up pressure. Hence, as the well produced 900 - 1000 bbl/d in the test period, the benefit of employing active well control was quite obvious on this test candidate.

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