Preventing Scale Deposition Downhole Using High Frequency Electromagnetic AC Signals from Surface to Enhance Production Offshore Denmark

Abstract

Mineral scale deposition is a significant impediment to efficient operation of oil and gas facilities. Deposition control strategies include brine demineralisation, chemical inhibition and mechanical intervention. Mitigation costs are highest at offshore locations requiring well intervention and include significant production deferment. Hydrocarbon production in the Danish sector of the North Sea has a number of specific regional challenges as reservoirs are often carbonate with high produced water calcium concentration resulting in a high potential for carbonate scaling. Secondary production techniques such as water injection flooding to maintain pressure are used and sea water is pumped directly into the reservoir introducing sulphate leading to downhole mineral scale deposition of barium sulphate, strontium sulphate etc. The offshore location of production facilities dictates that interventions are expensive and put pressure on valuable offshore bed spaces. This paper reports results of field application of a recently introduced scale control technology based on high frequency electromagnetic AC signals generated and impressed onto a well head or associated piping conduit. Field trial data is provided from a production well with a history of scaling where production pressure was held back to reduce scaling severity. Field trial data describes the impact of the technology in preventing scale in a high value well. Analysis of the results showed that physical treatment using this alternative approach effectively controlled scale deposition such that the production systems was protected and the production benefits included increased reliability of gas lift valves, cessation of any tubing acid washes and enhancing production. The economic value added and reduction in risk to personnel and emissions are described. An extended (9 month) pilot test has allowed production to be increased and no mineral scaling has been detected. The results achieved are promising. Stable and no lost production added a value to the producing asset and avoided significant revenue loss to the operator.