Track: Case Studies

Abstract

Scale in oil and gas wells is a major problem leading to significant losses in production and therefrom-potential revenue. Scale limits oil and gas production by plugging oil-producing matrix, perforations, tubing, flowlines and other production facilities. Most common scale deposits are calcium carbonate, calcium sulfate and barium sulfate. Scale problems cost the industry hundred of millions of dollars per year in both scale removal operations and lost production. Conventional chemical scale removal is often the first lowest cost option especially when mechanical removal methods are unemployable. The aim of this paper is to compare costs associated to scale removal in perforations using the chemical treatment and a somewhat expensive mechanical method. Chemical treatment considered involves injecting toluene or hot diesel while the mechanical method utilizes pressure difference between the reservoir and wellbore in order to remove scale. Five wells were considered which were first chemically treated and then, after some prolonged time, were mechanically treated. The results indicate that the mechanical treatment does not always efficiently remove scale from perforations compared to the chemical treatment. Water cut levels and source of scale play significant roles on the type of treatment that must be considered in order to minimise cost.