Abstract
Scale formation in the wellbore and pipelines during upstream processes can result in production disruptions and declines in revenue. Hence, treatment and removal of oilfield scales are important for avoiding production depreciation. Scale varies in chemical composition, being composed of layers of scale adhering to the inside of tubing and deposited during the well life cycle. Identifying the location and composition of scale deposits is the first step in designing a cost-effective remediation program. Scale removal could be mechanical or chemical. Scale removal techniques should be quick, non-damaging to the wellbore, tubing, or formation environment, and effective at preventing reprecipitation. There have been many significant advances in scale control and remediation in recent years. Improvements in placement technology, reservoir chemistry, and intelligent fluids provide more cost-effective options for chemical scale inhibition or removal in downhole tools. The purpose of the present study was to analyze scale composition and then develop and recommend a solution to effectively remove specific oilfield scale from downhole tools. In this study, scale samples were collected from downhole tools and compositional analysis conducted to characterize both crystalline and non-crystalline compounds. Composition of scale samples was determined by X-ray diffraction (XRD), X-ray fluorescence (XRF), and acid solubility for more accurate analysis. XRD and XRF results showed that the scale composition was mostly carbonate. Based on the scale composition, an acid-free carbonate scale dissolver was evaluated, and the results are presented in this paper.
