Scale precipitation is a common phenomenon that can be seen in a large number of oil fields worldwide. The presence of scaling is due to many reasons, including: temperature change, pressure drop, release of CO2 or the mixture of incompatible waters. Usually, scaling comes in a mixture of different scales, such as calcium carbonate (CaCO3), barium sulfate (BaSO4), and calcium sulfate (CaSO4). Scaling has a great impact on the production regimes where it sometimes ultimately decreases the well productivity to less than half of its potential. The presence of scaling can cause blockages in perforations, restrict/block flowlines or sometimes the failure of safety and choke valves.

Precipitation of calcium carbonate on surface or subsurface equipment creates operational problems and acts as a blockage agent. In this case study, water incompatibility caused the first scale formation in the flowlines where a pressure maintenance mechanismvia peripheral injection in this field is being utilized. It was predicted from the well performance data as it showed more than 50% of the production loss. The lab results revealed that the major element was calcium with minor amounts of strontium and barium.

This paper presents the results of both experimental and field work performed to identify scale formation. In addition, well performance data was used to predict future scale formation in parallel with the water geochemical analysis. The method used to remove scale precipitation is to use inhibited HCl acid mixture and it is required to be used either though squeeze treatments or by continuous treatments at the wellhead. Based on the lab and field studies, this paper will show new workflow for potential scale prediction and remedy actions prior to laboratory and well performance analyses.

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