A Novel Coating to Reduce Solids Deposition in Production Systems

Solids deposition in production systems can cause operational issues and costly mitigation. A novel hydrophobic coating has been developed that decreases deposition of solids, such as asphaltenes, scale and wax, under flowing conditions in well tubulars and flowlines. The coating may potentially lower field development costs by reducing umbilical tubing, chemical injection systems, and insulation that are currently used to manage deposition risks. Lab tests and field trials were used to evaluate the effectiveness of the coating. Lab tests, from benchtop to large-scale flowloop, were designed and undertaken according to the solid of interest. In all cases, coated test sections were compared to uncoated sections under similar operating conditions. The impact of the coating on asphaltenes deposition was studied using the Organic Solids Deposition and Control (OSDC) device. Three types of scale (i.e. calcite, barite and halite) were investigated using rotating cylinder electrode (RCE) benchtop experiments and a small-scale flowloop. Coating performance with respect to wax deposition was evaluated with over forty flowloop tests. A field trial with a waxy African crude complemented the flowloop results. Results from the lab tests and the field trial show that the coating does help mitigate the risk of asphaltene, scale and wax deposition under the conditions studied. Benchtop tests with two crude oils showed decreased asphaltene deposition for coated components. Lab results for scale also show a benefit from the coating. Calcite and halite deposition was dramatically lower on coated coupons and flowloop components, respectively, compared to their uncoated counterparts. Barite deposits on the coating were easier to remediate compared to the uncoated surface. The wax flowloop results have been consolidated into an operating envelope describing conditions where there is: no deposition with coating, reduced deposition with coating, and unaffected deposition (i.e. coated and uncoated behave similarly). A wellbore field trial with a waxy African crude validated the flowloop results. Wax deposition in the wells is typically managed with frequent scaping, sometimes as often as several times per day. With the coating applied to the inner wall of the tubular, the coated well showed a 75% decrease in scraping frequency relative to comparable wells with no coating. This novel hydrophobic coating has been shown to help mitigate asphaltene, scale and wax deposition under the conditions studied. Based on the positive results of the performance testing, a commercial-scale application facility is being designed and constructed by Shawcor. Plans are underway to deploy the coating, where conditions are applicable, throughout the industry.