Coating of wellbore grain surfaces to prevent scale deposition/adhesion

Mineral scale deposition/adhesion is one of the major challenges in the oil and gas industry. Besides, the new regulations in the oil and gas industry suggest substituting conventional inhibitors by more environmentally-friendly strategies which may include anti-scaling surfaces as a potential methodology. The objective of this work was to study a new potential application for surface modification near the wellbore to reduce mineral scale deposition in the rock. To achieve this purpose, it was required to form a thin layer of a chemical, which has a strong bond with quartz and does not block the oil path; and has a potential to reduce the scale deposition/adhesion on the rock. 3-aminopropyl-triethoxysilane (APTES) and p-aminophenyltrimethoxysilane (APhS) with various concentrations were chosen to create self assembled monolayer to alter the physical and chemical properties of the surface. The kinetics of the APTES (2-8%) film formation on the surface was studied by QCM. Langmuir isotherm was used to interpret the QCM results and to calculate the surface coverage of APTES film on the surface. Also the performance of quartz surfaces which were treated by different concentrations of APTES and APhS in terms of reduction of scale deposition was studied in low=4.77 and high=54.8 saturation ratios. The best film performances (up to 95%) were obtained by 0.06% APhS and 6% APTES, respectively. It was assumed that the reduction of scale deposition could be related to the reduction of nucleation sites on the treated surfaces due to changing the surface charge of quartz surface from negative to neutral (slightly positive) surface. Surface composition, wettability and the roughness of APTES and APhS films were characterised by XPS, Contact angle Goniometry and surface profiler, respectively. Based on the film characterisation results, the most effective parameters in reduction of scale deposition were the surface composition and film conformation.