The deposition and subsequent growth of inorganic scale on completion equipment is a major problem within the oil and gas industry. An in-situ flow cell was designed to investigate barium sulphate surface fouling on stainless steel. The set-up allows realtime analysis of the formation of scale as well as following various scaling parameters such as the surface coverage or number and size of crystals growing on the surface. The experimental results were fitted to a diffusion-controlled crystallisation based model. The effect of PolyPhosphinoCarboxylic Acid (PPCA) scale inhibitor on the growth of crystals was studied and showed that the Minimum Inhibition Concentration (MIC) is different for the surface and bulk solution. The results show that the inhibition mechanism was controlled by the mass transport of scale inhibitor molecules to the active sites of the growing crystals.

There is a considerable interest to investigate surface crystallization in order to have a full mechanistic understanding of how layers of sparingly soluble salts (scale) build on component surfaces. Despite much recent attention, a suitable methodology to improve on the understanding of the precipitation/deposition systems to enable the construction of an accurate surface deposition kinetic model is still needed. In this work, an experimental flow rig and associated methodology to study mineral scale deposition is developed. The once-through flow rig allows us to follow mineral scale precipitation and surface deposition in situ and in real time. The rig enables us to assess the effects of various parameters such as brine chemistry and scaling indices, temperature, flow rates, and scale inhibitor concentrations on scaling kinetics. Calcium carbonate (CaCO3) scaling at different values of the saturation ratio (SR) is evaluated using image analysis procedures that enable the assessment of surface coverage, nucleation, and growth of the particles with time. The result for turbidity values measured in the flow cell is zero for all the SR considered. The residence time from the mixing point to the sample is shorter than the induction time for bulk precipitation; therefore, there are no crystals in the bulk solution as the flow passes through the sample. The study shows that surface scaling is not always a result of pre-precipitated crystals in the bulk solution. The technique enables both precipitation and surface deposition of scale to be decoupled and for the surface deposition process to be studied in real time and assessed under constant condition.

This is a repository copy of Examining the effect of ionic constituents on crystallization fouling on heat transfer surfaces.

This is a repository copy of Evaluation of laboratory techniques for assessing scale inhibition efficiency.

This is a repository copy of Inorganic mineral precipitation from potable water on heat transfer surfaces.