In situ X-ray diffraction analysis of the onset of mineral scale deposition from synthetic oilfield processing waters

The deposition of barite (BaSO4) scale on stainless steel has been investigated using in situ X-ray diffraction. Scale build-up in oilfield processing lines costs the industry millions of dollars per annum in lost production and maintenance, and improved strategies to combat scale build-up through greater understanding of the very early stage of scale deposition would be of significant benefit. Here, through the acquisition of very rapid diffraction datasets during scale deposition from the mixing of synthetic sea and formation waters, the barite growth curve – characterised by very rapid scale deposition during the period 0 ⩽ t ⩽ 105 s before a regime of more gradual linear growth in the range 105 ⩽ t ⩽ 450 s – was determined. In addition, during the period of rapid deposition the scale was found to exhibit significant preferred orientation along the (0 2 0) axis, which became less significant as deposition continued. Diffraction is the only technique which provides direct and simultaneous information about mineralogy and crystallographic orientation, and its implementation here to characterise the onset of barite scale formation is a significant advance in the analytical capabilities at the disposal of engineers to investigate scale formation in an oil and gas processing context.