A pilot-scale test system has been developed to evaluate scale deposition and inhibition under flow conditions that are more representative of the field than conventional laboratory methods. This system has been used to investigate an example of strontium sulphate scaling and the effect of hydrodynamics on the location and the quantity of scale deposit formed.

The approach used in this study involved flowing a large quantity of heated brine through a 1" diameter steel test piece at 5 L/min for several hours in a single-pass system. The test piece consisted of short sections allowing the configuration to be altered and allowing the scale deposited in each section to be quantified. Tests were run with configurations simulating a straight pipe, an ICD nozzle, and a gas lift system to investigate the effect of turbulence and shear stress on scale location and mass. The effect that injection of a chemical inhibitor had on preventing scale deposition in this system was also tested.

The results obtained demonstrated that the flow regime in the test piece had a significant effect on the mass and location of strontium sulphate scale deposits. A much greater quantity of scale was observed when the fluid experienced the increased shear stress and turbulence generated by passing through a narrow restriction, or by the injection of gas into the flow, compared with straight pipe flow. Successful chemical inhibition of surface deposits was demonstrated in this system. The use of smaller scale benchtop tests to demonstrate the effect of saturation ratio on obtaining sufficient deposition in single-pass tests compared with a recirculating approach are also discussed.

Design and implementation of large-scale tests is an important industry tool for laboratory evaluation of scaling in circumstances where conventional test methods do not give sufficient confidence to develop a scale management strategy and a more field-representative method is required. This paper describes an approach for successfully carrying out such tests and demonstrates the breadth of results that can be obtained from them. It also adds to industry knowledge of the effect that regions of high turbulence and shear have on promoting greater scale formation.

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