The deposition of inorganic scale from waters supersaturated with minerals is a significant flow assurance issue in oil and gas production. Several laboratory techniques are routinely used to assess scale deposition and qualify chemical inhibitors but these all have limitations with regard to matching field conditions such as the hydrodynamic regime and residence time that the fluids are likely to experience. In some cases, these tests do not give sufficient confidence to develop scale management strategies and a more field-representative method is required to bridge the gap between laboratory tests and full field trials.

The design and use of a large pilot-scale test system to evaluate scale deposition and inhibition is described in this paper. The system involves flowing large quantities of brine through a test piece at high flow rates for several hours. Different test piece configurations can be used and these are constructed from shorter lengths of pipe allowing scale deposit location and quantity to be readily analysed. An example is given in which sections of pipe made from different materials are used to investigate the effect that this has on scale adhesion. Chemical inhibition has been investigated by the injection of scale inhibitor into the flow stream and evaluating the reduction in surface deposits. Design considerations for these tests are also discussed with results from smaller scale preliminary tests used to ensure that sufficient deposits will be formed in the full-scale tests.

The successful implementation of the pilot-scale test system described provides an important industry tool enabling the evaluation of inorganic scale deposits under field-realistic flow conditions and methods to mitigate the flow assurance issues resulting from them. The results obtained from the tests also advance the understanding of the effect that the use of different materials in oilfield flow systems have on scale deposition.


The formation of common inorganic scales (such as BaSO4, SrSO4, CaSO4 and CaCO3) in production tubing presents a significant problem in the oil and gas industry. The mixing of incompatible waters or changes in temperature, pressure, pH or hydrodynamics of a fluid may result in scale deposition, with the potential to cause constrictions in production tubing when allowed to build up. This can lead to costly interventions that result in delayed production and loss of revenue. Therefore, an effective scale mitigation strategy is a crucial part of field development and management.

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