Despite the significant progress made for the expansion of oil and gas productions from conventional to unconventional sources in the last several years, the steady growth of the hydrocarbon demand is driving the oil and gas industries to explore new or under-explored areas that are often challenging. Because of technological difficulties associated with extremely high temperature (>150°C), pressure (>10,000 psia), and TDS (>300,000 mg/L) at deep water production environments, prediction and control of mineral scaling pose significant challenges. Appropriate experimental data is needed for better understanding of scaling risk in those harsh environments, but current literature lacks the experimental findings that correlate the importance of pressure and temperature on the mineral scaling kinetics. This study attempts to bridge this knowledge gap by formulating the pressure dependence of barite formation kinetics at various temperatures (T) and saturation indices (SI).

In order to study the effect of the pressure on the mineral scale formation kinetics, a high temperature high pressure (HTHP) flow loop apparatus was developed and experiments were carried out at various temperatures (70-175°C) and at a range of pressures (15-15,000 psia). Barite scale formation (precipitation) kinetics as a function of the pressure was investigated while maintaining constant pH, T, ionic strength, and SI. To determine the onset of scale formation (i.e. induction time), time dependent composition of reaction mixture containing Ba2+ and SO42- species was analyzed using ICP-OES. In a separate but independent study, barite induction time at various ionic strengths at constant T, P, and SI was determined by laser light scattering method. This work will show that barite precipitation kinetic is a strong function of applied pressure at constant T, SI and TDS. Based on experimental results, the relationship between induction time for barite formation as a function of T, P and SI was established.

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