Scale Solubility, Nucleation and Kinetics
Tomson Technologies performs all scale and corrosion work under strictly anoxic conditions (<< 1 ppb O2) as seen in oilfield reservoirs. Our research has shown that the presence of trace levels of oxygen can dramatically alter scale precipitation, corrosion and the inhibition process. This unique aspect allows for results to be more valid and directly applicable to the field.
The method to continuously create strictly anoxic solutions was developed in-house by Tomson Technologies and is proprietary. Failure to perform scale and corrosion research and testing under strictly anoxic conditions has been demonstrated to alter the processes substantially and does not yield results that are field representative. Oil and gas reservoirs are naturally strictly anoxic, so testing and research should be performed under these conditions.
Especially for iron containing species, oxygen plays a key role in the testing results and therefore strictly anoxic solutions should be used in all cases. Tomson has shown dramatic effects on thermodynamics, kinetics and inhibition in the presence of oxygen.
The deeper plays in deepwater development are projected to exceed 200°C (392°F) and 20,000 psig and will likely contain considerable carbon dioxide and hydrogen sulfide. The oil and gas industry has spent years understanding scale, corrosion and fluid properties, generally up to about 150°C (302°F) and 7,000 to 10,000 psig with limited work being done at higher temperature and pressure. Similarly, for modeling of the gas/oil/salt-water mix the literature is mostly related to these lower pressure and temperature conditions. It is known that many of the accepted theoretical frameworks, such as Peng-Robinson-like equation of state (EoS) models and Pitzer activity coefficients are reaching their limits of expected application and new methods are needed.
Finally, even less is known about the rate of scale formation and corrosion in any of these extreme conditions and little is known about the stability and effect of scale and corrosion inhibitors at these pressures, temperatures, and flow rates and the critical interplay of scale and corrosion inhibitors with specific metallurgies.
What little amount of work has been done at xHTHP is almost all on simple systems, such as only simple NaCl base solutions studying BaSO4 or CaCO3, simple buffers versus temperature and pressure, and even this work does not have an accepted set of data. Virtually no kinetic data has been measured and those that have are almost all simple equilibrium measurements. For example, even though the solubility of CaCO3 is rather well known to about 150°C (302°F), 7,000 psi (483 bar), and about 3M salt, if these conditions are increased to 250°C (482°F) and 25,000 psi (1,724 bar) then well-accepted Pitzer models vary by as much as several hundred percentage in predicted solubility, one of the most well studied systems in the oilfield. In addition, there is almost no inhibitor performance data at these conditions.
Tomson Technologies has performed significant research to expand the knowledge base on high temperature and high pressure thermodynamic and kinetic data of the most common scale species.
Tomson Technologies research includes solubility, nucleation, and kinetics of Calcite (calcium carbonate CaCO3), Barite (barium sulfate BaSO4), Halite (sodium chloride NaCl), Siderite (iron carbonate FeCO3),
Iron sulfide (FeSx(1to2)), Magnetite (iron oxide Fe3O4) and others at high temperature, high pressure and realistic brine conditions. Reservoir iron species can be studied accurately in the lab due to the ability to test at strictly anoxic conditions (<< 1 ppb O2) under reservoir temperature, pressure, and brine composition. Additional scale species can be studied according to research needs and these may include gypsum, hemihydrate, anhydrite, celestite, zinc sulfide, silicates, or virtually any material, as needed by our clients.