Since the early days of the industry, production technologists have grappled with the complexities of predicting scale formation in oil and gas wells. Traditional models, while useful, have often fallen short in accounting for the dynamic nature of scale buildup during operations. OLI’s Scale Kinetics and Optimization Tool represents a transformative approach to addressing this long-standing production problem.
The Evolution of Scale Prediction Models
Scale prediction has evolved significantly since the Stiff-Davis plots of the early ’50s, a tool that first considered the impact of temperature and salinity. The decades since have introduced enhancements in computational capabilities and experimental data, allowing for more refined equilibrium scale models. Yet, these models were limited by the basis of their assumptions, equilibrium.
Introducing Scale Kinetics
Scale buildup, the eventual result, is a combination of scaling tendency and excess solute (scale equilibrium predictions), and precipitation and deposition (scale dynamics predictions). Effective management therefore means understanding both equilibrium and dynamics.
The Scale Kinetics and Inhibitor Optimization Tool (SKIT)
OLI, in Version 12 of ScaleChem is introducing the scale dynamics part of this equation. The Scale Kinetics and Inhibitor Optimization Tool (SKIT) is a innovative capability that combines rigorous equilibrium models with scale kinetics. Its ultimate purpose is to predict the onset and location of scale buildup and then compute the type and concentration of scale inhibitor needed to mitigate the production risk.
SKIT contains several packaged functions, OLI’s Scale Tendency and Excess Solute model, an induction time model, a precipitation inhibition model, and lastly a chemical database that rigorously quantifies the interaction of scale inhibitors with the produce water and the nucleating scale.
Revolutionizing Scale Risk Analysis
By creating this tool, OLI is giving the industry a leap in how we manage scale risk during production operations. With this tool, users can augment their risk analysis from traditional scale tendency/excess solute/suspended solids analyses to one that includes a rigorous assessment of the potential scale’s surface energy and its ability to form a stable solid. Then, it applies the risk mitigation capability of predicting the impact of the scale inhibitor on the solid’s ability to form. By incorporating the complex nature of physical chemistry and chemical kinetics to the problem, this tool simplifies our efforts to identify and mitigate scale risks.
Primary Scaling Solids and Inhibitors
There are by far key scaling solids that impact worldwide oil and gas production. They are calcite (CaCO3), barite (BaSO4), celestine (SrSO4), and anhydrite/gypsum (CaSO4). Likewise, there are key inhibitors that are used worldwide and that would need to be part of our first release, NTMP, DTPMP, HEDP, PMLA, and PBTC. These are the first scales and inhibitors studied, and they are ready “out of the box”.
How Scale Inhibitors are integrated into the tool
SKIT meticulously models the interaction between scale inhibitors and scale nucleation. By understanding how inhibitors affect the energy dynamics of nucleation—increasing the energy required for surface formation while decreasing the volume free energy—it provides insights into the induction time changes with different inhibitor concentrations. This model reflects real-world conditions more accurately than ever before, aiding in the efficient design of scale management strategies.
Flexible and Customizable Risk Modeling
But SKIT’s range is not limited to the above list. The Optimization tool within SKIT makes it possible for users to take their own data, lab, or field and create their own risk model. SKIT is equipped with a regression capability that allows companies to enter data from their experiments, well samples, and archived lab reports, and build a proprietary risk database. This Optimizer can be used to enhance existing predictions, to add proprietary inhibitors, and to introduce additional scales.
Practical Applications and Benefits
OLI designs tools that make complex physical chemistry principles easy to use and capable of solving practical problems. SKIT is no different. It enhances the industry’s ability to predict and manage scale risks during production operations. SKIT is part of ScaleChem, the industry standard for scale prediction. ScaleChem is the most accurate and intuitive tool on the market, using first principles electrolyte thermodynamics that predicts the formation of 100+ solids in all known production conditions for all known brine compositions.
SKIT capability changes the risk equation from Risk=f(ST, ES, T) to R=f(ST, ES, tind, Inh). The benefits are several, a more accurate risk analysis, fewer sampling runs, fewer experimental runs, faster answers, and most importantly, defining more precisely, the integrity operating window.
Future Enhancements
As we look to the future, SKIT will continue to evolve. Plans are already underway to include more types of scales and scale inhibitors, including blends, to broaden the tool’s applicability across various oilfield and geothermal systems. The ongoing development of this tool is a testament to OLI’s commitment to continuous innovation in scale prediction technologies.
Conclusion
The introduction of SKIT in ScaleChem V12 marks a significant evolution in how the industry approaches scale risk prediction. This development reflects the culmination of OLI’s continuous efforts to enhance scale prediction accuracy and adaptability. We invite industry professionals to explore how this tool can optimize their operations and help manage scale-related risks more effectively