A convenient protocol for screening the potential efficacy of scale inhibitors is described. All of the techniques used require relatively inexpensive equipment. Two types of scale are addressed in this paper, calcium carbonate and calcium oxalate, but the general procedures are expected to be applicable to inhibitor screening for others as well.
Chemical treatment of reservoir fluids within the wellbore is essential for the control of associated corrosion and scale deposition. The Wafra Risk Assessment was developed with the Likelihood of Failure (LoF) based on historical corrosion well workover failures and the Consequence of Failure (CoF) directly tied to oil daily oil production.
In a bioinspired approach, we have used (as scale inhibitors) several non-toxic, “green” polyelectrolytes that possess “active” chemical moieties, capable of stabilizing silicic acid, for a prolonged time period. These additives include either neutral or charged polymers that stabilize two soluble forms of “Si”, silicic and disilicic acids.
This CorrCompilation series focuses primarily on equilibrium-formed scales, where an aqueous fluid changes from an unsaturated equilibrium state to a saturated and supersaturated state and then solids may start to form. These types of fouling minerals include alkaline earth salts, silicates, alkaline salts (NaCl), sulfides, and under specific circumstances, metal sulfide salts that form through equilibrium changes. While corrosion product scales are not the subject of this book, the importance of corrosion product layers to the deposition of other scales will be described.
Since this is a CorrCompilation and more than 90 copies of NACE papers are included, the work is published in four volumes. The editor, Wayne W. Frenier, FNACE, provides an extensive introduction to each volume, offering the reader a thorough mix of history, theory, and engineering techniques and methods for addressing scale.
Volume 1: Introduction to Equipment Subject to Inorganic Scale
Volume 2: Current Mechanisms for Understanding Inorganic Scale Formation and Deposition
Volume 3: Chemistry and Application of Scale Inhibitors
Volume 4: Alternative Methods of Scale Control
Predicting where, when, and, most importantly, how much scale will deposit and adhere to a critical surface has proven to be very challenging. This second volume, "Current Mechanisms for Understanding Inorganic Scale Formation and Deposition," will review literature for both the formation and deposition of the primary fouling mineral scales, CaCO3, CaSO4(X•H2O), BaSO4, metal sulfides, and silica/silicates.