Rice University


Recent Research Products

Recent Research Products (April 2015)


1.  Consortium Software:

1.1.  ScaleSoftPitzerâ„¢: An Excel based software program to predict scale formation for sixteen different minerals (Carbonates, sulfates, halite, sulfides, calcium     fluoride, and silicates).  This program is based upon the Pitzer theory of electrolytes, which is generally believed to be the best approach to calculate the effect of high T, P, TDS, composition on activity coefficients.  The effect of hydrate inhibitors on mineral scale formation is included for calcite and barite.  The effect of ten common scale inhibitors on nucleation kinetics, with or without hydrate inhibitors, is automatically calculated.  Mixing of up to five brines and gases in any proportion and conditions is permitted.  The latest versions of our software are distributed at Consortium meetings and are available in the password protected portion of our website: http://www.brinechem.rice.edu/  

1.2.  SqueezeSoftPitzer, squeeze modeling and design software: An Excel based software has been developed to guide the design and prediction of inhibitor return concentrations.  Several new innovations have been included in this code for squeeze design that move the state of art of oil field scale control closer to being based upon molecular understanding of the interaction and thereby predictable.  Most of the aspects of squeeze design, such as pill concentration effects, pill pH adjustment effects, and return temperature impact, are modeled with this new software.   

2.  Contribution to the scientific understanding of scale prediction and control:

2.1.  Unified inhibition model for calcite and NORM scale control and treatment:  Equations, based on common field measurement that can be used to estimate the minimum effective concentrations of each of eight common scale inhibitors has been developed and included in both ScaleSoft and ScaleSoftPitzer.  The predicted minimum effective concentrations are calculated based upon the specific well and production conditions.  Additivity rules for inhibitor blends have also been included.  Predictions of these equations are generally found to be reasonable compared to field observations. 

2.2.  Effects of methanol and ethylene glycol on Scale formation: Methanol and ethylene glycol effect on the formation of mineral scale has been measured over a wider range of conditions.  A systematic study of these co-solvents on nucleation kinetics and inhibition has been conducted for BaSO4 and calcite.  The impact on the solubility of BaSO4 is quite large, but the effect on nucleation kinetics and inhibition is even more dramatic and unexpected.  

2.3.  Molecular mechanism of how inhibitor squeeze works and inhibition takes place: Molecular mechanism of scale inhibition has been advanced substantially by detailed tests of the effect of solution condition and inhibitors on the inhibition of barite and calcite.  Due to improved reaction apparatus, experimental design, and theoretical analysis, a very wide range of inhibitor action seems to be explainable for the first time.  This work is potentially the first quantitative answer to why and under what conditions inhibitors work for both the squeeze and the return curve and "minimum effective dose".  A wide range of calcite and barite inhibition was modeled with one single model in both kinetics and equilibrium.  This new molecular-level understanding might permit numerical squeeze inhibition and return modeling as well as predicting the minimum effective dose in a well for the first time. 

2.4.  Chemical properties of scale inhibitors:  The acid/base speciation constants, metal complexation stability constants, and solubility constants of amorphous and crystalline phases for phosphonate inhibitors (NTMP, DTPMP, and BHPMP) and polymeric inhibitors (PPCA) as a function of temperature and ionic strength have been determined. 

3.  Developed improved analytical procedures to measure parameters pertinent to scale control:  

3.1.  Measurement of Low Phosphonate Concentrations.  U.S. Patent No. 5,270,216, 1993. 

3.2.  Elevated Temperature-Pressure Flow Simulator.  U. S. Patent No. 5,370,799, 1994. 

3.3.  A Novel Method for Scale Inhibitor Squeeze Application to Gas and Oil Wells. U.S. Patent No. 5,655,601, 1997. 

3.4.  An extraction method to measure scale inhibitors at trace concentration in complicated solution has been adopted by National Association of Corrosion Engineers (NACE) as a Standard Test Method, TM0399-99.  

3.5.  Developed a simple titration method to determine both bicarbonate and total carboxylic acid simultaneously and is programmed into Excel for ease of use. Alkalinity is of prime importance to any brine analysis because it is related to the pH and to the bicarbonate concentration, HCO3-, both used to predict scale tendency and corrosion potential in a well. Recommended Practices-type procedure has been written for routine use. Results have been tested with laboratory standards and with two field brines and results compared well with gas chromatography results.  

3.6.  Developed a new flow-through test loop for testing inhibitors has been developed and tested with synthetic field brines. 

4.  Provide technical support to Consortium companies:

4.1.  Involved in design, implementation, and monitoring of innovative squeeze procedures with Consortium companies.  Often software needs to be modified or the input/output needs slight changes for a particular use and these changes are done routinely, at no cost to members. 

4.2.  Provide technical advice on difficult analytical and scale-related problems observed by Consortium members.  The experience in observing and solving field related problems is used to guide future research direction of the Brine Chemistry Consortium.