|Publisher||Society of Petroleum Engineers||Language||English|
|Content Type||Conference Paper|
|Title||Pressure and Temperature Effects on Brine Completion Fluid Density|
|Authors||Thomas, D.C., Amoco Production Co.; Atkinson, Gordon, Atkinson, B.L., U. of Oklahoma|
SPE Formation Damage Control Symposium, 13-14 February 1984, Bakersfield, California
|Copyright||Copyright 1984 Society of Petroleum Engineers of AIME|
A model has been developed to predict the density of a brine containing CaCl2, CaBr2, and ZnBr2 from its composition. The model accounts for the effects of pressure and temperature using experimental results and literature data. The theoretical framework and equations used are presented.
Brine completion fluids are used to control wells during gravel-packing and other open perforation completion work. Since they are usually perforation completion work. Since they are usually filtered to minimize particulate invasion, careful adjustment of the overbalance pressure is required to minimize fluid loss to the formation. The methods presented here will allow the engineer to more accurately estimate the density requirements for the fluid.
The model has been compared to published brine density data and matches that data well. The model predicts the effects of temperature on CaCl2, CaBr2 predicts the effects of temperature on CaCl2, CaBr2 and ZnBr2 solutions. The effect of pressure on these fluids is small and less documented, but where data are available for comparison purposes the model matches the data well up to 200 degrees F.
Methods of predicting the density of brine completion fluids are needed for well control pressure calculations and cost control of fluids, and are major factors in brine completion fluid optimization. This work represents the first application of modern solution thermodynamics to field completion brine problems.
Brine completion fluids are being used throughout the world to provide pressure control in a solids-free environment. The technology has been developing over the past ten years. Suman reviewed the state-of-the-art in 1975 and pointed out that modern completion fluids should be readily removable to leave the wellbore clean for production or other operations. Millhone updated the state-of-the-art in 1983 focusing on the need to minimize completion damage by minimizing particulate contamination of the formation.' He described underbalanced, balanced, and overbalanced completion methods that have been used successfully in the field.
Industry interest in these fluids is evident from the number of papers and articles being published that discuss the benefits and proper use of published that discuss the benefits and proper use of these fluids. Amoco has used heavy brines extensively in the Gulf Coast area with success. Initial difficulties with emulsion formation and crystallization in flow lines led Amoco Research to begin a research program on completion brines. One of the main objectives of the program was to develop methods to calculate the density of a brine throughout a wellbore. Accurate knowledge of the pressure exerted by a brine under downhole pressure exerted by a brine under downhole conditions would allow precise control of overbalance levels in high pressure completions. Ignorance of the pressure and temperature effects on a brine could easily cost an operator a well either through low estimates that would provide insufficient pressure control or through conservative estimates that pressure control or through conservative estimates that would overpressure the formation. Excessive fluid loss to the formation through overpressuring can unnecessarily lengthen the cleanup time and increase well costs due to large losses of expensive brine.
The rationale and equations used to calculate the density of brines are discussed here without derivations to allow the reader to see the logical process in the development of the calculation process in the development of the calculation method. The theoretical background is presented in Appendix A.
The density of any solution can be represented by the following general equation:
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