Dimensionless Methods for the Study of Particle Settling in Non-Newtonian Fluids
- Liang Jin (Stim-Lab Inc.) | G.S. Penny (Stim-Lab Inc.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1995
- Document Type
- Journal Paper
- 223 - 228
- 1995. Society of Petroleum Engineers
- 4.3.4 Scale, 2.7.1 Completion Fluids, 4.3.1 Hydrates, 2.4.3 Sand/Solids Control, 1.6 Drilling Operations, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 2 Well Completion, 1.8 Formation Damage, 2.5.2 Fracturing Materials (Fluids, Proppant)
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A systematic study of particle settling in polymer solutions and crosslinkedgels used in the oil industry has been conducted. Friction factors obtainedwith failing sphere experiments and a newly developed direct drag forcemeasurement technique are correlated to two dimensionless groups. One group isthe Reynold's number, Re, defined by the steady shear rheogram of the testfluids. Another group, Nve, is defined by the viscoelastic parameters of thepolymer systems. Unique methods of obtaining parameters for these twodimensionless groups are discussed and an algorithm for the prediction ofparticle settling is introduced.
Definition of the Work
The transport and settling of particles in drilling and fracturing fluidsare extremely important parameters to be considered in the successfulcompletion of oil and gas wells. For that reason, many researchers haveattempted to predict particle settling based on fluid properties provided byrheological models such as the power law model or the Bingham plastic model,where the rheological parameters are measured under steady shear conditions atmoderate to high shear rates. Low shear viscosity as well as elasticity ofborate crosslinked fluids in terms of G' has also been shown to correlate tostatic proppant settling. Recent work has shown that proppant transport can beaccurately modeled when the effects of single particle settling, density drivenflow, particle velocity profiles and slurry rheology are accounted for. Thesingle particle setting velocity is important because it is used to predict theparticle settling velocities in slurries based upon the shear rate and thevolumetric solids loading. Single particle settling velocities are easilydetermined in clear time-independent fluids such as linear gels. However, whenthe fluid is crosslinked, the fluid changes with time making it difficult toobtain instantaneous settling velocities. de Kruijf et al. have shown settlingvelocities to vary by an order of magnitude depending upon the time aftershearing and with exposed shear rate. Thus, a method of measuring properties topredict instantaneous settling velocities is needed to augment transportpredictions.
The objectives of the work reported herein are threefold. The firstobjective is to systematically determine impact of viscous and elasticproperties upon single particle settling. The second objective is to create aset of dimensionless relationships, which are capable of predicting settlingover a broad range of fluid properties. Finally, the third objective is toprovide a simple means of measuring fluid properties on shear historyconditioned fluids in order to instantaneously predict settling behavior intime dependent fluids.
This paper begins with a discussion of dimensionless groups that relate thephysical parameters involved in the settling process to the rheologicalproperties of the test fluids. Experimental investigations are carried out tocharacterize the rheological properties of fluid systems with a range ofviscous and elastic properties.
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