Ajay Suri's theses
by
Ajay Suri, MSE
University of Texas at Austin, 2000
Supervisor: Dr. Mukul M. Sharma
A model has been developed to estimate the depth and degree of formation damage caused by mud
particles present in drilling or completion fluids. The mud components are characterized as particles with
different sizes. The depth of damage and permeability loss is calculated after invasion of the mud and also
after flowback. The effect of the particle size distribution in the fluid, particle concentration, differential
pressure across the core, and permeability of the formation are studied. It is demonstrated that particle
invasion and flowback processes are largely dependent on the particle size in the mud and the permeability
of the formation. The results of the model are shown to agree well with mud filtration experiments.
To better estimate the particle size distribution in drill-in and completion fluids, different methods for
measuring particle sizes were investigated. These results show that the measured particle sizes can vary over
two orders of magnitude depending on the technique used and on sample preparation. Based on a comparative
analysis of several samples, light scattering techniques are recommended for measuring the particle size
distribution. Recommendations for sample preparation are also provided.
Based on the model and our ability to measure particle size distributions, fluids can be designed and formulated
to minimize solids invasion and maximize return permeability.
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