Evaluation of Formation Permeability Using Time-Lapse Logging Measurements duringand After Drilling. Annual Report, December 1991

摘要

The authors have developed a concept to compute mudcake buildup based upon theflux of mud filtrate into the formation. The buildup of mudcake depends upon a parameter the authors call adhesion fraction. The adhesion fraction is the percent of the clay particles associated with the filtrate that sticks to form the mudcake on the borehole walls. The adhesion fraction should be a function of the pressure differential between the borehole and the formation, the formation permeability, the shear rate when mud is being circulated, and the drilling mud type. To assist in the development of the mudcake buildup model, the authors have made numberous measurements in the laboratory at the University of Texas to evaluate the mudcake properties and the adhesion fraction. The authors have also analyzed field data during 1991. Drilling information, cores, and logs have been analyzed on GRI's Staged Field Experiment No. 3 and the Mobil Lake Creek Unit 48 well in Montgomery County. The authors have successfully historically matched the mud filtrate invasion data i four zones in SFE No. 3 The authors have also successfully correlated the core permeability with the deep and medium induction log readings in SFE No. 3. Additional analyses for Lake Creek Unit 48 will be completed after the final logging runs and the special core analyses have been completed. During 1991, the authors collected most of the radial response functions they needed to write a topical report and explain how these functions can be used to analyze data from repeat logging measurements. The radial response functions are being used in a Logging Tool Response Simulator to predict the readings from logging tools given the distribution of water saturation, water salinity, and fluid density around the borehole.