RITTIPAT, AREE, Colorado School of Mines, Department of Geology and Geological Engineering, Golden, CO

ABSTRACT: Vug Quantification from Core and Well Logs, Ratherford Unit, Aneth Field, Utah

The purpose of this research is to apply a new technique for vug quantification by using digital core images to calibrate borehole images to improve exploitation of carbonate reservoirs. The premise is that conventional logs tend to average, or even underestimate vuggy porosity.

The data set available for this study is 175 ft of core, 32 thin sections, a Formation Microimager, plus conventional logs. All data will be analyzed using the following procedure:

1. Core and thin sections will be described in terms of rock fabric, facies and cyclicity. Vuggy porosity will be classified in terms of type, size and amount. I will use the carbonate classification of Dunham (1962) and the vug classification of Lucia (1983).

2. Conventional well logs will be displayed with the core description to study the log signature of the various rock types.

3. Vugs will be quantified by using digital core images which will be used to calibrate and compare to borehole images and conventional well logs.

The results of this research will help to better interpret conventional well logs that commonly do not reveal the existence of vuggy porosity in carbonate reservoirs. The larger problem is that undetected vuggy porosity, when averaged with low matrix porosity, can lead to bypassed pay. Units that should have been perforated may be cased and left behind.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid