ABSTRACT: The Role of Gas Chromatography in Field Management: Wonsits Valley Field, Uintah County., Utah

M. L. Schuh, G. A. Pickett

Hydrocarbon extracts from four cored wells were analyzed by capillary gas chromatrograpby to determine the unique characteristics of the five main producing reservoirs at Wonsits Valley field. Peak ratios were selected to maximize variations of oil. The resultant chromatographic fingerprints were used to determine reservoir contribution to swab and wellhead oil samples in wells with multiple completions.

Chromatrography of swab samples is used to determine whether communication of cross-flow has occurred between zones. The relative pressures of perforated zones can be established in cross-flowing wells. Chromatography of wellhead samples is used to select wells for stimulation, as evidence for deciding which zones to exclude in high water-cut wells and to determine reservoir continuity. Before and after wellhead analyses are used to evaluate the effect of workovers.

The waterflood is monitored by annually collecting of wellhead samples from all producers. The resultant production allocations allow for pattern recovery estimates, and sweep efficiency is evaluated. The monitoring program also identifies patterns where selective injection equipment may be necessary.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990