Characterization of Flow Units in Carbonate Reservoirs Enhances Exploration and Development Decision Making

Jeff Martin, Steve Solomon, Dan Hartmann

An interpretation procedure which involves the identification and characterization of flow units, has been used to resolve some of the key challenges faced in the exploration and production of carbonate reservoirs in the Middle East and Midcontinental U.S.

The procedure requires a multi-disciplined team to create status maps of the area of interest, in order to identify populations of similar data that can be represented by key wells. Using the key wells, the team then review the vertical wellbore data for intervals that are likely to have similar, consistent and predictable flow behavior ("flow units"). The use of an inter-related series of petrophysical cross plots and calculation of a pore throat diameter log, assist in the identification and quantitative characterization of the flow unit types in the key wells.

By determining the water saturation versus height relationship for each flow unit type, it is possible to predict the free water level, oil/water contact and hydrocarbon distribution in the reservoir. When a relationship exists between depositional facies and flow units, a common geological and engineering zonation is developed and parasequences can be characterized in terms of flow unit types. Combining the Sw/h/ flow unit relationships with the interpreted sequence stratigraphy of the area, provides a useful tool for quantifying parasequence quality and predicting the location of hydrocarbon productive stratigraphic traps.

In producing reservoirs, the same approach has been used to exploit by-passed pay and to establish pre-simulation performance predictions.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995