Rienecke field is one of a series of fields in the Horseshoe Atoll of the Midland Basin. This carbonate reservoir has fairly good lateral and vertical continuity and is confined in a dome-like structure. A gravity-stable crestal carbon-dioxide flood was begun in 1997 by injection into five wells at the high point of the structure. Pulsed-neutron logs run through casing provide a method to monitor reservoir dynamics and locate oil production targets.

The first step in developing a cased-reservoir analysis model is to estimate the carbon dioxide content. This is done by correlation of the cased-hole neutron and density porosities from the pulsed-neutron system. In developing a three-phase saturation model (oil, water, carbon dioxide)the effects of the carbon dioxide on the oil and water saturation measurements must be determined. Computer simulations of tool response are utilized in conjunction with field data to develop the model and the uncertainties in the saturations.

An example log and analysis demonstrate the capabilities of the reservoir analysis model. The analysis results are compared to production and historical data for the field.

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