The primary objective of this work is to perform a complete characterization of the Womack Hill (oil) Field in Southern Alabama using petrophysical and reservoir performance data - and to provide reservoir management strategies that lead to improved oil recovery at Womack Hill Field. The process for achieving this goal requires the following specific objectives:To develop correlations between the core and well log data in order to generate spatial distributions of reservoir properties such as: porosity, permeability, net pay, etc.To analyze the production history on a per well basis using the decline type curve technique which pro-vides estimates of the following properties:Oil-in-place (N),Effective permeability (k),Flow capacity (kh),Reservoir drainage area (A), andNear-well skin factor (s).To determine the Estimated Ultimate Recovery (or EUR) for each well using the historical production data. The EUR is used to establish the volume of recoverable oil-in-place.To draw conclusions and provide recommendations regarding infill drilling, well completions, and pro-duction practices based on the results of integrating the geological data and the production history analysis.
Womack Hill Field is located on the border of Choctaw and Clarke counties, Alabama (Fig. 1). Hydrocarbon production is found in the Jurassic sequence consisting of the Smackover and Norphlet formations. Bottomhole pressure analysis has confirmed the pressure separation of the Lower Smackover-Norphlet reservoir from the Upper Smackover reservoir (Daigre, et al.1 (1986)). Womack Hill Field produces from the Upper Smackover carbonate reservoir at depths ranging from 11,090 feet (subsea) at the crest of the structure to 11,360 feet (subsea) at the water-oil contact. The oil trap on top of the reservoir is provided by the anhydrite in the overlying Buckner member of the Haynesville formation. A very large normal fault to the south of the field provides a lateral seal (Qi, et al.2 (1998)). Pruet and Hughes Company discovered Womack Hill Field, in November 1970 (Carlisle Unit 16–4 Well No.1 (Well Permit 1573)). This well was completed in the Upper Smackover carbonates and initially flowed 600 STB/D through perforations at 11,302 to 11,312 feet (subsea).
The original oil in place (OOIP or N) at Womack Hill Field is estimated to be 87.1 MMSTB (Core Labs3 (1974)) and the cumulative production has reached over 30 MMSTB, so we estimate the oil recovery to be on the order of 35 percent. We believe that because the recovery is apparently high, additional development opportunities are probably limited to isolated compartments.
The objective of this work is to develop an integrated reservoir description for this field in order to establish reservoir management strategies and to provide a basis for reservoir simulation. To develop such a study we must analyze all of the available data. The core and well log data are used to generate distributions of reservoir properties across the field and the production history is analyzed using both simplified analysis of rate (i.e., EUR plots), as well as the decline type curve technique to obtain estimates of oil-in-place and reservoir properties. The results of the analysis of the petrophysical and production data will be combined and interpreted simultaneously in order to draw conclusions and recommendations with regard to the continued operations and developments at Womack Hill Field.