The Utikuma Lake oil field produces under primary production driven by an active aquifer. The determination of historical and future positions of the rising oil/water (O/W) contact is important for identifying reserves, infill drilling locations and production problems.
Geological complexities such as thin interbedded shales, faulting, uncertain pool boundaries and varied initial O/W contacts throughout Utikuma prevents accurate performance analysis. Potential water coning and varied drainage areas limits the effectiveness of costly saturation logging programs in determining pool O/W contacts. The analytical technique used to analyze pool performance in Utikuma, is an easy to apply, low-cost approach for determining the rise of the O/W contact in fields with bottom or flank water-drive aquifers.
The technique used completion histories, production and petrophysical data, and geological mapping to determine an initial estimate of the historical O/W contact rise. The O/W contacts were then adjusted for production anomalies by comparing fluid wnhdrawals with rate of contact rise. Future O/W contacts based on fluid withdrawals were forecasted from decline analysis and adjusted to approximate historical sweep efficiencies. A final material balance was done to balance the remaining plus the swept oil-in-place volumes with the mapped oil in place.
This paper describes the technique's application to the Utikuma Keg River A East pool, and the results obtained, including the final position of the O/W contact and ultimate reserves. A major impact of the technique was the identification of unswept reserves and infill drilling locations. Preliminary results from the first well in an infill drilling program are also presented.
The Utikuma Lake field is located 300 km north of Edmonton in Townships 81 to 82 and Ranges 8 to 10 w5m. The field's 25 Keg River sandstone pools produce under primary production driven by the active Peace River Arch aquifer. Geological complexities, potential water coning and varied drainage areas limit the effectiveness of costly saturation logging programs in determining rising pool oil/water (O/W) contacts. The analytical technique presented in this paper is a simple, low-cost approach for determining historical and future O/W contact positions, The paper illustrates the technique's application to the Utikuma Keg River A East pool, shown in Figure 1, to develop production forecasts, identify ultimate reserves and infill drilling locations.
A comparison is made between the technique's results and a simulation study done on the same area. Preliminary results from the first infill well are also presented.
Utikuma Keg River Basin sands came from the Peace River Arch to the west. The sands were deposited in topographic lows and on the flanks of irregular Precambrian highs in an environment that has been interpreted as deltaic. Trapping mechanisms included compactional draping of the sands over the Precambrian topography, faulting, sand pinch outs against the Precambrian highs and along the depositional edge, The porous sands are sealed above and below by impermeable shales.
Water underlaying the Keg River oil pools is part of the Peace River Arch aquifer which extends over 225 km south of the Utikuma field.