Abstract: Glauconite Sandstone Exploration: A Case Study from the Lake Newell Project, Southern Alberta

Kevin Broger, Garth Syhlonyk

Fluvial/estuarine Glauconite channel sands of the Lower Cretaceous are arguably one of the most prolific oil and gas reservoirs in Southern Alberta. The Countess-Alderson trend extends over 70 km and is one of several channel fairway systems that trend in a northwesterly direction away from the Kevin-Sunburst Dome in Northern Montana. Cumulative production along this trend has been in excess of 100 MMbbls of oil and 200 BCF of gas.

Although exploration activity in the area began in the early 1950s, it was not until 1989 that the effectiveness of three-dimensional seismic programs in exploration and pool delineation became apparent. Existing well and seismic control indicated the Glauconite channel fairway likely extended beneath the man-made reservoir, Lake Newell. To enhance drilling success and maximize potential hydrocarbon recoveries, a shallow-water land/marine 3-D survey was conducted over 40 % of the lake.

Based on the interpretation of several amplitude anomalies, an exploratory drilling program was undertaken. Environmental concerns and recreational development plans around Lake Newell meant the restriction of any further oil and gas development beneath the lake to four surface-pad locations. Some of the drilling locations required horizontal displacements of up to 2640 metres and rather than using conventional equipment, preference was given to slant drilling technology utilizing the Precision 9SE Rig, which was developed jointly with PanCanadian.

Cores from five of the wells were interpreted, and the results indicate the portion of the Countess-Alderson trend beneath Lake Newell is representative of several facies within the bayhead-delta environment of a wave-dominated estuary model. Channel deposits northwest of the lake are brackish, while those southeast of the lake are predominantly fluvial. Reservoir quality is best in the bayhead-delta deposited Glauconite sands, and knowing this we can use the theoretical wave-dominated estuary model as a predictive tool for maximizing the oil production from these reservoirs.

At the completion of the exploratory and development program, 15.3 MMbbls of recoverable oil had been discovered beneath the lake. This case study illustrates the value of integrating geology, geophysics and drilling technology in a multi-disciplinary approach toward hydrocarbon exploration and development of the Glauconite channel play in Southern Alberta.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994