Reservoir Modeling to Investigate the Impacts of Geological Properties on Steam-Assisted Gravity Drainage (SAGD) at the Orion Project, Lower Cretaceous Clearwater Formation, Alberta

Abstract

When compared to steam-assisted gravity drainage (SAGD) operations in the McMurray Formation, Athabasca Oil Sands, the Orion SAGD from the Clearwater Formation at Cold Lake did not perform as expected, likely because of geological properties. The net pay zone is 24m in thickness, consisting mainly of shoreface unconsolidated sand at a depth of 425m. This study aims to: (1) investigate the impacts of reservoir petrophysical properties, including shale content, porosity, permeability and oil saturation, on each of the seven well pads at Orion; (2) identify and assess major geological challenges for Orion; and (3) propose a new well pair location within the Orion lease boundary. To characterize reservoir quality in detail, wireline log data were interpreted to quantify reservoir petrophysical properties, which were used to build four 3-D property models. 3-D visualizations and 2-D cross sections of the reservoir revealed spatial distribution and heterogeneity of each property. Production performance analyses of the well pads were conducted using: (1) temperature profiles that monitored the growth of the steam chamber and (2) cumulative steam-oil ratio (CSOR) and monthly oil production rates, which are direct indicators of thermal efficiency. Results show that impermeable barrier and low-permeability zones were detrimental to steam injectivity and steam chamber growth, as some observation wells in Pilot Pads 1 and 3 did not detect any steam saturation. High permeability zones resulted in high injectivity and high mobility of steam, especially in Pad 105. Steam chambers in high shale-content zones were irregularly shaped, as two sharp spikes displayed on the temperature profile in Pad 103. Low oil saturation zones and thin net pay zones increased the CSOR, as seen in Pads 104 and 106. Because impermeable layers inside the reservoir are almost horizontal, bed inclination did not make any difference on well pad orientation. Lack of porosity variation made it difficult to identify the impact of porosity on each well pad. The key geological parameters influencing each well pad at Orion have been documented in this research. The relatively widespread distribution of impermeable layers and low-permeability zones between and above well pairs, as well as the relatively large area of low oil saturation and thin net pay, have been identified as major geological challenges for the Orion SAGD. Location of a new well pair was proposed to the north of Pilot Pad 1.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016