The Influence of Fabric Arrangement on Oil Sand Samples from the Estuarine Depositional Environment of the Upper McMurray Formation

Bell, Julie D.¹; Boateng, Anane ¹; Olawale, Olaknule ¹; Roberts, David ¹
(1)Petroleum Engineering, London South Bank University, London, United Kingdom.

The Upper McMurray formation of Canada, more specifically, samples from the estuarine depositional settings taken in Athabasca displayed high porosity based on an initial study. This work involved thin section imaging and micro CT-scanning in determining reservoir characteristics. The results from the thin section analysis for the porosity estimation showed that the estimated porosity lied between 30 and 50%, which is analogous to tests performed in well laboratories. Data and results obtained from the two experiments were then used to compute the pore size distribution, connectivity of pores and estimates of the porosity and permeability of the reservoir. The analysis of the spatial arrangement and distribution of the oil sand constituents showed that bitumen was distributed within the quartz grains and also between the quartz grains. Another distinctive feature was the distribution of bitumen in the non-connecting large pores (vughs). The clay material was observed as forming bridges between the quarts grains and may be associated to larger clay bands. Importantly, soil structure was observed in thin section to be associated with Spodic horizons and the fabric of the grains ranged from enaulic to gefuric c/f related distribution. This indicates that the oil and meteoric water migrated into a sandy material with inherited soil structure. An analysis of this type has the potential to differentiate between parts of the formation where connectivity will have a bearing on the relative ease and cost of production of steam-assisted gravity drainage (SAGD) projects. It should then be possible to identify “sweet” spots along the reservoir interval where completion design factors such as sand/clay control or temperature/pressure profile control between injector and producer can be employed more effectively to target specific intervals for optimum production.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.