TY - JOUR
T1 - Impact of reservoir heterogeneity on oil migration and the origin of oil-water contacts
T2 - McMurray Formation type section, Alberta, Canada
AU - Fustic, Milovan
AU - Strobl, Rudy
AU - Fowler, Martin
AU - Jablonski, Bryce V.
AU - Martinius, Allard W.
PY - 2019
Y1 - 2019
N2 - This study documents and attempts to describe the processes leading to the formation and preservation of exposed oil, water, and paleo-gas contacts at the McMurray Formation type section, Alberta, Canada. The McMurray Formation type section, a part of the Athabasca Oil Sands Deposit (AOSD), the largest exhumed oil reservoir on Earth, is unparralled, still underutilized, natural laboratory for veryfing and refining existing, and developing new concepts, for oil migration and post oil-emplacement fluid diffusion and biodegradation processes in a sedimentologically complex reservoir setting. Exposures, coupled with adjacent borehole data, provide a three-dimensional insight into reservoir heterogeneities and their influence on oil migration, entrapment, post-emplacement fluid mixing, and biodegradation processes and products, in a hierarchical and chronological order from early charge to present-day conditions. The principles of oil above water and of horizontal or tilted oil/water contacts are challenged by outstanding examples of: (i) centimetre to decimetre scale inter-fingering oil-water stringers/contacts, created by capillary pressure differences and partial charge; (ii) irregular oil-water contacts in both clean and heterogeneous reservoirs characterized by gravitational effects caused by severe biodegradation that caused the formation of extra heavy-oil commonly referred to as “bitumen” that sank through the water column; (iii) occurrences of multiple metre-scale intervals with less than 50% oil saturation, commonly referred to as lean zones that formed during microbial gas generation following oil entrapment. Studied contacts provided excellent opportunity to study oil migration and charging mechanisms from pore and sedimentary bed to reservoir scale at various stages of oil migration into the reservoir, as well as oil, water, and gas re-migration within the reservoir (trap). Described exposures can play an additional role in advancing geoscience education, petroleum exploration, reservoir characterization, field development, and production optimization studies.
AB - This study documents and attempts to describe the processes leading to the formation and preservation of exposed oil, water, and paleo-gas contacts at the McMurray Formation type section, Alberta, Canada. The McMurray Formation type section, a part of the Athabasca Oil Sands Deposit (AOSD), the largest exhumed oil reservoir on Earth, is unparralled, still underutilized, natural laboratory for veryfing and refining existing, and developing new concepts, for oil migration and post oil-emplacement fluid diffusion and biodegradation processes in a sedimentologically complex reservoir setting. Exposures, coupled with adjacent borehole data, provide a three-dimensional insight into reservoir heterogeneities and their influence on oil migration, entrapment, post-emplacement fluid mixing, and biodegradation processes and products, in a hierarchical and chronological order from early charge to present-day conditions. The principles of oil above water and of horizontal or tilted oil/water contacts are challenged by outstanding examples of: (i) centimetre to decimetre scale inter-fingering oil-water stringers/contacts, created by capillary pressure differences and partial charge; (ii) irregular oil-water contacts in both clean and heterogeneous reservoirs characterized by gravitational effects caused by severe biodegradation that caused the formation of extra heavy-oil commonly referred to as “bitumen” that sank through the water column; (iii) occurrences of multiple metre-scale intervals with less than 50% oil saturation, commonly referred to as lean zones that formed during microbial gas generation following oil entrapment. Studied contacts provided excellent opportunity to study oil migration and charging mechanisms from pore and sedimentary bed to reservoir scale at various stages of oil migration into the reservoir, as well as oil, water, and gas re-migration within the reservoir (trap). Described exposures can play an additional role in advancing geoscience education, petroleum exploration, reservoir characterization, field development, and production optimization studies.
KW - Biodegradation
KW - Biogenic gas
KW - Capillary pressure
KW - Compartmentalization
KW - Heavy oil
KW - McMurray Formation
KW - Oil-water contacts
KW - Petroleum migration
UR - http://www.scopus.com/inward/record.url?scp=85062344631&partnerID=8YFLogxK
U2 - 10.1016/j.marpetgeo.2019.01.020
DO - 10.1016/j.marpetgeo.2019.01.020
M3 - Article
AN - SCOPUS:85062344631
VL - 103
SP - 216
EP - 230
JO - Marine and Petroleum Geology
JF - Marine and Petroleum Geology
SN - 0264-8172
ER -