saturation increase the relative permeability making
the migration more efficient.
Migration through sandstones occurs mostly along
the top of sloping beds. The depositional environments
determine the sandstone geometry, and diagenesis
determines the internal flow properties. Coarseningupwards sequences have a higher migration efficiency
than fining-upwards sequences or poorly sorted sand.
Migration through shales requires that they fracture
due to overpressure or tectonic deformation to overcome the capillary resistance. A cap rock must have a
capillary entry pressure which is higher than the pressure in the petroleum phase.
During progressive burial to about 4 km depth
(120
C) the shales often become almost impermeable
and fracture pressure is likely to be reached unless the
fluids can be drained laterally. Fracturing and leakage
of petroleum will occur at the top of the highest structure in the pressure compartment where the fracture
pressure is lowest (least overburden). On a global basis
oil reservoirs are mostly at temperatures less than
120
C. This is because at that depth the permeability
of shales serving as cap rocks (seals) may become
very low. Without lateral drainage, fracturing and
leakage may occur. Quartz cementation will in most
cases cause reduced porosity at depths where the temperature is higher than 120
C.
During subsidence, fault zones are not likely to
provide open conduits for oil migration unless fracture
pressure is reached.
Further Reading
Abrams, M.A. 1996. Distribution of subsurface hydrocarbon
seepage in near-surface marine sediments. In: Schumacher,
D. and Abrams, M.A. (eds.), Hydrocarbon Migration and its
Near-Surface Expression. AAPG Memoir 66, pp. 1–14.
Bjørkum, P.A., Walderhaug, O. and Nadeau, P. 1998. Physical
constraints on hydrocarbon leakage and trapping revisited.
Petroleum Geoscience 4, 237–239.
Bjørlykke, K. and Aagaard, P. 1992. Clay Minerals in North Sea
Sandstones. In: Houseknecht, D.W. and Pittman, E.D. (eds.),
Origin, Diagenesis and Petrophysics of Clay Minerals in
Sandstones. SEPM Special Publication 47, pp. 65–80.
Bugge, T., Knarud, R. and Mørk, A. 1984. Bed rock geology on
the mid-Norwegian continental shelf. In: Spencer, A.M.
et al. (eds.), Petroleum Geology of the North European
Margin: Norwegian Petroleum Society. Graham and
Trotman, London, pp. 549–555.
di Primeo, R. and Horsfield, B. 2006 From petroleum-type
organofacies to hydrocarbon phase prediction. AAPG
Bulletin 90, 1031–1058.
Geoff, J.C. 1983. Hydrocarbon generation and migration from
Jurassic source rocks in the E. Shetland Basin and Viking
Graben of the northern North Sea. Journal of Geological
Society 140, 445–474.
Hantchel, T. and Kauerauf, A.I. 2009. Fundamentals of Basin
and Petroleum System Modeling. Springer, New York, NY,
476 pp.
Hovland, M., Garder, J.V. and Judd, A.G. 2002. The significance of pockmarks to understanding fluid flow processes
and geohazards. Geofluids 2, 127–136.
Karlsen, D. A., Nyland, B., Flood, B., Ohm, S. E., and BackerOwe, K. 1995. Petroleum geochemistry of the Haltenbanken,
Norwegian continental shelf. In: Cubitt, J.M. (ed.), The
Geochemistry of Reservoirs. Geological Society Special
Publication 86, pp. 203–256.
Leonard, R.C. 1993. Distribution of subsurface pressure in the
Norwegian Central Graben and applications for exploration.
In: Parker, J.R. (ed.), Petroleum Geology of Northwest
Europe: Proceedings of the 4th Conference. The Geological
Society, pp. 1295–1303.
Lindgren, H. 1987. Molecular sieveing and primary migration in
the Upper Jurassic and Cambrian claystones source rock. In:
Brooks, J. and Glennie, K. (eds.), Petroleum Geology of
Northwest Europe. Graham and Trotman, London,
pp. 357–364.
Nadeau, P.H., Bjørkum, P.A. and Walderhaug, O. 2005. Petroleum system analysis: Impact of shale diagenesis on reservoir fluid pressure, hydrocarbon migration, and
biodegradation risks. In: Dore ´, A.G. and Vining, B.A.
(eds.), Petroleum Geology: North-West Europe and Global
Perspectives – Proceedings of the 6th Petroleum Geology
Conference. The Geological Society, pp. 1267–1274.
Olstad, R., Bjørlykke, K. and Karlsen, D.K. 1997. Pore water
flow and petroleum migration in the Smørbukk Field area,
offshore Norway. In: Møller-Pedersen, P. and Koestler, A.G.
(eds.), Hydrocarbon Seals – Importance for Exploration and
Production. Norwegian Petroleum Society, Special Publication 7, 201–216.
Schowalter, T.T. 1979. Mechanism of secondary hydrocarbon
migration and entrapment. AAPG Bulletin 63, 723–760.
Sylta, Ø., Pedersen, J.I. and Hamborg, M. 1998. On the vertical
and lateral distribution of hydrocarbon migration velocities
during secondary migration. In: Parnell, J. (ed.), Dating and
Duration of Fluid Flow and Fluid-Rock Interaction. Geological Society Special Publication 144, pp. 221–232.
Teige, G.M.G., Hermanrud, C., Thomas, W.L.H., Wilson, O.B.
and Nordga ˚rd Bola ˚s, H.M. 2005. Capillary resistance and
trapping of hydrocarbons; A laboratory experiment. Petroleum Geoscience 11, 15–129.
Thrasher, J., Fleet, A.J., Hay, S.J., Hovland, M. and
Du ¨ppenbecker, S. 1996. Understanding geology as the key
to using seepage in exploration: The spectrum of seepage
styles. In: Schumacher, D. and Abrams, M.A. (eds.), Hydrocarbon Migration and Its Near-Surface Expression. AAPG
Memoir 66, 223–241.
Thyberg, B., Jahren, J., Winje, T., Bjørlykke, K. and Faleide, J.I.
February 2009. From mud to shale: Rock stiffening by
micro-quartz cementation. First Break 27, 27–33.
384
K. Bjørlykke
the migration more efficient.
Migration through sandstones occurs mostly along
the top of sloping beds. The depositional environments
determine the sandstone geometry, and diagenesis
determines the internal flow properties. Coarseningupwards sequences have a higher migration efficiency
than fining-upwards sequences or poorly sorted sand.
Migration through shales requires that they fracture
due to overpressure or tectonic deformation to overcome the capillary resistance. A cap rock must have a
capillary entry pressure which is higher than the pressure in the petroleum phase.
During progressive burial to about 4 km depth
(120
C) the shales often become almost impermeable
and fracture pressure is likely to be reached unless the
fluids can be drained laterally. Fracturing and leakage
of petroleum will occur at the top of the highest structure in the pressure compartment where the fracture
pressure is lowest (least overburden). On a global basis
oil reservoirs are mostly at temperatures less than
120
C. This is because at that depth the permeability
of shales serving as cap rocks (seals) may become
very low. Without lateral drainage, fracturing and
leakage may occur. Quartz cementation will in most
cases cause reduced porosity at depths where the temperature is higher than 120
C.
During subsidence, fault zones are not likely to
provide open conduits for oil migration unless fracture
pressure is reached.
Further Reading
Abrams, M.A. 1996. Distribution of subsurface hydrocarbon
seepage in near-surface marine sediments. In: Schumacher,
D. and Abrams, M.A. (eds.), Hydrocarbon Migration and its
Near-Surface Expression. AAPG Memoir 66, pp. 1–14.
Bjørkum, P.A., Walderhaug, O. and Nadeau, P. 1998. Physical
constraints on hydrocarbon leakage and trapping revisited.
Petroleum Geoscience 4, 237–239.
Bjørlykke, K. and Aagaard, P. 1992. Clay Minerals in North Sea
Sandstones. In: Houseknecht, D.W. and Pittman, E.D. (eds.),
Origin, Diagenesis and Petrophysics of Clay Minerals in
Sandstones. SEPM Special Publication 47, pp. 65–80.
Bugge, T., Knarud, R. and Mørk, A. 1984. Bed rock geology on
the mid-Norwegian continental shelf. In: Spencer, A.M.
et al. (eds.), Petroleum Geology of the North European
Margin: Norwegian Petroleum Society. Graham and
Trotman, London, pp. 549–555.
di Primeo, R. and Horsfield, B. 2006 From petroleum-type
organofacies to hydrocarbon phase prediction. AAPG
Bulletin 90, 1031–1058.
Geoff, J.C. 1983. Hydrocarbon generation and migration from
Jurassic source rocks in the E. Shetland Basin and Viking
Graben of the northern North Sea. Journal of Geological
Society 140, 445–474.
Hantchel, T. and Kauerauf, A.I. 2009. Fundamentals of Basin
and Petroleum System Modeling. Springer, New York, NY,
476 pp.
Hovland, M., Garder, J.V. and Judd, A.G. 2002. The significance of pockmarks to understanding fluid flow processes
and geohazards. Geofluids 2, 127–136.
Karlsen, D. A., Nyland, B., Flood, B., Ohm, S. E., and BackerOwe, K. 1995. Petroleum geochemistry of the Haltenbanken,
Norwegian continental shelf. In: Cubitt, J.M. (ed.), The
Geochemistry of Reservoirs. Geological Society Special
Publication 86, pp. 203–256.
Leonard, R.C. 1993. Distribution of subsurface pressure in the
Norwegian Central Graben and applications for exploration.
In: Parker, J.R. (ed.), Petroleum Geology of Northwest
Europe: Proceedings of the 4th Conference. The Geological
Society, pp. 1295–1303.
Lindgren, H. 1987. Molecular sieveing and primary migration in
the Upper Jurassic and Cambrian claystones source rock. In:
Brooks, J. and Glennie, K. (eds.), Petroleum Geology of
Northwest Europe. Graham and Trotman, London,
pp. 357–364.
Nadeau, P.H., Bjørkum, P.A. and Walderhaug, O. 2005. Petroleum system analysis: Impact of shale diagenesis on reservoir fluid pressure, hydrocarbon migration, and
biodegradation risks. In: Dore ´, A.G. and Vining, B.A.
(eds.), Petroleum Geology: North-West Europe and Global
Perspectives – Proceedings of the 6th Petroleum Geology
Conference. The Geological Society, pp. 1267–1274.
Olstad, R., Bjørlykke, K. and Karlsen, D.K. 1997. Pore water
flow and petroleum migration in the Smørbukk Field area,
offshore Norway. In: Møller-Pedersen, P. and Koestler, A.G.
(eds.), Hydrocarbon Seals – Importance for Exploration and
Production. Norwegian Petroleum Society, Special Publication 7, 201–216.
Schowalter, T.T. 1979. Mechanism of secondary hydrocarbon
migration and entrapment. AAPG Bulletin 63, 723–760.
Sylta, Ø., Pedersen, J.I. and Hamborg, M. 1998. On the vertical
and lateral distribution of hydrocarbon migration velocities
during secondary migration. In: Parnell, J. (ed.), Dating and
Duration of Fluid Flow and Fluid-Rock Interaction. Geological Society Special Publication 144, pp. 221–232.
Teige, G.M.G., Hermanrud, C., Thomas, W.L.H., Wilson, O.B.
and Nordga ˚rd Bola ˚s, H.M. 2005. Capillary resistance and
trapping of hydrocarbons; A laboratory experiment. Petroleum Geoscience 11, 15–129.
Thrasher, J., Fleet, A.J., Hay, S.J., Hovland, M. and
Du ¨ppenbecker, S. 1996. Understanding geology as the key
to using seepage in exploration: The spectrum of seepage
styles. In: Schumacher, D. and Abrams, M.A. (eds.), Hydrocarbon Migration and Its Near-Surface Expression. AAPG
Memoir 66, 223–241.
Thyberg, B., Jahren, J., Winje, T., Bjørlykke, K. and Faleide, J.I.
February 2009. From mud to shale: Rock stiffening by
micro-quartz cementation. First Break 27, 27–33.
384
K. Bjørlykke