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Heavy oil is defined as liquid petroleum of less than 20°API gravity or more than 200 cp viscosity at reservoir conditions. No explicit differentiation is made between heavy oil and oil sands (tar sands), although the criteria of less than 12°API gravity and greater than 10,000 cp are sometimes used to define oil sands.<ref name="r1" /><ref name="r2" /><ref name="r3" /><ref name="r4" /> The oil in oil sands is an immobile fluid under existing reservoir conditions, and heavy oils are somewhat mobile fluids under naturally existing pressure gradients. Unconsolidated sandstones (UCSS) are sandstones (or sands) that possess no true tensile strength arising from grain-to-grain mineral cementation. Many heavy oil reservoirs are located in unconsolidated sandstones.
Heavy oil is defined as liquid petroleum of less than 20°API gravity or more than 200 cp viscosity at reservoir conditions. No explicit differentiation is made between heavy oil and oil sands (tar sands), although the criteria of less than 12°API gravity and greater than 10,000 cp are sometimes used to define oil sands.<ref name="r1">"NEB - National Energy Board." Government of Canada, National Energy Board. http://www.neb-one.gc.ca/index-eng.html.</ref><ref name="r2">Alberta Energy Regulator. http://www.eub.gov.ab.ca/.</ref><ref name="r3">"Our Oil & Gas Resources - Economy - Government of Saskatchewan." Our Oil & Gas Resources - Economy - Government of Saskatchewan. http://www.er.gov.sk.ca/OilGas.</ref><ref name="r4">"Energy." Government of Canada, Statistics Canada. http://www5.statcan.gc.ca/subject-sujet/theme-theme.action?pid=1741&lang=eng&more=0.</ref> The oil in oil sands is an immobile fluid under existing reservoir conditions, and heavy oils are somewhat mobile fluids under naturally existing pressure gradients. Unconsolidated sandstones (UCSS) are sandstones (or sands) that possess no true tensile strength arising from grain-to-grain mineral cementation. Many heavy oil reservoirs are located in unconsolidated sandstones.


==Importance of heavy oil==
== Importance of heavy oil ==


World conventional oil (light oil greater than 20°API) supply rates will peak eventually and enter into decline because of increasing world demand, inexorable reservoir production rate decline, and the indisputable fact that few new sedimentary basins remain to be exploited. Many believe that this will occur between 2005 and 2010.<ref name="r5" /><ref name="r6" /> Thereafter, light oil production will decline gradually at a rate that may be slowed but not reversed by the introduction of new technologies such as gravity drainage and pressure pulsing. '''Fig. 1''' shows world oil production predictions. Simply put, conventional oil is running out because new basins are running out. Furthermore, exploitation costs are large in deep, remote basins (deep offshore, Antarctic fringe, Arctic basins). Only larger finds will be developed, and recovery will be less than for "easy" basins.  
World conventional oil (light oil greater than 20°API) supply rates will peak eventually and enter into decline because of increasing world demand, inexorable reservoir production rate decline, and the indisputable fact that few new sedimentary basins remain to be exploited. Many believe that this will occur between 2005 and 2010.<ref name="r5">Campbell, C.J. and Laherrère, J.H. 1998. The End of Cheap Oil. Sci. Am. 278 (3): 78–83.</ref><ref name="r6">Deffeyes, K.S. 2001. Hubbert’s Peak: The Impending World Oil Shortage, 208. Princeton, New Jersey: Princeton University Press.</ref> Thereafter, light oil production will decline gradually at a rate that may be slowed but not reversed by the introduction of new technologies such as gravity drainage and pressure pulsing. '''Fig. 1''' shows world oil production predictions. Simply put, conventional oil is running out because new basins are running out. Furthermore, exploitation costs are large in deep, remote basins (deep offshore, Antarctic fringe, Arctic basins). Only larger finds will be developed, and recovery will be less than for "easy" basins.


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol6 Page 185 Image 0002.png|'''Fig. 1-World oil production: past and predictions.'''</gallery>
File:Vol6 Page 185 Image 0002.png|'''Fig. 1-World oil production: past and predictions.'''</gallery>


Nevertheless, the world will never run out of oil for several reasons. First, conventional oil comprises a small fraction of hydrocarbons in sedimentary basins. '''Table 1''' shows relative hydrocarbon resource size. Second, as technology evolves, other energy sources (ethanol, hydrogen cycle) will displace oil, just as oil displaced coal. Third, even if all the organic carbon (oil, gas, coal, kerogen) in basins is consumed, oil can be manufactured from wood or assembled from its elements, given a sufficiently high commodity price. To put the available heavy-oil resource into context, in Canada alone it is so large (~400 × 10<sup>9</sup> m<sup>3</sup>) that, at a US and Canadian consumption rate of 1.2 × 10<sup>9</sup> m<sup>3</sup>/yr, there is enough heavy oil to meet 100% of this demand for more than 80 years if the overall extraction efficiency is approximately 30%.  
Nevertheless, the world will never run out of oil for several reasons. First, conventional oil comprises a small fraction of hydrocarbons in sedimentary basins. '''Table 1''' shows relative hydrocarbon resource size. Second, as technology evolves, other energy sources (ethanol, hydrogen cycle) will displace oil, just as oil displaced coal. Third, even if all the organic carbon (oil, gas, coal, kerogen) in basins is consumed, oil can be manufactured from wood or assembled from its elements, given a sufficiently high commodity price. To put the available heavy-oil resource into context, in Canada alone it is so large (~400 × 10<sup>9</sup> m<sup>3</sup>) that, at a US and Canadian consumption rate of 1.2 × 10<sup>9</sup> m<sup>3</sup>/yr, there is enough heavy oil to meet 100% of this demand for more than 80 years if the overall extraction efficiency is approximately 30%.


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol6 Page 186 Image 0001.png|'''Table 1-Relative Hydrocarbon Resource Size.'''</gallery>
File:Vol6 Page 186 Image 0001.png|'''Table 1-Relative Hydrocarbon Resource Size.'''</gallery>


The claim that the world is irresponsible in rapidly consuming irreplaceable resources ignores technical progress, market pressures, and the historical record.<ref name="r7" /> Commodities have never been cheaper, efficiency is increasing, and new ideas such as deep biosolids injection may generate new sources of energy or may recycle energy.<ref name="r8" /> It is interesting to read the predictions of doomsayers<ref name="r9" /> in the context of continued technological advances. For example, the "Club of Rome," with the use of exponential growth assumptions and extrapolations under static technology, predicted serious commodity shortages before 2000, including massive oil shortages and famine.<ref name="r10" />  
The claim that the world is irresponsible in rapidly consuming irreplaceable resources ignores technical progress, market pressures, and the historical record.<ref name="r7">Simon, J.L. 1996. The Ultimate Resource, second edition, 734. Princeton, New Jersey: Princeton University Press.</ref> Commodities have never been cheaper, efficiency is increasing, and new ideas such as deep biosolids injection may generate new sources of energy or may recycle energy.<ref name="r8">"Slurry Fracture Injection," Terralog Technologies Inc., http://www.terralog.com.</ref> It is interesting to read the predictions of doomsayers<ref name="r9">Ehrlich, P.R. 1968. The Population Bomb. New York City: Ballantine Press.</ref> in the context of continued technological advances. For example, the "Club of Rome," with the use of exponential growth assumptions and extrapolations under static technology, predicted serious commodity shortages before 2000, including massive oil shortages and famine.<ref name="r10">Report on the Limits to Growth. 1972. Washington, DC: Intl. Bank for Reconstruction and Development.</ref>


These predictions relate to heavy oil for the following reasons. First, new production technologies are proof that science and knowledge continue to advance and that further advances are anticipated. Second, oil prices will not skyrocket because technologies such as manufacturing synthetic oil from coal are waiting in the wings. Third, the new technologies have been forced to become efficient and profitable, even with unfavorable refining penalties. Fourth, exploration costs for new conventional oil production capacity will continue to rise in all mature basins, whereas new technologies can lower production costs in such basins. Fifth, technological feedback from heavy-oil production is improving conventional oil recovery. Finally, the heavy-oil resource in UCSS is vast. Although it is obvious that the amount of conventional (light) oil is limited, the impact of this limitation, while relevant in the short term (2000 to 2030), is likely to be inconsequential to the energy industry in the long term (50 to 200 years).
These predictions relate to heavy oil for the following reasons. First, new production technologies are proof that science and knowledge continue to advance and that further advances are anticipated. Second, oil prices will not skyrocket because technologies such as manufacturing synthetic oil from coal are waiting in the wings. Third, the new technologies have been forced to become efficient and profitable, even with unfavorable refining penalties. Fourth, exploration costs for new conventional oil production capacity will continue to rise in all mature basins, whereas new technologies can lower production costs in such basins. Fifth, technological feedback from heavy-oil production is improving conventional oil recovery. Finally, the heavy-oil resource in UCSS is vast. Although it is obvious that the amount of conventional (light) oil is limited, the impact of this limitation, while relevant in the short term (2000 to 2030), is likely to be inconsequential to the energy industry in the long term (50 to 200 years).


==Historical production technologies==
== Historical production technologies ==


Before 1985, heavy-oil production was based largely on thermal stimulation, Δ''T'', to reduce viscosity and large pressure drops, Δ''p'', to induce flow. Projects used:
Before 1985, heavy-oil production was based largely on thermal stimulation, Δ''T'', to reduce viscosity and large pressure drops, Δ''p'', to induce flow. Projects used:
* Cyclic steam stimulation (huff 'n' puff)
 
* Steam flooding
*Cyclic steam stimulation (huff 'n' puff)
* Wet or dry combustion with air or oxygen injection
*Steam flooding
or  
*Wet or dry combustion with air or oxygen injection
* Combinations of the above methods
 
or
 
*Combinations of the above methods


Until recently, these technologies used arrays of vertical to mildly deviated wells (< 45°). Some methods have never proved viable for heavy oil. These include:
Until recently, these technologies used arrays of vertical to mildly deviated wells (< 45°). Some methods have never proved viable for heavy oil. These include:
* Solvent injection
 
* Biological methods
*Solvent injection
* Cold gas (i.e., CH<sub>4</sub>, CO<sub>2</sub>, etc.) injection
*Biological methods
* Polymer methods
*Cold gas (i.e., CH<sub>4</sub>, CO<sub>2</sub>, etc.) injection
* In-situ emulsification
*Polymer methods
*In-situ emulsification


Also, all high-pressure methods experienced advective instabilities such as:
Also, all high-pressure methods experienced advective instabilities such as:
* Viscous fingering
* Permeability channeling
* Water or gas coning
* Uncontrolled (upward) hydraulic fracture propagation


Marginally economical nonthermal production with vertical wells was used in Canada, but wells typically produced less than 10 m<sup>3</sup>/d, recovery was less than 5 to 8% original oil in place (OOIP), and small amounts of sand usually entered the wellbore during production.  
*Viscous fingering
*Permeability channeling
*Water or gas coning
*Uncontrolled (upward) hydraulic fracture propagation
 
Marginally economical nonthermal production with vertical wells was used in Canada, but wells typically produced less than 10 m<sup>3</sup>/d, recovery was less than 5 to 8% original oil in place (OOIP), and small amounts of sand usually entered the wellbore during production.
 
== Newer technologies for recovering heavy oil ==
 
=== Steam-assisted gravity drainage ===


==Newer technologies for recovering heavy oil==
[[Steam_assisted_gravity_drainage|Steam-assisted gravity drainage]] (SAGD), used in horizontal wells, involves steam injection for viscosity reduction and gravity segregation for flow.<ref name="r11">Butler, R. 1998. SAGD Comes of Age! J Can Pet Technol 37 (7): 9–12. JCPT Paper No. 98-07-DA. http://dx.doi.org/10.2118/98-07-DA.</ref> Prototype wells were drilled from an underground mine from 1984 to 1986, and the first commercial projects began production in Canada in 2001.


===Steam-assisted gravity drainage===
=== Cold production ===
[[Steam assisted gravity drainage|Steam-assisted gravity drainage]] (SAGD), used in horizontal wells, involves steam injection for viscosity reduction and gravity segregation for flow.<ref name="r11" /> Prototype wells were drilled from an underground mine from 1984 to 1986, and the first commercial projects began production in Canada in 2001.


===Cold production===
Cold production is nonthermal heavy-oil production without sand. Economical rates are achieved by exploiting the large drainage area of long horizontal wells completed with slotted liners. In Canada, economic success in oils less viscous than approximately 1500 cp is common, even though production rates may drop by 40% per year and the OOIP recovery is less than 10%. This technology has found major application in the Faja del Orinoco in Venezuela, where multilateral branches are added to further increase the well drainage area.<ref name="r12">Santos, R., Robertson, G., and Vasquez, M. 2001. Geologic Reality Altered Cerro Negro Development Scheme. Oil Gas J. 99 (4).</ref>


Cold production is nonthermal heavy-oil production without sand. Economical rates are achieved by exploiting the large drainage area of long horizontal wells completed with slotted liners. In Canada, economic success in oils less viscous than approximately 1500 cp is common, even though production rates may drop by 40% per year and the OOIP recovery is less than 10%. This technology has found major application in the Faja del Orinoco in Venezuela, where multilateral branches are added to further increase the well drainage area.<ref name="r12" />
=== Cold heavy oil production with sand ===


===Cold heavy oil production with sand===
[[Cold_heavy_oil_production_with_sand|Cold heavy oil production with sand]] (CHOPS) exploits the finding that sand ingress can enhance the oil rate by an order of magnitude or more in heavy-oil UCSS. Pressure-pulsing technology (PPT) is a flow rate enhancement method introduced in heavy-oil fields that used CHOPS between 1999 and 2001.<ref name="r13">Dusseault, M., Davidson, B., and Spanos, T. 2000. Pressure Pulsing: The Ups And Downs of Starting a New Technology. J Can Pet Technol 39 (4). PETSOC-00-04-TB. http://dx.doi.org/10.2118/00-04-tb.</ref> The approach, applicable to any liquid-saturated porous medium, involves applying repeated tailored pressure pulses to the liquid phase. This has the effect of suppressing advective instabilities such as viscous fingering or permeability channeling, overcoming capillary barriers, and reducing pore-throat blockage.


[[Cold heavy oil production with sand]] (CHOPS) exploits the finding that sand ingress can enhance the oil rate by an order of magnitude or more in heavy-oil UCSS. Pressure-pulsing technology (PPT) is a flow rate enhancement method introduced in heavy-oil fields that used CHOPS between 1999 and 2001.<ref name="r13" /> The approach, applicable to any liquid-saturated porous medium, involves applying repeated tailored pressure pulses to the liquid phase. This has the effect of suppressing advective instabilities such as viscous fingering or permeability channeling, overcoming capillary barriers, and reducing pore-throat blockage.
=== Vapor-assisted petroleum extraction ===


===Vapor-assisted petroleum extraction===
Vapor-assisted petroleum extraction (VAPEX) is, in terms of physics and flow processes, the same process as SAGD, except that a condensable and noncondensable gas mixture (e.g., CH<sub>4</sub> to C<sub>4</sub>H<sub>10</sub>) is used to reduce the oil viscosity.<ref name="r14">Oduntan, A.R. et al. 2001. Heavy Oil Recovery Using the VAPEX Process: Scale-Up Issues. Proc., CIM Petroleum Society 51st Annual Technical Meeting, Calgary, paper 2001-127.</ref> VAPEX approaches can be integrated with SAGD approaches, such as by cycling between steam and miscible gases, the use of a mixture, injection of heated gas ("warm" VAPEX), etc. As with SAGD, all VAPEX variations use gravitationally stabilized flow to avoid advective instabilities and achieve higher recovery.


Vapor-assisted petroleum extraction (VAPEX) is, in terms of physics and flow processes, the same process as SAGD, except that a condensable and noncondensable gas mixture (e.g., CH<sub>4</sub> to C<sub>4</sub>H<sub>10</sub>) is used to reduce the oil viscosity.<ref name="r14" /> VAPEX approaches can be integrated with SAGD approaches, such as by cycling between steam and miscible gases, the use of a mixture, injection of heated gas ("warm" VAPEX), etc. As with SAGD, all VAPEX variations use gravitationally stabilized flow to avoid advective instabilities and achieve higher recovery.
=== Toe-to-heel air injection ===


===Toe-to-heel air injection===
Toe-to-heel air injection (THAI), essentially, is in-situ combustion but with horizontal wells so that the combustion products and heated hydrocarbons flow almost immediately downward into the horizontal production well, rather than having to channel through long distances and experience gas override and fingering.<ref name="r15">Greaves, M. et al. 2001. New Heavy Oil Technology for Heavy Oil Recovery and In Situ Upgrading. J. Cdn. Pet. Tech. 40 (3): 38.</ref>


Toe-to-heel air injection (THAI), essentially, is in-situ combustion but with horizontal wells so that the combustion products and heated hydrocarbons flow almost immediately downward into the horizontal production well, rather than having to channel through long distances and experience gas override and fingering.<ref name="r15" />
== Hybrid modes of heavy-oil technologies ==


==Hybrid modes of heavy-oil technologies==
Proven and emerging technologies will be used more and more in hybrid modes to achieve better recovery and investment returns. For example, CHOPS gives high early production rates, but SAGD gives better overall hydrocarbon recovery, suggesting phased or simultaneous use of the methods. Also, different technologies will be found to be suitable for different reservoirs and conditions. SAGD and other thermal methods are very inefficient in reservoirs less than 15 m thick, whereas CHOPS and pressure pulsing technology (PPT) have been successful economically in such cases. All these technologies will benefit from improvements in thermal efficiency, process control, and cost reductions.<ref name="r16">Greaser, G.R. and Ortiz, J.R. 2001. New Thermal Recovery Technology and Technology Transfer for Successful Heavy Oil Development. Presented at the SPE International Thermal Operations and Heavy Oil Symposium, Porlamar, Margarita Island, Venezuela, 12-14 March 2001. SPE-69731-MS. http://dx.doi.org/10.2118/69731-MS.</ref>


Proven and emerging technologies will be used more and more in hybrid modes to achieve better recovery and investment returns. For example, CHOPS gives high early production rates, but SAGD gives better overall hydrocarbon recovery, suggesting phased or simultaneous use of the methods. Also, different technologies will be found to be suitable for different reservoirs and conditions. SAGD and other thermal methods are very inefficient in reservoirs less than 15 m thick, whereas CHOPS and pressure pulsing technology (PPT) have been successful economically in such cases. All these technologies will benefit from improvements in thermal efficiency, process control, and cost reductions.<ref name="r16" />
== Key heavy oil deposits ==


==Key heavy oil deposits==
=== Typical Canadian reservoirs ===
===Typical Canadian reservoirs===
Heavy-oil development with CHOPS takes place in the Canadian heavy-oil belt ('''Fig. 2''') in reservoirs that may range from extensive 3- to 5- m thick blanket sands to 35-m-thick channel sands with sinuous traces no wider than a kilometer. All reservoirs are UCSS with ''φ'' ~ 28 to 32% and ''k''~ 0.5 to 15 darcy, depending on grain size. The highest ''k'' values are for occasional gravel seams found in river channel deposits; most reservoirs have average permeabilities of 1 to 4 darcy. It is impossible to obtain undisturbed specimens from these reservoirs because gas exsolution causes irreversible core expansion (the high oil viscosity impedes gas escape).<ref name="r2" />
Therefore, porosities are back-calculated from well logs, and permeabilities are back calculated from grain-size correlations and a limited number of well tests.


<gallery widths=300px heights=200px>
Heavy-oil development with CHOPS takes place in the Canadian heavy-oil belt ('''Fig. 2''') in reservoirs that may range from extensive 3- to 5- m thick blanket sands to 35-m-thick channel sands with sinuous traces no wider than a kilometer. All reservoirs are UCSS with ''φ'' ~ 28 to 32% and ''k''~ 0.5 to 15 darcy, depending on grain size. The highest ''k'' values are for occasional gravel seams found in river channel deposits; most reservoirs have average permeabilities of 1 to 4 darcy. It is impossible to obtain undisturbed specimens from these reservoirs because gas exsolution causes irreversible core expansion (the high oil viscosity impedes gas escape).<ref name="r2">Alberta Energy Regulator. http://www.eub.gov.ab.ca/.</ref> Therefore, porosities are back-calculated from well logs, and permeabilities are back calculated from grain-size correlations and a limited number of well tests.
 
<gallery widths="300px" heights="200px">
File:Vol6 Page 185 Image 0001.png|'''Fig. 2-Canadian heavy-oil and extra-heavy-oil deposits.'''</gallery>
File:Vol6 Page 185 Image 0001.png|'''Fig. 2-Canadian heavy-oil and extra-heavy-oil deposits.'''</gallery>


With the exception of a few geologically older fields, all the heavy oil unconsolidated sandstone (UCSS) reservoirs in Alberta and Saskatchewan are found in the Lower and Middle Mannville group, an undeformed and flat-lying Middle Cretaceous clastic sequence comprising:
With the exception of a few geologically older fields, all the heavy oil unconsolidated sandstone (UCSS) reservoirs in Alberta and Saskatchewan are found in the Lower and Middle Mannville group, an undeformed and flat-lying Middle Cretaceous clastic sequence comprising:
* sands
* silts
* shales
* a few coal seams
* thin (< 0.5 m) concretionary beds


The depositional environment ranged from channel sands laid down in incised valleys carved several tens of meters into underlying sediments, to estuarine accretion plains formed by lateral river-channel migration on a flat plain, to deltaic, shallow marine, and offshore bar sands. The UCSS mineralogy ranges from quartz arenites (> 95% SiO<sub>2</sub> ) to litharenites and arkoses. The more mature sands at the base of the Mannville group tend to be more quartzose.  
*sands
*silts
*shales
*a few coal seams
*thin (< 0.5 m) concretionary beds
 
The depositional environment ranged from channel sands laid down in incised valleys carved several tens of meters into underlying sediments, to estuarine accretion plains formed by lateral river-channel migration on a flat plain, to deltaic, shallow marine, and offshore bar sands. The UCSS mineralogy ranges from quartz arenites (> 95% SiO<sub>2</sub> ) to litharenites and arkoses. The more mature sands at the base of the Mannville group tend to be more quartzose.


A typical CHOPS stratum is a 10-m-thick fine- to medium-grained UCSS (D50 of 80 to 150 μm, ''k'' = 2 darcy) with ''So''~ 88%, ''S<sub>w</sub>''~ 12%, and ''S<sub>g</sub>''= 0 at a depth, ''z'', of 400 to 800 m. Initial pressure, ''p<sub>o</sub>'' , is on the order of 3 to 7 MPa, and reservoirs are most often underpressured. Taking γ¯ as mean overburden unit weight (γ¯=ρ¯z), generally ''p<sub>o</sub>''~ 0.7 to 0.9γ¯z.
A typical CHOPS stratum is a 10-m-thick fine- to medium-grained UCSS (D50 of 80 to 150 μm, ''k'' = 2 darcy) with ''So''~ 88%, ''S<sub>w</sub>''~ 12%, and ''S<sub>g</sub>''= 0 at a depth, ''z'', of 400 to 800 m. Initial pressure, ''p<sub>o</sub>'' , is on the order of 3 to 7 MPa, and reservoirs are most often underpressured. Taking γ¯ as mean overburden unit weight (γ¯=ρ¯z), generally ''p<sub>o</sub>''~ 0.7 to 0.9γ¯z.


===Heavy oil accumulations in the Faja del Orinoco===
=== Heavy oil accumulations in the Faja del Orinoco ===


'''Fig. 3''' shows the Faja del Orinoco in Venezuela, which contains one of the richest accumulations of heavy oil in the world, approximately 250 ×10<sup>9</sup> m<sup>3</sup> (similar in scale to the Canadian deposits).  
'''Fig. 3''' shows the Faja del Orinoco in Venezuela, which contains one of the richest accumulations of heavy oil in the world, approximately 250 ×10<sup>9</sup> m<sup>3</sup> (similar in scale to the Canadian deposits).


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol6 Page 191 Image 0001.png|'''Fig. 3-Venezuela's Faja del Orinoco heavy oil region.'''</gallery>
File:Vol6 Page 191 Image 0001.png|'''Fig. 3-Venezuela's Faja del Orinoco heavy oil region.'''</gallery>


The host Oficina formation is a fluvial and marine-margin deposit. Apparently, there were a number of large estuarine accretion plains and deltaic complexes (at least four) formed by rivers that drained the Guyana shield to the south. The focal area of deposition changed with sea level in response to sedimentation, the formation of the mountains to the north, and the subsidence of the eastern Venezuelan basin. The deposit is a unitary sequence of strata with general east-west continuity. Individual sand bodies range in thickness up to 40 to 45 m, although the majority of "discrete" oil-bearing beds are 8 to 12 m thick, with sharp lower boundaries from lateral erosional migration of channels and more gradational upper boundaries. Good permeability interconnectivity is shown by a high oil-saturation state in the vertical sequence of strata. Some sand bodies are thick channel sands of almost uniform properties over many meters; others contain multiple laminae of silt and have poor vertical flow properties. In general, the upper beds are of lower quality than the lower beds.  
The host Oficina formation is a fluvial and marine-margin deposit. Apparently, there were a number of large estuarine accretion plains and deltaic complexes (at least four) formed by rivers that drained the Guyana shield to the south. The focal area of deposition changed with sea level in response to sedimentation, the formation of the mountains to the north, and the subsidence of the eastern Venezuelan basin. The deposit is a unitary sequence of strata with general east-west continuity. Individual sand bodies range in thickness up to 40 to 45 m, although the majority of "discrete" oil-bearing beds are 8 to 12 m thick, with sharp lower boundaries from lateral erosional migration of channels and more gradational upper boundaries. Good permeability interconnectivity is shown by a high oil-saturation state in the vertical sequence of strata. Some sand bodies are thick channel sands of almost uniform properties over many meters; others contain multiple laminae of silt and have poor vertical flow properties. In general, the upper beds are of lower quality than the lower beds.


The Faja del Orinoco is a remarkably rich deposit, far richer locally than the Canadian deposits, although smaller in total reserves. Many sequences 100 to 150 m thick contain 60% net pay (i.e., 110 to 120 m of total pay), averaging greater than 80% oil saturation. The lower two to three zones have high permeability (3 to 15 darcy), are 20 to 30 m thick, and are laterally extensive. These reservoirs will be developed more extensively with the existing and emerging technologies mentioned previously.
The Faja del Orinoco is a remarkably rich deposit, far richer locally than the Canadian deposits, although smaller in total reserves. Many sequences 100 to 150 m thick contain 60% net pay (i.e., 110 to 120 m of total pay), averaging greater than 80% oil saturation. The lower two to three zones have high permeability (3 to 15 darcy), are 20 to 30 m thick, and are laterally extensive. These reservoirs will be developed more extensively with the existing and emerging technologies mentioned previously.




==References==
<references>
<ref name="r1"> National Energy Board, http://www.neb-one.gc.ca/.</ref>
<ref name="r2"> Alberta Energy Utilities Board, http://www.eub.gov.ab.ca.</ref>
<ref name="r3"> Saskatchewan Energy and Mines, http://www.gov.sk.ca/enermine/.</ref>
<ref name="r4"> Statistics Canada, http://www.statcan.ca/english/Pgdb/prim05a.htm.</ref>
<ref name="r5"> Campbell, C.J. and Laherrère, J.H. 1998. The End of Cheap Oil. Sci. Am. '''278''' (3): 78–83. </ref>
<ref name="r6"> Deffeyes, K.S. 2001. ''Hubbert’s Peak: The Impending World Oil Shortage'', 208. Princeton, New Jersey: Princeton University Press.</ref>
<ref name="r7"> Simon, J.L. 1996. ''The Ultimate Resource'', second edition, 734. Princeton, New Jersey: Princeton University Press.</ref>
<ref name="r8"> "Slurry Fracture Injection," Terralog Technologies Inc., http://www.terralog.com.</ref>
<ref name="r9"> Ehrlich, P.R. 1968. ''The Population Bomb''. New York City: Ballantine Press.</ref>
<ref name="r10"> Report on the Limits to Growth. 1972. Washington, DC: Intl. Bank for Reconstruction and Development.</ref>
<ref name="r11"> Butler, R. 1998. SAGD Comes of Age! ''J Can Pet Technol'' '''37''' (7): 9–12. JCPT Paper No. 98-07-DA. http://dx.doi.org/10.2118/98-07-DA.</ref>
<ref name="r12"> Santos, R., Robertson, G., and  Vasquez, M. 2001. Geologic Reality Altered Cerro Negro Development Scheme. ''Oil Gas J.'' '''99''' (4). </ref>
<ref name="r13"> Dusseault, M., Davidson, B., and  Spanos, T. 2000. Pressure Pulsing: The Ups And Downs of Starting a New Technology. J Can Pet Technol 39 (4). PETSOC-00-04-TB. http://dx.doi.org/10.2118/00-04-tb.</ref>
<ref name="r14"> Oduntan, A.R. et al. 2001. Heavy Oil Recovery Using the VAPEX Process: Scale-Up Issues. Proc., CIM Petroleum Society 51st Annual Technical Meeting, Calgary, paper 2001-127.</ref>
<ref name="r15"> Greaves, M. et al. 2001. New Heavy Oil Technology for Heavy Oil Recovery and In Situ Upgrading. ''J. Cdn. Pet. Tech.'' '''40''' (3): 38.</ref>
<ref name="r16"> Greaser, G.R. and Ortiz, J.R. 2001. New Thermal Recovery Technology and Technology Transfer for Successful Heavy Oil Development. Presented at the SPE International Thermal Operations and Heavy Oil Symposium, Porlamar, Margarita Island, Venezuela, 12-14 March 2001. SPE-69731-MS. http://dx.doi.org/10.2118/69731-MS. </ref>
</references>


==Noteworthy papers in OnePetro==
== References ==
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
 
<references />
 
== Noteworthy papers in OnePetro ==
 
Thakur, G. C. 1997. Heavy Oil Reservoir Management. Society of Petroleum Engineers. http://dx.doi.org/10.2118/39233-MS
 
Smith, G. E. 1992. Waterflooding Heavy Oils. Society of Petroleum Engineers. http://dx.doi.org/10.2118/24367-MS
 
Kumar, R., Dao, E. K., & Mohanty, K. K. 2010. Emulsion Flooding of Heavy Oil. Society of Petroleum Engineers. http://dx.doi.org/10.2118/129914-MS
 
Creux, P., Meyer, V., Cordelier, P. R., Franco, F., & Montel, F. 2005. Diffusivity In Heavy Oils. Society of Petroleum Engineers. http://dx.doi.org/10.2118/97798-MS
 
Bagci, A. S. 2007. Sagd Process In Fractured Heavy Oil Reservoirs. Offshore Mediterranean Conference.
 
Kumar, R., Dao, E., & Mohanty, K. 2012. Heavy-Oil Recovery by In-Situ Emulsion Formation. Society of Petroleum Engineers. http://dx.doi.org/10.2118/129914-PA
 
Tang, G.-Q., Temizel, C., & Kovscek, A. R. 2006. The Role of Oil Chemistry on Cold Production of Heavy Oils. Society of Petroleum Engineers. http://dx.doi.org/10.2118/102365-MS
 
== External links ==


==External links==
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro


==See also==
== See also ==
[[Cold heavy oil production with sand]]
 
[[Cold_heavy_oil_production_with_sand|Cold heavy oil production with sand]]
 
[[Electromagnetic_heating_of_oil|Electromagnetic heating of oil]]
 
[[Steam_assisted_gravity_drainage|Steam assisted gravity drainage]]
 
[[Combining_CHOPS_and_other_production_technologies|Combining CHOPS and other production technologies]]


[[Electromagnetic heating of oil]]
[[PEH:Cold_Heavy-Oil_Production_With_Sand]]


[[Steam assisted gravity drainage]]
== Page champions ==


[[Combining CHOPS and other production technologies]]
[https://www.linkedin.com/in/cenk-temizel-5a3b892 Cenk Temizel, Reservoir Engineer]


[[PEH:Cold Heavy-Oil Production With Sand]]
== Category ==
[[Category:5.4.6 Thermal methods]] [[Category:5.4.11 Cold heavy oil production]] [[Category:5.4.7 Chemical flooding methods]] [[Category:5.3 Enhanced recovery]] [[Category:5.8 Unconventional and complex reservoirs]]
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