44
The Chemistry and Technology of Petroleum
2.4.2 Future
Future energy resources will be found in what are currently considered to be unconventional reservoirs, especially low-permeability reservoirs in shale, siltstone, fine-grained sand, and carbonates.
However, there is inadequate geologic data to evaluate the contribution that such reservoirs will
make to the petroleum reserves in the future.
These unconventional resources are probably very large but their characteristics and distribution
are not yet well understood. Further research on modeling the geometry and distribution of porosity and permeability, as well as determining the chemical and physical sensitivity of hydrocarbon
reservoirs, is necessary. An important focus is the low-permeability (tight) gas reservoirs, heavy oil reservoirs, and tar sand deposits. In addition, understanding deep formations and reservoirs (>15,000 ft;
>4,572 m) is essential if deep-lying resources are to be recovered. In fact, detailed estimates of the
amount of petroleum and natural oil and gas recoverable under varying scenarios of economics and
technology are needed to guide long-range-energy policies. The resources that are currently termed
unconventional resources will play a critical role in the energy base for the remainder of this century.
One aspect of resource recovery from difficult formations (reservoirs) that is having some success
is deviated well drilling (Figure 2.4). Deviated well drilling involves drilling horizontal and slanthole wells to better intersect vertical fractures in tight formations (http://energy.usgs.gov/ factsheets/
Petroleum/drilling.html). Natural vertical fractures are important factors in the economic production of gas from these rocks because the permeability of the natural fractures is almost always much
higher than the nonfractured rock. However, most of the gas resources reside in the rock pores and
move out of the rock to the wellbore via fractures.
REFERENCES
Ancheyta, J. and Speight, J.G. 2007. Hydroprocessing of Heavy Oils and Residua. CRC Press, Taylor & Francis
Group, Boca Raton, FL.
ASTM D97. 2012. Standard Test Method for Pour Point of Petroleum Products, Vol. 05.03. Annual Book of
Standards, American Society for Testing and Materials, Philadelphia, PA.
ASTM D287. 2012. Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products
(Hydrometer Method), Vol. 05.03. Annual Book of Standards, American Society for Testing and
Materials, Philadelphia, PA.
ASTM D445. 2012. Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and
Calculation of Dynamic Viscosity), Vol. 05.03. Annual Book of Standards, American Society for Testing
and Materials, Philadelphia, PA.
Blanket
reservoir
Lenticular
reservoir
Slant-hole
well
Horizontal
well
FIGURE 2.4 Representation of deviated well drilling.
The Chemistry and Technology of Petroleum
2.4.2 Future
Future energy resources will be found in what are currently considered to be unconventional reservoirs, especially low-permeability reservoirs in shale, siltstone, fine-grained sand, and carbonates.
However, there is inadequate geologic data to evaluate the contribution that such reservoirs will
make to the petroleum reserves in the future.
These unconventional resources are probably very large but their characteristics and distribution
are not yet well understood. Further research on modeling the geometry and distribution of porosity and permeability, as well as determining the chemical and physical sensitivity of hydrocarbon
reservoirs, is necessary. An important focus is the low-permeability (tight) gas reservoirs, heavy oil reservoirs, and tar sand deposits. In addition, understanding deep formations and reservoirs (>15,000 ft;
>4,572 m) is essential if deep-lying resources are to be recovered. In fact, detailed estimates of the
amount of petroleum and natural oil and gas recoverable under varying scenarios of economics and
technology are needed to guide long-range-energy policies. The resources that are currently termed
unconventional resources will play a critical role in the energy base for the remainder of this century.
One aspect of resource recovery from difficult formations (reservoirs) that is having some success
is deviated well drilling (Figure 2.4). Deviated well drilling involves drilling horizontal and slanthole wells to better intersect vertical fractures in tight formations (http://energy.usgs.gov/ factsheets/
Petroleum/drilling.html). Natural vertical fractures are important factors in the economic production of gas from these rocks because the permeability of the natural fractures is almost always much
higher than the nonfractured rock. However, most of the gas resources reside in the rock pores and
move out of the rock to the wellbore via fractures.
REFERENCES
Ancheyta, J. and Speight, J.G. 2007. Hydroprocessing of Heavy Oils and Residua. CRC Press, Taylor & Francis
Group, Boca Raton, FL.
ASTM D97. 2012. Standard Test Method for Pour Point of Petroleum Products, Vol. 05.03. Annual Book of
Standards, American Society for Testing and Materials, Philadelphia, PA.
ASTM D287. 2012. Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products
(Hydrometer Method), Vol. 05.03. Annual Book of Standards, American Society for Testing and
Materials, Philadelphia, PA.
ASTM D445. 2012. Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and
Calculation of Dynamic Viscosity), Vol. 05.03. Annual Book of Standards, American Society for Testing
and Materials, Philadelphia, PA.
Blanket
reservoir
Lenticular
reservoir
Slant-hole
well
Horizontal
well
FIGURE 2.4 Representation of deviated well drilling.