Today's Article
Could potentially
disruptive gas
sediments off the Gulf
Coast have been a
cause behind the
explosion of BP's oil
rig? A 2008 federal
study may provide
clues.
disruptive gas
sediments off the Gulf
Coast have been a
cause behind the
explosion of BP's oil
rig? A 2008 federal
study may provide
clues.
The American Spark
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 |
 |
 |
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Do Gulf Sediments Make Oil Drilling Innately Dangerous?
By Cliff Montgomery - June 12th, 2010
A 2008 U.S. government study, which discussed potentially disruptive gas sediments on the Gulf Coast sea
floor, may offer a clue as to what caused the explosion of BP's Deepwater Horizon oil rig.
It's perhaps still too early to determine any certain causes for the blast, which in turn has allowed the release of
up to 50,000 barrels of oil every day.
That amount "is roughly five to six times the amount spilled in Alaskan waters in 1989 by the Exxon Valdez,"
according to The Washington Post.
The Congressional Research Service (CRS) report, entitled Gas Hydrates: Resource and Hazard, clearly
states its point:
"Offshore drilling operations that disturb gas hydrate-bearing sediments could fracture or disrupt the bottom
sediments and compromise the wellbore, pipelines, rig supports, and other equipment involved in oil and gas
production from the seafloor," according to the study.
The American Spark quotes major segments of the report below:
"Gas hydrates occur naturally onshore in permafrost, and at or below the seafloor in sediments where water
and gas combine at low temperatures and high pressures to form an ice-like solid substance.
"Methane, or natural gas, is typically the dominant gas in the hydrate structure. In a gas hydrate, frozen water
molecules form a cage-like structure around high concentrations of natural gas. The gas hydrate structure
[thus] is very compact.
"When heated and depressurized to temperatures and pressures typically found on the Earth’s surface (one
atmosphere of pressure and 70 degrees Fahrenheit), its volume expands by 150 to 170 times. Thus, one cubic
foot of solid gas hydrate found underground in permafrost or beneath the seafloor would produce between
150 to 170 cubic feet of natural gas when brought to the surface.
"Gas hydrates are a potentially huge global energy resource. The United States and other countries with
territory in the Arctic or with offshore gas hydrates along their continental margins are interested in developing
the resource."
Gas Hydrate Resources
"There are several challenges to commercially exploiting gas hydrates. How much and where gas hydrate
occurs in commercially viable concentrations are not well known, and how the resource can be extracted safely
and economically is a current research focus.
"Estimates of global gas hydrate resources, which range from at least 100,000 TCF [Trillion Cubic Feet] to
possibly much more, may greatly over-estimate how much gas can be extracted economically. Reports of vast
gas hydrate resources can be misleading unless those estimates are qualified by the use of such terms such
as in-place resources, technically recoverable resources, and proved reserves:
Gas Hydrates in the Gulf of Mexico
"On February 1, 2008, the MMS released an assessment of gas hydrate resources for the Gulf of Mexico. The
report gives a statistical probability of the volume of undiscovered in-place gas hydrate resources, with a mean
estimate of over 21,000 TCF.
"The MMS report estimates how much gas hydrate may occur in sandstone and shale reservoirs, using a
combination of data and modeling, but does not indicate how much is recoverable with current technology."
Gas Hydrate Hazards
"Gas hydrates are a significant hazard for drilling and production operations.
"Gas hydrate production is hazardous in itself, as well as for conventional oil and gas activities that place wells
and pipelines into permafrost or marine sediments. For activities in permafrost, two general categories of
problems have been identified:
"Similar problems could occur during offshore drilling into gas hydrate-bearing marine sediments. Offshore
drilling operations that disturb gas hydrate-bearing sediments could fracture or disrupt the bottom sediments
and compromise the well bore, pipelines, rig supports, and other equipment involved in oil and gas production
from the seafloor. [Emphasis added]
"Problems may differ somewhat between onshore and offshore operations, but they stem from the same
characteristic of gas hydrates: decreases in pressure and/or increases in temperature can cause the gas
hydrate to dissociate and rapidly release large amounts of gas into the well bore during a drilling operation.
"Oil and gas wells drilled through permafrost or offshore to reach conventional oil and gas deposits may
encounter gas hydrates, which companies generally try to avoid because of a lack of detailed understanding of
the mechanical and thermal properties of gas hydrate-bearing sediments.
"However, to mitigate the potential hazard in these instances, the wells are cased — typically using a steel pipe
that lines the wall of the borehole — to separate and protect the well from the gas hydrates in the shallower
zones as drilling continues deeper.
"Unless precautions are taken, continued drilling may heat up the sediments surrounding the well bore,
causing gas from the dissociated hydrates to leak and bubble up around the casing. Once oil production
begins, hot fluids flowing through the well could also warm hydrate-bearing sediments and cause dissociation.
The released gas may pool and build up pressure against the well casing, possibly causing damage.
"Some observers [further] suggest that exploiting the gas hydrate resources by intentionally heating or by
depressurization poses the same risks...as drilling through gas hydrates to reach deeper conventional oil and
gas deposits."
Like what you're reading so far? Then why not order a full year (52 issues) of The American Spark
e-newsletter for only $15? A major article covering an story not being told in the Corporate Press will be
delivered to your email every Monday morning for a full year, for less than 30 cents an issue. Order Now!
By Cliff Montgomery - June 12th, 2010
A 2008 U.S. government study, which discussed potentially disruptive gas sediments on the Gulf Coast sea
floor, may offer a clue as to what caused the explosion of BP's Deepwater Horizon oil rig.
It's perhaps still too early to determine any certain causes for the blast, which in turn has allowed the release of
up to 50,000 barrels of oil every day.
That amount "is roughly five to six times the amount spilled in Alaskan waters in 1989 by the Exxon Valdez,"
according to The Washington Post.
The Congressional Research Service (CRS) report, entitled Gas Hydrates: Resource and Hazard, clearly
states its point:
"Offshore drilling operations that disturb gas hydrate-bearing sediments could fracture or disrupt the bottom
sediments and compromise the wellbore, pipelines, rig supports, and other equipment involved in oil and gas
production from the seafloor," according to the study.
The American Spark quotes major segments of the report below:
"Gas hydrates occur naturally onshore in permafrost, and at or below the seafloor in sediments where water
and gas combine at low temperatures and high pressures to form an ice-like solid substance.
"Methane, or natural gas, is typically the dominant gas in the hydrate structure. In a gas hydrate, frozen water
molecules form a cage-like structure around high concentrations of natural gas. The gas hydrate structure
[thus] is very compact.
"When heated and depressurized to temperatures and pressures typically found on the Earth’s surface (one
atmosphere of pressure and 70 degrees Fahrenheit), its volume expands by 150 to 170 times. Thus, one cubic
foot of solid gas hydrate found underground in permafrost or beneath the seafloor would produce between
150 to 170 cubic feet of natural gas when brought to the surface.
"Gas hydrates are a potentially huge global energy resource. The United States and other countries with
territory in the Arctic or with offshore gas hydrates along their continental margins are interested in developing
the resource."
Gas Hydrate Resources
"There are several challenges to commercially exploiting gas hydrates. How much and where gas hydrate
occurs in commercially viable concentrations are not well known, and how the resource can be extracted safely
and economically is a current research focus.
"Estimates of global gas hydrate resources, which range from at least 100,000 TCF [Trillion Cubic Feet] to
possibly much more, may greatly over-estimate how much gas can be extracted economically. Reports of vast
gas hydrate resources can be misleading unless those estimates are qualified by the use of such terms such
as in-place resources, technically recoverable resources, and proved reserves:
- The term in-place is used to describe an estimate of gas hydrate resources without regard for technical
or economical recoverability. Generally these are the largest estimates.
- Undiscovered technically recoverable resources are producible using current technology, but this does
not take into account economic viability.
- Proved reserves are estimated quantities that can be recovered under existing economic and operating
conditions. [...]
Gas Hydrates in the Gulf of Mexico
"On February 1, 2008, the MMS released an assessment of gas hydrate resources for the Gulf of Mexico. The
report gives a statistical probability of the volume of undiscovered in-place gas hydrate resources, with a mean
estimate of over 21,000 TCF.
"The MMS report estimates how much gas hydrate may occur in sandstone and shale reservoirs, using a
combination of data and modeling, but does not indicate how much is recoverable with current technology."
Gas Hydrate Hazards
"Gas hydrates are a significant hazard for drilling and production operations.
"Gas hydrate production is hazardous in itself, as well as for conventional oil and gas activities that place wells
and pipelines into permafrost or marine sediments. For activities in permafrost, two general categories of
problems have been identified:
- (1) uncontrolled gas releases during drilling; and
- (2) damage to well casing during and after installation of a well.
"Similar problems could occur during offshore drilling into gas hydrate-bearing marine sediments. Offshore
drilling operations that disturb gas hydrate-bearing sediments could fracture or disrupt the bottom sediments
and compromise the well bore, pipelines, rig supports, and other equipment involved in oil and gas production
from the seafloor. [Emphasis added]
"Problems may differ somewhat between onshore and offshore operations, but they stem from the same
characteristic of gas hydrates: decreases in pressure and/or increases in temperature can cause the gas
hydrate to dissociate and rapidly release large amounts of gas into the well bore during a drilling operation.
"Oil and gas wells drilled through permafrost or offshore to reach conventional oil and gas deposits may
encounter gas hydrates, which companies generally try to avoid because of a lack of detailed understanding of
the mechanical and thermal properties of gas hydrate-bearing sediments.
"However, to mitigate the potential hazard in these instances, the wells are cased — typically using a steel pipe
that lines the wall of the borehole — to separate and protect the well from the gas hydrates in the shallower
zones as drilling continues deeper.
"Unless precautions are taken, continued drilling may heat up the sediments surrounding the well bore,
causing gas from the dissociated hydrates to leak and bubble up around the casing. Once oil production
begins, hot fluids flowing through the well could also warm hydrate-bearing sediments and cause dissociation.
The released gas may pool and build up pressure against the well casing, possibly causing damage.
"Some observers [further] suggest that exploiting the gas hydrate resources by intentionally heating or by
depressurization poses the same risks...as drilling through gas hydrates to reach deeper conventional oil and
gas deposits."
Like what you're reading so far? Then why not order a full year (52 issues) of The American Spark
e-newsletter for only $15? A major article covering an story not being told in the Corporate Press will be
delivered to your email every Monday morning for a full year, for less than 30 cents an issue. Order Now!
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