Friday, June 10, 2005
River Deep Mountain High - Turner Valley Troubles
If it rains for a solid week in semi-arid Southern Alberta eventually something will give. Rivers have flooded the last few days reminding everyone of the power of Mother Nature. Flood plains are great places to live, close to water, good soil, flat land. Unfortunately they are prone to flooding.
Alberta's booming oil industry got its start in Turner Valley. The Dingman #1 well was drilled beside a natural gas seep. Legend has it that the well's promoter cooked a frying pan of eggs to help raise drilling money. That seep is still active today.
Turner Valley Gas Seep
Gas Sample Collection
It was only logical that the gas plant be built beside the discovery well, the nice flat patch of ground on the inside bend of the Sheep River is now the Turner Valley Gas Plant Provincial and National Historic Site. The oil industry doesn't build gas plants in flood plains any more for all kinds of great environmental reasons. There have been efforts to remediate the contamination from the gas plant. Unfortunately, recent flooding has wrought havoc with remediation efforts and contaminated soil from the gas plant is now underneath the Sheep River.
The CBC reports that The Town of Turner Valley is concerned that not enough has been done to remediate the contaminated soil on the gas plant site:
Contaminated soil in Sheep River: town
If you look at the Jennifer Lee photo associated with the article, you will see an orange spot, slightly left of center. Natural gas leaks out of the riverbank and the area has been fenced off. A flare ignites the leaking gas to prevent any dangerous buildups from occurring.
Natural Gas Flare
It is interesting that this early geological cross-section between the Dingman #1 discovery well and the Dingman #2 well (shown below) doesn't show any evidence of gas seepage beside the #2 well. The area where the gas is flared is just a few meters down the river bank from the Dingman #2 well. This gas is likely migrating through a crack in the casing of the old well. Remediation of old leaky wells can be extremely difficult and expensive so the well's previous owners were probably happy to hand off the liability to the Government of Alberta.
Cross-section showing Dingman #1 and #2 Wells
One of the problems in remediating leaky gas wells is the fact that the gas might be not be coming from the original producing zone. There were numerous gas shows during the drilling of the Dingman #1 and #2 wells and any one of them could be leaking to surface. Dr. Muehlenbachs at the University of Alberta was instrumental in developing a method to fingerprint natural gases from different depths using carbon isotopes.
I collected gas samples from 4 locations (2 at surface and 2 from producing wells) and included the data in a paper called Stable isotope geochemistry of some natural gas macroseeps in Alberta. The best evidence for gas leakage from the Dingman #2 well comes from the old cross-section. It is highly unlikely that a gas seep the size of the one currently being flared would have been missed (for starters its a bit stinky due to the hydrogen sulphide content). My conclusions were as follows:
These 4 samples are all similar in isotopic composition and the natural gas plot (Chung et al., 1988) of the Turner Valley gases (Figure 1) indicate that they have a source with an isotopic composition of ~-23 ‰. The d13C C1 values for the surface seep samples are both depleted in 13C relative to the production samples. Isotopically light methane from shallow Cretaceous gas accumulations may be making a small contribution to the surface seeps at Turner Valley.
A great website about Turner Valley's oil and gas history is Hell's Half Acre
Alberta's booming oil industry got its start in Turner Valley. The Dingman #1 well was drilled beside a natural gas seep. Legend has it that the well's promoter cooked a frying pan of eggs to help raise drilling money. That seep is still active today.
Turner Valley Gas Seep
Gas Sample Collection
It was only logical that the gas plant be built beside the discovery well, the nice flat patch of ground on the inside bend of the Sheep River is now the Turner Valley Gas Plant Provincial and National Historic Site. The oil industry doesn't build gas plants in flood plains any more for all kinds of great environmental reasons. There have been efforts to remediate the contamination from the gas plant. Unfortunately, recent flooding has wrought havoc with remediation efforts and contaminated soil from the gas plant is now underneath the Sheep River.
The CBC reports that The Town of Turner Valley is concerned that not enough has been done to remediate the contaminated soil on the gas plant site:
Contaminated soil in Sheep River: town
If you look at the Jennifer Lee photo associated with the article, you will see an orange spot, slightly left of center. Natural gas leaks out of the riverbank and the area has been fenced off. A flare ignites the leaking gas to prevent any dangerous buildups from occurring.
Natural Gas Flare
It is interesting that this early geological cross-section between the Dingman #1 discovery well and the Dingman #2 well (shown below) doesn't show any evidence of gas seepage beside the #2 well. The area where the gas is flared is just a few meters down the river bank from the Dingman #2 well. This gas is likely migrating through a crack in the casing of the old well. Remediation of old leaky wells can be extremely difficult and expensive so the well's previous owners were probably happy to hand off the liability to the Government of Alberta.
Cross-section showing Dingman #1 and #2 Wells
One of the problems in remediating leaky gas wells is the fact that the gas might be not be coming from the original producing zone. There were numerous gas shows during the drilling of the Dingman #1 and #2 wells and any one of them could be leaking to surface. Dr. Muehlenbachs at the University of Alberta was instrumental in developing a method to fingerprint natural gases from different depths using carbon isotopes.
I collected gas samples from 4 locations (2 at surface and 2 from producing wells) and included the data in a paper called Stable isotope geochemistry of some natural gas macroseeps in Alberta. The best evidence for gas leakage from the Dingman #2 well comes from the old cross-section. It is highly unlikely that a gas seep the size of the one currently being flared would have been missed (for starters its a bit stinky due to the hydrogen sulphide content). My conclusions were as follows:
These 4 samples are all similar in isotopic composition and the natural gas plot (Chung et al., 1988) of the Turner Valley gases (Figure 1) indicate that they have a source with an isotopic composition of ~-23 ‰. The d13C C1 values for the surface seep samples are both depleted in 13C relative to the production samples. Isotopically light methane from shallow Cretaceous gas accumulations may be making a small contribution to the surface seeps at Turner Valley.
A great website about Turner Valley's oil and gas history is Hell's Half Acre
# posted by Jim : 9:46 PM
