PrepTest 43, Section 4, Question 4
The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells' potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.
When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry's concern for the purity of the wells' oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil-contaminated water.
The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth's surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.
Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well's location was based on a poor understanding of the area's subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area's groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.
The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells' potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.
When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry's concern for the purity of the wells' oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil-contaminated water.
The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth's surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.
Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well's location was based on a poor understanding of the area's subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area's groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.
The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells' potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.
When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry's concern for the purity of the wells' oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil-contaminated water.
The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth's surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.
Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well's location was based on a poor understanding of the area's subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area's groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.
The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells' potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.
When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry's concern for the purity of the wells' oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil-contaminated water.
The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth's surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.
Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well's location was based on a poor understanding of the area's subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area's groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.
The author uses the phrase "the hazards of insufficient knowledge" (near the beginning of the last paragraph) primarily in order to refer to the risks resulting from
a lack of understanding regarding the dangers to human health posed by groundwater contamination
a failure to comprehend the possible consequences of drilling in complex geologic systems
poorly tested methods for verifying the safety of newly developed technologies
an inadequate appreciation for the difficulties of enacting and enforcing environmental regulations
a rudimentary understanding of the materials used in manufacturing metal pipe casings
Explanations
This question asks us what risks the author refers to when using the turn of phrase "the hazards of insufficient knowledge."
I like to think of these questions in terms of local context and larger context. That is, by asking myself what this reference means in conjunction with the sentences immediately surrounding it as well as within the paragraph it resides and the passage as a whole.
Locally, this phrase seems to suggest that the example regulatory solution of requiring cement capping is just one of potentially many instances where we regulate in hindsight without understanding the full impact of our drilling.
Within the paragraph, we get other examples of how the capping regulation could fail in the field, as well as other examples.
That seems like sufficient context to predict the answer to the question. So I'm looking for something like, "We know not what we do when we drill in these systems because unknowns exist even when we follow regulations."
Let's see.
Nah. This one had me in the first half in that "a lack of understanding," is definitely characteristic of our author's concerns. However, it loses me at "dangers to human health." The health angle was only one of many concerns the author brings up regarding drilling contamination, and the author seems much more focused on the environmental challenges posed by drilling than the health impacts.
Yeah, this works. It rings true to my "they know not what they do" prediction. This is why the author makes this reference, because they proceed to explain why the capping regulation—while somewhat effective—has a lot of unknowns tied to it on top of a great many other unknowns that we don't adequately address.
No, the author isn't trying to say our methods are poorly tested, simply that there are several unknowns related to our methods that will probably rear their ugly heads before we regulate them away.
Nope. The author isn't trying to use this phrase to indicate that regulation is a difficult, nuanced process that we don't give its due.
Nah, this one misses the forest for the trees. This is just one of the things the author critiques about one specific regulation currently in use, but the author then proceeds to explain other potential pitfalls we don't regulate that are unrelated to this specific capping regulation.
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