Drilling fluids, including the various mixtures known as drilling muds

Question

Passage A

Drilling fluids, including the various mixtures
known as drilling muds, play essential roles in oil-well
drilling. As they are circulated down through the drill
pipe and back up the well itself, they lubricate the
  (5)   drill bit, bearings, and drill pipe; clean and cool the
drill bit as it cuts into the rock; lift rock chips
(cuttings) to the surface; provide information about
what is happening downhole, allowing the drillers to
monitor the behavior, flow rate, pressure, and
  (10)   composition of the drilling fluid; and maintain well
pressure to control cave-ins.

Drilling muds are made of bentonite and other
clays and polymers, mixed with a fluid to the desired
viscosity. By far the largest ingredient of drilling
  (15)   muds, by weight, is barite, a very heavy mineral of
density 4.3 to 4.6. It is also used as an inert filler in
some foods and is more familiar in its medical use as
the “barium meal” administered before X-raying the
digestive tract.

(20)   Over the years individual drilling companies and
their expert drillers have devised proprietary
formulations, or mud “recipes,” to deal with specific
types of drilling jobs. One problem in studying the
effects of drilling waste discharges is that the drilling
  (25)   fluids are made from a range of over 1,000, 
sometimes toxic, ingredients—many of them known, 
confusingly, by different trade names, generic descriptions, 
chemical formulae, and regional or industry slang words, 
and many of them kept secret by companies or individual
  (30)   formulators.

Passage B

Drilling mud, cuttings, and associated chemicals
are normally released only during the drilling phase of
a well’s existence. These discharges are the main
environmental concern in offshore oil production, and
  (35)   their use is tightly regulated. The discharges are 
closely monitored by the offshore operator, and releases 
are controlled as a condition of the operating permit.
One type of mud—water-based mud (WBM)—is
a mixture of water, bentonite clay, and chemical
  (40)   additives, and is used to drill shallow parts of wells. It
is not particularly toxic to marine organisms and
disperses readily. Under current regulations, it can be
dumped directly overboard. Companies typically
recycle WBMs until their properties are no longer
  (45)   suitable and then, over a period of hours, dump the
entire batch into the sea.

For drilling deeper wells, oil-based mud (OBM) is
normally used. The typical difference from WBM is the
high content of mineral oil (typically 30 percent).
  (50)   OBMs also contain greater concentrations of barite, a
powdered heavy mineral, and a number of additives.
OBMs have a greater potential for negative
environmental impact, partly because they do not
disperse as readily. Barite may impact some
  (55)   organisms, particularly scallops, and the mineral oil
may have toxic effects. Currently only the residues of
OBMs adhering to cuttings that remain after the
cuttings are sieved from the drilling fluids may be
discharged overboard, and then only mixtures up to a
  (60)   specified maximum oil content.  
 1 
 1. A primary purpose of each of the passages is to

(A) provide causal explanations for a type of environmental pollution
(B) describe the general composition and properties of drilling muds
(C) point out possible environmental impacts associated with oil drilling
(D) explain why oil-well drilling requires the use of drilling muds
(E) identify difficulties inherent in the regulation of oil-well drilling operations

2 
 2. Which one of the following is a characteristic of barite that is mentioned in both of the passages?

(A) It does not disperse readily in seawater.
(B) It is not found in drilling muds containing bentonite.
(C) Its use in drilling muds is tightly regulated.
(D) It is the most commonly used ingredient in drilling muds.
(E) It is a heavy mineral.

3 
 3. Each of the following is supported by one or both of the passages EXCEPT:

(A) Clay is an important constituent of many, if not all, drilling muds.
(B) At least one type of drilling mud is not significantly toxic to marine life.
(C) There has been some study of the environmental effects of drilling-mud discharges.
(D) Government regulations allow drilling muds to contain 30 percent mineral oil.
(E) During the drilling of an oil well, drilling mud is continuously discharged into the sea.

4 
 4. Which one of the following can be most reasonably inferred from the two passages taken together, but not from either one individually?

(A) Barite is the largest ingredient of drilling muds, by weight, and also the most environmentally damaging.
(B) Although barite can be harmful to marine organisms, it can be consumed safely by humans.
(C) Offshore drilling is more damaging to the environment than is land-based drilling.
(D) The use of drilling muds needs to be more tightly controlled by government.
(E) If offshore drilling did not generate cuttings, it would be less harmful to the environment.

5 
 5. Each of the following is supported by one or both of the passages EXCEPT:

(A) Drillers monitor the suitability of the mud they are using.
(B) The government requires drilling companies to disclose all ingredients used in their drilling muds.
(C) In certain quantities, barite is not toxic to humans.
(D) Oil reserves can be found within or beneath layers of rock.
(E) Drilling deep oil wells requires the use of different mud recipes than does drilling shallow oil wells.

6 
 6. Based on information in the passages, which one of the following, if true, provides the strongest support for a prediction that the proportion of oil-well drilling using OBMs will increase in the future?

(A) The cost of certain ingredients in WBMs is expected to increase steadily over the next several decades.
(B) The deeper an offshore oil well, the greater the concentration of barite that must be used in the drilling mud.
(C) Oil reserves at shallow depths have mostly been tapped, leaving primarily much deeper reserves for future drilling.
(D) It is unlikely that oil drillers will develop more efficient ways of removing OBM residues from cuttings that remain after being sieved from drilling fluids.
(E) Barite is a common mineral, the availability of which is virtually limitless.

7 
 7. According to passage B, one reason OBMs are potentially more environmentally damaging than WBMs is that OBMs

(A) are slower to disperse
(B) contain greater concentrations of bentonite
(C) contain a greater number of additives
(D) are used for drilling deeper wells
(E) cannot be recycled

mysterymanrog · Answer

Going to just post the answer for Q4, since that's the one I found most interesting.

D, E can easily be eliminated - they are not within the scope of the passages

C can be eliminated, since neither passage talks about offshore vs inland drilling - just the two depths used and the different "drilling muds".

A and B is where it gets tricky.

A is quite close, but it fails at the end. For the first portion of the argument (Barite is the largest by weight) you need passage A (line 15). The problem comes with the second part. There is nothing in either passage that allows us to think that Barite is the most damaging. Passage B (line 55) states: Barite MAY impact some organisms and the oil may have toxic effects. This is not enough to infer that it is the most damaging, as even the passage is not sure if its damaging (the passage uses the word may, which suggests a possibility rather than a certainty). So A is out.

B works nicely. Passage B is used to infer the first portion of the statement, and it is consistent (Barite CAN be harmful to organisms) and then passage A is used to infer the second portion, when it talks about the medical use of Barite. B is the correct answer.

Overall: 6/7 (silly mistake on Q2) Time: 11:52

pintukr · Answer

1. A primary purpose of each of the passages is to

(A) provide causal explanations for a type of environmental pollution
 only mentioned in Passage 2..not the primary aim

(B) describe the general composition and properties of drilling muds
  composition of drilling muds, and properties regarding efficacy, environmental impact etc have been discussed throughout the passage...CORRECT answer

(C) point out possible environmental impacts associated with oil drilling
 environmental impacts just a subsidiary concern while discussing various types of drilling muds

(D) explain why oil-well drilling requires the use of drilling muds
 only higlighted in 1st paragraph of passage 1

(E) identify difficulties inherent in the regulation of oil-well drilling operations
 'difficulties faced' is just additional information presented during the discussion regarding the oil-well drilling operations and thpes of drilling muds used therein

(B) is the correct answer

pintukr · Answer

2. Which one of the following is a characteristic of barite that is mentioned in both of the passages?

(A) It does not disperse readily in seawater.
 Not found mentioned anywhere in the passage..only that OBMs not getting dispersed readily--mentioned only in Passage 2

(B) It is not found in drilling muds containing bentonite.
 only in passage 2 (in conjunction with WBMs)

(C) Its use in drilling muds is tightly regulated.
 dumping regulations are discussed..No mention of barite regulation in the passage

(D) It is the most commonly used ingredient in drilling muds.
 cannot be ascertained using the contents of both the passages

(E) It is a heavy mineral.
  Line 15 (Passage 1) and Line 50-51 (Passage 2)..mentioned in both the passages..CORRECT answer

(E) is the correct answer

pintukr · Answer

3. Each of the following is supported by one or both of the passages EXCEPT:

(A) Clay is an important constituent of many, if not all, drilling muds.
 mentioned in lines 39-40 as 'bentonite clay'

(B) At least one type of drilling mud is not significantly toxic to marine life.
 Use of WBMs not toxic to marine organisms (1st paragraph of 2nd passage)

(C) There has been some study of the environmental effects of drilling-mud discharges.
 can be inferred using contents of Passage 2

(D) Government regulations allow drilling muds to contain 30 percent mineral oil.
 can be inferred using contens of OBMs (as presented in the 2nd paragraph of 2nd passage)

(E) During the drilling of an oil well, drilling mud is continuously discharged into the sea.
  Not mentioned anywhere that 'continuously' discharged ; in fact disposal is carried post recycling several times

(E) is the correct answer

pintukr · Answer

4. Which one of the following can be most reasonably inferred from the two passages taken together, but not from either one individually?

(A) Barite is the largest ingredient of drilling muds, by weight, and also the most environmentally damaging.
 'most' environmentally damaging amongst the constituents -- not mentioned in the passage

(B) Although barite can be harmful to marine organisms, it can be consumed safely by humans.
  can be inferred through Lines 19-20 (1st passage) , and Lines 40-41 (2nd Passage)

(C) Offshore drilling is more damaging to the environment than is land-based drilling.
 can be inferred using only passage 1

(D) The use of drilling muds needs to be more tightly controlled by government.
 No such suggestion presented in either of the passages

(E) If offshore drilling did not generate cuttings, it would be less harmful to the environment.
 No such mention in complete passage

(B) is the correct answer

pintukr · Answer

5. Each of the following is supported by one or both of the passages EXCEPT:

(A) Drillers monitor the suitability of the mud they are using.
 mentioned in the 1st paragraph of the Passage-1

(B) The government requires drilling companies to disclose all ingredients used in their drilling muds.
  Government regulations regarding composition of drilling muds do not find any mention in either of the passages..CORRECT answer

(C) In certain quantities, barite is not toxic to humans.
 mentioned in the 2nd paragraph of the Passage-2

(D) Oil reserves can be found within or beneath layers of rock.
 mentioned in the 1st and 2nd paragraphs of the Passage-1

(E) Drilling deep oil wells requires the use of different mud recipes than does drilling shallow oil wells.
 can be ascertained through requirements of WBMs and OBMs (as mentioned in the two paragraphs of the Passage-2)

(B) is the correct answer

pintukr · Answer

6. Based on information in the passages, which one of the following, if true, provides the strongest support for a prediction that the proportion of oil-well drilling using OBMs will increase in the future?

(A) The cost of certain ingredients in WBMs is expected to increase steadily over the next several decades.
 out of scope option

(B) The deeper an offshore oil well, the greater the concentration of barite that must be used in the drilling mud.
 no such linkage established in either of the passages

(C) Oil reserves at shallow depths have mostly been tapped, leaving primarily much deeper reserves for future drilling.
  since OBMs are ideal for drilling of deeper wells, future reserves (deeper, in nature) will support the prediction that the proportion of oil-well drilling using OBMs will increase in the future

(D) It is unlikely that oil drillers will develop more efficient ways of removing OBM residues from cuttings that remain after being sieved from drilling fluids.
 no such information presented in the passage

(E) Barite is a common mineral, the availability of which is virtually limitless.
 Again, can't be verified using the contents of the passage

(C) is the correct answer

pintukr · Answer

7. According to passage B, one reason OBMs are potentially more environmentally damaging than WBMs is that OBMs

(A) are slower to disperse
  clearly mentioned in the 2nd paragraph of Passage B, theat OBMs don't disperse readily..CORRECT answer

(B) contain greater concentrations of bentonite
 no comparisons made regarding concentration of bentonite

(C) contain a greater number of additives
 cannot be ascertained from the contents of both passages

(D) are used for drilling deeper wells
 drilling deeper wells is not the reason for greater environmental impact

(E) cannot be recycled
 recycling of OBMs and WBMs not discussed in the passage..Out of scope option

(A) is the correct answer

Sajjad1994 · Answer

Explanation

4. Which one of the following can be most reasonably inferred from the two passages taken together, but not from either one individually?

Explanation

The correct answer will require both passages in order to be correct. It will be partially supported by Passage A and partially supported by Passage B. As you go through the answer choices, keep this in mind: If an answer is fully supported by one passage or cannot be supported by either passage, eliminate it.

(A)  is Extreme. Although Passage A discusses barite as the largest ingredient of drilling muds, Passage B does not state that barite is the most environmentally
damaging; rather, Passage B only states that barite is contained in OBMs, which are more damaging that WBMs and may impact some organisms negatively. Eliminate.

(B)  Passage A mentions barite’s additional uses: as a food additive and an ingested component of X-raying the digestive tract. Coupled with Passage B’s discussion of barite’s toxicity to marine life,  (B)  is correct. Both passages are necessary to support this answer.

(C)  is Outside the Scope. The distinction between oilbased drilling and land-based drilling is never made in either passage. Eliminate.

(D)  is Outside the Scope. The author of Passage B never weighs in on her discussion of the acceptability of environmental regulations and practices concerning drilling muds. Eliminate.

(E)  is only supported in Passage B. While the author of Passage B might be alluding to this answer, Passage A never discusses the environmental impact of cuttings. Eliminate.

Answer: B

Drilling fluids, including the various mixtures known as drilling muds

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GMAT Reading Comprehension (RC) Questions

Drilling fluids, including the various mixtures known as drilling muds

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