Petroleum Production Operations Multiple Choice Questions on “Factors Affecting Perforating Results”.
1. The plugging of perforators is caused by the charge liner residue.
a) True
b) False
View Answer
Answer: a
Clarification: The statement is true. Plugging of perforators is caused by the charge liner residue and it can be very severe. By using the sintered metal or powdered metal cone a large number of residue slugs have been reduced in a number of premiums priced-charged.
2. Which type of tools is used to clean out of perforation?
a) Surging tools
b) Back-surge tools
c) Super Surging tools
d) Perforating guns
Answer: b
Clarification: Back-surge tools and perforation washers are used to clean out perforations. If perforations in sandstone cannot be cleaned out by back-surge tools and perforation washers then a breakdown of perforations or fracturing is done.
3. Plugging of perforations can’t happen during production.
a) True
b) False
Answer: b
Clarification: The given statement is true. Plugging of perforations may happen during production. This can happen with paraffin, asphaltenes, or scales. This may create severe problems. 24 to 72 hrs of solvent soaking will generally eliminate the paraffin or asphaltenes.
4. Which of the following is an incorrect statement?
a) Perforating with differential pressure into the wellbore doesn’t assist in perforation cleanout
b) As a rule of thumb permeabilities of 250 md or more will allow clay size particles to carry deep into the formation
c) Underbalanced and Overbalanced are the two ways to perforate a formation
d) Bullet perforation is cheaper than Jet perforation
Answer: a
Clarification: The incorrect statement is Perforating with differential pressure into the wellbore doesn’t assist in perforation cleanout. Actually, Perforating with differential pressure into the wellbore assists in perforation cleanout. The other statements are correct.
5. Which of the following is incorrect?
a) Penetration and hole size of Jet perforators are decreased as the compressive strength of the casing, cement and formation are increased
b) Penetration and hole size of Jet perforators are unchanged irrespective of the compressive strength of the casing, cement, and formation
c) Jet perforation is costlier than Bullet perforation
d) Perforating with differential pressure into the wellbore assists in perforation cleanout
View Answer
Answer: b
Clarification: The incorrect statement is Penetration and the hole size of Jet perforators are unchanged irrespective of the compressive strength of the casing, cement, and formation. Actually, Penetration and hole size of Jet perforators are decreased as the compressive strength of the casing, cement and formation are increased. The other statements are correct.
6. Which of the following explosives are used in Hot wells?
a) Very low-temperature explosives
b) Low-temperature explosives
c) Medium temperature explosives
d) High-temperature explosives
Answer: d
Clarification: High-temperature explosives are used in Hot Wells. Most high-temperature charges provide less penetration but high-temperature charges are more expensive as compared to other types of charges.
7. What is casing mass strength?
a) Yield strength*Weight/ft
b) Yield strength*Pressure/ft
c) Pressure*Weight/ft
d) Number of strings*Weight/ft
Answer: a
Clarification: The casing mass strength is defined as the product of the Yield strength and Weight/ft. Yield strength is the amount of stress a material can withstand without its permanent deformation.
8. What should be the perforation hole size for gravel packing?
a) 0.05 in
b) 0.5 in
c) 0.3 in
d) 0.75 in
Answer: d
Clarification: For gravel packing, the perforation size dole diameter should be large and round. The perforation hole size for gravel packing should be a minimum of 0.75 in. Gravel packing is a sand control method.
9. What should be the perforation hole size for plastic sand consolidation?
a) 0.05 in
b) 0.65 in
c) 0.5 in
d) 0.75 in
View Answer
Answer: c
Clarification: In the case of plastic sand consolidation, perforation should be done along with differential pressure or perforation surge or clean out tools with a minimum hole size of 0.5 in.
10. What should be the perforation hole size for hydraulic fracturing?
a) 0.75 in
b) 0.5 in
c) 0.3 in
d) 0.65 in
Answer: a
Clarification: For hydraulic fracturing, the entrance hole should be round and smooth. Hence, the hole size for hydraulic fracturing should be a minimum of 0.75 in. Hydraulic fracturing informally called “fracking” is a process used in the oil and gas well development, that involves injecting sand, water and chemicals under very high pressure into a bedrock formation via the well to create channels for the formation fluid to come into the well.
11. What should be the perforation penetration for carbonate rocks?
a) 3-7 in
b) 2-8 in
c) 4-6 in
d) 1-5 in
Answer: c
Clarification: The perforation penetration for carbonate rocks should be 4-6 inches. Carbonate rocks are a class of sedimentary rocks that are comprised primarily of carbonate minerals. They are mainly composed of limestone and dolomite.