This set of Petroleum Production Operations Multiple Choice Questions & Answers (MCQs) focuses on “Well Testing – Drill Stem Testing”.
1. What is the full form of DST in Petroleum Engineering?
a) Drill Stem Test
b) Drilling System Test
c)Data Surface Team
d) Driller’s System Test
View Answer
Explanation: The full form of DST in Petroleum Engineering is a Drill Stem Test. It is a temporary completion of a wellbore on the basis of which we decide whether or not to complete the well. The particular zone under consideration is sealed from the rest of the wellbore and we check the formation pressure and fluid.
2. What is the formula of dimensionless skin obtained from Drill Stem Test?
a) S = 1.151[{(Pwf– P1hr)/m}-log(k/(φμcrw2)+3.23]
b) S = 3.23[{(P1hr – Pwf)/m}-log(k/(φμcrw2)+1.151]
c) S = 1.151[{(P1hr – Pwf)/m}-log(k/(φμcrw2)]+3.23
d) S = 1.151[{(P1hr – Pwf)/m}-log(k/(φμcrw2)+3.23]
View Answer
Explanation: The formula of dimensionless skin obtained from Drill Stem Test is S= 1.151[{(P1hr – Pwf)/m}-log(k/(φμcrw2)+3.23]. The value of m needs to be taken from the straight line extrapolation. S gives information about the formation damage. A negative value of S is favorable.
3. When the well is put in a shut-in condition, then the pressure starts to build up.
a) True
b) False
View Answer
Explanation: Yes, When the well is put in shut-in condition, then the pressure starts to build up. And if the well is put in a shut-in condition for sufficient time then it will attain the reservoir pressure. That’s why we extrapolate the straight line portion in Horner’s plot in DST to calculate the reservoir pressure.
4. If the skin factor is positive then it indicates formation damage.
a) True
b) False
View Answer
Explanation: Yes, the skin factor is positive then it indicates formation damage. But if it is negative then it indicates a stimulated formation. These types of negative skin we generally get after stimulation servicing of the formation around the well bore.
5. If the mud plugs the pores of the formation then it is called ______
a) Formation Damage
b) Formation Stimulation
c) Well Activation
d) Well Completion
View Answer
Explanation: If the mud plugs the pores of the formation then it is called Formation Damage. The productivity of the well will decrease if the mud used in drilling or any type of activity plugs the pores and hence we need proper methods to remove the skin to put back the well to its original production. Well Activation is needed after the perforation to start the production of the well and well stimulation is needed to increase the productivity of the well by removing the skin.
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