Professional Engineering-
Petroleum Engineering
Questions and Correct
Answers the Latest Update
GRADED A+
QUESTIONS AND ANSWERS
Causes for INCREASE in Pore Pressure. ANSWER -1). Undercompaction by rapid
burial of low-perm sediments
2). lateral compression
3). Water release from clay minerals from heating & compression
4). Expansion of fluids from heating
5). Fluid density contrasts
6). Buoyancy effects
7). Fluid injection
Causes for DECREASE in Pore Pressure. ANSWER -1). Fluid shrinkage
2). Unloading
3). Rock dilation
4). Reservoir depletion
,Which faulting regime is the only one in which the vertical stress is the greatest
principle stress?. ANSWER -Normal
What is the only accurate way to determine pore pressure?. ANSWER -Direct
Measurement
Why is it difficult to measure the pore pressure of a shale?. ANSWER -very low
permeabilities and small pore volumes
What are the various strength criterions and their characteristics?. ANSWER -Mohr-
Coulomb - 2D w/2 criterions (Cohesion So & UCS); stress difference at failure is
linear to confining stress
Hoek and Brown (HB): 2D, 3 criterions
Tesca: simple version of Mohr-Coulomb
Modified Lade: 3D but requires only 2 empirical constants equal to UCS; preferred for
wellbore stability
What methods can be used to determine the strength properties of rock?. ANSWER -
Single-Sample Testing: triaxial tests are difficult & time-consuming, require
similar/identical cores
Scratch Testing: no special prep; in lab or in on rig; no damage to core
,Penetrometer Testing: no special prep; blunt probe
Note: estimating uniaxial compressive strength using rig site measurements is NOT
straightforward
Where are drilling mud samples typically taken?. ANSWER -Suction pit and Possum
Belly
- A possum belly is a metal container at the head of the shale shaker; its purpose is to
slow the flow of drilling fluid so it does not shoot out of the shale shakers; generally
used when bentonite or another form of "mud" is being used
- a mud tank connected to the intake of the main rig pumping system; last mud tank in
the surface mud system before mud is pumped into the well
Where are mud temperatures typically monitored?. ANSWER -Suction pit and Mud
Return Lines
What are the most common sources of drilling mud contamination?. ANSWER -Pipe
scale, pipe dope, and air entering the drill string at connections
During drilling operations, where are gas samples typically taken?. ANSWER -At the
"gas trap" or gas extractor
- the gas extractor is part of the mud conditioning system
, What is underbalanced drilling?. ANSWER -Drilling with the well's bottom hole
pressure intentionally lower than formation pressures
What aspects allow the well to be maintained under control during underbalanced
drilling operations?. ANSWER -1). drilled cuttings adding to fluid hydrostatic
pressure
2). friction pressures from circulation
3). choke pressures applied at the surface
What is the main well control issue during underbalanced drilling?. ANSWER -Flow
Control
Note: NOT pressure control
What are the advantages of underbalanced drilling?. ANSWER -1). avoids filter cake
buildup
2). avoids invasion of mud into formation for improved productivity
3). increased ROP
4). increased bit life
5). ability to acquire reservoir data is improved
6). decrease formation damage
7). decrease differential sticking
8). decrease lost circulation
Petroleum Engineering
Questions and Correct
Answers the Latest Update
GRADED A+
QUESTIONS AND ANSWERS
Causes for INCREASE in Pore Pressure. ANSWER -1). Undercompaction by rapid
burial of low-perm sediments
2). lateral compression
3). Water release from clay minerals from heating & compression
4). Expansion of fluids from heating
5). Fluid density contrasts
6). Buoyancy effects
7). Fluid injection
Causes for DECREASE in Pore Pressure. ANSWER -1). Fluid shrinkage
2). Unloading
3). Rock dilation
4). Reservoir depletion
,Which faulting regime is the only one in which the vertical stress is the greatest
principle stress?. ANSWER -Normal
What is the only accurate way to determine pore pressure?. ANSWER -Direct
Measurement
Why is it difficult to measure the pore pressure of a shale?. ANSWER -very low
permeabilities and small pore volumes
What are the various strength criterions and their characteristics?. ANSWER -Mohr-
Coulomb - 2D w/2 criterions (Cohesion So & UCS); stress difference at failure is
linear to confining stress
Hoek and Brown (HB): 2D, 3 criterions
Tesca: simple version of Mohr-Coulomb
Modified Lade: 3D but requires only 2 empirical constants equal to UCS; preferred for
wellbore stability
What methods can be used to determine the strength properties of rock?. ANSWER -
Single-Sample Testing: triaxial tests are difficult & time-consuming, require
similar/identical cores
Scratch Testing: no special prep; in lab or in on rig; no damage to core
,Penetrometer Testing: no special prep; blunt probe
Note: estimating uniaxial compressive strength using rig site measurements is NOT
straightforward
Where are drilling mud samples typically taken?. ANSWER -Suction pit and Possum
Belly
- A possum belly is a metal container at the head of the shale shaker; its purpose is to
slow the flow of drilling fluid so it does not shoot out of the shale shakers; generally
used when bentonite or another form of "mud" is being used
- a mud tank connected to the intake of the main rig pumping system; last mud tank in
the surface mud system before mud is pumped into the well
Where are mud temperatures typically monitored?. ANSWER -Suction pit and Mud
Return Lines
What are the most common sources of drilling mud contamination?. ANSWER -Pipe
scale, pipe dope, and air entering the drill string at connections
During drilling operations, where are gas samples typically taken?. ANSWER -At the
"gas trap" or gas extractor
- the gas extractor is part of the mud conditioning system
, What is underbalanced drilling?. ANSWER -Drilling with the well's bottom hole
pressure intentionally lower than formation pressures
What aspects allow the well to be maintained under control during underbalanced
drilling operations?. ANSWER -1). drilled cuttings adding to fluid hydrostatic
pressure
2). friction pressures from circulation
3). choke pressures applied at the surface
What is the main well control issue during underbalanced drilling?. ANSWER -Flow
Control
Note: NOT pressure control
What are the advantages of underbalanced drilling?. ANSWER -1). avoids filter cake
buildup
2). avoids invasion of mud into formation for improved productivity
3). increased ROP
4). increased bit life
5). ability to acquire reservoir data is improved
6). decrease formation damage
7). decrease differential sticking
8). decrease lost circulation
