Petrobowl Questions
Will a SP log spike lower or higher in a reservoir containing hydrocarbons?
Lower
With two phase flow, why does the flow regime not affect the pressure drop in horizontal flow as it does in vertical flow?
No potential energy contribution to the pressure drop in horizontal flow
Wildcatter's used to taste and classify oils as sweet, medium sour, and sour based on what property of oil?
Sulfur Content.
What is the equation for gas specific gravity?
Yg = Y/Yair
During infinite acting radial flow, what is the value of the pressure derivative slope?
Zero
The motion of atoms and molecules in fluids due to the temperature of a fluid appears to be random but is described by the relationships derived by the man for which this motion is named. What is the name of this motion?
Brownian motion
What are the two types of distributive flow?
Bubble and mist.
What is a raised metal lip that is around a perforation?
Burr
What is bubble flow?
Dispersed bubbles of gas in a continous liquid phase.
During pseudo steady state flow, the slope of the pressure change is 1 during which type of well test?
Drawdown
This term describes the difference between average reservoir pressure and the flowing bottomhole pressure.
Drawdown
What is the term for a gas that is a vapor in the reservoir and has no liquid dropout because separator conditions are still in the vapor region of the phase diagram?
Dry gas
When can a stabilized well test be conducted.
During steady state flow or pseudo steady state flow
Sonic Log, Density log and Neutron logs are all what type of logs in Well Logging?
Porosity Logs
What term is used to define a higher than expected production from existing oilfields possible due to improved management, adoption of more sophisticated and costly technologies or previous miscalculation?
Production Creeping
For a late time drawdown, the pressure change and pressure derivative are overlain for what flow regime?
Pseudo steady state
Which two flow regimes cannot be seperately distinguished in pressure buildup data?
Pseudo steady state and steady state
What are three types of non-newtonian fluids?
Psuedoplastic (shear thinning), dilatant (shear thickening), and Bingham plastic fluids
The amount of oil that can be produced from a reservoir under current economic conditions is said to be what?
Recoverable oil
Brill and Beggs described three flow regimes for horizontal gas-liquid flow, what are they?
Segregated flow, intermittent flow, and distributive flow
What is vessel used to separate gas oil and water after the mixture is produced from the well?
Separator
Graphing F vs Eo (underground withdrawals vs Oil Expansion) would result in a slope of what, for saturated reservoirs and with no gas cap.
Slope of N, original oil in place
What are the two types of intermittent flow?
Slug and Plug.
Which type of reservoir drive system is happening when a reservoir contains no gas cap but rapidly passes below the bubble point pressure after production commences.
Solution gas drive
What is the unused world oil production capacity called?
Spare Capacity
What are the three types of segregated flow?
Stratified, Wavy and annular.
In the USA, this type of well is defined as producing 10 BOE/d or less.
Stripper well
What type of well typically produces a few barrels of oil per day and accounted for 15 percent of total U.S. production in 1986?
Stripper wells
Describe what a z factor is also give the equation for it.
The "z" factor is the ratio of the volume actually occupied by a gas at a given pressure and temperature to the volume the gas would occupy at the same pressure and temperature if it behaved like an ideal gas. Z= VACTUAL /VIDEAL
What is the device inside the choke that restricts flow called?
The bean
How is the productivity index calculated?
Well flow rate q, divided by the drop in pressure from the average reservoir pressure,p, to the flowing wellbore pressure pwf.
What is caused by movement, expansion, and/or compression of wellbore fluids in response to a pressure change?
Wellbore storage
What is critical flow through a choke?
When the fluid is accelerated enough to reach sonic velocity in the throat of the choke
In two phase flow what is hold up?
When the lighter phase flows faster than the denser phase.
What is churn flow?
With a further increase in gas rate, the larger gas bubbles become unstable and collapse, resulting in churn flow, a highly turbulent flow pattern with both phases dipsersed. Churn flow is characterized by oscillatory, up and down motions of the liquid.
What do the variables represent in the gas specific gravity equation?
Yg is the specific gravity of the gas, ?g is the density of the gas, and ?air is the density of dry air.
Assuming uniform pipe diamters, what will be the pressure drop due to kinetic enery for an incompressible fluid.
Zero
What is the oilfield unit for Wellbore storage,C?
bbl/psi
What are the two types of chemical bonds?
Covalent and ionic bonds
The instersection of the IPR curve and VLP curve gives what result?
Well deliverability
In the majority of sedimentary basins the overburden pressure increases linearly with depth. In psi/ft, what is the typical value of this gradient?
1 psi/ft
For an infinite conductivity vertical fracture flow (linear flow) flow regime, what is the slope of the pressure change?
0.5
What is the average world's water cut associated with oil production?
25%
What is the conversion factor to obtain field units for Darcy's Law?
1.127 x 10-3
Contact angle is used to measure the wettability, the solid is called water-wet if the contact angle is below ___ and is oil-wet if the contact angle is more than ___
90, 90
On a log log plot of flow rate vs time, what characteristic describes storage?
A hump in the pressure derivative
How are the effects of valves and fittings included when calculating the pressure drop.
Adding the equivilent length to the actual length
What is annular flow?
At higher gas rates, gas becomes the continous phase, with liquid flowing in an annulus coating the surface of the pipe and with liquid droplets entrained in the gas phase.
What is slug flow?
At higher gas rates, the bubbles coalesce into larger bubbles, called Taylor bubbles, that eventually fill the entire pipe cross section. Between the large gas bubbles are slugs of liquid that contain smaller bubbles of gas entrained in the liquid.
Interpretation of a stabilized well test yields what information?
Average reservoir pressure in the well drainage area, and the well productivity or injectivity index.
Why for two phase flow would an increase in the imposed well head pressur result in a proportionaltely larger increase in the corresponding bottom hole pressure?
Because gas would be re-dissolved, increasing the density of the fluid in the wellbore.
Which two phase pressure gradient correlation can be used for any pipe inclination and flow direction?
Beggs and Brill
Name the five reservoir fluids.
Black oil, volatile oil, retrograde gas, wet gas, and dry gas
What is the term for the vented or drained off fluids from a pressured well?
Bleed Off
This volume of gas has been separated from produced water.
Blue gas
Who is considered the world leader in deep-offshore production?
Brazil's Petrobras.
This pressure is defined as the non-wet phase pressure minus wetting phase pressure in the interface between two immiscible fluids.
Capillary Pressure
This type of drawdown is the pressure differential from the formation near the wellbore to the wellbore.
Completion Drawdown
Name Five types of Packers used in the oil industry?
Compression set packer, drillable packer, hookwall packer, inflatable packer, hydraulic packer
what is the area of the rock adjacent to the perforation tunnel where permeability may be 50% less than initial, undamaged permeability?
Crush Zone
The integration fo flow rate versus time results in what?
Cummulative Production
This type of permeability is a measure of the conductance of a porous medium for one fluid phase when the medium is saturated with more than one fluid. What is the name of this type of permeability?
Effective permeability
What would the pressure be in a black oil reservoir at discovery?
Either above the bubble point or equal to the bubble point pressure
This is a rubber or plastic material used as a seal.
Elastomer
In offshore operations, what does FPSO stand for?
Floating Production, Storage, and Offloading Vessel
What are derivative responses that are commonly found and readily recognized in transient test data termed?
Flow regimes
What is the term for the ratio of the resistivity of a rock filled with water to the resistivity of that water?
Formation factor
For a finite conductivity vertical fracture flow regime(bilinear flow), the pressure change and derivate are offset by a factor of what?
Four
What is intermittent flow?
Gas and liquid phase alternates
Real gases have a factor that is used to relate the gas to ideal conditions, what is the name of this factor?
Gas deviation, or 'z' factor
What does the term, Bg, represent?
Gas formation volume factor
What is the term for a formation with constant permeability and no high or low 'streaks'?
Homogeneous
If the productivity of a well is low due to low permeability, how is this overcome?
Hydraulic fracturing
Why most a reservoir sample be taken before production in new wells?
Once the reservoir drops below bubble point it is no longer possible to acquire a fluid sample from which the hydrocarbon compostion can be determined.
During wellbore storage flow regime, what is the slope of the pressure derivative.
One
What is distributive flow?
One phase is dispersed in the other phase.
What is a drawdown test?
Opening a well to flow after a shut in.
What is the concept of a gas lift?
Increase gas liquid ratio resulting in a reduction to bottomhole pressure
There exists a limting gas liquid ratio, where the decrease in hydrostatic pressure will be offset by what?
Increase in frictional pressure drop
The partial penetration (shperical flow regime) occurs between well bore storage and what other flow regime.
Infinite acting radial flow
What process is used to determine the pore size distribution in a formation sample?
Inject the sample with mercury then plot a graph of capillary pressure vs. water saturation
What is the term for the effect of gas slippage at low pressure and is the cause for overestimation of absolute permeability in a gas saturated core?
Klinkenberg effect or slippage effect
The velocity profile is parabolic for what type of flow?
Laminar
Name at least four assumptions of Darcy's Law.
Laminar flow, viscous flow, incompressible flow, steady state, homogeneous formation, 100% saturation with flowing fluid phase.
What are the two possible ways single phase flow can be characterized?
Laminar or Turbulent
When calculating relative pipe roughness, Є=k/d, what is k?
Length of the protrusions on the pipe wall.
Production = Expansion + Influx + Injection
Material Balance Equation
What is the total amount of oil located in the subsurface of a reservoir of an oil field?
Oil in place
What is kro and how is it defined?
Oil relative permeability. kro = ko/k
What does the term "dead oil" describe"
Oil with no dissolved gas
If the contact angle between oil and water of a liquid on a core sample is less than 90°, what is the wetting phase?
Water
The fluid recover from an undersaturated oil reservoir depends entirely on what?
The fluid expansion as a result of underground withdrawal and associated pressure reduction.
What is indicated by low pore entry pressure?
The formation has large pores since low pressure is needed for a fluid to enter the formation
What is the term for the equilibrium point between the sublimation line, the melting point line, and the vapor pressure line?
The triple point
What is segregated flow?
The two phases are for the most part separate.
Why is the use of down hole shutin recommended in pressure buildup tests?
To avoid loss of early time data that may help to characterize damage and to avoid error in the test interpretation.
What chemical found in TNT is also found in oil, particularly Borneo crude?
Toloul
What is a vessel used to treat or separate water-oil emulsions?
Treater
In Havlena and Odehs application of the material balance what is m?
m= vol of gas cap/vol of oil
What is the linear flow form of Darcy's Law?
q=ka(p1-p2)/µL
