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Questions and Answers
Overburden pressure (OP) is the combined ______ of the formation rock and fluids.
Overburden pressure (OP) is the combined ______ of the formation rock and fluids.
weight
Overburden pressure increases ______ with depth.
Overburden pressure increases ______ with depth.
linearly
Overburden pressure typically has a pressure gradient of 1 ______/ft.
Overburden pressure typically has a pressure gradient of 1 ______/ft.
psi
Hydrostatic pressure is the pressure applied by a ______ at equilibrium.
Hydrostatic pressure is the pressure applied by a ______ at equilibrium.
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Hydrostatic pressure increases in proportion to ______ measured from the surface.
Hydrostatic pressure increases in proportion to ______ measured from the surface.
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Swc is the ______ or irreducible water saturation.
Swc is the ______ or irreducible water saturation.
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The ______ is a constant which is positive if the water is overpressured and negative if underpressured.
The ______ is a constant which is positive if the water is overpressured and negative if underpressured.
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Swc is expressed as a fraction of the ______ volume.
Swc is expressed as a fraction of the ______ volume.
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The value of hydrostatic pressure depends on the ______ of the fluid.
The value of hydrostatic pressure depends on the ______ of the fluid.
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The hydrostatic pressure gradient for fresh water is 0.433 ______/ft.
The hydrostatic pressure gradient for fresh water is 0.433 ______/ft.
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Swc is normally between ______ percent of the pore volume.
Swc is normally between ______ percent of the pore volume.
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For the ______ in any sand to be abnormally pressured, the sand must be effectively sealed off from the surrounding strata.
For the ______ in any sand to be abnormally pressured, the sand must be effectively sealed off from the surrounding strata.
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The pressure gradients are smaller for ______ because their densities are less than that of water.
The pressure gradients are smaller for ______ because their densities are less than that of water.
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Boi is the ______ formation volume factor.
Boi is the ______ formation volume factor.
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Hydrostatic pressure continuity to the ______ cannot be established when the sand is effectively sealed off.
Hydrostatic pressure continuity to the ______ cannot be established when the sand is effectively sealed off.
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Boi is the ______ volume/stock tank volume.
Boi is the ______ volume/stock tank volume.
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The parameters ϕ and Swc are normally determined by ______ analysis.
The parameters ϕ and Swc are normally determined by ______ analysis.
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Causes of abnormal pressure include temperature change, thermal effects, geological changes, and ______ between waters having different salinity.
Causes of abnormal pressure include temperature change, thermal effects, geological changes, and ______ between waters having different salinity.
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At a given depth, the ______ pressure can be equated to the sum of the fluid pressure (FP) and the grain or matrix pressure (GP) acting between the individual rock particle.
At a given depth, the ______ pressure can be equated to the sum of the fluid pressure (FP) and the grain or matrix pressure (GP) acting between the individual rock particle.
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The total pressure at any depth, resulting from the combined weight of the ______ rock and fluids, is known as the overburden pressure.
The total pressure at any depth, resulting from the combined weight of the ______ rock and fluids, is known as the overburden pressure.
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At the ______ the fluids in contact have the same pressure.
At the ______ the fluids in contact have the same pressure.
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In the majority of sedimentary basins, the overburden pressure increases ______ with depth.
In the majority of sedimentary basins, the overburden pressure increases ______ with depth.
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Since the overburden pressure remains constant at any particular depth, then a reduction in fluid pressure will lead to a corresponding increase in the ______ pressure, and vice versa.
Since the overburden pressure remains constant at any particular depth, then a reduction in fluid pressure will lead to a corresponding increase in the ______ pressure, and vice versa.
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The pressure gradient in the formula Pw is denoted by ______ divided by ______ water.
The pressure gradient in the formula Pw is denoted by ______ divided by ______ water.
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The fluid pressure in hydrocarbon columns are dictated by the dominant ______ pressure in the vicinity of the reservoir.
The fluid pressure in hydrocarbon columns are dictated by the dominant ______ pressure in the vicinity of the reservoir.
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The formula for Pw includes a constant term of ______ and another term related to pressure gradient.
The formula for Pw includes a constant term of ______ and another term related to pressure gradient.
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In a perfectly normal case, the fluid pressure at any depth can be estimated first by the ______ pressure connected to the reservoir.
In a perfectly normal case, the fluid pressure at any depth can be estimated first by the ______ pressure connected to the reservoir.
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Pw = the pressure of the ______ at depth D.
Pw = the pressure of the ______ at depth D.
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(dP/dD)w = the ______ pressure gradient, is dependent on the salinity, and for fresh water has the value of 0.4335 psi/ft.
(dP/dD)w = the ______ pressure gradient, is dependent on the salinity, and for fresh water has the value of 0.4335 psi/ft.
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Assumes: continuity of water pressure to the ______ and the salinity does not vary with depth.
Assumes: continuity of water pressure to the ______ and the salinity does not vary with depth.
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Equation is only applicable to ______ hydrostatic pressure.
Equation is only applicable to ______ hydrostatic pressure.
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The pressure at the ______ contact is equal to the pressure in both fluids.
The pressure at the ______ contact is equal to the pressure in both fluids.
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The linear equation for oil pressure above the oil-water contact is Po = 0.35D + ______.
The linear equation for oil pressure above the oil-water contact is Po = 0.35D + ______.
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The pressure at the gas-oil contact is calculated to be ______ psia.
The pressure at the gas-oil contact is calculated to be ______ psia.
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The equation of the gas pressure line is Po = 0.08D + ______ psia.
The equation of the gas pressure line is Po = 0.08D + ______ psia.
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The gas pressure at the top of the structure is calculated to be ______ psia.
The gas pressure at the top of the structure is calculated to be ______ psia.
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The gas pressure at the top of the structure exceeds the normal hydrostatic pressure by ______ psi.
The gas pressure at the top of the structure exceeds the normal hydrostatic pressure by ______ psi.
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When drilling through a sealing shale on the crest of the structure, there will be a sharp pressure ______ on first penetrating the reservoir.
When drilling through a sealing shale on the crest of the structure, there will be a sharp pressure ______ on first penetrating the reservoir.
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The pressure kick occurs from ______ psi to 2369 psia.
The pressure kick occurs from ______ psi to 2369 psia.
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The magnitude of the pressure discontinuity depends on the vertical distance between the point of well penetration and the hydrocarbon _____ contact.
The magnitude of the pressure discontinuity depends on the vertical distance between the point of well penetration and the hydrocarbon _____ contact.
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If the reservoir only contains gas, the pressure discontinuity will be much _____ for a given vertical distance.
If the reservoir only contains gas, the pressure discontinuity will be much _____ for a given vertical distance.
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In the example, a well test is conducted at a depth of 5100 ft to determine the gas _____ at that depth.
In the example, a well test is conducted at a depth of 5100 ft to determine the gas _____ at that depth.
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The exploration well is penetrating the gas reservoir only and assumes no _____ in the well.
The exploration well is penetrating the gas reservoir only and assumes no _____ in the well.
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The oil pressure at the depth of 5500 ft is given as 2600 psia, allowing estimation of the oil-water _____.
The oil pressure at the depth of 5500 ft is given as 2600 psia, allowing estimation of the oil-water _____.
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The gas oil contact is located at 5500 ft deep in the water _____ zone.
The gas oil contact is located at 5500 ft deep in the water _____ zone.
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Pressure measurements are essential in determining the gas pressure at the gas water _____ at 5281 ft.
Pressure measurements are essential in determining the gas pressure at the gas water _____ at 5281 ft.
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Assuming normal hydrostatic pressure, a well was drilled and hit the oil and gas _____ zones.
Assuming normal hydrostatic pressure, a well was drilled and hit the oil and gas _____ zones.
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Study Notes
Reservoir Engineering I - PEB2023/PFB2023
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Fluid Pressure Regimes
- The total pressure at a depth is the combined weight from the formation rock and fluids (water, oil, or gas) and is known as overburden pressure.
- Overburden pressure typically increases linearly with depth with a gradient of 1 psi/ft.
- Hydrostatic pressure is the pressure exerted by a fluid at equilibrium due to gravity. It increases with depth proportionally to the fluid's weight.
- Water salinity affects the value of hydrostatic pressure.
-
Hydrocarbon Volumes Calculation
- Oil volume in place (OIP) is calculated using the formula: OIP = V¢(1-Swc) (res.vol.)
- V = net bulk volume of the reservoir rock
- Φ = porosity (volume fraction of the rock)
- Swc = connate/irreducible water saturation (fraction of pore volume)
- Stock tank oil initially in place (STOIIP) is calculated using the formula: STOIIP = n = v¢(1-Swc)/Boi
- Boi = oil formation volume factor under initial conditions (reservoir volume/stock tank volume).
- The parameters porosity and water saturation are typically determined by petrophysical analysis
- Net bulk volume is derived from geological and fluid pressure analyses
- Oil volume in place (OIP) is calculated using the formula: OIP = V¢(1-Swc) (res.vol.)
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Reservoir Temperature
- Earth's temperature increases from the surface to the center
- Geothermal gradient: heat flowing outwards around 1.6°F/100 ft
- Local and regional temperature gradients are influenced by factors like lithology and local conditions (e.g., wellbore temperatures).
- Reservoir temperatures are obtained from wellbore temperature surveys.
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Lecture Summary
- Topics covered: Hydrocarbon Volumes Calculation, Fluid Pressure Regimes, Reservoir Temperature
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What's Next?
- Reserve Estimation
- Volumetric Calculation
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Recommended Textbook:
- L.P. Dake, Fundamental of Reservoir Engineering, Chapter 1
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Description
This quiz covers concepts in fluid pressure regimes and hydrocarbon volume calculations relevant to Reservoir Engineering. It addresses topics such as overburden pressure, hydrostatic pressure, and formulas for calculating oil volume in place. Test your knowledge on these essential principles for understanding reservoir behavior.
