Reservoir Engineering - New Mexico Institute of Mining and...

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Reservoir Engineering How much oil is in place? How much oil is recoverable? How can I maximize oil recovery? Under economic constraints

Transcript of Reservoir Engineering - New Mexico Institute of Mining and...

Page 1: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Reservoir Engineering

How much oil is in place?How much oil is recoverable? How can I maximize oil recovery?

Under economicconstraints

Page 2: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Origin of Petroleum

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Where are the resources?

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TrapsDome trap Fault trap

Unconformity trap

Salt dome trap

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Rock Properties

bVpV

=

=

φ

ebulk volum volumePorePorosity

⎥⎦

⎤⎢⎣

⎡ΔΔ

+ΔΔ

−=Lzg

LpKAq ρ

μ

Pore spacematrix

Bulk volume

Permeability - ability of porous media to transmit fluids

Path of fluid flow

Page 6: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Rock Properties

∑ =

=

1iSpVoV

oS

Page 7: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Rock Properties

•Grain size

•Sorting

•Packing

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Reservoir EngineeringHow much oil is in place?

oB

)wS1(Ah7758N

−=

φ

VolumetricMethod

N, oil-in-place,stbA, area, acresh, thickness, ftφ, porositySw, water saturationBo, Formation volume

factor,rbbl/stb

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Petroleum FluidsComposition

Fluids found in petroleum reservoirs consist of petroleum and brine

Petroleum maybe gaseous, liquid or solid

Chemical composition of petroleum• Molecules contain C and H• Alkane series form basis Cn H2n+2

Natural gases consist of 10,000s of compounds, but are mostly methane, > 90%

Crude oils consist of 100,000s of compounds, including methane

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Petroleum Fluids

Properties• Density = mass per unit volume• For crude oils, the density (or gravity) is expressed on the API scale,

American Petroleum Institute

• If Sp. Gr. = 1.0, then °API = 10

5.131..

5.141−=

GrSpAPI

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Petroleum Fluids

Properties• For gases, the density is expressed as the specific gravity with respect

to the density of air at the same T and P.

• The Sp. Gr. of a gas may be estimated by:

• Exmaple: Methane, MW = 16, the Sp. Gr. (air = 1) = 0.55.

P&T sameat air ofdensity P&Tat gas ofdensity )1.(. ==AirGrSp

29air of M.W.gas of M.W.)1.(.≈

==AirGrSp

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Petroleum FluidsProperties

Viscosity is the fluid property, which describes how much force (energy) is required to cause it flow.

The higher the viscosity, the more force required. Viscosity usually decreases as the T increases The common unit of viscosity in the oil field is the Poise or 1/100th of Poise, the centipoise

2sec1

cm

dyneP −=

Typical crude oil viscosity is 0.5 to 1.5 cp. Typical gas viscosity is 0.01 cp.

Shea

r stre

ss, τ

Rate of shear strain, du/dy

μ

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Petroleum Fluids

As crude oil flows from theReservoir to the surface, P and T decrease and gas isEvolved.

Remaining volume of 1 barrel of oil from the subsurface after gas has bubbled out.

Number of barrels of Reservoir oil to produce1 barrel of stock tank oil

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Reservoir EngineeringHow much oil is in place?

3D view of a multilayered reservoir, colors show oil saturation

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Reservoir Engineering

withdrawal = Expansion of oil and dissolved gas+ Expansion of gascap gas+ Reduction in HCPV due to connate water expansion and

decrease in the pore volume+ Net water influx

How much oil is in place?

MaterialBalanceMethod

Gascap gas

Oil + dissolved gas

Gascap gas

Oil + dissolved gas

Expansion of gascap gas

Expa

nsio

n of

oil

+ di

ssol

ved

gas

Red

uctio

n of

HC

PV…

Time

qo, qg, qw

water water

Water influx

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Reservoir Engineering

How much can be recovered?

One barrel ofOil-in-place Recover ~25% of OIP

From primary reservoirenergy

?

Page 17: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Secondary oil recovery Production from an oil reservoir can be enhanced by pumping water into the reservoir to displace the oil

Reservoir Engineering

How much can be recovered?

Page 18: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Reservoir Engineering

How much can be recovered?

One barrel ofOil-in-place

Recover ~25% of OIPFrom primary reservoirenergy

Recover ~25% of OIPFrom secondary means

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Enhanced oil recovery (EOR)

Production from an oil reservoir can be enhanced by:1. Injecting CO2 to displace and swell the oil2. Injecting surfactants …3. Injecting polymers..4. Steamflooding…

Reservoir Engineering

How much can be recovered?

Page 20: Reservoir Engineering - New Mexico Institute of Mining and ...infohost.nmt.edu/~petro/faculty/Engler101/6-reservoir.pdf · Reservoir Engineering How much oil is in place? How much

Reservoir Engineering

How much can be recovered?

One barrel ofOil-in-place

Recover ~25% of OIPFrom primary reservoirenergy

Recover ~25% of OIPFrom secondary means

Recover ~20% of OIPFrom EOR methods ?

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Reservoir challenges: Multilateral wells

1st Bone Spring Sand

1st Bone Spring Carbonate

Lower Avalon Shale

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A.F. Jubralla, P.C., and S.J. Whyte (1996) Middle East Well Evaluation Review - Horiozontal Highlights. Middle East & Asia Reservoir Review.

Reservoir challenges: Impact of deposition on performance

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SRV, frac spacing and azimuth are key for well placement and spacing strategies.

Optimization dependent on:1. Natural geologic and petrophysical features

thickness, stresses, natural fractures, barriers

kmin = 0.03 mD

kmax = 3.34 mD

kMatrix = 0.01 mD

N

10 m

Horizontal wellpaths

A

B

kmin = 0.03 mD

kmax = 3.34 mD

kMatrix = 0.01 mD

N

10 m

kmin = 0.03 mD

kmax = 3.34 mD

kMatrix = 0.01 mD

N

10 m

Horizontal wellpaths

A

B