Reservoir Characterization.pdf

January 23, 2018 | Author: Tèo Tí Tởn | Category: Petroleum Reservoir, Porosity, Permeability (Earth Sciences), Transparent Materials, Physical Sciences
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Reservoir Characterization 1

Reservoir Characterization (Part I) ƒ Reservoir stratification (reservoir lithology) ƒ Reservoir geometry ƒ Porosity, permeability, and water saturation ƒ Adjoining j g aquifer q ƒ Reservoir fluid properties

Reseroir Characterization 2

Reservoir stratification Most reservoirs are layered because of variations that existed in the depositional environment.

Reseroir Characterization 3

Reservoir Geometry (Areally)

Reseroir Characterization 4

Reservoir Geometry (Vertically)

Reseroir Characterization 5

Porosity Vb − Vma Porosity = φ = = Vb Vb Vp

Reseroir Characterization 6

Rock Matrix and Pore Space

Rock matrix

Pore space

Reseroir Characterization 7

Pore-Space Classification P S Cl ifi ti z Total porosity, φt =

Total Pore Space Bulk Volume z Effective p porosity, y, φe =

Interconnected Pore Space Bulk Volume

Reseroir Characterization 8

Permeability z Permeability is a property of the porous

medium and is a measure of the capacity of the medium to transmit fluids

Reseroir Characterization 9

Absolute Permeability z When the medium is completely

saturated with one fluid, fluid then the permeability measurement is often referred to as specific or absolute

permeability

Reseroir Characterization 10

Effective Permeability z When the rock pore spaces contain

more than one fluid, then the permeability to a particular fluid is called the effective permeability

z Effective permeability is a measure of

the fluid conductance capacity of a porous medium to a particular fluid when the medium is saturated with more than one fluid

Reseroir Characterization 11

Relative Permeability z Relative p permeability y is defined as the

ratio of the effective permeability to a fluid at a g given saturation to the effective permeability to that fluid at 100% saturation

Reseroir Characterization 12

Calculating Relative Permeabilities

z Oil

z Water

z Gas

k ro

k eo = k

k rw

k ew = k

k rg =

k eg k

Reseroir Characterization 13

In-Situ Saturation

Rock matrix

Water

Oil and/or gas

Reseroir Characterization 14

Fluid Saturation z The saturation of the fluid is the fraction of

the pore volume occupied by that fluid

Volume of fluid S= Pore volume

Reseroir Characterization 15

Fluid Saturations z Basic concepts of hydrocarbon

accumulation

– Initially, pore space filled 100% with water – Hydrocarbons y migrate g up p dip p into traps p – Hydrocarbons distributed by capillary forces and gravity – Connate water saturation remains in hydrocarbon zone

Reseroir Characterization 16

Determining Fluid Saturations z Core analysis z Capillary p y pressure p measurements z Electric openhole logs

Reseroir Characterization 17

Adjoining Aquifer The aquifer is the total volume of porous water-bearing g rock in pressure communication with a hydrocarbon reservoir. Areal View

Vertical view

Gas reservoir Gas reservoir

Aquifer water encroaches h ffrom the h side

B tt Bottom water t

Reseroir Characterization 18

Reservoir Fluid Properties The fluid properties of interest to the Reservoir Engineer are th those th thatt affect ff t th the mobility bilit off fl fluids id within ithi the th reservoirs i these are used in material balance calculations Properties at surface conditions for transportation and sales (API, viscosity, oil quality)

Reseroir Characterization 19

Reservoir Fluid Properties Oil Properties – Bubble Point Pressure – Bo – Rs – Bt – Co and μo Gas properties –z – Bg and μg Compositions oil & gas – Properties of the composition/mixture

Reseroir Characterization 20

Real Gas in Reservoir Equation of State:

pV = nZRT

Quantity Description

Unit/Value

p

Pressure

psia

V

Volume

ft^3 ft 3

n

Mole number

lb-moles

Z

Gas compressibility G ibilit factor

di dimensionless i l

T

Temperature

Rankine

R

Universal Gas constant

10.73

Reseroir Characterization 21

Calculating Z (1) 1,1

0

1

2

3

4

5

6

7

8

1,1

NHIEÄT ÑOÄ GIAÛ GIAÛM

3,0 2,8 2,6 2,4 2,2 2,0 1,9 1,8

1,0

0,9

1,0 1,5

1,6 0,8

1,3 11 1,1

1,4

1,7

1,05

1,5

1,1

0,9

1,7

1,45 1,4

07 0,7

1,2

1,35

HEÄ SOÁ LEÄ CH KH Í, Z

0,6

1,4

1,25

1,5

1,5 1,6 1,7 , 1,8 14 1,4 1,9 2,0 2,2

1,2 05 0,5 1,15 0,4

16 1,6

1,3

1,3

2,4 2,6 3,0

1,1

0,3

1,3

1,2 1,05 3,0

1,1

2,8

1,0 1,8 17 1,7 1,6 0,9

1,1

2,6 2,4 2,2 2,0 1,9

7

1,2 1,1 ,

1,0

1,05

1,4 1,3 8

9

10

11

AÙP SUAÁT GIAÛ GIAÛM

12

13

14

Step 1: Calculate pseudo-critical pressure and temperature (Sutton)

0,9 15

ppc = 756.8 −131.0γ g − 3.6γ g2 Tpc = 169.2 − 349.5γ g − 74.0γ g2 Step 2: Calculate pseudo-reduced pressure and temperature:

p

pr

=

p p

pc

;T

pr

T = T pc

Step 3: Use Standings-Katz plot to determine Z

Reseroir Characterization 22

Exercise 1 Calculate z-factor according to the given data as follows

Quantity

Value

Unit

Specific gravity g y

0.665

Dimensionless

Reservoir temperature

213

°F

Reservoir pressure

3250

psia

Reseroir Characterization 23

Solution to Exercise 1 1,1

0

1

2

3

4

5

6

7

8

1,1

NHIEÄT ÑOÄ GIAÛ GIAÛM

3,0 2,8 2,6 2,4 2,2 2,0 1,9 1,8

1,0

0,9

1,0 1,5

1,6 0,8

1,3 11 1,1

1,4

1,7

1,05

1,5

1,1

0,9

p pc = 756.8 − 131.0(.665) − 3.6(.665) 2 = 668 1,7

1,45 1,4

07 0,7

1,2

1,35

0,6

1,4

1,25

1,5

1,5 1,6 1,7 , 1,8 14 1,4 1,9 2,0 2,2

1,2 05 0,5 1,15 0,4

16 1,6

Tpc = 169.2 − 349.5(.665) − 74.0(.665)2 = 369

1,3

1,3 HEÄ SOÁ LEÄ CH KH Í, Z

Step 1: Calculate pseudo-critical pressure and temperature (Sutton)

2,4 2,6 3,0

1,1

0,3

Step 2: Calculate pseudo-reduced pressure and temperature:

1,3

p

pr

= 4 . 87 ; T

pr

= 1 . 82

1,2 1,05 3,0

1,1

2,8

1,0 1,8 17 1,7 1,6 0,9

1,1

2,6 2,4 2,2 2,0 1,9

7

1,2 1,1 ,

Step 3: Use Standings-Katz plot to determine Z

1,0

1,05

1,4 1,3 8

9

10

11

AÙP SUAÁT GIAÛ GIAÛM

12

13

14

0,9 15

Z=0.918

Reseroir Characterization 24

Calculate Z using Dranchuk and Abou-Kassem Correlation F Z = R1 ρ r −

R2

ρr

+ R 3 ρ r2 − R 4 ρ r5 + R 5 (1 + A 11 ρ r2 ) exp( − A 11 ρ r2 ) + 1 = 0

ρ r = 0 . 27 p pr /( ZT

pr

)

R 1 = A 1 + A 2 / T pr + A 3 / T pr3 + A 4 / T pr4 + A 5 / T pr5 R 2 = 0 . 27 p

pr

/ T pr

R 3 = A 6 + A 7 / T pr + A 8 / T pr2 R 4 = A 9 ( A 7 / T pr + A 8 / T pr2 ) R 5 = A 10 / T pr3

A1 = 0 . 3265 ; A2 = − 1 . 0700 ; A3 = − 0 . 5339 A4 = 0 . 01569 ; A5 = − 0 . 05165 ; A6 = 0 . 5475 A7 = − 0 . 7361 ; A8 = 0 . 1844 ; A9 = 0 . 1056 A10 = 0 . 6134 ; A11 = 0 . 7210

Reseroir Characterization 25

Exercise 2: PVT Analysis

Using the data in the table below and assuming real gas behavior, calculate the density of the gas phase under initial reservoir conditions. Compare the results with that of ideal gas behavior.

Component

C1 C2 C3 iC4 nC4 iC5 nC5 C6 C7 C8 C9 C10 H2S CO2 N2 H He Air O2

Mole Percent

Molecular Weight

(1)

(2) 0.85 0 04 0.04 0.03 0.03 0.02 0.00 0.00 0.00 0.00 0.00 0 00 0.00 0.00 0.00 0.02 0.01 0 00 0.00 0.00 0.00

16.043 30 070 30.070 44.097 58.123 58.123 72.150 72.150 86.177 100.204 114.231 128 258 128.258 142.285 34.080 44.010 28.013 4 003 4.003 28.960 31.999

Critical Press. (psia) (3)

Critical Temp. (R) (4) 666.4 706 5 706.5 616.0 527.9 550.6 490.4 488.6 436.9 396.8 360.7 331 8 331.8 305.2 1300.0 1071.0 493.1 33 0 33.0 546.9 731.4

343.00 549 59 549.59 665.73 734.13 765.29 828.77 845.47 913.27 972.37 1023.89 1070 35 1070.35 1111.67 672.12 547.58 227.16 9 36 9.36 238.36 278.24

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