Geo Mechanics Yn 3
Transcript of Geo Mechanics Yn 3
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 1/32
1
Effects Of Reservoir CompactionIn Deep Water Environment
N. Yusuf
Harold Vance Department
of Petroleum Engineering.Texas A&M University
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 2/32
2
• Objectives
• Linear Elastic properties of a solid material
• Elastic properties applied to reservoir rock
• Revie of !"E papers
Outline
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 3/32
3
• #nderstand Reservoir compaction
• Determination of parameters affectin$ δk δφ δ%
• Revie industr& orks to obtain'δ
k'δφ δ
%
• Develop a criteria ( selection tool
Objectives
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 4/32
4
•Linear Elastic properties of a solid material
Outline
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 5/32
5
Youn$)s modulus' E
zz
zz
zz
zz
εσ E
z
Δz ε
A
F σ
=
=
=
ModulusYoung
strainvertical
stressvertical*
+
δz
Z
psi x
psi x
valuesTypical
5
7
103
103
=
=
rock
steel
E
E
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 6/32
6
"oisson Ratio'
δz
δx
*
+
zz
yy
zz
xx
yy
xx
zz
zz
ε
ε
ε
ε
Y
Δy ε
X
Δx ε
z
Δz ε
A
F
σ
−=
−=
−=
−=
=
=
ratioPoisson
strainnormal
strainnormal
strainvertical
stressvertical
Z
X
3.0
3.0
=
=
rock
steel
v
v
valuesTypical
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 7/32
7
,ulk modulus' !
ΔV/V
σ K
V
ΔV
εb
=
=
ulusmod bulk
strain bulk *
*
*
2v)-3(1
EK =
psi x
psi x
valuesTypical
5
7
105.2
105.2
=
=
rock
steel
K
K
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 8/32
8
#nia-ial modulus'
zz
zz
zz
ε
σ
ε
=ulusmodUniaxial
for exceptalloed!strain"movement #o
Constrained
Constrained Constrained
*
psi x
psi x
valuesTypical
5
7
100$.$
100$.$
=
=
rock
steel
2v)-v)(1(1
v)-E(1
+=
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 9/32
9
• Elastic properties applied to reservoir rock
Outline
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 10/32
10
!train relations%ips for "orous Rock
( )
( )
φ
φ
φ
φ φ
−+=
+−=
+
=
+=
+=
+=
1!ε!ε!ε
!ε1!ε!ε
V
V
V
!V
V
V
V
!V
V
!V
V
!V
V
!V
V
!V
!V !V !V
V V V
"b #
#"b
#
#
b
#
"
"
b
"
b
b
b
#
b
"
b
b
" #b
" #b
V b: bulk volume
V p: pore volume
V g: grain volume
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 11/32
11
!train relations%ips for "orous Rock
( )
g b p
g pb
g pb
C 1
C 1
C
C )1( C C
V
1
V
1
V
1
−−=
−+=
−+=
φ
φ
φ
φ φ
φ φ !#
!V 1
!#
!V
!#
!V " #b
Wit% respect to c%an$e in pressure
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 12/32
12
Rock compressibilit&
Elastic Compressibilities- Definitions
Volume canges: !ulk volume:
"ore Volume:
"ressure canges: #verburden "ressure:
"ore "ressure:
bV
p p
pV
c p
pc
b
ibbc p
p
V
V
1c
−=
δ
δ c
p
b
ibbp p
p
V
V
1c
=
δ
δ
#c
#
$
#c # #!
V !
V
1c
b
−= p p
c
p
ib
pc
p
%
%
1&
δ
δ−=
!ulk Volume Compressibilities
"ore Volume Compressibilities
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 13/32
13
Compressibilit& relations%ips for a "orous Rock
pcibp.
g pc pp
g bc pb
C C 3
C C C .2
C C C .1
φ =
=
−=
−
/immerman' 0110
!I2NI*IC+NCE3
0 psi c%an$e in Confinin$ 4or Lab5 pressure produce more strain on t%e bulk 6 porevolume t%an 0 psi c%an$e in pore pressure b& an amount e7ual to t%e matri-compressibilit&.
If matri- compressibilit& is ne$li$ible' e7ual c%an$es in eit%er pore or confinin$ 4lab5pressure produce t%e same bulk and pore volume c%an$es.
!ulk strain due to pore pressure canges
Vs bulk strain due to lab pressure canges
"ore strain due to pore pressure canges
Vs pore strain due to lab pressure canges
!$%& '()*+, due to "#)E ")E''$)Ecanges related to "#)E '()*+, due toC#,+,+,. ")E''$)E canges/
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 15/32
15
Compressibilit& relations%ips for a "orous Rock
bc
g
g
pc
C
C
1 K
K
1
p p p eff
−=−=
−=
α
α
Nur 6 ,&erlee' 01:03 E**EC8I;E !8RE!! L+W
!I2NI*IC+NCE3
8o simulate an e7uivalent strain in a porous rock t%e laborator&stress s%ould be less t%an t%e pore pressure depletion b& a 1- α .
α is te !iot0s constant
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 16/32
16
• Loadin$ conditions3•constrained strain
•#nia-ial compressibilit& Cm
#nia-ial compressibilit&
Constrained
ConstrainedConstrained
Overburden
( )
( ) bcm C
13
1C
ν
ν
−
+=
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 17/32
17
σ
1
δ
1
δ
3/2
l
d
σ
1
δ
1
l
d
σ
1
δ
1
δ
3/2
l
d
σ
3
Hydrostatic Test Triaxial Test Uniaxial Strain Test
8&pical Lab 8estin$
To compute C bc,C pc To compute ν C m To compute C m
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 18/32
18
δ
1
l
d
σ
1
Uni-axial Strain Test / Oedometer Test
!imulates t%e reservoir boundar& condition of <erolateral displacement.
"rovide direct measurement of "m' unia-ialcompaction coefficient.
Difficult&3 Re7uires si<e of core to fit E-actl& in t%ecell.
2ap in cells3 Lateral strain' disinte$ration of
sample' measurement errors.
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 19/32
19
Tri-axial Test
2enerall& used to determine stren$t% under various
conditions of stress3 i.e. var& σ
1
σ
3
odifications3 σ
3
−> to balance lateral effect of σ0
Calculation of ν
Difficult&3 Re7uires si<e of core to fit E-actl& in t%e cell.
δ
1
δ
3/2
l
d
σ
3
σ
1
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 20/32
20
Hydrostatic Test
Easiest to conduct' 9&drostatic confinin$ pressure3
easure "ore compressibilit& 3 " pc
#ul$ compressi%ility " %c
Uni'axial compressi%ility (" m ) can %e calculated
using t*e uni'axial correction factor
δ
1
δ
3/2
l
d
σ
1
!1"3
!1"1
υ
υ
−+
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 21/32
21
Reservoir compaction
Constrained Deformation in t%e reservoir
+-ial Compaction co=efficient Ca3
8otal reduction in reservoir %ei$%t
Ne$lectin$ variation of Cm it% pressure
( )∫ ∫ =∆ H pf
pi
m z p z pC H 0
' δ δ
( ) ( ) z p z p z C H
H
m δ δ ∆=∆ ∫ 0
p
z
Z C m
δ
δ 1= pC z mδ ε =
Constrained
Constrained
Overburden
Constrained
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 22/32
22
Reservoir compaction
*actors leadin$ to Reservoir compaction
• Lar$e reduction in pore pressure
• Lar$e vertical e-tent of t%e <one of pressure reduction
• Lar$e order of ma$nitude of Cm
Controllin$ ma$nitude of compaction
• "ressure maintenance' Limitin$ "erf interval
• !tud& of Cm
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 23/32
23
•Revie of !"E papers
Outline
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 24/32
24
• Earl& ork to understand t%e subject
•Causes of compaction ( subsidence
•"rediction met%od
• +pproac%3
•Observations from field data
•at%ematical derivation
•Compaction ( !ubsidence prediction
"aper Revie 0
!"E >:>?3 Land !ubsidence +bove Compactin$ Oil and 2as Reservoirs @ A 2eeertsma
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 25/32
25
"aper Revie 0
!"E >:>?3 Land !ubsidence +bove Compactin$ Oil and 2as Reservoirs @ A 2eeertsma
•!usceptible reservoirs from observed field Data
•Loose ( eakl& cemented formation
•Lo dept% of reservoir burial 4ave3 0???m5
•!i$nificant δp 4e.$ depletion t&pe reservoir5
δ
p over lar$e interval
•Consolidated reservoirs it% lar$e δp 6 9
•*actors affectin$ Cm
•Rock t&pe 4%ard' consolidated' friable' loose5
•De$ree of cementation
•"orosit& 4%i$%φ
=B %i$% Cm5
Dept% of burial
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 26/32
26
"rediction tool3 Calculation of Cm• !andstone3
• > rock t&pes' dept%s
•Input variables3•Rock t&pe
•"orosit& ( !tress level
•Dept%
"aper Revie 0
!"E >:>?3 Land !ubsidence +bove Compactin$ Oil and 2as Reservoirs @ A 2eeertsma
Interpretation3
Lo Cm3 0=> 0?=
9i$% Cm3 B 0? 0?=
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 27/32
27
"aper Revie 0
!"E >:>?3 Land !ubsidence +bove Compactin$ Oil and 2as Reservoirs @ A 2eeertsma
Limestone3 rock t&pes' 0
dept%
"rediction tool3
Limited variables
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 29/32
29
• Results3 ;ar&in$ responses it% e-treme cases•Case +3
•2eolo$icall& &oun$er 3softer sands
•E-%ibitin$ %i$%er "; compressibilit& 45
•Compr increases to a ma- value 40?5
• Case D3
•2eolo$icall& older sands3 %arder
•E-%ibitin$ loer initial "; Compr 405
•!li$%t decrease40?5
"aper Revie
!"E GGF:13 Compaction Effects on "orosit& and "ermeabilit& in Deepater 2ulf of e-ico=R.. Ostermeier
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 30/32
30
• "orosit& 6 "ermeabilit& variations3 Case +
•Loadin$ Conditions3
•!tep increases of pressure to :'??? psi
•8ime period of 0'?? da&s
•Results3
•"orosit&3 ?.> @ ?.F 4H5'
•"ermeabilit&3 0.> @ ?. D 4F.GH5
"aper Revie
!"E GGF:13 Compaction Effects on "orosit& and "ermeabilit& in Deepater 2ulf of e-ico=R.. Ostermeier
5.(
ook
k
φφ
=
8/9/2019 Geo Mechanics Yn 3
http://slidepdf.com/reader/full/geo-mechanics-yn-3 31/32
31
• "orosit& 6 "ermeabilit& variations3 Case D
•Loadin$ Conditions3
•!tep increases of pressure to '??? psi
•8ime period of >?? da&s
•Results3
•"orosit&3 ?.G = ?.? 4.:H5'
•"ermeabilit&3 ?.G = ?.F: D 4G.1H5
"aper Revie
!"E GGF:13 Compaction Effects on "orosit& and "ermeabilit& in Deepater 2ulf of e-ico=R.. Ostermeier
3.5
ook
k
φφ
=