The rhob-velocity-effective stress (RhoVe) method represents an empirical approach to pore pressure analysis and calibration that utilizes a series of model-driven, genetically-linked “virtual” rock property relationships. The method is fundamentally a two-parameter approach (a-term and α), that is used to construct a velocity-vertical effective stress (VES) and density-VES family of curves that can be applied to a well of interest where convergence of the two transformed properties offers a robust solution. When the a-term is set as a function of α (a = ƒ(α)), the RhoVe method is reduced to a single parameter (α’) that includes the effects of compositional changes related to clay diagenesis and the effects of ongoing chemical compaction. Once calibrated, the construct represents a fully-populated” petrophysical (shale-only) model volume that can be queried and interrogated to perform advanced calculations leading to a new empirical approach for calculating pore pressure from temperature that both frames the structural-stratigraphic history of fine-grained clastics in a sub-regional setting and allows for an interpretation of local diagenetic effects. The method utilizes a single master power law reference relationship between temperature (in degrees Fahrenheit) and α’ that is applied as an instantaneous series. The same temperature – α’ power law function transforms sonic and density data for the entire stratigraphic section. Accounting for the effects of ongoing chemical compaction and diagenesis using alternate associations like temperature extends the predictability of high-velocity, high-density, low-effective stress rock types such as those found in the Deepwater Gulf of Mexico mudstones and older onshore unconventional shale-play reservoir sections.

1. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
RhoVeTM
Method
(U.S. patent 2018)
A New Empirical Pore Pressure Transform
This presentation and all intellectual property discussed in this presentation are the property of GCS Solutions, Inc. and/or Matt Czerniak. GCS Solutions, Inc.

2. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
The RhoVe method construct represents a fully-populated petrophysical
model that can be queried or interrogated to perform advanced
calculations leading to a new empirical approach for calculating pore
pressure from temperature that both frames the structural-stratigraphic
history of fine-grained clastics in a sub-regional setting and allows for an
interpretation of local diagenetic effects.
An immediate advancement of the RhoVe method has been the addition
of the density log, which is in play as a pore pressure indicator, and
density itself becomes an integral part of the pore pressure workflow.

3. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018

4. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
4
Temperature Bands (deg F)
50
100
150
200
250
300
350
400
Dutta-Wendt
Effective Stress vs Velocity by Temperature
after Alberty, SPE DL Series, 2004

5. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Dutta 2002 TLE
Shallow
Deep
All
Smectite
All
Illite
after Dutta, 2002 TLE
Dutta

6. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Dutta 2002 TLE
Shallow
Deep
All
Smectite
All
Illite
after Dutta, 2002 TLE
Dutta

7. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Illite:K2 Al4 (Si6 Al2) O20 (OH)4Montmorillonite (Smectite): Al2 Si4 O10 (OH)2
 n H2O
https://www.ihrdc.com/els/ipims-demo/t26/offline_IPIMS_s23560/resources/data/G4105.htm

8. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Alberty-McLean, OTC 2003
ILLITE
SMECTITE
after Alberty, SPE DL Series, 2004
Temperature Bands (deg F)
50
100
150
200
250
300
350
400
Dutta-Wendt
Alberty

9. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
after Sargent et al., 2015
Sargent

10. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
MECHANICAL
COMPACTION
(effective stress)
Modified from University of OSLO Dept of Geosciences
ONGOING CHEMICAL
COMPACTION
CHEMICAL
COMPACTION
(temperature) 4+ km
95-120 Co
(200-250o F)
2-3 km
60-80 Co
(140-175o F)

11. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
In this example from Viosca Knoll, the color code matches the (modified)
University of Oslo plot, where load transfer effect is expressed as orange
data points, and matches the temperatures shown in the legend.
The state of “ongoing chemical compaction” represents an upper limit or
plateau to compositional changes.
The background trends are from from the RhoVe method a-term series.

12. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
dT.usec/ft
RHOB.G/C3
o F
o F
o F
o F
Bowers “slow” trend
plateau

13. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
RhoVeTM
Method

14. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
The basic RhoVe method offers an interactive approach to pore pressure
calibration and analysis, where shale discriminated sonic and density data
are transformed to common estimates of effective stress and pore
pressure, where convergence of the two transformed properties offers a
robust solution.
At greater depths, mudstone to shale transformation continues and is
dominated by changes in physical rock property relationships where
“ongoing chemical compaction” and shale diagenesis are controlled
principally by temperature.
The temperature-based RhoVe T method (an executable) continues on
where compositional changes leave off.

15. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
RhoVeTM
T
Thermodynamic Solutions
(executable)
Sonic, Density,
Acoustic Impedance
RhoVeTM
Auto
Compositional Changes
(executable)

16. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00. 1.00.
1.00.
1.00.
v-rho v-z rho-z P-z
v-VES rho-VES
1.00.
RhoVE-S
RhoVE-ε
RhoVE-ε
RhoVE-S
RhoVE-ε
RhoVE-S
RhoVE-ε
RhoVE-S
RhoVE-ε
RhoVE-S
RhoVE-ε
Generalized
Display
1.0
0.
RhoVE-S

17. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00.
0.
1.00.
v-rho rho-z P-z
v-VES
1.00.
rho-VES
a-term
1.0
a-term
v-rho
0.
1.0
v-z
α
0. 1.0
Generalized
Display

18. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
BOWERS GOM “Slow” Trend RhoVE-ε RhoVE-S
Vo: 4790 4800 4900
A: 2953 2000 4500
B: 3.57 4.2 3
ρo: 1.3 1.3 1.3
V-Rho equation (Bowers, OTC 2001) :
V = V0 + A (ρ - ρo) B
γ = 2.0
RhoVE-S
RhoVE-Ɛ
RhoVE interm: a * (RhoVE-Ɛ– RhoVE-S) + RhoVE-S
Bowers GOM “slow” trend
0.6
a-term

19. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
meters Ebrom & Heppard, 2010
0.4
0. 1.0
α : calculated property
α

20. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
RhoVe Method
dT Compaction Trend:
Δtn = (Δtml –Δti) e –cz + Δti
Δti = øi (Δtml – Δtmx) + Δtmx
BOWERS DW GOM “Slow” Trend RhoVE-ε RhoVE-S
Vo: 4790 4800 4900
A: 2953 2000 4500
B: 3.57 4.2 3
ρo: 1.3 1.3 1.3
V-Rho equation (Bowers, OTC 2001) :
V = V0 + A (ρ - ρo) B
Δtmx: : dT matrix: 55 usec/ft
Δtml : dT mudline 200 usec/ft
c compaction coeff: 0.00016 - 0.00030
z: depth below mudline
øi : irreducible porosity (fractional)
: c
ongoing chemical
compaction
compositonal
changes

21. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00.
0.
1.00.
v-rho rho-z P-z
v-VES
1.00.
rho-VES
a-term
1.0
a-term
v-rho
0.
1.0
v-z
α
0. 1.0
v-z
Generalized
Display

22. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Examples
0.0
0.56
0.75
1.08
0.99
RhoVe-S
a : fractional distance
a-term

23. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
In this example from Offshore Nova Scotia, the a - alpha pairs have already
been determined for flow units P1 & P2 (which coincide with the first two
data point clusters). In simplest terms, “a-term” controls the convergence,
and alpha is the shift in pore pressure. When the transformed sonic and
density data converge, a horizontal red bar indicates that the interpretation
is locked for the flow unit above.
The next step involves mapping “a versus alpha” pairs for successive flow
units, and/or other wells in the area, hoping to reveal compositional
changes on a regional or sub-regional basis. Cross plot “a” versus “alpha”
pairs reveals the form: a = 2α – α2, which reveals the trend for
“compositional” changes along this curved trend line.

24. 0.3
Rhob Density
DTCO Sonic
0.0
0.56
0.75
1.08
0.99
a-term

25. 0.3
DTCO Sonic
Rhob Density
0.56
0.0
a-term

26. 0.3
Rhob Density
DTCO Sonic
0.750.75
0.56
0.0
a-term

27. 0.4
DTCO Sonic
0.75
Rhob Density
0.56
0.0
a-term
“kick”

28. 0.6
DTCO Sonic
0.0
0.56
0.75
0.99
Rhob Density
a-term

29. 0.7
DTCO Sonic
0.0
0.56
0.75
1.08
0.99
Rhob Density
a-term

30. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
BOWERS GOM “Slow” Trend RhoVE-ε RhoVE-S
Vo: 4790 4800 4900
A: 2953 2000 4500
B: 3.57 4.2 3
ρo: 1.3 1.3 1.3
V-Rho equation (Bowers, OTC 2001) :
V = V0 + A (ρ - ρo) B
γ = 2.0
DWGoM Sub-Regional Study
RhoVE interm: a * (RhoVE-Ɛ– RhoVE-S) + RhoVE-S
Bowers GOM “slow” trend
0.6
plateau
plateau
a = 2α – α2

31. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
BOWERS GOM “Slow” Trend RhoVE-ε RhoVE-S
Vo: 4790 4800 4900
A: 2953 2000 4500
B: 3.57 4.2 3
ρo: 1.3 1.3 1.3
V-Rho equation (Bowers, OTC 2001) :
V = V0 + A (ρ - ρo) B
γ = 2.0
(0.37,0.60)
DWGoM Sub-Regional Study
RhoVE interm: a * (RhoVE-Ɛ– RhoVE-S) + RhoVE-S
Bowers GOM “slow” trend
0.6
from Sargent et al., 2015
delimiter: “d”
plateau
a = 2α – α2
a >= d, a = d

32. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
13:00
The functional relationship may be expressed in the general form: a = γα –
αγ. The gamma term offers flexibility, and should be considered basin-
specific.
This functional relationship not only displaces the “linearly spaced” gray
contours, up to and including the delimiter, but now “a” can be expressed
as a function of alpha: f(α’) given the two conditions: a = γα – αγ and for
a >= d, a = d, which when combined with the delimiter, …reduces the
RhoVe method to a single parameter: α’

33. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
BOWERS GOM “Slow” Trend RhoVE-ε RhoVE-S
Vo: 4790 4800 4900
A: 2953 2000 4500
B: 3.57 4.2 3
ρo: 1.3 1.3 1.3
V-Rho equation (Bowers, OTC 2001) :
V = V0 + A (ρ - ρo) B
γ = 2.0
RhoVE interm: f(α’) * (RhoVE-Ɛ– RhoVE-S) + RhoVE-S
(0.37,0.60)
Bowers GOM “slow” trend
0.6
from Sargent et al., 2015
a = γα – αγ
a >= d, a = d
a-term
f(α’)
delimiter: “d”

34. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00.
rho-z
Genetically-Linked
v-z
α
1.00.
v-rho
a-term

35. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
At it’s simplest, the RhoVe method transforms the velocity - “virtual” depth
compaction trend “alpha” series (left), to density - virtual depth (on-the-fly)
using the a-term active curve and end-members as a series of velocity-
density transform functions.
The a-term itself consist of a series of successive and parallel contours
relative to the fixed end members – meeting the criteria for common
activation energies (S/I conversion) along any single contour in sonic-
density cross plot space. ….similarly, the transition to a temperature-based
approach, requires only an increase in temperature to move up vertically to
the next contour, independent of the starting point, but reflecting a
common, incremental change in activation energy, in this case, by
temperature.

36. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00.
rho-z
Genetically-Linked
v-z
1.00.
a-term
v-rho
a-term
v-rho
α

37. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00. 1.00.
v-rho v-z rho-z P-z
rho-VES
α
delimiter
v-rho
0.
1.0
α
0. 1.0
v-z
α
a-term
Generalized
Display
v-VES
0. 1.0
rho-VES
0. 1.0
ESnorm
ESnorm ESnorm
compositional
changes
ongoing
chemical
compaction
Genetically-Linked

38. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
For the GOM, compositional changes converge on an upper limit or plateau, with no
more information in the way of cross plot data to help steer the interpretation for the
effects of ongoing chemical compaction. The RhoVe T (temperature-based) method was
pursued, very specifically to bridge this gap, by developing a new methodology for pore
pressure analysis and calibration that extends the predictability of high-velocity, high-
density, low-effective stress rock types undergoing the effects of ongoing chemical
compaction.
A master Power Law relationship guides the “virtual” model for the calculation of pore
pressure that sets up the assignment of alpha’ compaction trends (extending from 0 –
1.0) by temperature for a well of interest, which are then applied automatically through
an executable series.
It applies to both sonic and density data, and can be used for predrill, real-time and
post-drill analysis. The only thing that is needed to apply RhoVe T to a well of interest is
a simple temperature versus depth profile.

39. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
39
σ
95o C
50o C
120o C
o F
o F
o F
o F
o F
o F
o F
o F
o F
o F
Power Law
α’ = k (To F – ΔƬ)b

40. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
40
σ
95o C
50o C
120o C
o F
o F
o F
o F
o F
o F
o F
o F
o F
o F
Temp oF vs Depth
Power Law
α’ = k (To F – ΔƬ)b

41. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
1.00.
0.
1.00.
v-rho v-z rho-z P-z
v-VES rho-VES
ESnormESnorm
α
1.0
α
0. 1.0
Genetically-Linked
v-z
1.00.
o F
o Fo F
o F
o F
o F
o F
o F
a-term
v-rho
Generalized
Display
v-VES rho-VES
0.
1.0
α
+300o F +300o F

42. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
σ
42
120o C
50o C o F
o F
o F
o F
o F
o F
o F
o F
o F
o F
95o C
Power Law
α’ = k (To F – ΔƬ)b
ΔTau vs. # wells

43. 43
ShenandoahTiber
Viosca KnollRask 1997
VK988
PI526

44. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
dT.usec/ft
RHOB.G/C3
o F
o F
o F
o F
Bowers “slow” trend
plateau

45. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
dT.usec/ft
RHOB.G/C3
o F
o F
o F
o F
Bowers “slow” trend
plateau

46. Sand Sand
Shale
ShaleShale
200 o F200 o F
Shale Shale
235 o F235 o F
305 o F305 o F
190 o F190 o F
140 o F
o F
o F
o F
o F
o F
o F
o F
o F
250 o F 250 o F

47. 47
0.0
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

48. 48
0.07
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

49. 49
0.1
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

50. 50
0.2
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

51. 51
0.3
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

52. 52
0.4
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

53. 53
0.5
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
sonic
rhob

54. 54
0.6
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

55. 55
0.7
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

56. 56
0.8
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

57. 57
0.9
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

58. 58
1.0
MDT
AREA: Viosca Knoll
DATA: wireline
rhobdT
Delimiter
sonic
rhob
“d”:0.6/0.84

59. 59
MDT
rhobdT
sonic
rhob 0 degrees FΔƬ:
rhob
sonic
‘
AI

60. 60
MDT
rhobdT
sonic
rhob 0 degrees FΔƬ:
rhob
sonic
‘
AI

61. 61
Tiber
Keathley Canyon
Walker Ridge
Rask 1997
Jack
Kaskida
VK988
PI526

62. 62
rhobdT
rhob
SALT
0 degrees FΔƬ:
+300
rhob
sonic
AI

63. 63
rhobdT
rhob
SALT
0 degrees FΔƬ:
+300
rhob
sonic
AI

64. 64
rhobdT
rhob
SALT
0 degrees FΔƬ:
+300

65. 65
sonic
rhob
SALT
rhobdT
0 degrees FΔƬ:

66. 66
sonic
rhob
SALT
rhobdT
0 degrees FΔƬ:

67. 67
sonic
rhob
SALT
rhob
sonic
AI
-55 degrees FΔƬ:
rhobdT

68. 68
sonic
rhob
SALT
rhob
sonic
AI
-55 degrees FΔƬ:
rhobdT

69. 69
ShenandoahTiber
Viosca KnollRask 1997
VK988
PI526

70. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
70
MDT
rhobdT
sonic
rhob 0 degrees FΔƬ:
rhob
sonic
‘
AI

71. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
Flattened contours of velocity-VES for alpha’ from 0.0 to 1.0 in
increments of 0.1 alpha’ with annotated temperatures.
Temperature-alpha’ contours are identical for VK988, WR759, KC102
and all other wells that fall on master power law relationship.
For the 20 well study, 16 out of 18 Gulf of Mexico deep water wells (or
89% of both subsalt and non-subsalt wells) fall within a +/-7% margin
of error (as measured in temperature or ~15o F), which translates to
+/- ½ PPG margin of error.

72. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
72
VK988
o F
o F
dT
0.
1.0
o F
o F
sonicsonic
198o F
227o

73. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
73
VK988
o F
o F
dT
0.
1.0
o F
o F
WR759
198o F
ΔTau vs. # wells
227o

74. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
74
VK988
o F
o F
dT
0.
1.0
o F
o F
WR759
KC102-1
198o F
ΔTau vs. # wells
227o

75. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
75
VK988
o F
o F
dT
0.
1.0
o F
o F
WR759
KC102
KC919
198o F
ΔTau vs. # wells
227o

76. 76
rhobdT
sonic
rhob
SALT
-15 degrees FΔƬ:

77. 77
rhobdT
sonic
rhob
SALT
-15 degrees FΔƬ:

78. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
78
VK988
o F
o F
dT
0.
1.0
o F
o F
WR759
KC102
KC919
Paleogene
“Wilcox”198o F
ΔTau vs. # wells
227o

79. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
79
VK988
o F
o F
dT
0.
1.0
o F
o F
WR759
KC102
KC919
Paleogene
“Wilcox”198o F
ΔTau vs. # wells
227o

80. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
80
VK988
Rhob
0.
1.0
WR759
KC102
KC919
ΔTau vs. # wells

81. 81
Tiber
Rask 1997
Jack
Kaskida
VK988
PI526
Shenandoah
SMI23-5

82. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
The inset in the upper right is the distribution of Tau shifts for a 20 well GOM
study using the temperature-based method, with the majority centered on a
Tau shift of zero, which becomes the baseline assumption independent of
water depth or age of section.
For the 20 well study, 16 out of 18 Gulf of Mexico deep water wells (or 89%
of both subsalt and non-subsalt wells) fell within a +/-7% margin of error (as
measured in temperature or ~15o F), which translates to +/-½ PPG margin of
error.

83. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018
83
Power Law
α’ = k (To F – ΔƬ)b
ΔTau vs. # wells
<smectite/drained
+75o F
+42o C
-55o F
-31o C

84. Pore Pressure and GeoMechanics: From Exploration to AbandonmentGeosciences Technology Workshop; Perth, 6-7 June 2018