MANCHESTER 1824
Seismic geomechanics of mud volcanoes –
Implications for drilling
Rashad Gulmammadov
Stephen Covey-Crump
Mads Huuse
MINISTRY OF EDUCATION REPUBLIC OF AZERBAIJAN
Study funded by
MANCHESTER 1824 Outline
Rationale
Overview of mud volcano case study
Feasibility calculations
2D model
Overpressure
Fluid flow
Stress regime
Drilling window
MANCHESTER 1824 Rationale
Active tectonics Rapid
sedimentation High rate of gas
generation
Mud volcano
Shallow earthquakes Gryphons & pockmarks
Lateral stress perturbations
Fractures
Mud flow/breccia hazard
Island/submarine banks
Sediment instability/landslide
Hydrate hazard
Gas emission/flame hazard
MANCHESTER 1824 Rationale
But how does the geomechanics of
mud volcanoes come into play?
MANCHESTER 1824 Why MV geomechanics?
Analytical models of
rock properties
Mud volcano growth/deformation
history
Pressure and fluid distribution
Stress state analysis
Fault and fracture quantification
FORMULATING DRILLING
STRATEGIES
MANCHESTER 1824 Study area
Azeri-Chirag-Guneshly (ACG) – a field complex within anticlinal structures in northern SCB
Water depths of 95-425m
Mobile shales from the organic rich Maykop sequence
MANCHESTER 1824 Review of the Chirag mud volcano
Geometric parameters & activity: WD – water depth, SD – surface diameter, HPE – highest point
elevation, MCT - mud cone thickness, MCV – mud cone volume, LEV – last eruption volume
Overburden: IOD – IT – illitization temperature, illitization onset depth
Sediment source: SSTD – sediment-source top depth, TH – thickness
Others: Poro – porosity, Perm – permeability, GG – geothermal gradient, PPG – pore-pressure gradient
IOD=4.8 km
IT=75-150 °C
WD=0.12 km
MCT=1.4 km MCV=22.5 km3
LEV=2.7 km3
HPE=15 m
Ge
om
etr
ic
pa
ram
ete
rs &
activity
SD=11 km
SSTD=5 km
Ove
rbu
rde
n
TH=1 km Poro=20 %
Se
dim
en
t
so
urc
e Poro=11 %
Perm=1 nD
Perm=0.1 nD
PPG=17.5 Mpa/km
PPG=19.5 Mpa/km
GG=12.5 °C/km
GG=21 °C/km
MANCHESTER 1824 Feasibility calculations
Vertical seismic section of an investigated mud volcano from the KAD structure in
the offshore western SCB (modified from Soto et al. 2011)
* Flank = 1500m
* Structural crest = 500m
MANCHESTER 1824 Feasibility input parameters
Generic P- and S-wave
velocities vs. depth curves in
marine sediments (modified
from Hamilton 1979)
Shale compaction curve in
northwest SCB (modified
from Bredehoeft et al. 1988)
MANCHESTER 1824 Feasibility results
Good consistency with published values
Empirical correlations are not significantly affected by local factors specific to the SCB
Values we estimated Estimated parameters Structural position Values from the literature
Type Name Unit Crest Flank Range Reference E
lasti
c p
rop
ert
ies
Bulk density kg/m3 2140 2243 1580 – 2600 Mavko et al. 2009, p. 458, 459
Shear modulus GPa 0.87 2.60 0.2-5.5 Horsrud 2001, p. 71
Lamé’s constant GPa 8.69 15.06 0.07-13.26 Islam & Skalle 2013, p. 1400
Poisson’s ratio - 0.44 0.40 0.35-0.50 Schön 2011, p 162
Young’s modulus GPa 2.52 7.25 3.2 – 9.5 Prasad et al. 2012, p. 3
Bulk modulus GPa 7.53 11.59 6 – 12 Vanorio et al. 2003, p. 325
Str
es
s a
nd
pre
ssu
res
Vertical stress MPa 13 35 10-35 Buryakovsky et al. 2001, p. 402
Horizontal stress MPa 8 22
Hydrostatic pressure MPa 5 15 4-14 Buryakovsky et al. 2001, p. 402
Pore fluid pressure MPa 6 16 12 – 20 Buryakovsky et al. 2001, p. 152
Fracture pressure MPa 11.57 28.41
Ro
ck s
tren
gth
Friction angle ° 19.67 26.30 21.75 – 38.09 Kohli & Zoback 2013, p. 5115
Cohesive strength MPa 3.58 4.94 0.3 – 38.4 Schön 2011, p. 256
UCS MPa 8.35 16.05 7.5 – 13.9 Schön 2011, p. 258
Critical shear stress MPa 7.11 17.52
Published values Estimated parameters Structural position Values from the literature
Type Name Unit Crest Flank Range Reference
Ela
sti
c p
rop
ert
ies
Bulk density kg/m3 2140 2243 1580 – 2600 Mavko et al. 2009, p. 458, 459
Shear modulus GPa 0.87 2.60 0.2-5.5 Horsrud 2001, p. 71
Lamé’s constant GPa 8.69 15.06 0.07-13.26 Islam & Skalle 2013, p. 1400
Poisson’s ratio - 0.44 0.40 0.35-0.50 Schön 2011, p 162
Young’s modulus GPa 2.52 7.25 3.2 – 9.5 Prasad et al. 2012, p. 3
Bulk modulus GPa 7.53 11.59 6 – 12 Vanorio et al. 2003, p. 325
Str
es
s a
nd
pre
ssu
res
Vertical stress MPa 13 35 10-35 Buryakovsky et al. 2001, p. 402
Horizontal stress MPa 8 22
Hydrostatic pressure MPa 5 15 4-14 Buryakovsky et al. 2001, p. 402
Pore fluid pressure MPa 6 16 12 – 20 Buryakovsky et al. 2001, p. 152
Fracture pressure MPa 11.57 28.41
Ro
ck s
tren
gth
Friction angle ° 19.67 26.30 21.75 – 38.09 Kohli & Zoback 2013, p. 5115
Cohesive strength MPa 3.58 4.94 0.3 – 38.4 Schön 2011, p. 256
UCS MPa 8.35 16.05 7.5 – 13.9 Schön 2011, p. 258
Critical shear stress MPa 7.11 17.52
MANCHESTER 1824 2D model input
Full Waveform Inversion image at
the ACG structure published by
Selwood et al. (2013)
Digitization workflow
1400 m/s 3900 m/s
TTI FWI
MANCHESTER 1824 Digitized FWI
P-wave velocity image generated from the Full Waveform Inversion image at the
ACG structure published by Selwood et al. (2013)
MANCHESTER 1824 Elastic rock properties
Profiles of elastic rock properties and acoustic wave velocities along the RM-1 pseudo-well
Markers indicate the magnitudes of these properties obtained on the structural crest of the
KAD mud volcano that was analysed in the feasibility calculations
MANCHESTER 1824 Overpressure detection
Top of pressure transition
(TPT) zone 620m
Base of pressure transition
(BPT) zone 2600m
Theoretical Inferred
MANCHESTER 1824 Fluid flow
~1.2
~1.5
~1.8
Variation of overpressure informing about the fluid flow direction near the mud volcano
Possibility of using P-wave data to assess fluid flow pathways within the stratigraphy
TPT
BPT
MANCHESTER 1824
Modified from
Hill et al. (2015)
Contemporary state of stress
MANCHESTER 1824 Contemporary state of stress
Depth, m 𝝈𝒗, MPa/m 𝑷𝒑, MPa/m 𝝁 𝝈𝑯, MPa/m 𝝈𝒉, MPa/m
620 0.0235 0.0123 0.3718 0.0356 0.0177 2600 0.0236 0.0174 0.5957 0.0369 0.0194 5000 0.0238 0.0200 0.6445 0.0328 0.0211
MANCHESTER 1824 Drilling window
TPT 620m
BPT 2600m
Variation of pressure gradients along the
pseudo-well RM-1
Vertical cross-section
across the ACG
showing the width of
the drilling window
MANCHESTER 1824 Conclusions
Geomechanical modelling based on published data allows:
realistic values for sediment properties and fluid pressures to
be estimated
spatial variations in pore pressure and prediction of overall
fluid flow vectors to be visualized
drillability assessment to support future drilling operations
MANCHESTER 1824 References
Buryakovsky, L. a., Chilingar, G. V. & Aminzadeh, F. 2001. Petroleum Geology of the South Caspian Basin, 1st ed. Elsevier, doi:
10.1016/B978-088415342-9/50000-X.
Bredehoeft, J.D., Djevanshir, R.D. & Belitz, K.R. 1988. Lateral fluid flow in a compacting sand-shale sequence: South Caspian
Basin. AAPG Bulletin, 72, 416–424, doi: 10.1306/703C9A1E-1707-11D7-8645000102C1865D.
Hamilton, E.L. 1979. Vp/Vs & Poisson’s ratios in marine sediments and rocks. Acoustical Society of America, 66, 1093–1101,
doi: 10.1121/1.383344.
Hill, A.W., Hampson, K.M., Hill, A.J., Golightly, C., Wood, G.A., Sweeney, M. & Smith, M.M. 2015. ACG field geohazards
management: Unwinding the past, securing the future. Offshore Technology Conference, OTC-25870, 1–22, doi: 10.4043/25870-
MS.
Horsrud, P. 2001. Estimating mechanical properties of shale from empirical correlations. SPE Drilling & Completion, 16, 68–73,
doi: 10.2118/56017-PA.
Islam, M.A. & Skalle, P. 2013. An experimental investigation of shale mechanical properties through drained and undrained test
mechanisms. Rock Mechanics and Rock Engineering, 46, 1391–1413, doi: 10.1007/s00603-013-0377-8.
Kohli, A.H. & Zoback, M.D. 2013. Frictional properties of shale reservoir rocks. Journal of Geophysical Research: Solid Earth,
118, 5109–5125, doi: 10.1002/jgrb.50346.
Mavko, G., Mukerji, T. & Dvorkin, J. 2009. The Rock Physics Handbook - Tools for Seismic Analysis of Porous Media, 2nd ed.
Cambridge University Press.
Prasad, M. 2002. Measurement of Young’s modulus of clay minerals using atomic force acoustic microscopy. Geophysical
Research Letters, 29, 2–5, doi: 10.1029/2001GL014054
Schön, J. 2011. Physical Properties of Rocks: A Workbook. Elsevier.
Soto, J.I., Santos-Betancor, I., Sanchez Borrego, I. & Macellari, C.E. 2011. Shale diapirism and associated folding history in the
South Caspian Basin (Offshore Azerbaijan). AAPG Annual Convention and Exhibition, 30162.
Vanorio, T., Prasad, M. & Nur, A. 2003. Elastic properties of dry clay mineral aggregates, suspensions and sandstones.
Geophysical Journal International, 155, 319–326, doi: 10.1046/j.1365-246X.2003.02046.x.