201307 Drillingcontractor Pemex Deepwater Gom Subsalt Drilling
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Transcript of 201307 Drillingcontractor Pemex Deepwater Gom Subsalt Drilling
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8/10/2019 201307 Drillingcontractor Pemex Deepwater Gom Subsalt Drilling
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L L D R I L L I N G A L L C O M P L E T I O N S A L L T H E T I M E
Dr i l l i n gC O N T R A C T O R
OFFICIAL MAGAZINE OF THE INTERNATIONAL ASSOCIATION OF DRILLING CONTRACTORS
J U LY / AU G U S T 2 0 1 3 W W W. D R I L L I N G C O N T R A C TO R . O RG
REGIONAL FOCUS:EUROPE
UK, Norway seeing record-high spendingas operators focus on optimizing recovery,
maximizing smaller-prize discoveries p.122
DATA DELIVERY MWD/LWD advances push telemetr y rateshigher, expand capabilities in horizontal, HPHT,
deepwater environments p.62
From assurance processes to capping toolkits to BOPmaintenance, multitude of initiatives are under way
to enhance industrys operational integrity p.18
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Innovating While Drilling
R E P R I N T E D F R O M T H E J U LY / A U G U S T I S S U E O F D R I L L I N G CONTRACTOR
As industry increasingly ventures
into deeper waters characterized
by complex reservoirs, the inte-
gration of upfront planning, risk manage-
ment, workflow strategies and technolo-
gies that provide operational reliability
are paramount. This trend has become
evident in regions such as the Gulf ofMexico (GOM), where subsalt formations
holding significant reserves are attract-
ing operators. Despite risks of wellbore
instability and lost circulation, technol-
ogy has made exploration and develop-
ment of these fields economically viable.
For its initial foray into the deepwa-
ter, subsalt arena, Petrleos Mexicanos
(PEMEX) opted to avoid the risk of drill-
ing directly through the salt dome in
an exploratory well, choosing instead a
more conservative drilling route around
and underneath the salt flank. While
less difficult in some respects, the option
posed its own challenges, such as the
need to design a more deviated trajectory
and drill through the sheared, or rubble,
zone commonly found under or adjacent
to salt bodies, where there is a risk of
becoming stuck.
The complexities of the project wereaddressed using a collaborative and
integrated approach. The eight-month
operation involved extensive upfront
planning; pre-drill, 3D geomechanical
modeling and simulation; contingency
planning for multiple well sections;
importing technology and hardware to
the well site; real-time data surveillance;
new technologies, such as seismic-
vision-while-drilling, to guide the well
under the salts, and the design of a long
bottomhole assembly (BHA) to reach the
target zone.
Real-time drilling
optimization key
to pre-drill modeling,
execution for complex
exploratory well
BYVICTORGERARDOVALLEJO, PEMEX;
MANUELE. TORRESANDLUISFELIPE
GONZALEZ, SCHLUMBERGER
Cap Rock
Rubble zone
Salt
Vel. Int_Subcubo RTMviVel. Int_Pseudo 3_RTMviVel. Int_Pseudo 4_RTMviVel. Int_Pseudo 1_RTMviVel. Int_Pseudo 2_RTMvi
Vel. Int_Subcubo RTMvi (m/s)
For PEMEXs foray into the deep-
water, subsalt arena, the company
planned a drilling route around the
Kabilil-1 subsalt well in the Gulf of
Mexico that incorporated a devi-
ated trajectory through a rubble
zone. The idea was to avoid the risk
of drilling through the salt dome in
an exploratory well.
Integrated approach
delivers GOM subsaltwell for PEMEX
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Innovating While Drilling
R E P R I N T E D F R O M T H E J U L Y / A U G U S T I S S U E O F D R I L L I N G C O N T R A C T O R
The well was drilled with a third-gener-
ation semisubmersible in 94 days, reach-
ing a total depth of 5,350 meters (17,552
ft). The well included a 20-in. riserless
section, an 8 -in. open-hole section and
several sections that required multiple
casing scenarios due to the need for con-
tingencies to isolate problematic zonesand manage the narrow mud weight drill-
ing window between pore pressure and
fracture pressure.
The real-time monitoring of drilling
parameters and geomechanics service
was also introduced during this project;
it is a workflow process executed by
Schlumberger that ties together various
operational elements to mitigate risk.
The Kabilil-1 well was located in a
Tertiary formation of the Mexican GOM,
about 105.5 km (66 miles) northeast of
Coatzacoalcos, Veracruz, and 253 km(157 miles) northwest of Ciudad del
Carmen, Campeche, in a water depth
of 739 meters (2,425 ft). The well exhib-
ited an overhang feature covered by a
large eroded area and was located in a
structural trap on the eastern side of a
large anticline that had been deformed
by the effects of salt intrusion. The target
reservoir held turbidites patterned in
upwardly-thickening sections and amal-
gamated turbidites in channels where
sandstone and mudstone deposits had
led to an increase in elevation. Analysisindicated complex geology and sediments
adjacent to the salt.
3D GEOMECHANICAL
MODELING
In performing the initial risk assess-
ment for determining the optimum drill-
ing strategy, the technical teams pre-
pared a pre-drilling analysis that includ-
ed a finite-element numerical model and
a 3D mechanical earth modeling simula-
tor to predict the effects of the initial
in-situ stresses, measure the influence ofsalt intrusion and induced pressures and
earth stresses, and determine adequate
mud weights.
The 3D simulator conducted a stress/
strain analysis on a small section of the
sedimentary layers and the salt bodies.
Element models were taken from geo-
logic structure maps using the VISAGE
modeling software. The methodology
incorporated data from one-dimensional
mechanical earth models of several off-
set wells, property propagations using
3D seismic data and 3D finite element
mechanical earth modeling. It also mea-
sured stresses and pore pressures to
analyze wellbore stability along the pro-
posed well path.
The stress/strain analysis showed sig-
nificant variations in stress orientation
and magnitude around the salt dome. Astress profile along the planned well path
indicated an obvious increase in horizon-
tal compressive stresses resulting from
salt perturbations, as well as an increase
in shear stresses at 1,500 meters to 2,100
meters (4,921 ft to 6,890 ft) total vertical
depth, where shear stresses peaked. That
depth range coincided with a decrease of
vertical effective stress, indicating a high
deformation zone with a fault at 2,100
meters (6,890 ft).
The analysis also suggested stress
in surrounding sediments located morethan 1.5 km (1 mile) from the salt dome.
The 3D analysis of the mud weight win-
dow resulted in a plan with adequate
mud weights.
REAL-TIME MONITORING
OF DRILLING PARAMETERS
AND GEOMECHANICS
Key to the validation of the pre-drill
modeling and plan execution was the
real-time drilling optimization program.
The program requires teamwork between
the operator and service company to
address drilling risks, classified with a
color-coded system, such as low rates
of penetration, caved hole sections, well
influxes, mud losses and BHA vibrations.
It also provides a structured methodol-
ogy for communication, where events are
communicated from drilling optimizationengineers and real-time geomechanics to
decision-makers. For the Kabilil-1 well,
the communication scenario included
members of various disciplines (drilling
engineers, geoscientists, rig crew mem-
bers) from both companies.
Working in tandem with this program
was the PEMEX multidisciplinary work-
flow program VCD-SE (Visualization,
Conceptualization Development), also
referred to as Front End Loading. It
identifies the most critical risks during
the pre-drill planning phase by building3D and 1D mechanical earth models with
data from offset wells.
The geo-modeling process produced
several findings that served as the basis
for developing the final drilling plan.
Among them was the determination that
drilling close to the salt dome would
result in higher-than-expected collapse
pressures at the end of the riserless sec-
tion. This required optimizing the drill-
ing fluid by combining seawater with
weighted bentonite mud. Other hazards
included:
Analysis using a fnite-element numerical model and 3D mechanical earth
modeling simulator indicated signifcant variations in stress orientation and
magnitude around the salt dome. The simulator also suggested stress in
surrounding sediments located more than 1.5 km from the salt dome.
Pore Pressure Cube
KABILIL-1KABILIL-1
KABILIL-1KABILIL-1
KABILIL-1
Pore Pressure(kPa)
1.1437e+005
85777.0
57185.0
28593.0
1.0000
-15000.0
-6250.0
-27500.0
-48750.0
-70000.0
15000.0-714.29.0-16429.0-32143.0-47859.0-63571.0
-79286.0-95000.0
Effective Vertical Stress(kPa)
Negativevalues =Compression
Positivevalues =Tension
East Effective Stress(kPa)
Negativevalues =Compression
Positivevalues =Tension
North-South Effective Stress(kPa)
Negativevalues =Compression
Positivevalues =Tension
North
North
North
11.7 km
(65 cells)
6 km
(127 cells)
10.6 km
(59 cells)
North
North
E-W Effective Stress Cube
Vertical Effective Stress Cube
N-S Effective Stress Cube
Visage Mesh
-15000.0
-6250.0
-27500.0
-48750.0
-70000.0
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Innovating While Drilling
R E P R I N T E D F R O M T H E J U LY / A U G U S T I S S U E O F D R I L L I N G CONTRACTOR
Shear stresses from the salt body
influence would result in narrower mud
weight windows for the 20-in. and 16-in.
open-hole sections; The presence of a reverse fault in
the open-hole sections posed the risk of
well losses;
Because the surface seismic model
contained uncertainties regarding the
precise location of the salt flank, the
planned well trajectory would require
precise navigation around the salt body.
Drilling into the salt dome would add
complexity to the operation;
The well design would need to be
optimized using unconventional cas-
ing (16-in. and 13 5/8-in. outer diameter
strings) to allow two additional contin-
gency casing strings (11 -in. and 5
-in.) for the interval with the narrow
drilling windows; Special underreaming BHA designs
were required to perform simultaneous
hole opening without the need for extra
drilling runs. Due to the hole-opening
initiatives, the BHAs would need to be
stabilized with drilling simulators to
minimize drilling vibrations that could
destroy downhole tools and damage the
borehole with BHA shocks;
Continual equivalent circulating den-
sity would be required to minimize mud
losses due to drilling-induced fractures
or during the well cement process. A
foam cement system would be required
to optimize cement placement;
Intermediate casing strings would
need to be set at the appropriate depthto improve the drilling performance of
the subsequent well sections, segregate
the overpressure intervals induced by
salt intrusion and separate incompatible
formations.
In transitioning from the pre-drill plan-
ning stage to the execution phase, a drill-
ing and engineering operations plan with
a course of action for each well risk was
created. Using the real-time drilling opti-
mization process, offshore engineers and
onshore geomechanics engineers worked
together to update prediction models.
845 m
Liner 16 in
Casing 13 5 8in
Hole 28 in
Hole 17 in 20 in
Water depth=739 m
Air gap=25 m
1,524 m
2,125 m
3,346 m
4,563 m
Casing 20 in
Landing sub at 1,200 m
Pilot Hole 14 in 17 in
Hole 12 in 14 in
Conductor 36 in
Liner 9 5 8in97 8in
Pills 1.06 g/cm 3
Synthetic Mud1.211.33 g/cm 3
Sea Water andViscous Pills
Pump and Dump
1.051.25 g/cm 3
Synthetic Mud1.77 g/cm 3
Synthetic Mud
1.371.53 g/cm 3
Synthetic Mud1.571.89 g/cm3
Open Hole 8 in
Vetco Gray Subsea Wellhead System 18 in15 M Model DMS-700
Rotary table=763 m
Top well head 18 in=758.75 mTop housing 36 in=759.6 m
Top mud mat=762.7 m
TD=5,350 m
REAL
850 m
Liner 16 in
Casing 13 5 8in
Hole 28 in
Hole 17 in 20 in
Water depth= 740 m
Air gap=25 m
1,500 m
2,200 m
3,000 m
3,400 m
4,600 m
4,450 m
Casing 20 in
Landing sub at 1,200 m
Pilot Hole 14in 17 in
Hole 12in 14 in
Hole 8in
Conductor 36 in
Liner 9 5 8in97 8in
Pills 1.05 g/cm 3
Synthetic Mud1.201.25 g/cm 3
Sea Water andViscous Pills
Pump & Dump
1.051.35 g/cm 3
Synthetic Mud1.551.65 g/cm 3
Synthetic Mud
1.301.40 g/cm 3
Synthetic Mud1.451.52 g/cm 3
Liner 7 5 8in
Rotarytable=765 mTop well head 18 in=2.30 mTop housing 36 in=2.30 mLanding sub colled 20 in 16 in=1,250 m
TD=5,350 m
KOP 3,420 m
PLANNED
Dark zone = 2 m Jetting
BL
BL
Temp. seafloor=4.5 degC
Sea Water and Viscous Sea Water and Viscous
Final Well Geometry
A real-time drilling optimization program was key to the success of the Kabilil exploratory well due to uncertainties that
remained even after extensive upfront planning. In the 16-in. casing section, seismic-while-drilling data was used to acquire
depth-velocity information, calibrate the geomechanical and geological models and provide real-time surveillance to
adjust the model against the pre-drill model. In the 9 5/8-in. and 8 -in. open-hole sections, real-time LWD tools were used to
gather petrophysical information.
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8/10/2019 201307 Drillingcontractor Pemex Deepwater Gom Subsalt Drilling
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Innovating While Drilling
R E P R I N T E D F R O M T H E J U L Y / A U G U S T I S S U E O F D R I L L I N G C O N T R A C T O R
REAL-TIME VISION
Because the Kabilil well was an explor-
atory well, it was prudent to acquire LWD
data while drilling to reduce uncertain-
ties. The primary objective of the look-
ahead seismic-while-drilling service was
to reduce the depth uncertainties andidentify potential risk zones. Additionally,
LWD measurements were acquired for
calibrating the geomechanical and pore
pressure models.
For example, a real-time look-ahead-
of-the-bit check shot and vertical seismic
profile (VSP) of the interval between
1,500 meters and 2,200 meters (4,921 ft
to 7,218 ft) was deployed in the 16-in.
casing section where the fault plane had
been predicted. The VSP data below the
drill bit revealed homogeneous reflec-
tions rather than the strong amplitudethat had been expected for salt pres-
ence.
The seismic-while-drilling information
made it possible to precisely map the bit
position and identify the location of the
fault plane to set the 16-in. casing just
below that point. When drilling resumed,
the location of the fault plane was used
to determine when to stop drilling for the
16-in. casing. The system also conducted
a salt proximity survey in the 13 5/8-in.
section, determining that the well was
actually closer than expected to the salt
dome, a minimum distance of approxi-
mately 163 meters (535 ft).
Real-time LWD tools, used for the ini-
tial formation evaluation and pore pres-
sure predictions, were deployed in the
9 5/8-in. and 8 -in. open-hole sections
to provide petrophysical informationto determine whether further data was
needed for each target zone.
The logging suite was enhanced with
sonic to measure formation velocity for
correlating seismic activity with the
seismic model. The sonic log calculated
the pore pressure profile, allowing geo-
mechanical engineers to calibrate the
mechanical earth model and devise a
wellbore stability model that included a
reliable collapse pressure, complement-
ing the 3D modeling work performed in
the pre-drill planning stage.The PEMEX Kabilil-1 exploratory well
demonstrated how optimum drilling per-
formance can be achieved in a challeng-
ing deepwater subsalt well through the
integration of effective pre-drill modeling,
risk management, real-time monitoring
and a workflow process built on strong
communication and teamwork.
Although the well ultimately did not
prove to not to be a viable producer
and has since been abandoned, the suc-
cessfully executed drilling program pro-
vided important lessons for the operator.
PEMEX has since drilled 18 deepwater
wells and four ultra-deepwater wells at
water depths approaching 3,000 meters
(9,843 ft) in the same basin.
VISAGE is a mark of Schlumberger.
References
Vallejo, V.G., Solis, E., Olivares, A., Aguilera,L.E.,
Torres, M.E. and Gonzalez, L. Drilling a
Deep-Water Well in a Subsalt Structure in
Mexico, Pennwell, Deep Offshore Technology
International. ID number 145. Conference held
in Perth, Australia 2729 November 2012.
Aguilera, L.E., Jimenez, G., Lougon, A., Macias,
J., Martinez, M. and Bracho, L., Geomechanics
and Pore Pressure Considerations for
Successful Deep-water Exploration Drillingpaper SPE WVS 040
South American Oil and Gas Congress, orga-
nized by the SPE Western Venezuela Section,
held in Maracaibo, Venezuela, 1821 October
2011.
Sanchez, A, Mora, A. Aguilera and L.E,
Gaitn, R., Minimizing Drilling Risks for
Exploration well in deepwater using Seismic
While Drilling Technology, in Rio Oil &
Gas Expo and Conference 2010, held in Rio
de Janeiro, Brazil, 13-16 September 2010.
To mitigate challenges
identifed during the
pre-drill planning phase,
seismic-while-drilling was
used to acquire depth-
velocity information in
real time. A real-time
check shot and VSP wasacquired of the interval
between 1,500 meters
and 2,200 meters in the
16-in. casing section,
where a fault plane had
been predicted. Further,
a salt proximity survey
was conducted in the 13
58-in. casing section. Raypath
Salt Salt
Energy source
Salt
Receiver
Depth, m
Horizontal DistanceBetween Receiver and
Salt Flank, m
2175.7 196.4
2204.3 185.7
2232.9 176.0
2261.1 182.0
2289.4 184.0
2318.2 187.5
2347.0 183.4
2375.8 178.4
2404.4 175.8
2432.6 177.9
2460.9 172.72489.1 171.4
2517.2 167.7
2545.8 164.1
2573.0 163.0
2601.3 171.3
2629.6 179.8
2658.1 175.7
Look Ahead Survey 17 in 20 in Salt Proximity Survey 14 in 17 in
Drill bit @ 1,761 m
Drill bit @ 2,140 m
Salt
Fault
Lower Miocene
Corridor stack with
BPF 6-30Hz and using
just seven levels