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INTEGRATING REAL-TIME GEOMECHANICS INTO DRILLING OPERATIONS
KYLE GRAVES, SR ENGINEERING ADVISOR, PERTH D&C TEAM MARCH 6 2014
Why What Aha Moments How What’s in it for you
INTEGRATING GEOMECHANICS INTO DRILLING? REALLY??
2
We were planning a very challenging ERD well. Recent Key Failure 2012 – Bambra 10H Lots of Horizontal / High Angle Wells on the NW Shelf
Use offsets and good practices – meet objectives – in most cases
Some wells are more difficult than others – that’s normal right?
WHY BOTHER?
3
BAMBRA 10H – PLAN VS OFFSETS – RESULTS
4
Proposed Bambra 10H & 11H vs. wells reviewed in OWR
MEM RESULTS FOR BAMBRA 10H Previous Apache rock mechanics model Schlumberger MEM (January 2013)
Bambra 10H Hindcast, with MW, ECD and swab loads shown
Static EMW in high-risk zone in several places
But ECDs kept EMW at low-medium risk level when drilling
Results are explainable … • Absence of problems while drilling is not surprising, • But problems on trip out to be expected with 1.25 sg MW
In hind-sight, needed at least 1.35 sg MW from start, increasing to > 1.40 sg near section TD
High Probability of Well Failing to Meet Objectives with Current Design
We were well into the Taunton Planning at this stage Decided to revisit our MEM and see if it would impact our
design Based case plan
Drill pilot hole with 1.25 SG mud Drill 12 ¼” to land with 1.25 SG mud Drill 8 ½” lateral with 1.15 SG mud
AHA MOMENT – SHOULD WE REVISIT OUR TAUNTON DESIGN BASED ON THIS?
7
MECHANICAL EARTH MODEL THE BASIS FOR ACCURATE GEOMECHANICS ANALYSES
Seismic
Core Data
Drilling Data
Wireline & LWD Logs
Analysis and Design for:
WBS Sanding
Frac Design Compaction Subsidence
Res. Simulation Etc.
Results
In Situ Stresses & Pore Pressure
Pp σ h σ Hσ V
0 100In Situ Stresses W N E
Stress Direction σh
Fault
Regional Trend
In Situ Stresses & Pore Pressure
PpPp σ hσ h σ Hσ Hσ Vσ V
0 100In Situ Stresses W N E
Stress Direction σh
Fault
Regional Trend
B. Downhole Stresses
Input Data
A. Mechanical Properties
Mechanical Earth Model
Youngs Modulus
Poisson’s Ratio
UCS…..
History Match
Bore
hole
Imag
es
SHmax
Sv
Shmin
SHmax?
8
TAUNTON 5H MEM
9
Well: Taunton-5
Field: Taunton
Air Gap: 32.0 mWater Depth: 17.0 m
Pore PressureCollapse
Least Stress
Made by:SMW Date:1/22/2013
Mea
sure
d D
epth
(RK
B),
m
Mud Weight (RKB), SG0.8 1 1.2 1.4 1.6
1500
2000
2500
3000
3500
Production Casing9.625''@1864
3862
Relationship of Collapse Gradient to Angle and Direction
3 iterations – multiple meetings needed to get to this point
PLANNED TAUNTON 5/5H AND KEY OFFSET WELLS: TAUNTON-2 AND TAUNTON-4
BATH-1
Planned Well Taunton-5H
10
Taunton-2 and Taunton-4 wells have been considered as the offset wells for constructing the Mechanical Earth Model for the planned well Taunton-5H
How does Taunton-5H model compare to Taunton-2L experience ? • Here is Taunton-2L MW-ECD window • With drilling MW & ECDs
Wellbore Stability Interpretation : 1. Pack-offs in Muderong & high angle hole are
explainable
2. 1.20 sg MW is too low
11
12¼” ECDs & swab, with 1.25 – 1.33 sg MW
With 1.25 sg MW, there will be some tunnel failure in the Muderong Fm, but risk level will likely be OK • This is lowest MW that should be considered
With 1.33 sg MW, all risk is removed • Since there is no risk of losses, this is Schlumberger’s
preferred / recommended MW to be used
Final Version of MEM Indicated we might have problems if we stuck to base case plan
Especially in the 8 ½” Lateral section in the Mardie
Make sure model honors offset data Take a calculated risk in the pilot hole Select a mudweight in the low angle pilot hole to initiate breakout
Measureable breakout Test for percieved conservatism in MEM
Optimize mud weight for lateral Low risk of breakout impacting well objectives or operations in 38 deg pilot hole
Calibration Methods Use Density Image Logs Perform XLOT at 13 3/8” and 9 5/8” shoes Use time lapsed caliper data
Use updated MEM for drilling the 2000m long reservoir section
Provide support in the field and in the office – K&M
DECISION MADE TO USE THIS LEARNING ON TAUNTON 5H
13
Requested a Pilot Hole MEM – all work to date was considering a horizontal hole – stresses would be less in a 38 degree hole – chose MWs to cause slight breakout – calibrate model – react accordingly
PILOT HOLE ATTACK PLAN
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PILOT HOLE - DRILLING 12¼” TO CORE POINT (811M–1523M)
GEOMECHANICS UPDATE Initial Model
Updated Model
Geomechanics model was updated after processing LWD
data from drilling run. Updated model shows
significantly more risk of collapse
XLOT Fracture Closure Pressure
12¼” TD TRIP OUT OF HOLE TO LOG PILOT HOLE
1.35 SG Selected as there was little downside – hi fracture gradient
TAUNTON 5H 12 ¼” HOLE LANDING
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DRILLING 12¼” SECTION TO 1668M TD Drilled to section TD without issue,
and good hole cleaning parameters 1000 – 1200 gpm 160 – 170 RPM Backreamed ½ stand prior to
connections
TD called just in top of Mardie GS Generally good ROP, with some slow
spots – instantaneous ROP f/ 5 – 105 m/hr
FFs: PU & TQ = 0.30, SO = 0.25
DRILLING 12¼” SECTION TO 1668M TD Potential indications of
diminished hole cleaning and/or wellbore instability Spike in FFs at ~1300m Increased ECD/ESD near end of
run Increasing MW near TD (possibly
hole cleaning related)
No cavings noted while drilling with MW 1.35 – 1.36
Increasing ECD/ESD
12¼” SECTION – TRIP OOH TO RUN CASING
Difficulties noted backreaming
Circulated 8 B/U with 160 RPM and 1200 gpm For 2 – 3 B/U, large quantity of cuttings
over shakers At 5 B/U, increase in cuttings noted, and
10% - 15% cavings At 8 B/U, still some cuttings over shakers,
cavings at 5%
Attempting to POOH on elevators, drag increased over 3 stands to 40k at 1568m
RIH 3 stands to 1643m and circulated 2 B/U at 160 RPM and 1200 gpm. Still some cuttings flow over shakers at 2 B/U
Attempted again to POOH on elevators. Again saw drag after a few stands – overpull up to 30k at 1590m
RIH to bottom and began backreaming out of the hole
9⅝” CASING RUN Good run in, although FFs
increased with depth CH FF – 0.15 OH FF increased from ~0.3 to
~0.4, then further increased to 0.60 in the bottom of the Muderong
Tight spot at 1342m entering the Muderong Shale, which fell of quickly
No losses while running in Ran in and set casing at
1663m
Updated T-5H prediction (12 ¼” section), Based on updated T-5 pilot hole results
& corrected PP
Previous T-5H prediction (for 12¼” section), based on T-2
Previous recommendation for MW = 1.30 –
1.35 sg Prefer 1.33 sg
Forward recommendation for MW = 1.42 –
1.47 sg Prefer 1.45 sg
MEM UPDATE AFTER 12 ¼” LANDING
Previous 8½” ECDs vs MEM, with 5½” dp, for +/- 6m uncertainty • 1.32 sg is minimum MW (again, NO allowance for swab)
Updated 8½” ECDs vs MEM in Reservoir, for 5½” dp • 1.20 sg is adequate MW
MEM UPDATE FOR 8 ½” HOLE AFTER XLOT
Good news – updated MEM indicated we could drill with a lower MW than originally thought
WE asked if there was a sensitivity to the XLOT result – there would be – good thing we asked
MEM UPDATE FOR LATERAL SECTION RESULTS
25
9 5/8” SHOE - XLOT RESULTS
LOP = ~1.68 sg
Closure = ~1.63 sg
• Closure pressure less than 1.7 SG use 1.25 SG mud weight – if higher we could stay with the 1.2 SG mud weight
• Observed lower closure pressure than expected (lower minimum horizontal stress)
• Updated rock mechanics modeling based on this data showed smaller MW window than previously estimated (see next slide)
• MW increased to 1.25 sg given increased collapse gradient in revised model
Birdrong Sandstone
Updated 8½” ECDs vs MEM in Reservoir, for 5½” dp • 1.20 sg is adequate MW
T-5H 8-1/2” Section Model Update after T-5P TD logs
Model Update of T-5P with XLOT closure pressure
XLOT Closure Pressure=
1.64 sg
What has changed? 1. XLOT Closure pressure
came at 1.63-1.65 sg (lower than expected).
2. Loss curve has moved to the left.
3. MW to prevent breakout has increased to 1.25 sg
What was this model based on? 1. T-5P logs 2. XLOT closure pressure at 13-3/8”
shoe = 1.73 sg
GM- 5H (post 9-5/8” XLOT) For T-5H 8-1/2”
Updated with T-5H 9-5/8” XLOT results
GM- 4H (post coring) For T-5H 8-1/2”
based on T-5 ST2 results
27
Interval drilled successfully 2083m
Two unplanned trips Multiple passes for FE data No issues tripping in to
bottom, although ran out of weight at 3630m and had to ream to bottom. SO FF – 0.30 PU FF – 0.32 TQ FF – 0.39
SUCCESS DRILLING 8 ½” HOLE
28
A complex well was drilled to total depth The lower completion was stuck while running and
the well was lost Primary Objectives not met Structure came in high – glimmer of hope This information will be useful in the future for any
subsequent Taunton work
FINAL OUTCOME
29
A Mechanical Earth Model is useful for planning complex wells
The MEM needs to be calibrated with offset data Multiple iterations typically required Lots of stakeholders input needed You can collect data to validate the accuracy of the
MEM Hint – if your offsets indicate some drilling problems –
backreaming out of hole – tight hole – look into the possibility of geomechanical issues
CONCLUSIONS – WHAT’S IN IT FOR YOU?
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INTEGRATING REAL-TIME GEOMECHANICS INTO DRILLING OPERATIONS
KYLE GRAVES, SR ENGINEERING ADVISOR, PERTH D&C TEAM AUGUST 6, 2013