Cymric Diatomite 0510 SEEP DOGGR ReviewThermal Diatomite Team
Agenda • Present root cause analysis of 5-10-2019 Cymric 1Y surface expression event,
diagnostic testing performed, and corrective actions taken to prevent future surface expression resulting from the source. • Per NOV V19-0008 dated May 20, 2019 – part (1)
• Orientation & Geologic Overview • Summary of Event & Current Status • Actions taken on 05/10 (with Map) • RCA determination • Area remaining actions • Historic Seeps in Area (Map) • Mitigation of Surface Expressions
Location & Orientation
(Pliocene-Miocence (PM) or
Antelope Unconformity)
Antelope Reservoir
• Pair of doubly-plunging, NW – SE trending erosionally truncated anticlines • Structure covers portions of 35W, 36W, 1Y, 6Z and 7Z • Antelope Unconformity bounding the top of the reservoir • Antelope reservoir internal dips range from 20 – 75 degrees • Heavy Oil 12-13°api • Lithology: Diatomite, Siliceous Shale, Sandy Diatomite, Sandstone, and Dolomite • Stratigraphy: Uniformly interbedded, fine to laminated bedding associated with deep
water deposition • Diagenesis: Opal A transitioning to Opal CT
1Y Antelope Antelope Unconformity
Event Summary • Seep identified 05/10 05:30 (am)
• Agencies notified 5/10 08:00 (am)
• Confirm steam block 800 ft 5/10 10:18 (am)
• Containment in place 05/10 11:22 (am) • Fluids were contained by earth berms
• Signage & access restriction at potential access points installed
• 24 hour Monitoring • Light plants and propane cannon (wildlife deterrent)
• Seep stopped flowing, Inactive at 05/10 15:30 (pm) • 100 bbls fluid/material removed on 5/11
• Corrective actions communicated to agencies
• Daily updates provided by Chevron to DOGGR
• Conducting Root Cause Analysis 05/10-06/20
• Re-activation on 6/8 08:15 (am) to 6/12 16:20 (pm)
• Volumes of material removed 750 bbl – 6/13
• 33% Oil cut (250 bbl oil)
• Current Status 06/20 – Active since 6/18 12:30 (pm)
• Coiled tubing operations on 1405S re-started 6/18 (am)
Timeline of Actions 05/10 1:00 Shallow event (<100') detected
5:30 Seep identified
8:00 Reported to Agencies
(1403A, 1304V, 1303Y, 1404A, 1402A)
10:18 1622S RTP'd from Steam
(800' block now in place)
11:22 Berm installed
13:00 0900U & 1105B RTP'd from Steam
(1000' steam block now in place)
14:13 12 wells SI to prepare for mudding, 22 wells listed
15:03 Started mudding 1402A (finished mudding ~16:01)
15:11 1602B RTP'd from FX
15:12 1604V RTP'd from FX
15:30 Seep is Dormant
16:50 Re-mudded 1402A (finished ~17:00)
RTP = Return to Production FX = Shut-in to manage subsidence
Root Cause Analysis (1) aim to improve understanding of seep cause and take action
• Multi-discipline team approach [Operations, Decision Support Center, Geoscientists, Petroleum Engineers, D&C]
• Review of time line and data integration tools
• Well integrity diagnostics and steam testing carried out 5/11-06/20 showed no wells identified in the area with damage above Antelope Unconformity
> Investigate re-abandonment activities on 1Y-1405S
14 day cumulative ground movement at 05/10 seep site No deformation rate or magnitude anomalies noted
cu m
u la
ti ve
g ro
u n
d m
o ve
m e
n t
Date [14 days prior to 05/10 Seep]
Root Cause Analysis (2) – 05/10 Timeline aim to improve understanding of seep cause and take action
C TU
O p
s W
05/10 10:18 1622S RTP
05/10 14:13 12 wells S/I for mudding
05/10 15:03 1402A Mudded
05/10 16:04 1503B Mudded
05/10 15:30 Seep Dormant
05/10 15:12 1602B RTP 1604V RTP
05/07 08:30-13:30 1405S Drilling Out Cement 16 ft – 237 ft Pumping 3BPM Full Returns
05/08 06:30-11:30 1405S Drilling Out Cement 237 ft – 392 ft Pumping 3BPM Full Returns to 392 ft Free-fall 392-397 ft 40 bbl lost circulation
05/09 06:30-15:30 1405S Drilling Out Cement 397 ft – 510 ft Pumping 3BPM Free Fall 398-421 ft Cement 412ft-505 ft Cement & Oil partial Returns 505 ft-510 ft Kill Well 600-700 bbl lost circ
05/09 1304V choke reduced 26 > 24
05/07 1403A choke reduced 26 > 2 (64th) Increased 2 >29 (64th) Over 3-5 hours
05/09 1403A choke Reduced 29 > 0 Increased 0 >26 Over 1 hour
Root Cause Analysis (3) 06/08 Re-Activation aim to improve understanding of seep cause and take action
W el
06/10 15:30 Seep Inactive
06/08 12:30-15:30 1405S Pump on test 260 bbl Pumping 3BPM
06/10
06/06 12:45-15:30 Shallow activity 125 ft Pinnacle Comms on 6/7 11:14 am
06/08 1502B RTP 11:36 1601A RTP 13:50 1602B RTP 13:50 1503B RTP 13:50 1307B RTP 14:00 1208B RTP 14:00
06/08 08:15 Seep Reactivation 2 sites 1) Low flow trickle (Stops at 15:30) 2) Dormant
06/09 13:00 1403A S/I for N2 Test
06/11 06/12 06/13 06/14
06/11 08:30 Seep Active Low flow rate
06/12 08:30 1304V S/I for N2 Test 6/12 12:25 1303Y S/I
06/10 08:45 Seep Inactive
06/11 10:30 Seep Active Low flow rate
06/10 12:39 Seep Active Low flow rate
06/09- 06/10 Seep Re-starts Inactive at 12:10
6/12 16:17 1303Y RTP 6/12 17:48 1303Y S/I 6/12 18:59 1303Y RTP
06/10 16:20 Seep Inactive
06/13 09:49 1304V RTP 06/13 09:56 1502B on steam
06/13 08:43 1303Y S/I for N2 RTP 06/14 09:6
06/13 11:30-13:10 1405S Camera run on WL Damage at 495ft 263 bbl Pumping 1-3 BPM Well Mudded
06/18
06/10 12:30 Seep Active Low rate
• Root Cause: Flow path from reservoir to surface for both 05/10 event was established during re-abandonment activities on 1Y 1405S (originally abandoned in 2004). Reactivation on 06/08 caused by DOGGR approved testing of wells to find source for 05/10.
Root Cause Analysis (4) Summary aim to improve understanding of seep cause and take action
Reason for reabandoning this well is the possibility of cement integrity issues in the 5-1/2” x 7-5/8” OH annulus.
Currently drilled out to 510’. Possible casing part at 397’ but ran through multiple times with no issue.
Observed oil in returns and losses at 505ft-510 ft
18 ppg mud placed in wellbore
05/1006/08
Path Forward • Maintain barriers and signage
• Clean up site (Per Regulations Section 1724.11, OSPR approval pending) • Protecting people and environment
• Complete Re-abandonment of 1405S • Coiled Tubing
• Coiled Tubing drill past Side track and below top reservoir
• Perf and squeeze cement behind liner and lay cement plug
* Based on understanding of Root Cause, may have re-activation in area
• Maintain 300 ft steam block around 05/10 & 06/08 sites until 1405S re-abn complete
• Keep 1403A, 1304V, 1303Y, 1404A open at full choke until 1405S re-abn complete
• Monitor ground movement at 05/10 & 06/08 site (pinnacle & INSAR)
• Follow Tilt ID and response procedure
Historic Seeps in Area
SE 2000- Reactivation of SE 1999A
SE 2009- Short lived low energy seep Reactivation of 1999A and 2000 near 1303R (pad built afterwards, no source identified)
SE 2010A- abandoned 1302A and 1304B SE stopped
SE 2011A- Wells abandoned: 1303R (Jan 2011), 1202V (Mar 2011), 1303U (Nov 2011))
SE 2012A- Caused by 1203V
• Operated area with no seeps for 7 years
• Prior seeps associated with damaged wells
• 05/10 event initiated by proactive re-abandonment activity
• Safeguards in place
Surface Expression Mitigation Safety of people and environment, and containment are the principal goals of our operations
• Ground Monitoring via Tilt Meter Array & INSAR (11 day frequency) • TILT ID & Response Procedure
• Subsidence Management Plan (formally TZSM – target zero surface movement) – to avoid breaking wells (net injection withdrawal balancing plan)
• Steam Scheduling (blocked wells, anti-clustering, target reviews)
• Production/Injection Process Monitoring & Alarms
• 1st Steam Procedure
• Annual temperature surveys and secondary integrity diagnostics if required
• Annual wellhead audits