horizontal drilling pilot in a shallow heavy oil reservoir
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Authors: John Lavelle, Amin Yaghoobi
Horizontal Drilling PilotIn a Shallow Heavy Oil Reservoir in
Northwestern Romania
2 Horizontal Drilling Pilot – Suplac 2010
Discovered 1958Oil Density 960 kg/m3 (16 API)Viscosity 2300 cpArea 1700 hectares – 70 sections Cold production 1960 (0.5t/well/day)Fireflood started 1964Oil to date 20 million tonnesCurrent rate ~1000 t/d from 750 wells
About Suplac Oil Field
3 Horizontal Drilling Pilot – Suplac 2010
Unconsolidated sandDepth 80 to 200mTVD, dipping to northThickness 10 to 25 metresFireflood line-drive and cyclic steamSchist basement below the sandSouthern boundary is a faultNorthern Boundary is the Oil-Water contact
About Suplac Reservoir
5 Horizontal Drilling Pilot – Suplac 2010
Challenges
Using a vertical mast rig, can we turn to horizontal in 200mTVD or less?Will the unconsolidated sand be stable when drilling 300m drains?Will wellbores maintain integrity under steam injection and oil extraction?Will equipment work – liner, slots, pumps?Will the project be economic?
6 Horizontal Drilling Pilot – Suplac 2010
Execution Timeline
Reservoir proposal 2008Pilot go-ahead Q2 2009Well concept Q3 2009Slotted liner testing Q1 2010Peer reviews, tendering, ordering Q2 2010Location construction Q3 2010Spud August 22, 2010
7 Horizontal Drilling Pilot – Suplac 2010
Location Selection
Undeveloped area of reservoirSufficient TVD Available utilities – close to existing electricity, steam and oil linesChosen site:Directional offsets to 60 degrees and 12/30m DLSLow risk of shallow losses
11 Horizontal Drilling Pilot – Suplac 2010
Well Construction
20” at 5m
9 5/8” TB casing
8 1/2” open hole, 7” slotted liner
Liner “hanger”
300 meter
Pannonian
• 9 5/8” close to base reservoir until an inclination of 93+˚ (parallel to basement)
• Horizontal slotted liner is placed in open hole through the zone
• Steam injection through a 3 1/2” tubing, thermal expansion joint and thermal packer
• Production through conventional rod pump / linear rod pumping unit
BOP Waiver
12 ¼” hole
9 5/8” N80 Tenaris Blue casing
Thermal cement to surface
12 Horizontal Drilling Pilot – Suplac 2010
Equipment
Rig► Top drive 75 tonne stroking mast design► Small footprint – typically under 1000 m2 (1800 here)
“Conventional” DD tools – PDM, MWD, GRLogs – DP conveyed memory toolsLiner – flush joint, fine slots, hydraulic rotating running tool, reamer shoe
14 Horizontal Drilling Pilot – Suplac 2010
Operations
Drilled centre well in 26 days with two plugbacks – total losses at limestone top
Drilled the West well in 12 days with one plugback (trajectory)– horizontal at 197.55mTVD
Drilled the East well in 20 days with two plugbacks (trajectory, losses) and an open hole sidetrack at 201mTVD in 8 ½” hole
15 Horizontal Drilling Pilot – Suplac 2010
Trajectories – Section View
150
160
170
180
190
200
210
-20 80 180 280 380 480 580
H1C PlanH2E PlanH3W PlanH1CH3WH2EBasementLimestone
16 Horizontal Drilling Pilot – Suplac 2010
Trajectories – Plan View
642700.00
642800.00
642900.00
643000.00
643100.00
643200.00
643300.00
316400.00 316450.00 316500.00 316550.00 316600.00 316650.00 316700.00
H3WH1CH2EH1C PlanH2E PlanH3W Plan
17 Horizontal Drilling Pilot – Suplac 2010
How did we do?
Successful shallow KOP of 10m KBSuccessful shallow landing – horizontal at 200mTVD or less in all wellsSuccessful 300m drains in eachSuccessful open hole sidetrackDemonstrated that:
► The time plan of ~ 10 days is achievable► The budget is achievable► Production rates of 50 t/day are realistic► Slotted liner gives acceptable sand control
19
RISK LEARNING
Trajectory Immediate KickOff Up to 14/30m DLS At-bit inclination Low flow rates Sidetrack earlier rather than later Cement and open-hole S/T proven
Hole Cleaning Hydraulics models incorrect – low flow rates cleaned well “High viscosity” and weighted sweeps were ineffective Pumping out – packoffs occurred Casing to bottom
Hole Stability, Differential Sticking No issues
Liner running No issues – rotation, reamer not rqd Liner setting Prototype tool success Geology Unexpected uncertainty – losses in
limestone
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