RAG.ENERGY .DRILLING Heimo Heinzle RAG.ENERGY.DRILLING, Schwarzmoos 28, A-4851 Gampern, www.rag-energy-drilling.at Drilling, a high precision technology - current challenges and possible ways forward
RAG.ENERGY.DRILLING
Heimo Heinzle RAG.ENERGY.DRILLING, Schwarzmoos 28, A-4851 Gampern, www.rag-energy-drilling.at
Drilling, a high precision technology - current challenges and possible ways forward
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Introduction • Directional / Extended Reach Drilling
• Underbalanced Drilling
• Casing Drilling
• Coiled Tubing Drilling
• Dual Gradient, Managed Pressure Drilling
• Laser Drilling
• Plasma Drilling
• Automated Drilling / Rigs
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Summarizing the Challages
• Well should be: • Deeper • Longer • Drilled faster • Drilled cheaper • Drilled at remote Locations • …
Driven by the Oil Prize
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Safety !
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Directional Drilling – WHY ?
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Extended Reach Drilling – WHY ?
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Wytch Farm Field
• Discovered 1973
• Production before ERD
~10k-20k bbl/day
• Since 1993 ERD
• Production peak in 1997
with 110,000 bbl/day
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Sakhalin (RUS) Extended Reach 12.700m
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ERD Challanges
• Surveying
• Directional Drilling
• Geosteering
• Hole Cleaning
• Torque & Drag
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ERD - Margin of Error
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Directional Terminology
azimuth
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Approximation By Radius Of Curvature Method
P1
P2
ERD - Margin of Error
Accuracy of Compass
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Mud Pulse Telemetry
• Mud pulse telemetry utilizes an incompressible transmission path (mud column in drillpipe) to carry pressure waves created by a downhole pulser
• Sensor data can be encoded in many different ways but all methods require the pressure pulses to be detected at the surface in order for the data to be decoded
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Mud Pulse Telemetry – Positive Pulse
MEASURED TIME
MINIMUM PULSE TIME DATA TIME
• Data values (4 to 6 bits) are encoded as the time interval between two pulses
Choke Piston Turbine
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Electromagnetic Telemetry
• EM emitting antenna injects an electric current into the formation around the hole
• An electromagnetic wave is created, which propagates in the formation while being “channeled” along the drillstring
• Data is transmitted by current modulation and decoded at the surface
• Propagation of EM waves along the drillstring is strongly enhanced by the guiding effect of the electrically conductive drillstring
• If deeper than ~1,700m to 2,000m – repeaters installed within drillstring
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Directional Control
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PDM Motors
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• Push the Bit
• Point the Bit
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Rotary Steerable Systems
Push Point
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Rotary Steerable System
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• For straight hole sections, the RSS operates in a neutral position with the drive shaft concentric with stabilizer sleeve.
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Rotary Steerable System
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• For direction changes, hydraulic pistons deflect the drive shaft from the centerline, forcing the bit-to-point in the opposite direction.
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Rotary Steerable System
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Neutral Position
Maximum Deflection
Intermediate Deflection
• Eccentric rings
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Cuttings Bed Behavior
�Slip-velocity (suspension)
�Avalanching �Stationary cuttings bed �Cuttings transport depends on GPM/RPM
>
Legend: With flow No flow
> ±65° ±30° to ±65°
< ±30°
Hole Cleaning
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Gravity
Hole Cleaning
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Hole Cleaning
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Rotation Effects Why is it easier to clean 8-1/2” (& smaller holes)?
5” DP in 8-1/2” Hole 61% Eccentric
5” DP in 12-1/4” Hole 81% Eccentric
Pipe is better centralized by tool joint in small hole
Viscous coupling more effective
Higher annular velocity (usually), more evenly distributed
Fewer cuttings to remove for same ROP
Tool Joint
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Torque & Drag
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• Friction Factor is a coefficient that depends on wellbore roughness, tortuosity, drilling fluid lubricity, string stabilization, etc...
WOB has to be compensated for inclination and drag
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Torque & Drag - Buckling
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• Sinusoidal Buckling • Helical Buckling
INTERVALS OF AN E.R. WELL WHERE BUCKLING IS MOST LIKELY TO OCCUR
Near heel, on longhorizontal sections
In the lower tangent section, above the build/turn.
Buckling will probably not occur in the build or turn itself
as 'bent' pipe is more resistant to buckling.
Buckling is significantly more likely to occur with small
OD drillpipe above a liner top.
Intervals where bucklingis most likely to occur
In the vertical section, if in compression.
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Underbalanced Drilling • Bottomhole circulating pressure is less than the static reservoir
UBD Conventional pressure
• Reservoir fluids enter the wellbore as drilling proceeds
• Preventing loss of drilling fluids to the formation
• Eliminating many causes of formation damage
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Underbalanced Drilling
• Five forms of flow regimes in UB
drilling exist. Actually all of these
grade into each other at some
point due to compression of gas.
• The flow patterns and lifting
capacity will change with gas
percent and fluid properties.
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Underbalanced Drilling
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Foam / Aerated Fluid Drilling
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Advantages of UBD • Reduced Formation Damage (Skin effect) - Especially for low-pressure reservoirs
• Reduced Completion and Stimulation Costs
• Expensive horizontal well stimulations can be eliminated
• Decrease of drilling costs (for material and time) by avoiding lost circulation, especially across fractured, low-pressured or highly permeable zones
• Elimination of Differential Sticking - Especially across low-pressured zones
• High Penetration Rates Reversed chip hold down effect increases ROP, especially in horizontal wells with low WOB
• Real Time Reservoir Investigation Proper data monitoring and interpretation allows identification of geological anomalies like fractures, hydrocarbons or water zones Production rates during drilling permits real-time decision regarding change in drilling depth, wellbore orientation and overall length.
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Disadvantages of UBD
• UBD has its own unique damage mechanisms, such as surface damage of the formation due the lack of heat conduction capacity of underbalanced drilling fluids.
• It is more complicated to model and predict the behavior of compressible drilling fluids.
• Reduced wellbore pressure gradients can cause hole stability problems.
• Stable foam condition is not easy to achieve.
• Water Influx – effect on cuttings transport
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• There is a higher risk of blowout, fire or explosion.
• Underbalanced drilling is still an expensive technology. Depending on the drilling fluid used, the cost can be significant, particularly for extended reach wells.
• It is not always possible to maintain a continuously underbalanced condition. Since there is not a filter cake around the wellbore, any instantaneous pulse of overbalance might cause severe damage to the unprotected formation.
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Casing Drilling
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Casing Drilling - 2 systems
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Casing Drilling
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Torque ring
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Casing Drilling – possible applications
• Shallow well sections
• Depleted zones / Mature fields / Differential Sticking
• Wellbore Stability Problems / Reaming Runs
• Lost Circulation during drilling
• Hole cleaning issues / large diameters
• High NPT (non productive time) (BHA / DP change)
• Cost effective (vs. rig rate)
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Casing Drilling - Disadvantages
• Drilling shoe to shoe (if BHA not retrievable)
• Time for R/U and R/D
• Back-up plan if problems (stuck casing, …)
• Torque Limitations – special connections (backreaming, …)
• Additional personnel at rig site
• Bit not re-useable
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Coiled Tubing Drilling
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Coil Tubing Drilling – possible applications: • Deepening Wells
• Conventional re-entry
• Through Tubing Re-Entry
• New wells from surface
• Rigless platforms
• Underbalanced Drilling
• Open Hole Sidetracks
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Coil Tubing Drilling - Advantages • Safety
• Less Personnel • Reduced Pipe and Tool Handling
• Operational • Underbalanced Drilling Capability (with higher ROP) • Thru-Tubing Drilling Capability • Reduced Trip Times (Very few Connections to Make up) • “Wired CT Telemetry” gives fast data rates for LWD & has protected cable
• Environmental • Smaller Footprint • Reduced Noise and Emissions
• Economic • Lower Mobilization Cost (Less Equipment and Personnel) • Slimhole Technology
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Coil Tubing Drilling – Disadvantages / Limitations • Operational
• Hole Size (Mostly Slimhole Drilling – max. up to 8 ½”)
• Rotation (Inability to Rotate CT String)
• Hole cleaning
• CT String Limitations (Lifetime of string / Mechanical & Hydraulic Limitations)
• Economic
• CT String = Consumable
• Downhole Motor Cost
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Dual Gradient, Managed Pressure Drilling
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DEPTH
Dual Gradient Drilling
¾ Single Gradient Wells
9 Wellbore contains a single density fluid
9 Single pressure gradient
¾ Dual Gradient Well
9 Wellbore feels seawater gradient to the seafloor, and mud gradient to bottom
DGD vs. Conventional Riser Drilling
SEAFLOOR
PORE PRESSURE
MUD HYDROSTATIC
PRESSURE DGD
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
MUD HYDROSTATIC
PRESSURE Conventional
FRACTURE PRESSURE
DGD vs. Conventional Riser Drilling
SEAFLOOR
PORE PRESSURE
MUD HYDROSTATIC
PRESSURE DGD
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
MUD HYDROSTATIC
PRESSURE Conventional
FRACTURE PRESSURE
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Dual Gradient Drilling
Conventional Deepwater Casing Design:
Can result in 7+ casing strings !
Where to place/land them within wellhead ?
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Dual Gradient Drilling
12.4 ppg mud
13.5 ppg mud
12.4 ppg mud
13.5 ppg mud
12.4 ppg mud
13.5 ppg mud
Pressure, psi
Depth
ft
Seafloor @ 10,000’Seawater HSPSeawater HSP
23,880 psi
@ 37,500’
2 different fluid gradients
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Dual Gradient Drilling
Casing Requirement Conventional
SEAFLOOR
PORE PRESSURE
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
MUD HYDROSTATIC
PRESSURE Conventional
FRACTURE PRESSURE
Casing Requirement Conventional
SEAFLOOR
PORE PRESSURE
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
MUD HYDROSTATIC
PRESSURE Conventional
FRACTURE PRESSURE
Casing Requirement DGD
DEPTH
SEAFLOOR
FRACTURE PRESSURE
PORE PRESSURE
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
DEPTH
MUD HYDROSTATIC
PRESSURE DGD
Casing Requirement DGD
DEPTH
SEAFLOOR
FRACTURE PRESSURE
PORE PRESSURE
SEA WATER HYDROSTATIC
PRESSURE
PRESSURE
DEPTH
MUD HYDROSTATIC
PRESSURE DGD
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Dual Gradient Drilling
Wellhead and BOP
Return Line
Drillpipe
Rotating Diverter
BHADrill String Valve
Mud Return and Pump
Seawater-Driven MudLift Pump
Seawater Filled Marine RiserSeawater Power Line,
Control Umbilicals
Seawater Pumps(Existing Mud Pumps)
Wellhead and BOP
Return Line
Drillpipe
Rotating Diverter
BHADrill String Valve
Mud Return and Pump
Seawater-Driven MudLift Pump
Seawater Filled Marine RiserSeawater Power Line,
Control Umbilicals
Seawater Pumps(Existing Mud Pumps)
Seawater Power Line,Control Umbilicals
Seawater Pumps(Existing Mud Pumps)
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Dual Gradient Drilling Alternative Dual Gradient Systems: • Nitrogen Injection at Wellhead or below
• Injection of Hollow Glass Spheres at seabed
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Managed Pressure Drilling The idea is to keep the static and dynamic pressure the same. How to go from static balance to dynamic (circulating) balance without either losing returns or taking a kick. This can be done by gradually reducing pump speed while simultaneously closing a surface choke to increase surface annular pressure until the rig pumps are completely stopped and surface pressure on the annulus is such that the formation “sees” the exact same pressure it saw from ECD while circulating.
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Way Forward
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Laser Drilling • A laser is a device that emits light through a process of optical amplification based
on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation".
• It is generated by a device which converts energy to electromagnetic beams or photons.
• This light radiation is then focused to form intense high powered beams which can fragment, melt or vaporize rock.
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Laser Drilling + Small Rig Site
+ No conventional Drilling Equipment needed (bit, DC, …)
+ Rate of Penetration (10x faster compared to conventional drilling)
+ Sealing wellbore due to melting prozess
- Energy consumption (wellbore diameter 8 1/2“ or bigger) ?
- Energy supply to rig site ?
- Bigger hole diameters – means overlapping laser beams
- Well Control Mechanism ?
- Formation Damage in Reservior Section due to melting process ?
- Wellbore Cleaning ?
- Wellbore stability ?
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High-energetic electrical plasma is a technology currently being developed in deep drilling applications
• An electric arc is an electrical breakdown of a gas that produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air or gas. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on thermionic emission of electrons from the electrodes supporting the arc.
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Plasma Drilling
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Automated Rigs
• Automation • Conventional or • Robotics
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Automated Rigs
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+ Less personnel
+ Hands OFF - Safety
+ Eliminates human errors
+ Reliable ?
+ Reduced NPT
� What if equipment breaks down ?
� Maintenance Intervalls/Cost
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