Pressurized Mud Cap Drilling for Premier Oil

© 2013 Weatherford. All rights reserved. 1© 2013 Weatherford. All rights reserved.

Pressurized Mud Cap Drilling for Premier Oil

Ardia Karnugroho

January 9, 2013


Outline

• Safety / Drivers

• Pressurized Mud Cap Drilling (PMCD)

• Equipment

• Rig Up

• Procedures


Safety / Drivers

• Optimize drilling process by drilling with a closed-loop drilling system.

• Returns-flow-control reduces risk to personnel and the environment from drilling fluids and well control incidents.

• To be able to conduct Pressurized Mud Cap Drilling (PMCD)

• Basic well control, surface diverter techniques, and other rig equipment remain unchanged.


Permits safe and efficient drilling in total loss zones.• No returns to surface (returns

flow into the formation)• Viscous fluid is pumped at low

rate down the annulus at just below reservoir pressure

• Disposable drilling fluid (normally water) is pumped down drillstring

• Annular back-pressure is used to balance the reservoir pressure and maintain system balance.

Pressurized Mud Cap Drilling (PMCD)


Conventional Drilling

• Drilling fluid is pumped down the drillstring, and returns to the surface via the annulus

• The annulus hydrostatic column is weighted to exceed the reservoir pressure and prevent any flow into the wellbore

• Losses are tolerable


Drilling with Mud Losses

• Drilling fluid is pumped down the drillstring, as further loss zones are uncovered

• Increased losses mean little or no mud returns to the surface


Drilling with Total Losses

• Drilling fluid is pumped down drillstring, but nothing returns to surface. Fluid column drops, reducing BHP, compromising primary well control and leading to a kick.

• BOP has to be closed and kick circulated out – but increasing the mud weight leads to more losses and kicks. Ultimately cement may have to be pumped or the well abandoned.



• The annulus is closed at surface with the rotating control head. Drillstring injection is switched to sacrificial fluid.

• Light annular fluid is pumped down the annulus to maintain hole fill and prevent annular gas migration.

• Sacrificial fluid and cuttings are lost to the formation.



• Permits safe and efficient drilling in severe or total loss zones, while allowing for the detection of influx.

• Pore Pressure has to be calculated in order to know the Density of Annular Fluid

• Injection Test to determine whether that injection will continue once the switch has been made to PMCD

• Video

Annular Pressure

Standpipe Pressure

Drilling Mud

Water

RCD 200 psi100 psi

100 psi


Equipment

• Equipment Required

– Model 7875 Docking Station Rotating Control Devices (RCD)

– Valves and Hoses

– Riser Crossover – MR-6C


Model 7875 DS RCD

• Certified API 16 RCD compliant

• 2000 PSI Static Rating

• Removable Bearings With Dual

Sealing Elements

• Hydraulic Latch

• Minimum ID: 18.75”


Model 7875 DS RCD


Model 7875 DS RCD

RCD Hydraulic Control SystemRCD Human Machine

Interface


Model 7875 DS RCD

Protective Sleeve

Protective Sleeve Running

Tool Test Plug

Starter Mandrel

Pneumatic Control Panel

Bearing Assembly

Running Tool


Rig Up

• PMCD / RCD stack will be pre-assembled offline.

• Conduct toolbox talk with the rig crew before commencing.

• RCD stack consisting of Riser Adapter Crossover, Model 7875 DS RCD and valve manifolds is assembled in the moonpool area.

• Install or prepare the hoses for the required setup and secure with the rig tugger lines.

• During installation, the RCD stack up will be picked up from BOP crane and connection to the riser slip joint is made. A separate lift is required to install the mud funnel which is transferred through the rig floor to be installed on the RCD top flange.

• The BOP crane will be dedicated during this time until full installation of the PMCD stack is installed.


Rig Up

16


Rig Up

17


PID


Bearing Assembly Installation


Conventional Drilling with Bearing Assembly

DRILL PIPE


PMCD Decision Tree


Unmanageable Losses Chart


Switching to PMCD

• Shutdown drillstring injection.

• Line up on of the pump for pumping seawater down the annulus.

• Zero stroke counter. Begin annulus injection with minimum of 200gpm. Monitor RCD surface pressure, the RCD surface pressure should increase as the lower weight seawater displaces the mud in the annulus. Rotate and reciprocate the drillstring if required.

• At 150psi RCD surface pressure, record volume of seawater pumped down the annulus. Stop annulus injection and observe RCD static pressure. Calculate formation pressure and density of LAM required for the operation (plan for 50 to 200psi RCD surface pressure).


Switching to PMCD

• Also, evaluate if the cause for RCD pressure increase is due to change in annular fluid density or due to loss zone plugging/fill up. If formation is plugging or filling up, it may be possible to return to conventional drilling. If due to annular fluid density change, continue with next step.

• Observe for gas migration and revise calculation for required annulus injection rates.

• Resume pumping LAM down the annulus at minimum 100gpm.

• Line up to pump seawater (SAC) down drillstring.

• Commence pumping down drillstring at required drill rates for effective hole cleaning.


Switching to PMCD

• Observe for signs of gas migration with the lowered annulus injection rate. If gas migration is observed, increase pump rate.

• If no gas migration observed, stop annulus injection, monitor well and opt for continuous annulus injection.

• Commence drilling in PMCD mode.


Drilling Ahead with PMCD

• Annular fluid must be injected to maintain BHP and stop gas migration.

• Pump down drillstring at required drill rates for effective hole cleaning (200-300gpm) or as per DSV recommendation.

• Maintain annulus pressure within the PMCD well control matrix.

• Monitor torque and drag for hole cleaning, pump high-viscosity pill every half stand as per Premier Oil drilling program.

• Extra high-viscosity sweeps may be pumped if torque and drag (T&D) become excessive.


Drilling Ahead with PMCD

• Do not exceed 10m/hr drilling rate of penetration.

• Monitor SPP and Annulus Pressure.

• Cementing pump lined up to pump LAM down injection line for emergency.


PMCD Drilling – No Injection

DRILL PIPE


PMCD Drilling – Injection

DRILL PIPE


PMCD Well Control Matrix

PMCD Well Control MatrixRCD Surface

Pressure 0 to 200psi 200 - 350psi at 100rpm Greater than 350psi

Well Control Action

Manageable Pressure/

Continue Drilling

Investigate cause of RCD pressure increase. Possible causes are listed but not limited to:

Fractures plugging: switch back to conventional drilling (Standpipe pressure will increase)

Gas migration: increase annulus injection rate

Higher than expected pore pressure: increase annulus injection fluid weight

Shut-in on rig BOP.

Similar to yellow zone, further actions to be taken will depend on the cause of the annulus pressure increase. e.g.

Fracture plugging: Return to conventional drilling

Gas migration: bullhead at high rates through the kill line

High pore pressure: increase annulus injection fluid weight

Green 40% or lesser of the Marine Riser Pressure Rating (500psi)Yellow 40% to 70% of the Marine Riser Pressure RatingRed Above 70% of the Marine Riser Pressure Rating

Pressurized Mud Cap Drilling for Premier Oil

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