Revised Outer Continental Shelf Lease Exploration Plan Chukchi Sea, Alaska 

Shell Gulf of Mexico Inc. May 2011 

Appendix L 

Well Control Plan 
Revised Outer Continental Shelf Lease Exploration Plan Chukchi Sea, Alaska 

Shell Gulf of Mexico Inc. May 2011 

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Shell Gulf of Mexico Inc. 1 May 2011 

Well Control Plan Outline 

Revised Chukchi Sea Exploration Plan 

Well control is the process of maintaining pressure inside the drilled wellbore in a manner that 

prevents gas or fluids from underground reservoirs flowing into the wellbore and escaping at the 

surface in an uncontrolled manner. 

Shell Gulf of Mexico Inc. (Shell) believes that no single operational error or equipment failure 

should lead to loss of well control. Therefore, Shell will apply the following layers of prevention 

and response to avoid well control issues: 

 Layer I - includes proper well construction, risk identification, training, scheduled tests 

and drills on the rig (e.g., blowout preventer [BOP] tests, pit drills, and trip drills), all of 

which build a strong foundation for well control incident avoidance. 

 Layer II - includes early kick detection and timely implementation of kick response 

procedures. Continuous monitoring including the use of computerized pit volume 

monitoring, return flow detection, returned drilling fluid analysis and data sharing with 

Shell’s Real Time Operations Center provide early kick detection. When a kick is 

detected, the general response is to immediately shut down the pumps, perform a flow 

check, shut in the well, and kill the flow using one of several methods that prevent the 

situation from escalating into a blowout (an uncontrolled flow at the surface). 

 Layer III - involves the use of mechanical barriers, including but not limited to subsea 

wellheads with tested seal assemblies, casing, dual floats (i.e., check valves), cement, 

weighted drilling fluid and tested BOPs. Testing and inspections of all mechanical 

barriers are performed to ensure competency. 

 Layer IV - incorporates detailed relief well planning and drilling, blowout kill operations, 

subsea capping equipment and containment capabilities that would be implemented if all 

other kick control methods fail. 

In the unlikely event that well control is lost despite these precautions, Shell will immediately 

mobilize specialized emergency response personnel and equipment, including Shell’s capping 

equipment and arctic Containment System, to the site. Shell will also consult a well control 

specialist such as Wild Well Control for the intervention and prompt action to resolve the 

emergency. 

Surface Control Options 

If well control is lost, every effort will be made to regain well control using dynamic surface 

control measures. Dynamic pressure control involves pumping weighted fluid at rates sufficient 

to create fluid friction in the annulus of the blowout well to match or exceed reservoir pressure. 

Once this condition is achieved, flow from the reservoir ceases and control is regained. 

Historically, these measures of regaining control have been rapid and effective. However, 

uncontrolled flow at the surface presents a safety hazard. Safety procedures are employed to 

protect personnel, the environment, and equipment. These procedures can involve rapid 

disconnection from the well and escape from the drill site. 

Although the specific surface control methods used will depend on the situation, potential 

mechanical surface control methods include the following: 
Well Control Plan Outline 

Revised Chukchi Sea Exploration Plan 

Shell Gulf of Mexico Inc. 2 May 2011 

 Induced natural bridging (or plugging) of the well 

 Pumping mud, plugging material, and/or special fluids down the well to kill it 

 Replacing failed equipment if control was lost due to equipment malfunction 

 Capping (attaching a device to the well to stop the flow) 

Relief Well 

In the scenario developed for a blowout, the Discoverer will attempt to stop the blowout by 

pumping mud and/or some other specially formulated fluid down the hole. Should these efforts 

fail, the Discoverer will disconnect and pull away to a site upwind and upcurrent from the 

blowout location and initiate relief well drilling operations. As a precautionary measure, relief 

well preparation operations are initiated in parallel with surface capping/intervention methods 

being employed on the blowout well. Unless it is damaged, the Discoverer can commence relief 

well drilling if intervention measures prove to be unsuccessful. It is noted that throughout 

capping/intervention efforts and relief well drilling, Shell’s Oil Spill Response (OSR) fleet will still 

be onsite collecting and storing oil from the surface of the sea.

The general strategy for killing a blowout using a relief well is to drill a specially designed well to 

intersect the blowout well at some point along its path, usually near the top of the source 

reservoir. Then, kill weight fluid is pumped from the relief well into the original wellbore at 

sufficient rates to stop formation fluids from flowing bringing the blowout well under control. 

Finally, both wells are properly plugged and abandoned using procedures approved by the 

BOEMRE. 

In the event that the Discoverer is disabled and not capable of drilling the relief well for any 

reason the Conical Drilling Unit Kulluk (Kulluk) will cease drilling in the Camden Bay area of the 

Beaufort Sea, suspend the well so that it cannot flow, recover its BOP stack and moorings, and 

transit to the relief well drill site in the Chukchi Sea. The Kulluk will initiate relief well drilling 

operations upon arrival and mooring and will remain at the site through plugging operations on 

both the relief well and the blowout well before returning to Camden Bay to resume drilling 

operations on the suspended well. 

If the Kulluk is not drilling in Camden Bay, it will be standing by in Dutch Harbor and if the 

Discoverer is disabled, the Kulluk will immediately rig for towing and mobilize and transit to the 

Chukchi Sea. Because the Kulluk would not be drilling in this scenario, it would not be 

necessary to suspend a well, recover moorings, pull the riser and BOP stack. 

A relief well in this situation will not have a mudline cellar (MLC). Relief well drilling is rapid and 

the relief well drilling vessel will only be on the site temporarily. The relief well will intercept the 

blowout and perform the kill even if extreme ice management efforts are required. All materials, 

equipment and supplies including wellhead housings, casing, drillpipe, mud materials, and 

cement in sufficient quantities to at least start the relief well will be available at the relief well drill 

site. Additional materials and supplies will be mobilized quickly to ensure that there are no 

delays in drilling the relief well and killing the blowout. A detailed Relief Well Plan will be 

submitted to BOEMRE as part of the Application for Permit to Drill for each planned exploration 

well. 

 
Well Control Plan Outline 

Revised Chukchi Sea Exploration Plan 

Shell Gulf of Mexico Inc. 3 May 2011 

Relief Well Location and Timing 

The optimum location for a relief well depends on several factors, including the depth and 

direction of the intercept point, personnel safety, and weather conditions. The location of the 

relief well is selected so that it can be drilled in the most efficient manner practicable. 

The estimated total duration from the start of a blowout to well killing through a relief well would 

be approximately 25 days for a Burger blowout well from initial mooring through kill pumping. It 

is expected that a total of nine days will be required for the Kulluk to suspend the Camden Bay 

well, recover its moorings, pull the BOP stack and riser and rig for towing then transit to the 

Burger relief well drill site. If transiting from Dutch Harbor, the Kulluk would take an additional 4 

days to reach the well location in the Chukchi Sea. 

Often, relief wells are designed to intercept a blowout at some point above the true vertical 

depth (TVD) depending on flowrates, reservoir pressures and fluid types (oil, gas or salt water), 

so the relief well intercept and kill may require less than 25 days. 

In general, all available resources are quickly accessed and funneled into drilling the relief well 

and killing the blowout as quickly as possible. Resupply of critical supplies and equipment, 

mobilization of specialized equipment and assignment of drilling personnel and well control 

specialists occurs rapidly in this type emergency situation. Normal time requirements for 

planning and scheduling activities are compressed and deliveries are expedited. All reasonable 

and safe measures are employed to kill the blowout as quickly as possible. 

Blowout Well Ignition 

The decision to ignite a blowout will be made only after assessing the probability of 

implementing successful surface control (i.e., capping), reviewing potential safety hazards, 

addressing pertinent environmental considerations and obtaining necessary agency approvals. 

Placing human safety as the highest priority, Shell will consider the feasibility and benefits of 

igniting the blowout after all personnel, equipment, and vessels have been located at a safe 

distance from the surfacing oil and gas. 

Ignition and sustained combustion of vapors from the surfacing gas and oil would likely result in 

a safer working environment for relief well operators and for responders attempting to contain 

and/or recover oil downstream of the blowout. Most shallow water subsea blowouts have been 

allowed to burn on the ocean’s surface to consume dangerous vapors in the area when these 

vapors could threaten capping and containment work, relief well drilling operations and surface 

oil spill cleanup efforts. 

Blowout Well Intervention 

Many wells bridge over naturally within 24-48 hours of blowing out. The flowrate from other 

wells may drop over a few days due to near wellbore depletion or formation subsidence. In 

these situations it may be possible to re-enter the blowout well and use conventional well kill 

methods to regain control and secure the well against further flows. If this is possible, the 

Discoverer (or Kulluk, as appropriate) will move over the blowout well when it is safe to do so, 

re-attach the lower marine riser package (LMRP) and riser to the BOP remaining on the well, 

test all equipment to ensure integrity, and run tools and equipment into the blowout wellbore to 

affect a final kill. 

 
Well Control Plan Outline 

Revised Chukchi Sea Exploration Plan 

Shell Gulf of Mexico Inc. 4 May 2011 

Often, the wellbore is damaged by the blowout to the extent that it is no longer usable and 

permanent abandonment is indicated. The decision to continue drilling operations or plug the 

well after such an intervention will be made in conjunction with BOEMRE. Drilling may proceed 

only if doing so would not introduce the risk of a subsequent blowout from the damaged 

wellbore.