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Shell - new well control equipment

Thursday, April 12, 2012

Shell is developing a range of new equipment and tools for preventing uncontrolled releases of hydrocarbon during the construction of wells, including well control automation, explosive devices to cut drill pipe apart, blow out preventer caps and pipe crushers.

One possible reason for the blow out preventer failure in Macondo was that by the time the instruction was given to close it, there was so much fluid passing through it that it did not close properly.

If this was true, then the situation could have been avoided if there was a system to close the blow out preventer automatically.

Many people may be nervous about the computer making the multi-billion dollar decision to close a blow out preventer, but computers could be better at making this decision than people can, Shell believes.

Computers can be programmed to close the BOP automatically if certain conditions arise, such as more fluids coming out of the well than going into it.

'We are working on a system that will automatically close the BOP, in advance of the flow rate being so fast that it can't be closed,' said Jan Brakel, Manager Wells Research & Development at Shell Projects and Technology.

Shell is working with drilling contractor Nobel Corporation and drilling equipment manufacturer National Oilwell Varco to develop the technology. 'We are looking at systems which will reduce the potential for human error.'

It is a very big decision to close a BOP, something which humans are understandably nervous about.

'In my time I hesitated many times before closing the BOP as part of routine functional checks being concerned about inadvertent equipment damage,' said Mr Brakel.

The computer could first show a 'yellow traffic light' to indicate 'don't panic but pay attention,' he said.

'If the driller ignores all these warning signs, then the computer takes over (red traffic light).'

The computer system could also automatically stop drilling, stop the pumps, and pull the bit off the bottom, by controlling the pumps, draw works and rotary speed.

'Processes which are highly automated are more efficient and safer,' said Mr Brakel. 'In the airline industry, it can be fully automated. No one thinks about that. The drilling industry can be fully automated as well.'

'Many rigs still operate with manual controls. 'These are perfectly acceptable rigs. There are a handful of dials. But the information the driller gets is fairly limited,' he said.

Severing any equipment located across the BOP

In 2011, Shell started work on a system which can sever the drill pipe above the blow out preventer, if the blow out preventer shear ram fails to cut it.

The system will sever any component that the current BOP shears cannot sever. The system utilizes current shape charge technology that's field proven, safe and reliable.

There was speculation in the investigations into Macondo that the blow out preventer might have failed due to a failure of the rams to cut drill pipe. The investigation showed that the real reason was more complex, but nevertheless it highlighted the importance of making sure it is possible to sever drill pipe on the seabed.

Shell has developed an explosive device, which is fitted inside the riser, in the first flex joint above the blow out preventer.

Once activated the cut is achieved in milliseconds and with very little deformation of the pipe. This will allow the pipe to fall back through the BOP. Clearing the BOP allows the unrestricted function of BOP sealing rams, so that the uncontrolled flow of hydrocarbons is stopped.

'It will sever any equipment above the BOP when experiencing any well control issues,' said Jan Brakel, Manager Wells Research and Development at Shell Projects and Technology.

The system might also need to be used if a dynamically positioned rig loses its position due to equipment failure, and a fast disconnect with the well head is required.

Crushing the inner pipe beneath the BOP

Shell is also developing an explosive pipe-in-pipe device that crushes a metal insert inside the casing deep in the well but above the hydrocarbon zones. It provides an additional means to stop or significantly reduce the uncontrolled flow of hydrocarbons in an emergency situation.

The device is run in the primary protective casing. It uses a pyrotechnic device to produce a engineered collapse of the internal insert while maintaining the integrity of the casing.

Once the flow has subsided or been shut off, the crew can go into the bore hole and either mill out, or drill out, the collapsed insert and replace with new casing. At all times, the integrity of the casing string has been maintained, Mr Brakel said.

'We've tested this on different casing sizes,' he said.

The device is known as a 'collapsible insert device'.

Caps

Shell's subsea wells around the globe are designed to be capped and the external flow controlled, through either shutting in the well or flowing the well to a containment system. Shell either owns or has ready access to the equipment required to cap its deepwater wells.

A modular Shell-owned capping system covers Shell's global portfolio of deepwater wells. It can also be used for other wells that are designed to accept the cap. One capping stack designed with a 10,000 psi working pressure is stored and maintained in Aberdeen. 'The system is available for emergency deployment on Shell operations worldwide within ten days', said Thierry de Meyer, Senior Well Engineer at Shell.

A second cap is currently being built and designed for 15,000psi working pressure and will be housed in Singapore as of mid-year.

In Alaska, Shell's plan is to have a dedicated oil spill cap and containment system that will be stored for deployment in the Arctic. The system is designed to deal with Arctic weather conditions such as cold, potentially ice-laden water and its remote location.

Associated Companies
» Royal Dutch Shell plc

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