AI
Thursday, May 20, 2010 2:11:18 AM
Charlie, I know the limitations of the shear rams. They test them on a regular basis and if they, or any other critical component dont test, the well is suspended and the BOP is pulled to surface and repairs made.
I have been listening to C-Span and found it very interesting.
http://www.c-span.org/Watch/Media/2010/05/12/HP/A/32852/House+Energy+Cmte+Hearing+on+Oil+Spill.aspx
I guess those old boys who run Transocean, BP and Haliburton cant volunteer much with all the litigation probably pending. They sure seemed to be tap dancing around a few vital issues. I would be hesitant buy a used car from any of them.
The rig was drilling in about 5000' water depth, this is only medium depth. There are rigs in the gulf right now capable of drilling in 10,000'. There are more of these rigs heading that way and I dont see a problem. I dont work GOM. There are many rigs all over the world drilling those water depths and much deeper.
What I got out of it was, and this is just my opinion based on what I heard.
Cause failing to control the blowout=Possible lack of experience/incopentence/mistakes under pressure/delays reacting.
Inability to close the BOP later i.e. the oil slick = Human error/Gross Negligence and possible obstruction inside BOP.
The equipment to prevent all this was there.
They are looking for new ways to ensure this cant happen again. Before they find new equipment and technologies, which may or may not be kept servicable, they need to make shure the safety systems they have work and are activated in time. Everything was there to prevent the blowout and subsequently everything was in place which should have been able to shut the well in from remote or ROV(robot submarine).
The Transocean guy stated the rig had two sets of shear rams. They only had one ROV intervention to shear rams. They didnt say which shear ram had the ROV. One is a "supershear" meaning it has a much bigger hydraulic actuation cylinder, making it capable of shearing heavier pipe. No specific question about that.
The oil slick, emergency equip for closure of the BOP.
Diverter
Bolted right below the rig floor. Once a large amount of gas was in the riser above the BOP this was the only thing which could have saved the crew. 30 seconds to function if set up right. Seals off the riser just under the floor and diverts the flow overboard. Under full blowout conditions, there is no guarantee these will work for more than a few minutes. Imagine trying to divert a 5,000psi large bore inflammable high velocity gas flow containing abrasives around a corner. You cant hear yourself think when this breaks surface. It is terrifying. If you can divert you buy some reaction time and time to get the crew clear. To close the shear rams or do a full EDS takes less than one minute. No questions were asked about the diverter.
Deadman system.
This requires the correct parameters to occur to operate. The control system must lose all signals and power to trigger it. They didnt all go off at the same time the one of the battery they recovered was way down on charge, so the system may have been ineffective. From what I heard their deadman fires the EDS sequence from a battery controlled pod mounted on the BOP. There were a lot of questions on this.
The Autoshear
This system is operated by a hydraulic trigger valve which functions if the top section of the BOP is unlatched. It wasnt unlatched, so autoshear didnt come into it. There are bottles on the BOP with compressed nitrogen over hydraulic fluid with enough pressure and volume to shear pipe. The compressed nitrogen acts as a spring pushing the fluid and ensuring enough volume.
The autoshear was discussed.
The EDS
This is a two button sequence of events fired from a button in the drillers cabin and other remote panels around the rig. Probably the toolpushers office or bridge. There is one button to enable it, pressed at the same time as the button to actuate it. Buttons are close, so 1 man operation. It fires off a sequence from a surface mounted PLC through the electrical control cables
attached to the riser, down to the BOP main control pods. Put simply, it arms the autoshear if not already armed, it puts all functions not needed in neutral, it closes the shear rams with full hydrauilc operating pressure, it engages locks which will keep the shear rams closed tight even after pressure is removed from the operating cylinders, it unlatches the top section of the BOP from just above the shear rams. The riser is kept in constant pull tension. The tension is calculated to be sufficient to lift the top section of the BOP clear from the BOP with no adjustments required at surface. As the top section(LMRP) parts away from the BOP, the autoshear trigger valve fires, sending a flow of maximum pressure hydraulic fluid onto the close side of the shear ram operating cylinders. The autoshear alone has enough power and volume to shear pipe and seal off the well, but they should already be closed from the EDS.
In less than a minute, the rig can be floating clear of the well leaving the main part of the BOP behind, sealed with a pressure integrity of 15,000psi.
This was fired from one of the remote panels, it was probably operated too late, the control cables to the riser had probably already been destroyed by fire.(I heard that the hand called to operate the EDS saw lifeboats already in the water before he got to the panel, from chat channels) Cant verify that, but for sure the EDS didnt function.
They were questioned on EDS a little. So the manual activation of the EDS was probably too late and the deadman activation of the EDS didnt work, either through fault or correct activation parameters not reached.
On most rigs the driller is not permitted to leave the drillers office on the rig floor while the BOP is connected without relief, in case the need to EDS arises. After this maybe they need to stipulate same for the remote panel in the rig sups office. The delay of a competent person reaching this panel possibly is the reason the EDS activation failed. There were no questions on that aspect.
ROV intervention
A typical ram function ROV intervention circuit is set up-
A small stainless steel panel on the outside edge of the BOP frame. There is a small funnel shaped guide on the front of the panel. Behind the funnel, mounted to the back of the panel, is a socket which will accept a stab from the ROV. The ROV pushes the stab fitting through the funnel into the socket behind the funnel. The stab seals off front and back and delivers hydraulic pressure to the sealed off center section of stab socket. This center section is ported to a threaded hose adapter fitting. There is a high pressure hose screwed to this fitting. The high pressure hose is routed to a similar hose adapter fitting at the function to be operated. The fitting at the function is on a shuttle valve, which shuttles across under pressure to isolate any other control circuits, which may or may not damaged. The ROV then applies pressure, through the stab, the hose, the shuttle and directly into the function. It is a very simple system. About the only way it could fail is if the hose fails. All control hoses are tested to 1.5 times operating pressure before installation. Trouble is one end of the hose had not been fully screwed onto one of the two fittings. It was loose several turns. Having a large leak under pressure means, you cannot be sure full pressure is getting to the function(shear rams need full pressure to shear pipe) and you cannot measure fluid volume to verify you have the correct volume to indicate full close.
Questions danced around this a little, but I dont think everyone was aware this was the main game. The last shot. Some complained it held up operations. So it didnt give 100% because someone neglected/forgot to tighten the hose, it can happen, and with no final tests on bottom, or pre run logged tests, would not be picked up.
Possibly now you have the shear rams partially closed, exposed to serious damage from abrasives and high velocity gas/oil flows, now that the shear rams are pushed out into the bore. One of the ladies worked that out. The Cameron rep confirmed the possibility.
Then they plugged the ROV into the variable bore ram ROV intervention stab. This variable ram would seal the annulus between the 5" drill pipe and the ID 18 3/4" of the BOP bore and protect the shear rams from damage. The variables pressure integrity is also 15,000psi. It turns out that after hours of trying, the hose from the variable bore ram ROV stab is attached to an ineffective test ram. Not the variable ram.
So this ROV stab was also useless. They couldnt have done a much better job of crippling these functions if they tried, yet nobody would admit any mistakes. All last line of defense functions were unserviceable.
Somebody may have started to remove the hose and been distracted, then not returned.
These functions are the ones you know you will never need to use. Not all rigs even test them on surface every time. MMS oversight on these tests has obviously been lax. Most test sheets I have seen do not record ROV intervention circuit tests. Procedures I have seen do ask for these tests.
IMHO the failasfe method of making sure those functions are kept right is to mandate they are tested on bottom with the ROV. If they are not right, pull the BOP back to surface for repairs. That costs big bucks and you know they will be tested on surface.
Stupak was trying to get some info on the ROV stab leaks but they perhaps used his technical weakness to somehow end up talking about the pressure storage bottles on the BOP. It looked a bit slippery to me, but maybe they just didnt understand Stupak. Worth every bit of their $6m dollar pay packets. Probably cant wait to get back to the holiday house on lake Geneva
Transocean asked all crew to sign a document stating they saw nothing as part of their quest for the truth.
Its 5 hrs+ but well worth a listen if you have time.
I have been listening to C-Span and found it very interesting.
http://www.c-span.org/Watch/Media/2010/05/12/HP/A/32852/House+Energy+Cmte+Hearing+on+Oil+Spill.aspx
I guess those old boys who run Transocean, BP and Haliburton cant volunteer much with all the litigation probably pending. They sure seemed to be tap dancing around a few vital issues. I would be hesitant buy a used car from any of them.
The rig was drilling in about 5000' water depth, this is only medium depth. There are rigs in the gulf right now capable of drilling in 10,000'. There are more of these rigs heading that way and I dont see a problem. I dont work GOM. There are many rigs all over the world drilling those water depths and much deeper.
What I got out of it was, and this is just my opinion based on what I heard.
Cause failing to control the blowout=Possible lack of experience/incopentence/mistakes under pressure/delays reacting.
Inability to close the BOP later i.e. the oil slick = Human error/Gross Negligence and possible obstruction inside BOP.
The equipment to prevent all this was there.
They are looking for new ways to ensure this cant happen again. Before they find new equipment and technologies, which may or may not be kept servicable, they need to make shure the safety systems they have work and are activated in time. Everything was there to prevent the blowout and subsequently everything was in place which should have been able to shut the well in from remote or ROV(robot submarine).
The Transocean guy stated the rig had two sets of shear rams. They only had one ROV intervention to shear rams. They didnt say which shear ram had the ROV. One is a "supershear" meaning it has a much bigger hydraulic actuation cylinder, making it capable of shearing heavier pipe. No specific question about that.
The oil slick, emergency equip for closure of the BOP.
Diverter
Bolted right below the rig floor. Once a large amount of gas was in the riser above the BOP this was the only thing which could have saved the crew. 30 seconds to function if set up right. Seals off the riser just under the floor and diverts the flow overboard. Under full blowout conditions, there is no guarantee these will work for more than a few minutes. Imagine trying to divert a 5,000psi large bore inflammable high velocity gas flow containing abrasives around a corner. You cant hear yourself think when this breaks surface. It is terrifying. If you can divert you buy some reaction time and time to get the crew clear. To close the shear rams or do a full EDS takes less than one minute. No questions were asked about the diverter.
Deadman system.
This requires the correct parameters to occur to operate. The control system must lose all signals and power to trigger it. They didnt all go off at the same time the one of the battery they recovered was way down on charge, so the system may have been ineffective. From what I heard their deadman fires the EDS sequence from a battery controlled pod mounted on the BOP. There were a lot of questions on this.
The Autoshear
This system is operated by a hydraulic trigger valve which functions if the top section of the BOP is unlatched. It wasnt unlatched, so autoshear didnt come into it. There are bottles on the BOP with compressed nitrogen over hydraulic fluid with enough pressure and volume to shear pipe. The compressed nitrogen acts as a spring pushing the fluid and ensuring enough volume.
The autoshear was discussed.
The EDS
This is a two button sequence of events fired from a button in the drillers cabin and other remote panels around the rig. Probably the toolpushers office or bridge. There is one button to enable it, pressed at the same time as the button to actuate it. Buttons are close, so 1 man operation. It fires off a sequence from a surface mounted PLC through the electrical control cables
attached to the riser, down to the BOP main control pods. Put simply, it arms the autoshear if not already armed, it puts all functions not needed in neutral, it closes the shear rams with full hydrauilc operating pressure, it engages locks which will keep the shear rams closed tight even after pressure is removed from the operating cylinders, it unlatches the top section of the BOP from just above the shear rams. The riser is kept in constant pull tension. The tension is calculated to be sufficient to lift the top section of the BOP clear from the BOP with no adjustments required at surface. As the top section(LMRP) parts away from the BOP, the autoshear trigger valve fires, sending a flow of maximum pressure hydraulic fluid onto the close side of the shear ram operating cylinders. The autoshear alone has enough power and volume to shear pipe and seal off the well, but they should already be closed from the EDS.
In less than a minute, the rig can be floating clear of the well leaving the main part of the BOP behind, sealed with a pressure integrity of 15,000psi.
This was fired from one of the remote panels, it was probably operated too late, the control cables to the riser had probably already been destroyed by fire.(I heard that the hand called to operate the EDS saw lifeboats already in the water before he got to the panel, from chat channels) Cant verify that, but for sure the EDS didnt function.
They were questioned on EDS a little. So the manual activation of the EDS was probably too late and the deadman activation of the EDS didnt work, either through fault or correct activation parameters not reached.
On most rigs the driller is not permitted to leave the drillers office on the rig floor while the BOP is connected without relief, in case the need to EDS arises. After this maybe they need to stipulate same for the remote panel in the rig sups office. The delay of a competent person reaching this panel possibly is the reason the EDS activation failed. There were no questions on that aspect.
ROV intervention
A typical ram function ROV intervention circuit is set up-
A small stainless steel panel on the outside edge of the BOP frame. There is a small funnel shaped guide on the front of the panel. Behind the funnel, mounted to the back of the panel, is a socket which will accept a stab from the ROV. The ROV pushes the stab fitting through the funnel into the socket behind the funnel. The stab seals off front and back and delivers hydraulic pressure to the sealed off center section of stab socket. This center section is ported to a threaded hose adapter fitting. There is a high pressure hose screwed to this fitting. The high pressure hose is routed to a similar hose adapter fitting at the function to be operated. The fitting at the function is on a shuttle valve, which shuttles across under pressure to isolate any other control circuits, which may or may not damaged. The ROV then applies pressure, through the stab, the hose, the shuttle and directly into the function. It is a very simple system. About the only way it could fail is if the hose fails. All control hoses are tested to 1.5 times operating pressure before installation. Trouble is one end of the hose had not been fully screwed onto one of the two fittings. It was loose several turns. Having a large leak under pressure means, you cannot be sure full pressure is getting to the function(shear rams need full pressure to shear pipe) and you cannot measure fluid volume to verify you have the correct volume to indicate full close.
Questions danced around this a little, but I dont think everyone was aware this was the main game. The last shot. Some complained it held up operations. So it didnt give 100% because someone neglected/forgot to tighten the hose, it can happen, and with no final tests on bottom, or pre run logged tests, would not be picked up.
Possibly now you have the shear rams partially closed, exposed to serious damage from abrasives and high velocity gas/oil flows, now that the shear rams are pushed out into the bore. One of the ladies worked that out. The Cameron rep confirmed the possibility.
Then they plugged the ROV into the variable bore ram ROV intervention stab. This variable ram would seal the annulus between the 5" drill pipe and the ID 18 3/4" of the BOP bore and protect the shear rams from damage. The variables pressure integrity is also 15,000psi. It turns out that after hours of trying, the hose from the variable bore ram ROV stab is attached to an ineffective test ram. Not the variable ram.
So this ROV stab was also useless. They couldnt have done a much better job of crippling these functions if they tried, yet nobody would admit any mistakes. All last line of defense functions were unserviceable.
Somebody may have started to remove the hose and been distracted, then not returned.
These functions are the ones you know you will never need to use. Not all rigs even test them on surface every time. MMS oversight on these tests has obviously been lax. Most test sheets I have seen do not record ROV intervention circuit tests. Procedures I have seen do ask for these tests.
IMHO the failasfe method of making sure those functions are kept right is to mandate they are tested on bottom with the ROV. If they are not right, pull the BOP back to surface for repairs. That costs big bucks and you know they will be tested on surface.
Stupak was trying to get some info on the ROV stab leaks but they perhaps used his technical weakness to somehow end up talking about the pressure storage bottles on the BOP. It looked a bit slippery to me, but maybe they just didnt understand Stupak. Worth every bit of their $6m dollar pay packets. Probably cant wait to get back to the holiday house on lake Geneva
Transocean asked all crew to sign a document stating they saw nothing as part of their quest for the truth.
Its 5 hrs+ but well worth a listen if you have time.
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