U.S. firm mulls building geothermal power plant from Sidoarjo mudflow
What actually happened.....as far as I can make out
BPJ-1 Well data sheet
Well Name = Banjar Panji 1
Basin = East Java Basin
Political Province = Jawa Timur
Situation = Onshore S
pud Date = March 08,2006
Well Class = Exploration New-field wildcat
Operator = Lapindo Brantas Inc
Contract area = Brantas PSC
Original Latitude = -7.527083 deg
Original Longitude = 112.712500 deg
TD = 9272 ft Depth
Ref Elevation = 37.00 ft
Ground Elevation = 11.00 ft
Objective Depth = 8500 ft
Objective Lithology = carbonate
Objective Lithologic Unit = Kujung Formation
Objective Age Miocene
On 30 May 2006, PT Energi Mega Persada (EMP) announced that it was engaged in well control operations on its subsidiary, Lapindo Brantas’ wildcat Banjar Panji 1. EMP reported that it was undertaking standard well control operations after steam, water and minor amounts of gas bubbling were observed at the surface at 5am on 29 May 2006.
Banjar Panji 1 is the second well in a new drilling campaign in its on/offshore East Java Brantas PSC, and had been drilled to 2,833m in 12-1/4″ hole at the time of incident.
The well had previously been logged prior to the running of 13-3/8″ casing. Spudded on 8 March 2006 using the “TMMJ” rig, Banjar Panji 1 is targeting Miocene Kujung Formation reefal carbonates at a location on the eastern margin of the Wunut gas field which produces from Pleistocene volcaniclastic sandstones.
Banjar Panji 1 has a PTD (Potential Total Depth) of about 3,050m and the prospect has 1-50 Million Barrels of Oil (MMboe) upside resource potential according to partner Santos. Drilling costs to end April 2006 have been quoted at US$ 3,548,926.
Well diagram (when it was killed after mudflow)
The diagram above shows the condition of the well when the incident happened.
It is worth noting here that when you drill a well, drilling fluids are pumped down the drill pipe where they exit into the well bore, collect the rock cuttings and these cuttings travel back to the surface, the drilling fluid is filtered and is reused.
The drilling fluid is given additives to make it heavier than water. The resulting weight of this column of fluid is what keeps the well under control. This is known as the circulation system. Everything involved in the drilling activity is dependant upon constant controlled circulation.
The weight of these fluids being pumped down hole at is critical, too much and the formation can fracture, too little and the well bore pressure can overcome the drilling fluid weight and flow to surface causing a possible blowout.
A stable circulating system is monitored by measuring the volume being pumped and measuring the volume returning to surface. This occurs at the “Trip Tanks” where the filtered fluid is returned for reuse.
As you will see, there are a number of concentric strings of casing which are all suspended from the surface.
The largest of these is the 30” Conductor which only goes to a depth of 150 feet and is used mainly as a guide for the next stretch of hole to be drilled.
The next string is a 20” Casing which was set at a depth of approx 1,200 ft. There is what is termed a liner hanger installed which allows a 16” casing string to be suspended, however, rather than brining this all the way back to the surface, it is suspended within the lower section of the 20” Casing String to a depth of approximately 2,300 feet.
The area between these 30”, 20” and 16” concentric strings is then cemented.
This has now secured the well from Ground level to a depth of approximately 2400 ft and ensures that if there is any flow from the formation that it will be directed into the well bore and the blow out preventers on surface can contain any such unusual action.
The hole was drilled deeper, to a depth of 3,500 ft and a string of casing with a 135/8’ diameter is run into the hole, suspended within the wellhead at the surface and once again, the internal area between the casing strings is cemented.
The next stage in the drilling process involved the drilling to a depth of 8,500 feet in preparation for the last of the casing strings which was (I presume) 9-5/8” in diameter and as above the pipe would be suspended from the wellhead at surface and once again cemented.
The completion process would then normally be undertaken and the hole would be drilled to its final depth of approximately 9,300 feet and a string of tubing would be lowered into the hole.
Where this tubing leaves the bottom of the 9-5/8” casing at a depth of 8,500 feet, a device called a Packer would be installed to seal off the area between the outside diameter of the tubing and the inside diameter of the 9-5/8” casing.
The tubing was to have been set at a depth of approximately 9,200 - 9,300 feet, the Christmas Tree on the top of the wellhead is secured and the well can handed over for production.
What happened here is that once the drill crew reached the depth of 8,500 feet, they were instructed not to follow the drilling programme which was to stop drilling and run the 9-5/8” casing string.
It was then instead decided to drill ahead and at somewhere around 9.000 feet, and without the protection of the 9-5/8” Casing String they hit problems.
At this depth they encountered losses with drilling fluid entering the formation. This would normally result in the cessation of returns to surface. On this occasion, the “Trip Tank” volume remained relatively stable which indicated that formation fluid was entering the well bore above the area where the losses were occurring.
The rig apparently continued to circulate and commenced pulling out of the hole. This was undertaken slowly in order to ensure safety, and at some pint during this operation the Rig took a “Kick” A “kick” occurs when the formation pressure is greater than the weight of the drilling fluids. The formation fluids, in this case the mud, started to flow to surface, at first slowly and then increasing in volume.
The illustration above which shows the circulation system shows a number of various ways that this could occur.
It is unclear what happened at this point. Certain reports indicated that the drill crew abandoned the rig, but this has been unconfirmed.
Upon the crews return to the rig, efforts were made to deal with this “Kick” and the primary surface safety devices known as the Blow Out Preventers (BOP) and the Choke and Kill Manifold (a series of valves and pressure reduction devices) performed their task. The well was eventually brought under control.
With this stabilisation in place, efforts were made to retrieve the drill string and start remedial work to eliminate the problem.
The drill string however got stuck at about 4,300 feet and attempts were made to free the string. These were unsuccessful. A primary safety device in the drill string called a drilling jar, (a device which can be used to impart a jarring force in an effort to “unstuck” drill pipe may have failed to operate) and a decision was made to unscrew the drill pipe above the area where the pipe was stuck, retrieve what drill string they could and leave the stuck drill pipe in the hole.
In order to make the well bore secure the next operation was to pump cement on top of the drill pipe and drill bit.
This cementing was performed thoroughly, the drill string was backed off and brought to surface and a second cementing operation was undertaken.
With this plug in place it would then be possible to commence milling on the drill pipe, in an attempt to clear the well bore of any debris. With this operation completed it would then be possible to resume normal drilling activities and run the protective 95/8” casing.
However, this is where nature lends her hand. The area where they were drilling has potential fractures which rise from the depths to the surface.
Within the same period, there was the earthquake in Yogokarta. This seismic activity could have resulted in geological changes which made the area less secure.
As the pressure from the mud flow attempted to flow from the reservoir to the surface, the cement plug in the well bore contained this pressure, however, as the 9-5/8” casing had not been set, this whole section of the well bore was allowed to become over-pressured and consequently, the mud found an easier path to surface and created the mini vlocano’s as well as causing the area surrounding the rig to crater.
At this point it can be presumed that the rig was deemed unstable and removed from site. After the rig was removed, nothing further could be done to rectify the original problems from this location and a new location was sought for the drilling of a relief well, which was unsuccessful.
As you will appreciate, a full report has not yet been made public (despite caims that it has), accordingly most of the above is an educated guess. However, it is fair to say that errors were made.
1)
The decision to drill ahead without the protection of the 9-5/8” casing string was incorrect. Without this barrier, influx from the formation was not prevented, the Rig encountered a “Kick” and later as a result the drill pipe became stuck.
2)
It is possible that more could have been done to free the stuck drill pipe (was the drilling jar function tested prior to use) and retrieve it to surface. This would have prevented the necessity of pumping cement into the hole as a barrier around the stuck drill pipe. Unfortunately, with no published evidence this cannot be confirmed.
3)
The decision to pump the cement may not have been fully assessed prior to the operation. Consideration of the geology, the possible after effects of the earthquake and well bore conditions may not have been fully researched and the consequences not foreseen.
In each of the above, the Drill Crew would not have been taken part in the decision making process. The decisions would have been made by the Oil Company and transmitted to the Drill Crew by the Company Representative on site.
The rest is history!
BPJ-1 Well data sheet
Well Name = Banjar Panji 1
Basin = East Java Basin
Political Province = Jawa Timur
Situation = Onshore S
pud Date = March 08,2006
Well Class = Exploration New-field wildcat
Operator = Lapindo Brantas Inc
Contract area = Brantas PSC
Original Latitude = -7.527083 deg
Original Longitude = 112.712500 deg
TD = 9272 ft Depth
Ref Elevation = 37.00 ft
Ground Elevation = 11.00 ft
Objective Depth = 8500 ft
Objective Lithology = carbonate
Objective Lithologic Unit = Kujung Formation
Objective Age Miocene
On 30 May 2006, PT Energi Mega Persada (EMP) announced that it was engaged in well control operations on its subsidiary, Lapindo Brantas’ wildcat Banjar Panji 1. EMP reported that it was undertaking standard well control operations after steam, water and minor amounts of gas bubbling were observed at the surface at 5am on 29 May 2006.
Banjar Panji 1 is the second well in a new drilling campaign in its on/offshore East Java Brantas PSC, and had been drilled to 2,833m in 12-1/4″ hole at the time of incident.
The well had previously been logged prior to the running of 13-3/8″ casing. Spudded on 8 March 2006 using the “TMMJ” rig, Banjar Panji 1 is targeting Miocene Kujung Formation reefal carbonates at a location on the eastern margin of the Wunut gas field which produces from Pleistocene volcaniclastic sandstones.
Banjar Panji 1 has a PTD (Potential Total Depth) of about 3,050m and the prospect has 1-50 Million Barrels of Oil (MMboe) upside resource potential according to partner Santos. Drilling costs to end April 2006 have been quoted at US$ 3,548,926.
Well diagram (when it was killed after mudflow)
The diagram above shows the condition of the well when the incident happened.
It is worth noting here that when you drill a well, drilling fluids are pumped down the drill pipe where they exit into the well bore, collect the rock cuttings and these cuttings travel back to the surface, the drilling fluid is filtered and is reused.
The drilling fluid is given additives to make it heavier than water. The resulting weight of this column of fluid is what keeps the well under control. This is known as the circulation system. Everything involved in the drilling activity is dependant upon constant controlled circulation.
The weight of these fluids being pumped down hole at is critical, too much and the formation can fracture, too little and the well bore pressure can overcome the drilling fluid weight and flow to surface causing a possible blowout.
A stable circulating system is monitored by measuring the volume being pumped and measuring the volume returning to surface. This occurs at the “Trip Tanks” where the filtered fluid is returned for reuse.
As you will see, there are a number of concentric strings of casing which are all suspended from the surface.
The largest of these is the 30” Conductor which only goes to a depth of 150 feet and is used mainly as a guide for the next stretch of hole to be drilled.
The next string is a 20” Casing which was set at a depth of approx 1,200 ft. There is what is termed a liner hanger installed which allows a 16” casing string to be suspended, however, rather than brining this all the way back to the surface, it is suspended within the lower section of the 20” Casing String to a depth of approximately 2,300 feet.
The area between these 30”, 20” and 16” concentric strings is then cemented.
This has now secured the well from Ground level to a depth of approximately 2400 ft and ensures that if there is any flow from the formation that it will be directed into the well bore and the blow out preventers on surface can contain any such unusual action.
The hole was drilled deeper, to a depth of 3,500 ft and a string of casing with a 135/8’ diameter is run into the hole, suspended within the wellhead at the surface and once again, the internal area between the casing strings is cemented.
The next stage in the drilling process involved the drilling to a depth of 8,500 feet in preparation for the last of the casing strings which was (I presume) 9-5/8” in diameter and as above the pipe would be suspended from the wellhead at surface and once again cemented.
The completion process would then normally be undertaken and the hole would be drilled to its final depth of approximately 9,300 feet and a string of tubing would be lowered into the hole.
Where this tubing leaves the bottom of the 9-5/8” casing at a depth of 8,500 feet, a device called a Packer would be installed to seal off the area between the outside diameter of the tubing and the inside diameter of the 9-5/8” casing.
The tubing was to have been set at a depth of approximately 9,200 - 9,300 feet, the Christmas Tree on the top of the wellhead is secured and the well can handed over for production.
What happened here is that once the drill crew reached the depth of 8,500 feet, they were instructed not to follow the drilling programme which was to stop drilling and run the 9-5/8” casing string.
It was then instead decided to drill ahead and at somewhere around 9.000 feet, and without the protection of the 9-5/8” Casing String they hit problems.
At this depth they encountered losses with drilling fluid entering the formation. This would normally result in the cessation of returns to surface. On this occasion, the “Trip Tank” volume remained relatively stable which indicated that formation fluid was entering the well bore above the area where the losses were occurring.
The rig apparently continued to circulate and commenced pulling out of the hole. This was undertaken slowly in order to ensure safety, and at some pint during this operation the Rig took a “Kick” A “kick” occurs when the formation pressure is greater than the weight of the drilling fluids. The formation fluids, in this case the mud, started to flow to surface, at first slowly and then increasing in volume.
The illustration above which shows the circulation system shows a number of various ways that this could occur.
It is unclear what happened at this point. Certain reports indicated that the drill crew abandoned the rig, but this has been unconfirmed.
Upon the crews return to the rig, efforts were made to deal with this “Kick” and the primary surface safety devices known as the Blow Out Preventers (BOP) and the Choke and Kill Manifold (a series of valves and pressure reduction devices) performed their task. The well was eventually brought under control.
With this stabilisation in place, efforts were made to retrieve the drill string and start remedial work to eliminate the problem.
The drill string however got stuck at about 4,300 feet and attempts were made to free the string. These were unsuccessful. A primary safety device in the drill string called a drilling jar, (a device which can be used to impart a jarring force in an effort to “unstuck” drill pipe may have failed to operate) and a decision was made to unscrew the drill pipe above the area where the pipe was stuck, retrieve what drill string they could and leave the stuck drill pipe in the hole.
In order to make the well bore secure the next operation was to pump cement on top of the drill pipe and drill bit.
This cementing was performed thoroughly, the drill string was backed off and brought to surface and a second cementing operation was undertaken.
With this plug in place it would then be possible to commence milling on the drill pipe, in an attempt to clear the well bore of any debris. With this operation completed it would then be possible to resume normal drilling activities and run the protective 95/8” casing.
However, this is where nature lends her hand. The area where they were drilling has potential fractures which rise from the depths to the surface.
Within the same period, there was the earthquake in Yogokarta. This seismic activity could have resulted in geological changes which made the area less secure.
As the pressure from the mud flow attempted to flow from the reservoir to the surface, the cement plug in the well bore contained this pressure, however, as the 9-5/8” casing had not been set, this whole section of the well bore was allowed to become over-pressured and consequently, the mud found an easier path to surface and created the mini vlocano’s as well as causing the area surrounding the rig to crater.
At this point it can be presumed that the rig was deemed unstable and removed from site. After the rig was removed, nothing further could be done to rectify the original problems from this location and a new location was sought for the drilling of a relief well, which was unsuccessful.
As you will appreciate, a full report has not yet been made public (despite caims that it has), accordingly most of the above is an educated guess. However, it is fair to say that errors were made.
1)
The decision to drill ahead without the protection of the 9-5/8” casing string was incorrect. Without this barrier, influx from the formation was not prevented, the Rig encountered a “Kick” and later as a result the drill pipe became stuck.
2)
It is possible that more could have been done to free the stuck drill pipe (was the drilling jar function tested prior to use) and retrieve it to surface. This would have prevented the necessity of pumping cement into the hole as a barrier around the stuck drill pipe. Unfortunately, with no published evidence this cannot be confirmed.
3)
The decision to pump the cement may not have been fully assessed prior to the operation. Consideration of the geology, the possible after effects of the earthquake and well bore conditions may not have been fully researched and the consequences not foreseen.
In each of the above, the Drill Crew would not have been taken part in the decision making process. The decisions would have been made by the Oil Company and transmitted to the Drill Crew by the Company Representative on site.
The rest is history!