Antelop 7 depth x time

[Syb3rm0nkey]

I have friend in Singapore that forward this plot to me.

He said it shows that sidetrack is werticle no horizontal.

He also sent comparison of all elk n antelop wells showing target and dept.

He also gave me copy of total planning sumary in pdf file for antelop well. On this link

https://yadi.sk/d/FbnGomSU39rnjw

[hirosan]

So what does this mean?

[jft310]

Lost control of original hole . Broken drill stem ??? Could have happened if they hit the fault ???
Today they are drilling straight down at 1675 meters on Jan 17th .

[ebster123]

So could that mean lots of pressure and therefore gas/condensates?

[jft310]

Ask someone else . I don't know . Sorry .

[Northoil]

[quote='ebster123'

So could that mean lots of pressure and therefore gas/condensates? [/quote]

______________________________________________________________________

There is no "therefore".  It's a very informative drilling history, but tells you nothing about what to expect.  It's true that carbonate reservoirs under an overpressured shale is good for production (expansion drive vs water drive), but sometimes a nightmare to drill. Overpressured shale can be plastic in nature.  So you can drill through it and if you're not careful, or even if you are, it can flow back in above you and trap the drill string.  If you can, normal procedure is to drill though the bad stuff and set casing into the much more competent limestone.  Of course, nothing tells you what fluids are in the limestone.

The green curve is the technical limit for the casing program.  I.e., they have the ability to go to 3300m.  The blue and red curves are the anticipated program and the AFE (Authorization For Expenditure), or budgeted program (note the slack). 

What's really interesting is that the well was AFE'd for 3300m, but planned to go only to 2300m.  Which means the partners all agreed to the money to keep the option to drill the deep prospect.

The black curve is the actual time-depth curve of the well.  It shows they drilled through the anticipated limestone top and casing point, continued to drill and lost the well, moved back to the last casing point, cut a window and drilled out to a current depth of 1675m.  The only other information is  the additional confirmation that the sidetrack is a vertical re-drill.  So they believe there's still room to hit the carbonates and maybe go deep.

[sageo]

[quote='ebster123'

So could that mean lots of pressure and therefore gas/condensates?

______________________________________________________________________

There is no "therefore".  It's a very informative drilling history, but tells you nothing about what to expect.  It's true that carbonate reservoirs under an overpressured shale is good for production (expansion drive vs water drive), but sometimes a nightmare to drill. Overpressured shale can be plastic in nature.  So you can drill through it and if you're not careful, or even if you are, it can flow back in above you and trap the drill string.  If you can, normal procedure is to drill though the bad stuff and set casing into the much more competent limestone.  Of course, nothing tells you what fluids are in the limestone.

The green curve is the technical limit for the casing program.  I.e., they have the ability to go to 3300m.  The blue and red curves are the anticipated program and the AFE (Authorization For Expenditure), or budgeted program (note the slack). 

What's really interesting is that the well was AFE'd for 3300m, but planned to go only to 2300m.  Which means the partners all agreed to the money to keep the option to drill the deep prospect.

The black curve is the actual time-depth curve of the well.  It shows they drilled through the anticipated limestone top and casing point, continued to drill and lost the well, moved back to the last casing point, cut a window and drilled out to a current depth of 1675m.  The only other information is  the additional confirmation that the sidetrack is a vertical re-drill.  So they believe there's still room to hit the carbonates and maybe go deep.

[/quote]

Thank you ,Northoil - For your fine input ! For them all to have agreed to the authorization to go to 10,560 ft tells me that they all saw something on the latest seismics that made them very comfortable with their decision . Maybe OSH will "throw us a bone" during the first week of February ! My best to you and yours .

[Kaliboo]

Building on Northoil's comments:

This is a typical Drilling Plan or Program or Prognosis.  All terms have the same meaning.  The French label (TOT) is "Programme".  The TOT drilling engineer(s) prepared this plan, with inputs from many others.  In the PDF file you can see the well objectives.

This document is classed by TOT as "Confidential" so whoever released this violated companies policies.

Section 3 says they were expecting the Orubadi to be very similar to Antelope 5 and 6.  Notice that the expected gas composition of 5% CO2 and 180 ppm H2S.  These are the acid gases which are contaminants that you don't want and require special, h igher cost metallurgy.  The well is lethally sour (H2S) which requires special drilling and safety precautions that are costly.  This is much more expensive to treat as these gases have to be removed at some point before converting to LNG.  You don't sell the H2S and CO2.

The Orubadi shale is expected to have distinct stratifications as in A5, but the document says seismic is blind to seeing these intra-Orubadi markers and extrapolation to A7 is not possible.  That means they won't know where they are in this sediment until they see it on the downhole logs and mudlogs (surface cuttings analysis).  Also drilling rates can give an indication of a change in lithology.

Section 3.4 shows the targets they are aiming to reach with the bit.  The target box or circle has a 100 m radius at the target depth.  The high (shallowest) target depth is 1803.5 m MD (measured depth from the rig floor elevation).  The base case is 1983.5 m MD (quite a bit lower).  They got to 2127 m MD and ran into well stability problems but they did not see the Kapau pay zone.  Note that OSH must have had a different, deeper estimate of the top of zone depth than TOT as was noted in the last drilling report from OSH.  They expected the Kapau to be deeper.  Looks like they are right and TOT was wrong or maybe it is faulted out and not present.

Section 3.5 they state the intention was to drill a vertical well.  Also it appears they anticipated losing returns while drilling the 22" section.  That means the mud gradient is too high and fracs away into the earth.  These events can lead to kicks and in worst case, blowouts.  Apparently they got through that OK and set 18 5/8" casing.  Also they successfully drilled the next section and set 17 1/2" x 13 3/8" casing successfully.  Drilling out of 13 3/8" casing is where the trouble began.  It was in this next section where they were supposed to find the top of the Kapau.  Apparently they went as deep as they could and ran into hole stability problems and could go no further.  They have plugged back, set a whipstock and milled out through 13 3/8" casing at 1170 m MD.  They are calling it a "sidetrack".  So that term means they are deviating away from the old wellbore and may have changed the target parameters.  If keeping the same target then the hole should have been called a "bypass" which essentially parallels the abandoned hole to reach the same target.

Given that TOT at least thinks the top of the Kapau should have been penetrated, they likely have moved the target back to the east hoping to hit it.  But from my reading it sounds like OSH and TOT never agreed on this.  I would assume that TOT would have set casing and drilled a bypass along the same well plan to the original target if they still thought the target was right.  It is common that when payzones don't come in within the target range, then you plug back up in casing and sidetrack away from the old target to a more likely place.

As of Jan 5 they are drilling a 12.25" hole at 1285m MD.

The procedure calls for setting a 9 5/8" liner which will be hung off inside the 13 3/8" casing, as soon as they drill ~2 m into the Kapau.  That will seal off all of open hole section above the pay zone. There is a strongly worded statement that this is a critical step.  They risk losing total returns as soon as they penetrate the Kapau.  The mud will be too heavy for the Kapau.  If this happens, then the Orubadi in the open hole section can collapse inward losing the hole and/or the Kapau can then flow in causing a big kick.  Of course they would implement well control procedures immediately to regain control of the well as they are anticipating this.  This is where BP lost control in their Macondo blowout as they were not expecting a kick which resulted in gas to atmosphere and a full blowout.  Another story.  Then they will drill out of 9 5/8" through the whole payzone down to the GWC and TD.

Wireline logging is planned after drilling 8 1/2" hole to TD.  They have one contingency string in case they run into problems in the 8 1/2" section.  There is a provisional drill stem test (DST) planned for the 8 1/2" open hole section if it is warranted.  That will be issued as a separate document/plan.

TIMING: The original duration of the well from spud to end was 79 days including a DST and an injectivity test BUT not including NPT (non productive time).  Looking at the progress curve they were at ~45 days (just over half way) when they ran into problems.  According to the days vs. depth plot they were exactly on the Technical Limit curve.  This curve is the fastest, no problems occur, time estimate.  As of 6 AM January 19 (PNG time) they had plugged back, sidetracked and were at 1675 m MD.  They are as of that date, ~48 days behind the Technical Limit curve (which estimated 79 total days).  Or another way to say it, effectively they have only 30 days of progress according to the orginal plan.  So if things were to go perfectly forward, they would be done and P&A'd in 49 days from January 19 OR around March 9.  So much for finishing in January.

The challenge is the Kapau limestone has a significantly lower pore pressure gradient than the Orubadi shale above it.  Hence the need to stop drilling as soon as the Kapau is penetrated, because all returns could quickly be lost, and lose the entire well, requiring another sidetrack or bypass.   On top of that the Orubadi is tough to drill as well as we have seen.  Because seismic is blind here, it's easy to drill your way into trouble if you aren't paying very close attention and/or you get into a hurry.

Section 6.1 Geomechanical Prognosis gives a clue as to what may have led to the instability problems.  The seismic is blind in the Orubadi and they could not determine its dip angle. They believed that if the dip angle was over 60 deg, then instability problems would be much more likely.  Below that angle it was to be less risky.

So this well could be a very long, and very expensive endeavor.  There is no assurance they will be able to reach TD as we have experienced before at Wahoo.

[Stavros]

Thanks Syb3rm0nkey for posting the documents.

Thanks Northoil and Kaliboo for taking your valuable time to study the content and post your conclusions in close-to-layman's terms that we can all understand.

[Kaliboo]

Building on Northoil's comments:

This is a typical Drilling Plan or Program or Prognosis.  All terms have the same meaning.  The French label (TOT) is "Programme".  The TOT drilling engineer(s) prepared this plan, with inputs from many others.  In the PDF file you can see the well objectives.

This document is classed by TOT as "Confidential" so whoever released this violated companies policies.

Section 3 says they were expecting the Orubadi to be very similar to Antelope 5 and 6.  Notice that the expected gas composition of 5% CO2 and 180 ppm H2S.  These are the acid gases which are contaminants that you don't want and require special, h igher cost metallurgy.  The well is lethally sour (H2S) which requires special drilling and safety precautions that are costly.  This is much more expensive to treat as these gases have to be removed at some point before converting to LNG.  You don't sell the H2S and CO2.

The Orubadi shale is expected to have distinct stratifications as in A5, but the document says seismic is blind to seeing these intra-Orubadi markers and extrapolation to A7 is not possible.  That means they won't know where they are in this sediment until they see it on the downhole logs and mudlogs (surface cuttings analysis).  Also drilling rates can give an indication of a change in lithology.

Section 3.4 shows the targets they are aiming to reach with the bit.  The target box or circle has a 100 m radius at the target depth.  The high (shallowest) target depth is 1803.5 m MD (measured depth from the rig floor elevation).  The base case is 1983.5 m MD (quite a bit lower).  They got to 2127 m MD and ran into well stability problems but they did not see the Kapau pay zone.  Note that OSH must have had a different, deeper estimate of the top of zone depth than TOT as was noted in the last drilling report from OSH.  They expected the Kapau to be deeper.  Looks like they are right and TOT was wrong or maybe it is faulted out and not present.

Section 3.5 they state the intention was to drill a vertical well.  Also it appears they anticipated losing returns while drilling the 22" section.  That means the mud gradient is too high and fracs away into the earth.  These events can lead to kicks and in worst case, blowouts.  Apparently they got through that OK and set 18 5/8" casing.  Also they successfully drilled the next section and set 17 1/2" x 13 3/8" casing successfully.  Drilling out of 13 3/8" casing is where the trouble began.  It was in this next section where they were supposed to find the top of the Kapau.  Apparently they went as deep as they could and ran into hole stability problems and could go no further.  They have plugged back, set a whipstock and milled out through 13 3/8" casing at 1170 m MD.  They are calling it a "sidetrack".  So that term means they are deviating away from the old wellbore and may have changed the target parameters.  If keeping the same target then the hole should have been called a "bypass" which essentially parallels the abandoned hole to reach the same target.

Given that TOT at least thinks the top of the Kapau should have been penetrated, they likely have moved the target back to the east hoping to hit it.  But from my reading it sounds like OSH and TOT never agreed on this.  I would assume that TOT would have set casing and drilled a bypass along the same well plan to the original target if they still thought the target was right.  It is common that when payzones don't come in within the target range, then you plug back up in casing and sidetrack away from the old target to a more likely place.

As of Jan 5 they are drilling a 12.25" hole at 1285m MD.

The procedure calls for setting a 9 5/8" liner which will be hung off inside the 13 3/8" casing, as soon as they drill ~2 m into the Kapau.  That will seal off all of open hole section above the pay zone. There is a strongly worded statement that this is a critical step.  They risk losing total returns as soon as they penetrate the Kapau.  The mud will be too heavy for the Kapau.  If this happens, then the Orubadi in the open hole section can collapse inward losing the hole and/or the Kapau can then flow in causing a big kick.  Of course they would implement well control procedures immediately to regain control of the well as they are anticipating this.  This is where BP lost control in their Macondo blowout as they were not expecting a kick which resulted in gas to atmosphere and a full blowout.  Another story.  Then they will drill out of 9 5/8" through the whole payzone down to the GWC and TD.

Wireline logging is planned after drilling 8 1/2" hole to TD.  They have one contingency string in case they run into problems in the 8 1/2" section.  There is a provisional drill stem test (DST) planned for the 8 1/2" open hole section if it is warranted.  That will be issued as a separate document/plan.

TIMING: The original duration of the well from spud to end was 79 days including a DST and an injectivity test BUT not including NPT (non productive time).  Looking at the progress curve they were at ~45 days (just over half way) when they ran into problems.  According to the days vs. depth plot they were exactly on the Technical Limit curve.  This curve is the fastest, no problems occur, time estimate.  As of 6 AM January 19 (PNG time) they had plugged back, sidetracked and were at 1675 m MD.  They are as of that date, ~48 days behind the Technical Limit curve (which estimated 79 total days).  Or another way to say it, effectively they have only 30 days of progress according to the orginal plan.  So if things were to go perfectly forward, they would be done and P&A'd in 49 days from January 19 OR around March 9.  So much for finishing in January.

The challenge is the Kapau limestone has a significantly lower pore pressure gradient than the Orubadi shale above it.  Hence the need to stop drilling as soon as the Kapau is penetrated, because all returns could quickly be lost, and lose the entire well, requiring another sidetrack or bypass.   On top of that the Orubadi is tough to drill as well as we have seen.  Because seismic is blind here, it's easy to drill your way into trouble if you aren't paying very close attention and/or you get into a hurry.

Section 6.1 Geomechanical Prognosis gives a clue as to what may have led to the instability problems.  The seismic is blind in the Orubadi and they could not determine its dip angle. They believed that if the dip angle was over 60 deg, then instability problems would be much more likely.  Below that angle it was to be less risky.

So this well could be a very long, and very expensive endeavor.  There is no assurance they will be able to reach TD as we have experienced before at Wahoo.

Here's a commentary update and correction to my prior comments on this well.

I wonder if this drilling status report received today (from IOC - what a shocker!!!!) is a result of my notifying the proxy company of a serious problem if IOC fails to update us frequently (like daily) up to the meeting date of Feb 14.  As I noted to them, there is a big problem in that proxy votes who have to vote by the 10th cannot change their vote after that day,even though the meeting is 4 days later AND as we can see very big stuff will happen or will fail to happen during that time period.  In either case it is valuable MATERIAL INFORMATION to people making a decision.  Again as I said, Hession's poor planning is creating two classes of shareholders - the majority which are proxy voters and then the rest who will attend the meeting and can vote 4 days later, and have advantage of 4 additonal days of progress info on Antelope 7ST.  NOT FAIR.  Potential lawsuits could happen no matter what they do now, other than delay the vote until well AFTER well operations are finished.  The first deal is botched by Hession and now this one too!  He's being consistent at least.

Speaking of botched, it look's like I botched my statements in the TIMING section above.  My bad.  First of all the well program says the well TD is planned to be 2300 m (before sidetracking).  And now the sidetrack still has the same measured depth TD.   That doesn't quite add up unless they shortened the total TVD depth of the well because the press release is in measured depth.  A sidetrack requires drilling a deviated hole at least a short distance away from a wellbore to get away from the damaged/problem zone.

Also their days vs. depth plot shows they might be drilling a much deeper hole down to 3300m perhaps to Deep Antelope.  It looks like they have plans under consideration.  That's a contingency.  They were NOT tracking their Technical Limit curve as I stated above, when they ran into problems and had to sidetrack.  Sorry about that error.  They were behind about 12 days when they ran  into trouble.  The graph was based on the Most Likely top of Kapau depth of 1983.5 m  (at least the most likely depth per Total and IOC, but probabaly NOT agreed by OSH).  They drilled below this depth to 2127 m and did not see the Kapau top (which was well within expectations per OSH comment in their drilling report o n their web site).  TOT did not run casing at this point, which is typically what a flat spot on a days vs. depth plot represents.  Rather they plugged back and sidetracked and are giving it another go to drill to the same planned TD.  So apparently this well is more like a "Bypass" than a true sidetrack.

So what's left is this?

1.  Drill to top of Kapau.  Based on prior attempt this would be somewhere below 2127 m.  They were at 1980 m ~1.5 days ago probably early Tuesday Jan 31.  They have made about 24 m/day on average from the depth reported on 6 am Jan 19 in a prior posting which was at 1675 m depth.    If they kept this pace, they could drill to TD of 2300 m in about 12 more days from Jan 31  or in others words TD could come near Feb 12. This would be the case where they don't see the Kapau top and just drill on to TD.  But they may see the Kapau.  If so they will stop.

2.  IF they are sure they have penetrated the top of the Kapau, their plan was to stop and run a 9 5/8" liner to the top of it.  Then drill ahead an 8.5" hole to the bottom of the water leg of the Kapau which originally was expected at 2303 m TVDRT.  But their days vs. depth plot is inconsistent from here on.   Clearly if they are in the Kapau, they will want to drill all the way through it.  They will have to get permission from the government to go beyond their permitted depth of 2300 m.    It appears they intended to case off the pay zone after logging it, presumably for flow testing and possible further deepening of the well. Any further deepening would be a contingency case which has not been revealed to us publicly.

So finding or not finding the Kapau pay zone and getting to TD is iminent.  They should know it by readings on their Log While Drilling tools, cuttings in the mud and increase in gas (or oil) content in the mud and cuttings.  Also the Orubadi shale could slow them down, and averaging 24 m/day (78.7 ft/day) may not be possible due to hole problems.  In any case that is a glacial pace.    If things were to speed up, they could surprise us.  It would be nice if they got through it and started logging it with open hole logs, taking samples etc., before casing it off OR P&A the well or deepening it (after permit revision).

So if things go well and we find the Kapau pay zone, we could have it all logged in tested in February.  But from there on that affects only the CRP and those filing lawsuits.

Good luck to all.

Kaliboo