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.