Spartina- A very good question. Instead of me answering let me refer you to a quote from the last PR and a statement by Phil:
"We believe that the pressure data, flow rates recovered from the DSTs and well logs demonstrate a high quality porous reservoir," stated Mr. Phil Mulacek, Chief Executive Officer of InterOil. "We are pleased to find that our aero-magnetic and gravity data utilized in combination with modern seismic data has yielded our second significant discovery of hydrocarbons in a reefal reservoir in Papua New Guinea. Our forward plan to obtain definitive test results from the lower reservoir section is to set casing over the entire reservoir interval and perforate zones of interest."
http://www.interoil.com/newsrelease/2012..._Final.pdf
Now it can’t be any more clear than that can it? He says it is a “reefal reservoir”. Now the next question. Can it be reefal without being a reef?
Before you asked the question I had always assumed that Triceratops-2 was drilled on a reef. I visualize a reef as being a buildup on a limestone platform. So the reef should be thicker than the surrounding limestone platform. If we look at all of the diagrams presented by IOC such as http://www.interoil.com/presentation/201..._Final.pdf pages 6 & 7 it appears that the seismic indicates several “mounds” around the area. So it looks like we should have reefs.
I am beginning to think the geology here is more complicated than we first believed. Of course nothing is ever as simple as it seems. After looking more carefully at the data, or more specifically comments, IOC has presented I am more inclined to think Triceratops-2 may not be on the “main” reef. We have several hints that Triceratops-2 may not be the “original” or primary reef:
1. http://www.interoil.com/presentation/201..._Final.pdf page 13. “Reef development can only be confirmed by well logs and cores.” (Phil’s comment above was after they had the logs and cores.)
2. “Rock cuttings, believed consistent with the wells off flank position, appear to be mainly detrital and finer grained than the Antelope-1 and Antelope-2 wells.” This sounds like the cuttings indicate the well is on the flank of a reef. “Detrial” means they are seeing rock that has been eroded off of another primary source and re-deposited and cemented at a different location than the original source. This sounds like we are drilling on the flank of a reef that has been eroded and re-deposited.
3. The reef at Antelope has dolomite in layers. The dolomite at Triceratops is distributed throughout the section. I believe this is what you might expect if a nearby reef with layers of dolomite and limestone was eroded off and re-deposited it would be found distributed throughout the section at the new location and would not be found in layers like the original source.
3. The porosity is lower than we expected if we were drilling a true “original” reef.
4. The texture of the rock is finer grained than the reef at Antelope.
5. There is a thick layer of marl in the middle of the section at Triceratops.
6. There are two pressure systems or two separate reservoirs. This does not sound like one big reef.
7. The lower reservoir appears to be separated from the reservoir at Bwata-1. So how is it separated? Is it a fault or some geological phenomenon like a pinch out or a separation by some impermeable limestone barrier (compartmentalization)?
So, what does it all mean? It is like the joke about the pony. With all of this evidence there must be a pony around here somewhere.
The good news about all of this:
1. Phil says it is “a reefal reservoir”.
2. Whatever it is we know it has some porosity and permeability and is capable of producing gas at a rate of at least 28 MMCFD.
3. It is fairly thick, maybe up to 2,200 feet. (Waiting on tests at the bottom for confirmation.)
4. Seismic indicates mounding in the area that might be reefs.
5. Seismic indicates a mound up dip from Triceratops-2 which may be the primary reef or source of the rock we drilled through at Triceratops-2.
6. It appears that we may not have to have a “primary” reef in order to have substantial reservoir rock containing significant gas reserves.
7. Even if all of the rock at Triceratops Field is the same as Triceratops-2 it will be a great discovery.
8. If we find some “primary” reefs the porosity and permeability will be better than Triceratops-2.
9. These eroded and re-deposited reefs make acceptable reservoir rock. This may have good implications for all of the prospects we have around the Antelope reef.. Mule Deer, Deer, Raptor Duckbill, Mountain Lion, White Tail, Grizzly etc. http://www.interoil.com/presentation/201...inal-1.pdf page 21 (magnify to 400%) Eroded and re-deposited reef may be better than fractured limestone only. If we have this type of rock at other locations all we need is a seal and a trap. In this hydrocarbon province, if we have reservoir rock, a seal and a trap it will probably contain either gas or oil or both.
10. There are millions of acres of this limestone platform. There is no reason why we should not find more reefs. Some may be primary and some may have been eroded and re-deposited. We prefer the primary reefs but we can live with the eroded and re-deposited rock if that is what we find.
I have no inside information. All of the above is just speculation on my part, so take it all with a grain of salt or if you prefer, just read the first paragraph and let go at that.
"We believe that the pressure data, flow rates recovered from the DSTs and well logs demonstrate a high quality porous reservoir," stated Mr. Phil Mulacek, Chief Executive Officer of InterOil. "We are pleased to find that our aero-magnetic and gravity data utilized in combination with modern seismic data has yielded our second significant discovery of hydrocarbons in a reefal reservoir in Papua New Guinea. Our forward plan to obtain definitive test results from the lower reservoir section is to set casing over the entire reservoir interval and perforate zones of interest."
http://www.interoil.com/newsrelease/2012..._Final.pdf
Now it can’t be any more clear than that can it? He says it is a “reefal reservoir”. Now the next question. Can it be reefal without being a reef?
Before you asked the question I had always assumed that Triceratops-2 was drilled on a reef. I visualize a reef as being a buildup on a limestone platform. So the reef should be thicker than the surrounding limestone platform. If we look at all of the diagrams presented by IOC such as http://www.interoil.com/presentation/201..._Final.pdf pages 6 & 7 it appears that the seismic indicates several “mounds” around the area. So it looks like we should have reefs.
I am beginning to think the geology here is more complicated than we first believed. Of course nothing is ever as simple as it seems. After looking more carefully at the data, or more specifically comments, IOC has presented I am more inclined to think Triceratops-2 may not be on the “main” reef. We have several hints that Triceratops-2 may not be the “original” or primary reef:
1. http://www.interoil.com/presentation/201..._Final.pdf page 13. “Reef development can only be confirmed by well logs and cores.” (Phil’s comment above was after they had the logs and cores.)
2. “Rock cuttings, believed consistent with the wells off flank position, appear to be mainly detrital and finer grained than the Antelope-1 and Antelope-2 wells.” This sounds like the cuttings indicate the well is on the flank of a reef. “Detrial” means they are seeing rock that has been eroded off of another primary source and re-deposited and cemented at a different location than the original source. This sounds like we are drilling on the flank of a reef that has been eroded and re-deposited.
3. The reef at Antelope has dolomite in layers. The dolomite at Triceratops is distributed throughout the section. I believe this is what you might expect if a nearby reef with layers of dolomite and limestone was eroded off and re-deposited it would be found distributed throughout the section at the new location and would not be found in layers like the original source.
3. The porosity is lower than we expected if we were drilling a true “original” reef.
4. The texture of the rock is finer grained than the reef at Antelope.
5. There is a thick layer of marl in the middle of the section at Triceratops.
6. There are two pressure systems or two separate reservoirs. This does not sound like one big reef.
7. The lower reservoir appears to be separated from the reservoir at Bwata-1. So how is it separated? Is it a fault or some geological phenomenon like a pinch out or a separation by some impermeable limestone barrier (compartmentalization)?
So, what does it all mean? It is like the joke about the pony. With all of this evidence there must be a pony around here somewhere.
The good news about all of this:
1. Phil says it is “a reefal reservoir”.
2. Whatever it is we know it has some porosity and permeability and is capable of producing gas at a rate of at least 28 MMCFD.
3. It is fairly thick, maybe up to 2,200 feet. (Waiting on tests at the bottom for confirmation.)
4. Seismic indicates mounding in the area that might be reefs.
5. Seismic indicates a mound up dip from Triceratops-2 which may be the primary reef or source of the rock we drilled through at Triceratops-2.
6. It appears that we may not have to have a “primary” reef in order to have substantial reservoir rock containing significant gas reserves.
7. Even if all of the rock at Triceratops Field is the same as Triceratops-2 it will be a great discovery.
8. If we find some “primary” reefs the porosity and permeability will be better than Triceratops-2.
9. These eroded and re-deposited reefs make acceptable reservoir rock. This may have good implications for all of the prospects we have around the Antelope reef.. Mule Deer, Deer, Raptor Duckbill, Mountain Lion, White Tail, Grizzly etc. http://www.interoil.com/presentation/201...inal-1.pdf page 21 (magnify to 400%) Eroded and re-deposited reef may be better than fractured limestone only. If we have this type of rock at other locations all we need is a seal and a trap. In this hydrocarbon province, if we have reservoir rock, a seal and a trap it will probably contain either gas or oil or both.
10. There are millions of acres of this limestone platform. There is no reason why we should not find more reefs. Some may be primary and some may have been eroded and re-deposited. We prefer the primary reefs but we can live with the eroded and re-deposited rock if that is what we find.
I have no inside information. All of the above is just speculation on my part, so take it all with a grain of salt or if you prefer, just read the first paragraph and let go at that.