# Seismic Data

I have a question about seismic data. In a comment below Don Underwood left a comment that part of what you do is interpret seismic data, so perhaps you could answer this question or if someone else knows please reply.

There has been some seismic work done around Calumet recently. So can you tell me what they hope to learn from the seismic work?

They already know how thick the woodford is in the area because there have been many wells drilled in the area into the woodford and deeper. Since they have a well on almost every section, they know which area has gas, oil, NGL’s and based on the production records know which area has more oil and liquids than other areas. I understand the seismic testing is very expensive so what do they hope to learn that they don’t already know?

Gary-Being a Geophysicist for a very long period of time I think I can help you with this.

Seismic data today is collected in what is termed 3D meaning that an area to be surveyed has geophones (listening devices) spread over the area to be surveyed at intervals of approximately 220 feet apart in one direction and, I am guessing here, 660 feet apart in the direction at right angles to the line of geophones in the other direction. That puts 192 geophones in a square mile. Vibroseis is the usual energy source today. It shakes the ground to produce controled frequency waves that a complex truck mounted recording unit puts the data received from the listening devices on discs. The data is sent to a processing center and "processed" meaning it goes through about 15 to 25 different applications of programming to bring out the clearest images possible from surface to 30,000 feet or deeper. Then the data is sent to the interpreter.

Even though the Woodford shale has been penetrated within the coverage of the 3D survey, the close spacing of the seismic traces allow the interpreter to integrate the existing well penetrations into the seismic data and gain much more insight into just how the Woodford is underlying the area that was surveyed. It is very likely that the area surveyed extended beyond the dense well penetration area. By interpreting the combination of the seismic data with the well data on the Woodford a more complete understanding of the Woodford will be derived. This would include structural configuration as well as variations in stratagraphic information.

I have not seen any seismic data from a survery of the Woodford but I would not be surprised to learn that variations in the stratigraphy of the Woodford could be observed and lead to better placement of infill drilling. Also, coverage of the 3D survey beyond the dense well spacing would lead to the drilling of wells in better locations than could be done without the seismic data.

Yes it is very expensive. Probably around \$35,000 per square mile or more. A 50 square mile survey (7 by 7 miles) could cost \$2 million. With the drilling of the Woodford wells costing \$7-9 million each if you could save just one bad location being drilled you can come out way ahead. You will save a lot more than that in the long run.

I my personal experience having a 3D seismic survey properly interpreted is like "shooting fish in a barrel", meaning the results of the drilling program is highly successful.

Don, thanks for the very good information! I talked to one of the guys doing the seismic work last weekend, and he said they are surveying 125 square miles in the area. The guy said that he expected they might drill as many as 5 to 8 wells per section in the area in the next 6 to 8 years. So I guess they will begin drilling more than one well per section, in the areas that show the most promise, as soon as the seismic data is interpreted.

What County was that survey in? It could cross County lines being that large.

I think there is some movement towards 1280 acre units coming. With the long laterals some Companies are doing that would make sense. I saw one published report that a Company had stretched a lateral over 8000 feet. That would require something like a 1280 acre unit. However I also heard that there is evidence that 80% of the production comes out of the first 1000 feet of the lateral. If that is true that would preclude very long laterals and still hold the unit size to 640 acres. It would also lead to cheaper drilling costs not drilling such long laterals.

I also think several companies are considering 80 acre spacing. That being the case, 5 to 8 wells per 640 would be the optimum to drain the unit. There is a lot more coming from the engineering side of this equation before the final decision on how many wells to drill per section is known. The price of natural gas will play a big part in this decision. However the price of a barrel of oil also plays a large part of this decision.

Don, the survey was taking place south of Calumet in Canadian county. I saw some work a couple of miles north of Calumet, some as much as 5 south and at least 3 miles wide, beyond that I don’t know how far they are going because I just did not go that far. This is an area that has some oil and NGL’s so I am hoping they will drill more wells in the area.

A couple of weeks ago I heard that Dawson was doing some 3D in Grady County. I understand that is the same size survey-125 square miles.

The operators will definitely go for the areas with the better liquid content with the price of natural gas being depressed at around \$4 a thousand. Historically natural gas to oil was at a 6 to 1 ratio based on energy content. With oil at \$85 a barrel that would make natural gas worth, again based on equivalent energy content, \$14.16 per thousand cubic feet. In the reverse with gas at \$4 a thousand, oil should be \$24 a barrel. They diviorced a long time ago and will probably never get back in an energy equivalent equilibrium.

With the number of successful shale gas plays going on all over the U.S. the price of natural gas will probably stay at these levels and may drift down some more.

Hey Don, the folks doing the seismic work around Calumet were Dawson. So maybe when the guy told me they were doing 125 sq mi he was talking about the area in Canadian Co and Grady Co.

Could be. The survey may be trying to extend the "Core", meaning the thicker Woodford and the more oily Woodford southeastward into northern Grady and possibly NE Caddo Counties.

Sooner or later there will be some technical papers written and presented at the Professional meetings and they will make interesting reading. But, they will not be presented or published until the company or two with the inside track based on this research has made their land play.

There is a really good well with oil with the gas in far Southeast Grady. I have lost track of where the test report is. I think it was a Sheridan or Marathon well, not sure about that. The operators would jump at connecting that"core" trend in Canadian County southeastward across Grady County. How wide NE-SW could it be? Unknown at this time and probably will not be known, exactly, for a few years.

I can tell you this, there will be a lot of leases made in the process.

Hopefully good news for all of us.

Great information Don. The Grady well you are thinking of could be Continental Resources in 3N/5W. My section is in 2N/4W Stephens County and Continental has a pooling order pending. So it looks like it is definitely, or should I say hopefully, moving Southeast.

Don Underwood said:

Could be. The survey may be trying to extend the "Core", meaning the thicker Woodford and the more oily Woodford southeastward into northern Grady and possibly NE Caddo Counties.

Sooner or later there will be some technical papers written and presented at the Professional meetings and they will make interesting reading. But, they will not be presented or published until the company or two with the inside track based on this research has made their land play.

There is a really good well with oil with the gas in far Southeast Grady. I have lost track of where the test report is. I think it was a Sheridan or Marathon well, not sure about that. The operators would jump at connecting that"core" trend in Canadian County southeastward across Grady County. How wide NE-SW could it be? Unknown at this time and probably will not be known, exactly, for a few years.

I can tell you this, there will be a lot of leases made in the process.