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Permalink Reply by The_Baron on June 9, 2010 at 4:15

directional drilling is nothing new. We have been doing it for a long time. Used to be important for drilling under water bodies like lakes and rivers. Also proves useful for drilling under land where you have no surface use, or where there is sensitive surface conditions.

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Permalink Reply by Mac Davis on June 9, 2010 at 4:20

I understand. What I'm asking is do they use active steering techniques to guide the vertical section of typical horizontal HA wells?

If the vertical is slanted, do you start vertical at the surface and then steer off to the side to hit the top of the turn?

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Permalink Reply by awharris on June 9, 2010 at 11:13

I'm not a drilling engineer or part of any HA drilling but here's my understanding.

If the surface location is in the correct spot (ie, 330' off of the SW corner), then a traditional vertical wellbore will be drilled to near the top of the HA. While all wellbores wander a bit, it usually isn't significant in this area. Almost all wellbores today (vert and horiz) have a "check-shot" survey from top to bottom to verify for the State that the well is drilled within the bounds of the section and lease, etc.

For horizontal wells, the directional crew usually won't be called out until the horizontal section is drilled off of casing point of the vertical hole. However, if the surface location is different than the intended entry point into the reservoir, horizontal drilling techniques will be used to steer to the right spot...even crossing section lines, etc.

Years ago (and sometimes still today) directional holes were drilled via a single or multiple kickoff points (whipstocks) set in the hole. Most current horizontal wells are now drilled through a cocked-bit tool that allows optionally rotating the whole string to drill straight in the current path or not rotating and turning a downhole motor in order to build angle. The latest (and highest $$$) technique is "rotary steerable" drilling whereby surface rotation of the drillstring is continuous but angle is built via a downhole tool that nudges the bit to the correct and intended compass spot on each circuit.

The way the directional drillers ascertain the path of the wellbore is by a downhole tool which transmits the azimuth and inclination up the annulus with a mud pulse. This allows an integration of the wellbore trajectory to be calculated.

So to elucidate some of the terminology:

"vertical" means the well was not intended to be horizontal well and was drilled without looking at where it was going while it was being drilled.
"directional" can be either vertical or horizontal but was drilled using one of the three techniques discussed above. A vertical, directional well may be drilled to hit a very tight target or stay off of boundary lines or enter the reservoir at a point other than near the surface geolocation.
"horizontal" means the well was intended to go more or less perpendicular to the surface in order to maximize the reservoir contact in a single-horizon, primary target.

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Permalink Reply by Mac Davis on June 10, 2010 at 4:33

Thanks.

Wow, I'm amazed that you can "blindly" drill down 10,000' and end up anywhere close to the spot you were aiming for. However, since you're going to go directional before you make any perforations, I guess you have some "wiggle room" to straighten things out there, too. Even if you ended up too close to the edge of your unit with the vertical bore, as long as no perforations are too close to the edge of the unit, you don't end up "stealing" any gas from the wrong unit.

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Permalink Reply by Skip Peel - Mineral Consultant on June 10, 2010 at 4:38

Mac, there is no set back required from the unit line for the surface location. Or the vertical portion of the wellbore. The surface location can even be across the line in an adjoining section. The 330' minimum setback from the unit boundaries applies only to the perforation points in the lateral.

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Permalink Reply by Mac Davis on June 10, 2010 at 5:34

Yes, I understood that, Skip. What I was saying was that if the bit wanders and you end up closer to the line than you wanted to be for the top of your curve, you can make it up by directional drilling techniques between the top of the curve and your first perforation point.

The perforation points are the only ones that "count," I guess.

I guess if you accidentally wander across the section line with your well bore, you might need to negotiate with the property owner over on that side.

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Permalink Reply by Skip Peel - Mineral Consultant on June 10, 2010 at 5:45

You bring up a good point, Mac. One of the advantages of negotiating a "no surface use" clause in a lease is that a landowner will have the opportunity to negotiate a surface location (and associated rights of way) and wellbore easement for wells drilled into adjoining sections for which they receive no royalty income. Lacking such a clause, the lessee will receive that benefit.

As I understand it, bits are not allowed to wander through the use of MWD (Measurement While Drilling) and other sophisticated tech beyond my pay grade. Since the play began there have been significant tech improvements including mud motors that can turn tighter radiuses and improved bit design that increases ROP (Rate of Penetration). That's how the spud to TD times are being shortened and the cost of drilling a well reduced.

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Permalink Reply by Walter Phillips on June 11, 2010 at 3:52

Just to clarify, a gyro(scopic) survey is used to follow and document the position of the well bore. A check-shot survey is used to measure the velocity of sound in the rock layers around the well and is used to build a time-to-depth relationship for tieing seismic data to well logs.

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Permalink Reply by Skip Peel - Mineral Consultant on June 11, 2010 at 5:47

Walter, thanks. There are a lot of members interested in the technology of the Play. Please consider authoring a blog on the subject.

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Permalink Reply by Walter Phillips on June 15, 2010 at 4:52

Thanks, Skip. I wish I had the time to think about a blog, but it's just not there right now. I'm happy to help answer geological or geophysical questions when I can. I really appreciate what this whole forum does to help folks understand all the different aspects of the Haynesville play. I know I've learned a lot from the different topics that come up and the responses from knowledgeable members.

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Permalink Reply by Skip Peel - Mineral Consultant on June 15, 2010 at 5:02

I have a question regarding faults. Though faults are a fact of life in the stratigraphic column in the area of the Play, we have seen little mention by the operators. There are now maps that have been made public which show a number of faults to an accurate degree to the best of my knowledge. I have noticed that some sections on a continuous fault line have horizontal wells and some do not although some that do not have status 10 wells for other formations likely holding leases in force. In your opinion, is it likely that operators will drill horizontal wells in only a portion of a section avoiding the fault or will they attempt to drill through the fault?

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Permalink Reply by Walter Phillips on June 17, 2010 at 10:53

Skip, for the most part I would be very surprised to see an operator drill a horizontal well across a fault in the Haynesville. I have looked in detail at more than a few directional surveys for Haynesville wells and am amazed at how tightly controlled they are. They manage to steer the bit to keep it within a few feet of their reference point within the section. Any vertical offset across a fault would make it much harder to keep a horizontal well in that sweet spot. Also, faults often act as pressure barriers and you might see enough of a pressure difference across a fault to cause drilling problems. Right now, with so many undrilled sections that are clear of faults, operators are drilling the "easy" sections and not worrying about the faults. At some point as we learn more about the Haynesville and as economics dictate, it will make sense to survey the faults in much greater detail and decide how close you can drill to them and get the benefit of the resources on those sections.

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