A well site is at 4000' in elevation, the bore is proposed to sink 9000' into the ground and enter a production zone. The horizontal pipe is bored through the production zone north from the entry point and is to stop 660' south of the north section line 4000' more or less north of the entry point.
The drilling company wants coordinates to create a plan to make all this happen.
The well plat shows surface distances and coordinates are given in State Plane which is at sea level. How much error is there 4000' below sea level with SPC coordinates and would it cause the end pipe to stop too close to the section line and does it mean anything at those depths anyway? Can anyone really check those underground locations. I've been told they can but I'm skeptical. The elevation scale factor is simple enough to calculate 9000/20906000x4000'=1.7'.
That oil field stuff is plus or minus a few feet anyway. Can't count the wells that I have staked to find later that they were moved around to fit the terrain.
It doesn't make any difference. Wellbore technology, well spacing, drilling limits normally take in the errors inherent with the drilling process involved. Traveling around the oil patch last week I was "invited" on to a drilling rig doing a horizontal well of approximately 12,000' from the surface borehole location. It was an eyeopener. When it takes up to 8 million or more to drill one of them they don't do it by guess or by golly! On site computerization was giving a constant update of the bottom hole conditions i.e. bit pressure, temperature, elevation, gamma ray readouts etc. It was cool.
Pablo
Can't count the wells that I have staked to find later that they were moved around to fit the terrain.
They are doing that with the vertical bores and small pads, but with these horizontal ones and the 8 acre pad sites, they are taking more care. I'm not sure how they locate the downhole endpipes but they insist it works and they get an accurate location.
They do want to push the limits.
I don't show anything that I can not locate.
Any thing that is of plan or of theory underground is just that.
The people that I have staked units for have a well design engineer that will put all that on a drawing and summit that information to the state for approval.
0.02
feel free to forego the dimple on this one.... 😉
My oldest boy has been all over the world doing this. He now is one of the owners of a company in Texas still doing directional drilling and have opened 4 or 5 offices.
Different states have different requirements for well drilling and down hole survey and location requirements. Some clients have the reservoir data, seismic data, and drilling plans on NAD27 datum. It is not unusual to supply both NAD83 & NAD27 coordinates for corners in a 4 section area for just one well bore. Dimples are something I don't care about unless attached to SWMBO......B-)
Pablo
A directional drilling company purchased software from me twenty years ago in order to compute the convergence angle between Grid North and True North. My impression is that they want it to be perfect on paper, and they attempt to match that in the real world. I have no idea how successful they are, but they sure do make lots of money.
Most of the drilling companies have the software that takes most of it in to account, we show NAD83 & NAD27 coordinates on the well and all four corners of the section and if the is much deflection, we'll show the ¼ corners too. Some just ask for a .dwg or .dwt showing just the line work on the section.
I just can't help but believe accurate elevations are important too! To drill down 9,000' feet and then horizontally 10,000' while staying within a 13' vertical pay zone is story within itself. B-)
Pablo
I have a friend that has been an engineer for Chevron for the last 30 years or so. He has worked drilling all over the world. Been years ago that I asked him how they do it. They have or did back then a down hole tool that measures all the angles as they go. Then you could calculate vectors from one point to the next (sort of a traverse). He said it was very accurate. It's probably super accurate this many years later with newer technology.
Sounds like a NCEES test question....:'(
The people that I have staked units for have a well design engineer that will put all that on a drawing and summit that information to the state for approval
They do the same here, what I'm not quite clear about is how does the bottom hole location relate to the section line 9000' higher in elevation. For some reason a client I have needs to push the bottom hole location right up to the limit.
Should the section line be projected down or the bottom hole location projected up. The implication is that if the pipe gets too close to the section line then the mineral owner in the next section gets a part of the mineral rights.
And if they lay out the pipe using surface distances then they will be 2' too long each mile so for a 10000' foot horizontal length they are 4' too long
They get the elevation at the "surface hole location" from us, and I guess the "pay zone" they probably get from the 3d seismograph
gyroscope
Never met anyone in the oil industry that worries about feet.
They talk in rods and pipe length and then skip all the way to miles.
B-)
In our neck of the woods the mineral rights from the surface (whether section line/unit line or property line) project down to what ever the depth the target sand that is leased. Meaning the unit line/section line is a representation of the mineral rights lease below ground.
So a lot of states have spacing rules in place to ensure (in theory) that the producing well will not produce from the adjacent mineral lease. Some are field specific but usually it is either 330' or 440' from the lease line (ie section/unit line).
In LA the shale frac wells are usually leased on a sectional (1mi sq) basis, but the traditional non-shale wells are based on the actual geologic structural trap they are drilling in. Which is typically defined by the oil/water line and closing faults.
Hope this helps.
Of course I could have completely missed mark on your question. In this case enjoy free info.
> A well site is at 4000' in elevation, the bore is proposed to sink 9000' into the ground and enter a production zone. The horizontal pipe is bored through the production zone north from the entry point and is to stop 660' south of the north section line 4000' more or less north of the entry point.
>
> The drilling company wants coordinates to create a plan to make all this happen.
>
> The well plat shows surface distances and coordinates are given in State Plane which is at sea level. How much error is there 4000' below sea level with SPC coordinates and would it cause the end pipe to stop too close to the section line and does it mean anything at those depths anyway? Can anyone really check those underground locations. I've been told they can but I'm skeptical. The elevation scale factor is simple enough to calculate 9000/20906000x4000'=1.7'.
It doesn't matter. What you'll end up furnishing is a cad plat for the driller to steer by and the will TD the well close and plug back. Then, if it's like Texas, you'll be given a downhole survey to prepare an as drilled plat to note the POP (point of penetration), FTP (first take point), LTP (last take point) and BH (bottom hole). You will have to get them to give you those values as the downhole survey only notes tvd and md and they will know where they enter the zone, begin producing, quit producing, and stop drilling but you won't be able to discern it from any downhole survey I've ever seen by halliburton, slumberger, or scientific. Some are better tha others.
Kris is correct. The client needs to furnish you the take points. With out it the directional plan is useless.
