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Off Topic Driller questions

Last Post 17 Jun 2009 01:40 AM by cajundriller. 4 Replies.

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TechGromit User is Offline

Advanced Member

Posts:634

26 May 2009 09:58 AM
I have some questions for drillers I'm curious about. From what I understand about drilling, at least what I've seen on TV with oil rigs. There a drill bit on the end of a shaft and the drill rotates around digging into the ground. When the shaft get too close to the ground. Drilling stops, you use a gripper to hold the shaft section into place, reverse the drill, there by unscrewing the shaft section from the drill, screw in a new section of shaft onto the end of the shaft that the gripper is holding, screw the drill onto the top of the new shaft section, uncouple the gripper and continue drilling until the new shaft section is near the ground, repeat. Now my question is what if the drill bit become stuck, do you just pull the bit up, I'm assuming you can't reverse the drill, wouldn't that unscrew a shaft section? Then the ultimate screwup, let's say the hole done and your backing the bit out, one shaft section at a time and the gripper that's holding all the shafts and the drill bit on slips off the gripper and into the hold. How do you fish it out? After the hole is complete say for a water well, you do pull the bit and shafts out and insert new pipe leading to the water, right? The pipe sections are hollow, so you know when you strike water, but isn't the drill bit a pricey item? You wouldn't want to lose one right? What about when they drill for oil and you see oil gushing out when they strike oil, is it more cost effective you just leave the 10k bit in the ground instead of going to the trouble of removing it and inserting standard pipe? If so when the well runs dry, can you recover the bit then?

BillN

New Member

Posts:53

27 May 2009 07:18 AM
nothing is left in the well the bit never reverses bits dont really get stuck the drill rods are hollow for air, or mud to travel down to the bit for cooling & lubrication pipes are inserted after the drill rods & bit come out. oil rigs are different

Brock

Advanced Member

Posts:599

27 May 2009 11:00 AM
I just found out most of the wells drilled around here (upper Midwest) don't have a casing or sides more than 20 feet down and that they are just left as a hole. Does the casing go in after the fact? Or is it larger than the hole being drilled? How often do wells cave in or collapse?

Green Bay, WI. - 4 ton horizontal goethermal, 16k gallon indoor pool, 3kw solar PV setup, 2 ton air to air HP, 3400 sq ft

waterpirate User is Offline

Basic Member

Posts:467

27 May 2009 06:57 PM
WOW!!!! That is a lot of requested info, but here it goes. In direct mud rotary drilling, drill fluid is circulated down the rods and cuttings are removed up the annular space between the rods and the borehole. Yes rods and bits and everything your helper can drop does fall down the hole. In the oil fields there is a niche market of drillers who do nothing but "fish" lost tooling out of holes. On a smaller scale fishing tools are made by the person who lost the tools in an effort to recover them and not get fired. The hydraulic pressure of the fluid in the borehole keeps the hole open for the insertion of the casing or the loop. In water well work it very uncommon to get tooling stuck as the process is very controlled with the hole needing to produce a product at the end. In geothermal drilling it is verry likely that you will lose a string of rods down the hole as it is common practice to overdrill your rate of circulation to make production. A geo hole only needs to remain open long enough to send the loop and grout, water work is another animal. I tell people that if it is on the drill site I have lost it down the hole at one time or another. If you are drilling geo work and have not lost a tool string you are not drilling fast enough, and taking up to much room by not being on the edge. In air rotary drilling in consolidated formations (rock) it is only neccassary to case the overburden and set it in the rock. When drilling rock, once you make hole it stays, much like drilling in a piece of wood, sortof. Hope this helps, or maybe more questions? Eric

Eric Sackett<br>www.weberwelldrilling.com<br >Visit our Geothermal Resource Center!

cajundriller User is Offline

New Member

Posts:13

17 Jun 2009 01:40 AM
If you did need to fish you would need either a tapered threaded tap to screw inside joint of pipe or sometimes you would use an overshot which is for example take a plastic cup and turn it upside down. Overshot to go over fish and rotate w/ weight untill it threads itself onto the fish then trip pipe out of the hole hopefully w/fish. Sackett is right any decent driller is aware of mud properties/pick-up weight/torque/ect and better not twist off or usually gets run off anyway.But if you do get stuck then there is what they call free-point back off and you would find that point then back out above stuck point then set a cement plug on top of fish then kick off and side track then continue to TD. FYI don't do any drilling untill you have worked under a driller for a while, or it could get really expensive.

William Wainwright