---I posted a message for additional information on Casing Drilling. I need some help with tooling up for setting 1500 to 2000 ft of 9 5/8. Anyone that has some technical advice is welcome to comment---
Will this be surface casing, or something different? Will you need to drill it out? Do you need cement to surface? What are the connections of the pipe you propose? Do you know what the drill ability of the rock is? Is your proposed rig a top drive or kelly drive rig?
I have drilled in many strings of 9 5/8" casing. We spud with this casing, drill 12 1/4" hole from 550' to 2500', depending on TNRC fresh water protection depths. It can be done on just about any rig you can imagine. The questions become, do you want it to be a retrievable system or a drill-in system? Ask more questions and give more information
This is surface casing. No retrieval planned. It has to be cemented and the well will continue out the bottom to a final TD of 5000 to 8000 ft. We will be using a top drive 55 to 75 ton rig with R3 stroke.
Formations are variable. Sandstones and shales mostly with a sticky clay and some gauge zones along faults when encountered. Most of the formations are not very hard.
Normally we are using straight air circulation with a dth hammer. We have considered reverse circulation and trying to set the casing after the hole is complete, but casing drilling (I think) offers some interesting possibilities.
I have looked a lots of webpages and think there is some merit.
I do have questions about thread design. None of the websites offers much in the way of technical details.
When I referred to retrieval or not, I was talking about the drilling assembly. If you elect to use a retrievable assy., you would require a profile nipple in your casing string and a means to pull it (i.e. wireline unit capable of pulling it to surface from TD.)
Without going to this system described above, you may want to look at a type 1 Weatherford Drill Shoe
For casing connections, look at Buttress connections with Noetic torque rings. For centralizers as required by your local regulatory agency, use crimp on style. (Texas Railroad Commission requires 1 cent per 4 joints on surface casing) Both the torque rings and centralizers are readily available from Tesco Corp. We routinely drill in 1500’-2000’ of 9 5/8”. Drilling torque at that depth runs 2-4000 ft/lbs at 120 RPM. Our normal ROP is 100 FPH. I do not install any type wear protection for the couplings due to the short time frame this casing is rotated, but for longer rotating times, it is also available.
Two ways to cement: If using a drillshoe, you can install a normal float collar into your string or you can leave it open and volumetrically displace the cement and WOC holding pressure on the surface. That is how we cement all our surface casing strings and have had 100% success on our 90 wells drilled to date. WOC time w/ Class A “Neat” and 1% CaCl2 is +/-3 hrs.
The type 3 drillshoe from Weatherford is still a little pricy. But you may also look at it. At the website above, there is an animation on how the cutting structure displaces into the wellbore prior to cementing.
Here is another good website that discusses using Weatherford’s drill shoe technique. The drawback to these systems are:
1) Formation strength. I am unable to tell you what compressive strength formations these shoes will drill, but soft sands and shales comes to mind….”i.e. whale BallS**t, snow bank, etc…..” Your local experience and discussions with Greg Galloway w/ Weatherford will provide you an answer to this question.
2) If the bit doesn’t make it to TD for whatever reason, you have to pull the casing to replace it. This probably makes the whole process uneconomical.
3) No directional drilling capability, if it was required.
About the time I sent the last reply I realized what you meant by retrieval.
You must pardon my crossing terms. I come from a varied drilling background i.e. mining exploration, core drilling, foundation, blast hole, HDD and oil and gas.
We have not been in the casing shoe business for some time now, but I really don't see the big problem about making a wireline retrievable system that doesn't need to be drillable materials. The shoe materials outside the drilliout diameter can be premium grade materials with PDC backed yp with harder formation cutters if needed. The drop in system can easily be made to seat at the casing shoe and use medium pressure drop jet nozzles hydraulics without O-Rings.
The devil is in the details, but depending on required sizes you could also do some applications with retrievable BiCenter bits too. Just because there is one or two ways being used doesn't mean they are the only ways.
I would be glad to share our experience and ideas with anyone that is interested. We don't have lawyers to tell us otherwise.
Bi-center technology won't work for casing drilling. First, it does not always drill a true hole size, second, the pass thru to opening size doesn't work out. I don't remember the numbers, but you try the math here. Drilling w/ 23# 7" casing...pass thru is 6.25". I want a minimum of 8.5" hole, but I really need larger. We currently drill 8.875", and we have learned to adequately adjust the ECD's. Smaller hole sizes to pipe size become very finicky with pump rates and cause more occurrences of stuck pipe.
Your idea of putting cutters on the OD of the shoe sounds fine, but does not work in areas where one bit won't make it to TD. If your bit wears out or becomes damaged, you will be required to pull the entire string of casing to replace the bit/drilling assembly. And it is usually the gage cutters that take the abuse in harder formation drilling. The only flow on the OD cutters is fluid moving past them, you don't have jets to help keep them clean in softer formations. Then there are other problems that can be referenced to $$$$ to build something like this. Believe me, I have a drawing on my desk of what you described.
You say a drop in (retrievable) system is easy to build. After having drilled 90+ wells with an average depth of 10,500', I will have to disagree with that statement. After all this time, we continue to have problems reliably running and pulling our drilling systems. Don't get me wrong, we are very successful, but to be able to run a drilling assembly thru 7" casing, land it in a profile that will take all the torque, pressure, WOB, won't release under pressure from below or above, flow of fluid that has been weighted with barite...and 100 other problems...it ain't easy.
You said you would be glad to share your ideas with anyone? Please send me an email at A1driller@aol.com. I would like to discuss on the phone or you can come by my office in Houston. From someone who eats & breathes casing drilling every day, I am very interested if someone has a better idea.
Joined: Mar 2003 Gender: Male Posts: 1,584 Location: Brisbane,Queensland,Australia
Re: Casing Drilling « Reply #9 on Dec 7, 2004, 9:23pm »
Dear Members & Visitors:
Recv'd notification 2004-12-06 16:41:36 for:
Antony Fisher Paper SPE 87998: Extending the Boundaries of Casing Drilling
Shell has targeted casing and liner drilling as one of five mature technologies for an accelerated uptake within its exploration and production companies.
A 9 5/8-in.-surface-casing drilling job performed onshore Brunei in September 2003 used a new casing-drill-shoe design that extends the depth range of rotary casing drilling.
The convertible drill shoe has a novel feature that enables the cutting structure and blades to be extruded once section total depth (TD) is reached.
By this process, the drill shoe converts to a cementing shoe, enabling the casing to be cemented in place.
The cementing shoe and next hole section then can be drilled without interference from the casing-drill-shoe cutting structure and blades.
The mud circulation path in casing drilling is identical to the path taken in conventional drilling means: The mud is pumped through casing drive assembly (top drive, drive spear), through casing and circulated up casing x hole annulus.
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