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TH Drilling Gumbo Issues
30 August 2019
Whilst drilling 24" / 26" hole sections with seawater& sweeps prior to switching over to DKD mud, gumbo is a major issue with it at times dislodging the DAT from the LPWHH, blocking dispersion tubes on the wellhead, stabs balled up, large accumulations around the wellhead etc etc
Anyone on the forum got similar experiences and possibly suggestions on how to facilitate drilling through these sections.
Looking at 21 previous wells yesterday there was only 2 - 3 wells when gumbo was not an issue and the only common denominator was higher ROP.
8 answer(s)
Enserch
CEO
Opal Petroleum Partners
Total Posts: 2
Join Date: 17/11/16
It been a while since I sat a rig but Mother Nature is fairly constant and I’m sure the gumbo issues we fought 20 years ago are the same as you’re seeing today. We just hit it with lime and worked our way past the gumbo. I tried changing the polarity of the bit to repel the cuttings and all sorts of voodoo but we always come back to the lime. 

Good luck. 

Marc Duncan 
CEO
Opal Petroleum Partners llc. 
Herdi
Performance Improvement Consultant
SPREAD Associates
Total Posts: 11
Join Date: 20/08/07
Many thanks for all the replies.
Wells spud 2021 so hopefully we will have a good handle on the gumbo prior to spud.
Thanks again
Allan
Companyrep
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 413
Join Date: 10/01/05
Search for this previous post on SPREAD
Dealing with "Gumbo attacks"
08 July 2009 quite a few useful points.

As was stated in 2009 and recent post.
There are 'limits to drilling clay' that will evidently result in gumbo. 
Cause and effect that in fact can be quite readily determined and evaluated. 

We know this because in the late 90's we could not figure or understand  out why Unocal and others could drilling top hole (predominantly claystone) so fast. e.g. typically deepwater 17 1/2" (slender well sections) at 80-110m/hr, as this was the max limits where above drillers had noted problem then tended to result.

This was for Sedco 600 and 601 2nd gen semi's with limited pumping capacity i.e 1400hp mud pumps. 

To analyse this I created a simple Mathcad top hole drilling model to see where limits were based on 4-6% by cuttings concentration that historic books have stated is the limit for clay drilling) that I still use today. The limits predicted not surprisingly tied in with what the drillers wells ROP limits as experienced. 

From the model therefore we can state (quite conservatively) what APWD EMW will result (note: this evidently changes as will max ROP permissible as section deepens. Where as section length increases ROP will likley may have to be cut back as hole cleaning and bottoms up times becomes more increasing difficult.) 

If we don't account for this (note we see very little drilling programs stating this) then we are simply asking for problems to result.  

 Above these limits? drillers informed us they started to have mud balls, mud rings, gumbo events etc. So rest assured there are 'soft problem' limits when drilling clay. Mud rings, mud balls, pack offs gumbo etc.

So if your rig has bigger mud pumps with more HHP psi and pump rate capabilities, the max ROP is likely far higher. 

If you are drilling a 26in top hole ROP's are likely halved. 
i.e. 40-60m/hr max at same pump rate i.e. 900-1000gpm.

Rest assured Gumbo does not simply just happen. It is evidently caused by drillers not understanding what causes and effects the problem.

Therefore understand the evident causes, that today one can readily measure downhole conditions i.e. with a APWD sub, to stay in full control, drill at the max limits predicted, and prevent versus cure what often results w.r.t soft claystone.  

Wishing you success on future wells.


Companyrep
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 413
Join Date: 10/01/05
- Pump more.
- reduce ROP as there are limits to how fast instantaneous clay drilling can be drilled .  Model this  (   I.e. based on  4-6% vol by concentrations) 
- afford more energy to bit 100-150 m/sec
to avoid making toothpaste at the bit 
- prehydrated bentonite pulls or pad mud with some polymer etc all helps to 

prevent vs cure this every present problem in certain environments 
ianpetitt
(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 45
Join Date: 14/06/06
Allan ,

As it is easier hole conditions with high ROP this suggest you have an inhibition issue . The longer the exposure the more water is us being absorb into your shale/clay. The more water absorbed the higher the gel strength.  

If you take a shale sample  (gumbo sample) you can get it  analysed. Different types of shale  (i.e. illite or smectite etc,) are better inhibited by different ions. This may lead you or your mud company to a solution for spotting an inhibitive pill during drilling or possible displacing to a weighted inhibited fluid in your well  before running your casing. 

Regards Ian 




tommacrae
Well Control Specialist - Senior Drilling Supervisor
SPREAD Associates
Total Posts: 36
Join Date: 04/11/07
How many outlets have you open on your LPWHH? Some years ago when we had a similar gumbo issue, we used 6 x 4" ROV ball valves. It helped but it would have been better if we had wellheads with larger outlets.
rockbit
Consultant
SPREAD Associates
Total Posts: 23
Join Date: 31/07/11
Look at your cutting size. big cuttings ball up. Higher rpm s help me and less WOB. And anti clay thinner such as Baraphos.
rockbit
Consultant
SPREAD Associates
Total Posts: 23
Join Date: 31/07/11
Look at your cutting size. big cuttings ball up. Higher rpm s help me and less WOB. And anti clay thinner such as Baraphos.
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