Private Forums
anti-balling procedures
12 January 2017
Happy 2017 all!

Have had reported some symptoms of bit balling (low tq, poor ROP response to WOB) whilst drilling a proven unreactive shale (!?) using high performance WBM (c/w 1% K Silicate), 4000m, high mw/overbalance for BHS. Limited/No accretion visible on bits at surface.

1. Is this possible?

2. What anti-balling practises do you all use?
     A. pills?
     B. additives?
     C. drilling practises/equipment to drill through or shake off?

I note the below interesting discussion on sodium silicate muds can cause sticky cuttings:
http://my-spread.com/discussions/4968
9 answer(s)
davidaiii
Well Engineer
Shell
Total Posts: 5
Join Date: 02/10/14

Just to feedback to all your kind replies almost a year ago! we never did get fully get to the bottom of it... however eventually managed to make good progress by using a more stabilised BHA and more controlled and measured drill off tests...  we actually continued to see the issue whenever tripping and back on bottom but learnt to be patient and eventually would drill through whatever it was until normal parameters returned. We called this BOB (clue above what it stands for!).

as with all unexplained events downhole... I blame the mud! :)


ericvillepreux
FCW Coordinator
N Operating Company
Total Posts: 6
Join Date: 19/10/14
My feeling is given by Scott, we need to think too in term of bit choice and hydraulics not to minimize drilling fluid influence but to understand the complexity of the phenomena.
davidaiii
Well Engineer
Shell
Total Posts: 5
Join Date: 02/10/14
Hi Ian et al, Thanks all for the discussion and ideas. Topic above was apparently resolved but not through use of any specific anti-balling procedures! Or through use of mill tooth. Sometimes i guess these things can be subtle. Interesting. David
Anderson.Bissoon
Fluids , Cementing and Waste management Advisor
SPREADAssociates
Total Posts: 2
Join Date: 10/02/09
Dave
            Some very good solutions given already. I would question weather the fluid system is too inhibitive. Most times when well conditions change the fluid sys does not change when it as tried and proven systems are always the first choice but not often the correct choice. If you can not change the fluid system and the fluid was in specification not only for properties but also for concentration i.e. Not being overtreated by the mud engineers. Then a bit change may be your only solution. Other than this I would use a fluid that lubricant can be added too effectively if water base mud is a must have. If not then good old oil base mud is also answer. If you are looking to unplug the bit then I would recommended scouring the bit with a high concentrated150 too 300 micron calcium pill or the famous nut plug pill which I don't like or recommend. However your MWD company will be screaming at you.

good luck
ianpetitt
(retired) Well Fluids Team leader
SPREADAssociates
Total Posts: 37
Join Date: 14/06/06
Dave,

If you are in Expro Aberdeen - Gary Wright, a DSV on the Sedco rigs in the 90s had excellent Silicate drilling best practices. Someone may have a copy some where ! 

Ian


ianpetitt
(retired) Well Fluids Team leader
SPREADAssociates
Total Posts: 37
Join Date: 14/06/06
Dave,

Still enjoying yourself?  There is a huge volume of silicate information in Shell Expro which you could purloin.  I assume Niall has also now retired! 

1. Yes is possible 
2. Limited non actually known. 
 

An extract from a TIR "the search for a silicate lubricant" in 2007 

"Silicate mud has proven over the years to be a very effective mud system in our  XXX operations for overburden intervals and can be considered to be our preferred High Performance Water Based Mud (HPWBM) system.  However, at present we limit the use of silicate mud to wells with inclination below 45 degrees due to torque and drag concerns. 

Despite exhaustive testing of commercially available lubricants and development chemicals in either liquid or solid form, there is currently no competent lubricant available for this type of mud. Friction coefficients for both unweighted and barites-weighted silicate mud are typically in the range of 0.25 - 0.30

Identifying an effective lubricant for use in silicate mud would significantly expanded the potential scope of use of this mud system.

I paid for a round of testing of potential lubricants in 2007 as part of our R&D budget the work was completed in BTC Houston. The equipment description and example test results are included in the report. 

In this round of testing we did not identify a potential outstanding effective silicate lubricant. 

Of the eight mixtures/products tested only one product F, was identified, as a possible candidate for consideration as a lubricant for future drilling operations. 

The report "Report on Silicate Lubricant Testing conducted at BTC June 2007" was done by Joe Cartwright working in the Houston laboratory using the large scale Alkco Services LUBE tester we had there.  You should be able to get a copy from Ron Rock. 

Some products not tested at the time were Techlube 2 (used in Netherlands) and Cosmolubric  ETL (China). At the time I also identified solid lubricants such as glass beads and particularly graphite with which we were having good secondary success reducing torque and drag in NAM water based mud operations. As far as I am aware no additional testing has been. 

Scott_McNeil
Consultant
SPREADAssociates
Total Posts: 103
Join Date: 05/03/08
Hi David,

I've come across similar situations several times when drilling a deep unreactive shale section with a high overbalance mud weight.

It was eventually put down to the shale plastically deforming around the PDC cutters, so that each cutter instead of shearing the rock, effectively pushed the ridge it should be cutting to one side. The cutter following would push the ridge back into place and so on, producing very low ROP.

The only answer we found was to use a milled tooth bit with a high gouging action (i.e. IADC 1-1 or 1-3) to get through the section.

Best Regards

Scott
gomdriller
Offshore Engineering Manager Western Hemisphere
Noble Energy, Inc.
Total Posts: 13
Join Date: 24/06/14
I have seen something similar with High Performance WBM in both Indonesia and the Falklands, PDC's just stop drilling , torque goes to zero and the bits come out clean. to this day we are still scratching our heads as to what caused it, the only thing we could come up with was that we created some kind of ultra slick surface that we could not get a bite in. The solution for both wells was a mill tooth bit, TCI bits faired the same as the PDC's. Again our thoughts are that the teeth on the mill tooth are shoveling the slick stuff out of the way and allowing progress.
rollintr1
Drilling & Completions Advisor
SPREADAssociates
Total Posts: 2
Join Date: 17/05/15
David - what is the MW? Have u tried raising silicate % or possibly pumping glycol pills

need a little more data
Posted by

david moss

Well Engineer

Shell

Total Posts: 5
Jump to top of the page