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Tank-cleaning
24 March 2019
Dear all

At a recent CWOP that we facilitated, we got round to the topic of tank-cleaning.  
  • Offshore rig
  • Casing is run and cemented prior to TCP perforation and then frac-pack
  • Previous fluid = SOBM. 
  • Next fluid = completion brine
The client had used a "semi-automatic" tank cleaning system in the past, but the Drilling Supervisor advised that it was a total waste of time and money, with human intervention needed all along.

It was also intended to minimise the volume of slops that needed to be sent ashore for disposal.

We are all uncomfortable with the notion of sending people into confined spaces for this kind of task.

I'm sure that our 3000 members have either experienced or are working on solutions to this.

We have (almost) stopped working at height and making super progress on hands-free, so what about this?

Bring it on!


8 answer(s)
radson
Consultant Drilling Fluids Engineer
Woodside Petroleum Ltd
Total Posts: 3
Join Date: 10/01/16
Yeah, I asked the Drilling Superintendent that he only secure MODUs with conical tanks for our next campaign :) 

This has been an ongoing issue with us for quite some time and it something that the Support Vessels do much better than the rigs. 

Kind of different parts to the story but as discussed a completely segregated and independent pit system allows concurrent preparation and storage of brines and SBM. On our last rig a separate brine return line was also installed to bypass the gumbo box and shakers which really helped with clean up times.

With the maxim that prevention is generally better than cure, we spent a lot of time preventing the build up of slops by spending a lot of time on our displacements and pill trains between the fluids. SBM detrimus from the rig floor was diverted to specially fabricated settling pit. We used stratification over time to separate out base oil from slops. Slops that could not be 'processed further we sent back to town in tote tanks which was 'recycled' in a cement kiln process. 

We investigated the MISWACO and Halliburton tank cleaning and processing units but could not pass master on a cost - benefit analysis. We also minimally investigated emulsion breakers for slops to onboard process but in this particular campaign, customs and procurement thwarted us.  
admin
Managing Director (rp-squared.com)
Relentless Pursuit Of Perfection Ltd.
Total Posts: 422
Join Date: 10/01/05
* This response was emailed to me, by a helpful members whose company tends to frown upon using the names of their personnel on social media.  I am happy to post on his behalf, with thanks *

Hi Dave,

I’ve been watching changes in pit cleaning equipment and technology over the last 20+ years and I’m yet to be convinced that there is a universal solution.  There’s been some great progress made for newer rigs and some good technology but true pit-less entry is seldom as easy as it seems on paper, especially on older rigs and platforms where we are still hampered by poor pit design and “structural” obstructions such as pipework

____

Note from moderator: What do other industries do?
admin
Managing Director (rp-squared.com)
Relentless Pursuit Of Perfection Ltd.
Total Posts: 422
Join Date: 10/01/05
* This response was emailed to me, by a helpful members whose company tends to frown upon using the names of their personnel on social media.  I am happy to post on his behalf, with thanks *

Hi Dave,

I’ve been watching changes in pit cleaning equipment and technology over the last 20+ years and I’m yet to be convinced that there is a universal solution.  There’s been some great progress made for newer rigs and some good technology but true pit-less entry is seldom as easy as it seems on paper, especially on older rigs and platforms where we are still hampered by poor pit design and “structural” obstructions such as pipework

____

Note from moderator: What do other industries do?
Harald
Senior Wells Advisor
Rowan Drilling
Total Posts: 28
Join Date: 13/09/07
edwin.damasena
Drilling Superintendent
Petronas
Total Posts: 21
Join Date: 31/10/07
Requirement during rig tendering was to tackle this issue. on the last 8-9 development wells very little effort were needed on tank cleaning. we had up to 8-9 mudpits with a total capacity approaching 4000 bbls and the lucky case that the wells were relatively shallow so we were able to segregate mud pits for completion brine. in addition there were mixing lines available to take on brine without interfering w the obm line. only on 1 well did we had to send a tank cleaner down the pit to clean. With proper JSA and PTW that went w/o an issue
Harald
Senior Wells Advisor
Rowan Drilling
Total Posts: 28
Join Date: 13/09/07
As long as mud pits are rectangular tanks with square angles, pit cleaning will remain a challenge. If only we would built rigs with cylindrical mud pits with a conical bottom with a drain, pit cleaning would be less of an issue as the vortex when draining the pit would almost create a self cleaning pit .... (and of course the vortex would be clock wise in the northern hemisphere and anti-clock wise in the southern hemisphere ...)
scott68
Performance Improvement Coach
SPREADAssociates
Total Posts: 11
Join Date: 03/11/08
Cuttings Reinjection technology should be used.
PaulHowlett
CEO
Sudelac
Total Posts: 97
Join Date: 10/04/08
Dave, Is this dilemma still running? We worked on this back in the early 2000's when SPS merged with AFOS and we became a fully fledged down-hole and surface cleaning pre-completion wellbore clean-up company. My recollection is this, no matter what kit and people with chemicals you mobilise to go from your drilling fluid to your completions fluid it matters more about what you did with the drilling fluid in the pits/tanks than the kit you mobilise. This means if you have not surveyed your tanks and pits and have not modified them with proper tank cleaning nozzles, not modified them to prevent solids build ups in corners, not created hatches for getting cleaning equipment in you are wasting your time. We had several guys at SPS in those days that developed those surveying skills and a number of drilling contractors listened and invested in the works necessary to have effective tank/pit cleaning processes. These days I would contact www.sasenvironment.com for advice.
Posted by

Dave Taylor - SPREAD Moderator

Managing Director (rp-squared.com)

Relentless Pursuit Of Perfection Ltd.

Total Posts: 422
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