OBM Cuttings - Options
23 March 2009
I would like to understand better how the rest of the industry is managing their OBM cuttings. The main options all have their pros and cons (technically, economically and politically). Any information on what your Company does with the cuttings is useful, (CRI, skip and ship, bulk transfer, inter-field transfer etc), with the reasoning behind your choice would be useful. In a development of 8 to 12 wells with a new jacket etc what would you plan to do with the OBM cuttings?
My experience in BP Tangguh, Indonesia, was running CRI from Scomi Oil Tools. We were drilling with Jack up rig to 13k - 15k ftMD. We were lucky to have total loss zone in our 12.25" section. We were injecting the whole cutting to that zone.
It worked excellent for us and spent $150,000 - 250,000 per well.
I have just joined the. group hence the delay in the response.
There are obviously a number of different options available for cuttings treatment and the best option will vary dependent on local circumstances and legal requirements.
I am the Environmental Manager for a company (TWMA Ltd) who specialize in the treatment of OBM Cuttings. One option that is available that you may not have come across is our TCC-RotoMill technology. in a nutshell it is a fully mobile unit that can be used on a rig to treat the cuttings. It reclaims most of the oils which can be recirculated into the mud system and produces a powdered solid which has much less the 1% residual oil, this makes it appropriate in most areas for discharge to the marine environment.
Have a look on our website, www.twma.co.uk, for further details and please do not hesitate to get in touch.
All the evidence suggests that with a project of the scale you describe, cuttings slurrying and injection is the most cost effective and environmentally sound solution to oily cuttings disposal, assuming, of course, you have a suitable conduit and receiving formation(s). Historical problems, often cited as being the reason for not selecting CRI,are the result of poor quality control of the slurry properties, poor practices and a failure to monitor the pressure profile of the injection well. So, a properly designed CRI Assurance programme is necessary but that will manage the failure risks and deliver the best solution.
Also, Peter's comment vis-a-vis cuttings drying are significant, even where CRI has been selected. A review of historical performance will show you that about half of the cuttings 'waste' is perfectly good drilling fluid which could be recovered for re-use. Just look at the volumes involved and you will see the cost benefits.
Independent Fluids Consultant
Assuming a Jack-up over the Jacket?
On a multi well project, a disposal well is likely the norm.
However there is an associated cost for this well, plus all associated injection equipment, personnel etc that should be fully equated, costed etc for the rig and campaigns duration.
Other alternate would be:
Here a recent offshore study demonstrated a Â£650,000 saving per well, can be gained for an offshore (Semi or Big jack up)well using this approach vs. skip an ship. Some points to benefit viewed as:
- Less skip and ship. (perhaps half!)
- Less deck space, less handling risks. (less skips etc)
- Less wasteage (loss of oil on cuttings etc that is recovered).
- Oil is recovered from cuttings (canbe serveral hundred barrels per well) reducing costs further here?
- One can increase solids removal efficiency (as more oil can be passed over shakers that will be recovered anyway!)
- This reduces solids in mud etc and associated benefits gained here?
- Less environmental fingerprint.
- Dry cuttings could perhaps be sent to a land fill vs. a more specialised treatment siteplant, with further associated cost savings.
There is also an option to bulk collect 'dry cuttings' and transfer to vessels if needed eliminating skips further, reducing WOW exposure and ROP bottlenecks often experienced particularly in larger hole. I don't think anyone has done this yet but for me I don'y see what we cannot deliver a system that could manage this at minimal loss?
A portable drier system could be built to meet projects needs or rented where on a multi well development either will be re-paid (based on what recent studies and results suggest)quite a few times in overall benefits gained.
Not being a specialist in this subject I have asked a specialist I know to feedback his views to this post.
Finally driers are used exclusively in the GOM.
I would check with operators there the pro's and cons.