High Loss circulation in Deep and Ultra deep water
13 December 2011
When experiencing high loss circulation events in deep and ultra deepwater notably with OBM or SBM. i.e. >100-300-500bbls/hr
What cure, notably non-standard mud company products (where for me these generally do not work, where we waste days trying), are being sucessfully used and applied in a more rapid-time solution time frame.
What case studies or references to successful applications in such high loss circulation environments are available?
I am not really pertaining to fracture, vugs or cavities etc.
The most common high loss circulation events I have observed and experienced offshore in shallow and deeper water environments are generally high loss zones when a formation sequence changes from one to another. e.g. Normally in the intermediate and/or production drilling sections.
In between the sequence geology e.g. at the base or start of new stratigraphy, one commonly experiences a mish-mash transition zone, often thin and discreet that is not obvious on logs etc. However it is generally quite evident via drilling parameters that something is going on. e.g. A hard stringer, change in WOB, torque etc.
The well takes a big drink here, where if ROP is good and formation is clay/shale dominant often simply drilling ahead is the best, quicker, safer solution and commonly works at minimal loss. If not an option. e.g. Much lower ROP and morer silt/sand or chalk dominant formations.
The standard protocol is to follow the decision trees, i.e. a conventional LCM mix, with 95% often returning via the shakers and then a day or so trying to get loss levels that contractor accepts to drill ahead.
I have reviewed operators case studies in the past where alternate methods were succesful applied on numerous occasions e.g. using non-mud company products. All events resulting in back to drilling in far less time with virtually no losses from these zones there after.
Therefore I was seeking to be informed any other areas, who have used such products, what the outcome was vs. conventional methods.
Merry Xmas to all SPREAD members.
Thanks for starting two good discussions. I'm not entirely sure of your situation offshore, but, by entering the word losses in the SEARCH feature at the top right hand side of the screen you will see that one of the previous discussions (2007) was about extreme losses in carbonates; my memory was prompted by Milap's response.
Such severe losses normally occure in fractures/cavities and they sometimes heel when the fracture/cavity has drunk mud to its capacity, if not inter-connected to other fractures. However, should losses continue with same magnitude, then ideal would be to use thixotropic type of LCM which have the property to build compressive strength with passage of time when exposed to bottom hole temperature. Such jobs are to be meticulously engineered with correct bottm hole information and selecting the cross-lionking type of LCM which will not only convert into thick gelled structure, but will also acquire adequate compressive strength to with stand the deformation of gelled structure over a period of time when operations resume. Without naming any particular company it can be share that such products are available in market which are not polymer based and hence they do not degrade when exposed to high temperature,high sheating over a period of time.