Trips – tend not to do these. Actually, can’t remember when I last did one. A wiper
trip over 200m gives you a false sense of security as it only checks that 200m of hole. So if you are going to plan on doing one you really need to
trip over the full open hole to check its condition. Better option is to use
good hole cleaning practises, monitor your drag, and adjust you drilling
parameters / mud rheology to optimise your hole cleaning and remove the need
for any sort of wiper trip. Are you monitoring your torque and drag? Are you
plotting your actual against theoretical real time? This will give you an
indication of a developing problem and then you can react before it gets out of
control. The wiper trip was a band aid to another disfunction.
practices – I tend to refrain from extensive reaming at connections unless my drag
measurements indicate I need to do otherwise. As a starting point look to clear
your cuttings from around the collared BHA, also make sure you have freedom of
movement around setting your slips. Overall that tends to be working half a
single, if that. Then you are taking weights to monitor your torque and drag
and then into connection. Make sure you keep the parameters up whilst you are doing
any sort of back reaming – drilling flow and RPM. If drag in the well is showing
signs of increasing, you may decide to ream a joint or more. But you would also
want to be investigating why the drag is increasing. Have you drilled into a
new formation? Has the efficiency of removing cuttings from the hole decreased?
You may just have to ream a little bit more at connections to allow for some
catch-up in hole cleaning.
– not something you do lightly, but definitely something that needs to be
planned for under certain circumstances.
Couple of points of note when back-reaming:
a. Don’t expect to be able to do it quickly
You need to be back-reaming with parameters that
will lift your cuttings out of the well as you are going to be lifting anything
that is moveable – as such you are looking at possibly the same parameters that
you were drilling with. You may be able to go lower on the RPM but there are
minimal limits depending on hole size (>120 in 9 7/8” and above, >100 in
smaller hole sizes). Monitor your torque, pressure and hookload like a hawk, and be ready to react accordingly.
You mention that you try to avoid back-reaming due to shale break-out in the upper regions of your well bore. Does this breakout happen all the time, or just when the BHA is across a specific zone? There are Lo-Energy practises that have been utilised successfully in various places to combat this - back ream to below the fragile zone, clean the well bore up, trip through the fragile zone, continue back-reaming is one option. But patience is the name of the game when back-reaming. Can be a stand an hour, maximum I have done is about 8, understanding the faster you go the greater the chance of pack-offs and possibility of damaging the wellbore.