Hole cleaning and the minimum requirements to achieve this are well documented and proven from field experience and research. High angle (>30 deg inc) sections requires drill-string rotation and flow above certain minimum thresholds. For your application ”œ12.25in hole, OBM, 40 deg inc to 90 deg inc” these thresholds are:
The 1.83 deg bend limits string rotation to 60 rpm, thus hole cleaning will be sub-optimal and should be highlighted as a high-high risk (high risk of problem, high risk of severe consequence). Assuming that you can´t change the BHA what are you going to do? Options include adding bladed DP; one jnt per std approx, which provides cuttings transport at lower string rpms. Assuming that this isn´t possible, lets assess the risk:
I´m guessing that you have around 250m to drill (BUR 7 deg/30m; 40 deg to 90 deg = 220m)
It´s a short section, so you should be OK, however you´d want to revise the BHA for future wells to remove the associated hole cleaning risks, especially if high angle sections are longer (including casing).
Sorry for the late reply, you may already have drilled it! Happy to share more of the best in class relevant practices from record ERD wells as interest demands.
Merlin ERD Ltd
This is generally the classic ballbreaker section where most historic problems have resulted. i.e. 12 1/4" 30 to 90deg (horizontal) through long clay (deeper then shale), inter-bedded sections.
Rule no 1: go back several steps. recognise and analyse everything planned, engineered, right down to bit/bha design, stabiliser placement etc etc e.g. 7deg doglegs (on some wells) may be biting off more than you can safely achieve!
However there is potential and evident 'pit falls' within the information you have provided.
60rpm rotary? ( vs. don't drill a hole faster than you can clean it?)
note: once angle builds and section deepens ROP capabilities reduce. This needs to be understood and managed otherwise problems will result later.
1.83bent sub (7deg may be the capability, on stringers in inter-bedded sequences etc, this could be much higher, especially with aggressive PDC bits, we have seen this in the past. Note: you generally then don't see this as a wellbore deteriorations problem till you POOH on trips and then through further misunderstood and bad stinger, drilling, tripping practices etc, strings often get stuck via the domino of bad causes and effects that result.)
Note: Commonly several things lead to getting stuck not just one or two!
OBM (if mud is new and you drill ahead too fast hole cleaning becomes a problem. Managing rheology from start to finish optimal solids control is important.) Sometime ROP has top be controlled till mud rheology builds that can then afford higher ROP.
PDC bit? (If wrong type/design of bit is used you to best suit all formation types, (often one needs to compromise) we end up sliding more than rotating, having other loss of wellbore quality problems in certain formations etc, this is all counterproductive to staying free at lowest risk. You want to spend more time rotating if one can.)
Poor/inadequate Bit bottom hole cleaning; People think OBM is unforgiving, however at higher ROP;s more energy MUST be expended at bit otherwise cuttings get reground, mush is generated at bit, and no matter what flow rate is then used you will not be able to POOH without likely having to resort to working pipe, pumping out of hole and more likely having to resort to backreaming.)
vs 'do the right things', get the drilling and connections 'right first time' evident via POH on elevators.
Pump capability: If you are limited on pump then you are also limited on ROP that changes (reduces) as sections deepen and hole inclination increases.
Mud weight management; Too low instability can result, too high other problems can result. A good geo-mechanics understanding and mud weight plan for drilling and tripping needs to be worked. We generally look at offsets, identify the problems and risks, get a specialist to do a study and then stick to their plan unless we take a time out for safety and manage further risk and change accordingly. Often we will drill with a few points less then increase weight for the trip to try and maintain stress in the hole the same throughout.
In critical sections as identified on trips out we often use the low pump method (simply pulling and pumping to get through these zones with minimal well disturbance.) Then return to POH on elevators.
Hole fragility often in these wells in certain sections is critical, where avoiding rotation (after hole has been drilled) is often the imperative on connections and trips.
vs Rotating all the time and doing far more damage than good (note: this is the most common disagreement I have with DD's. However I'm the DSV to manage all risks and make sure we do the right things and get it right first time.)
Some best practices hole cleaning stuff attached.