Hole cleaning checklist.

Process. Yes No Planning Quality assured on all mud products. (especially weighting and viscosifying material)

Hole cleaning modelling conducted for filed use based on anticipated ROP’s, mud rheology, cuttings size, rotational speed, anticipated transport ratio’s etc.

Hole cleaning modelling conducted for cleaning sweeps. (will they be effective at all?)

Benchmark, offset data, lessons learned from previous wells, other ERD projects, incorporated into plans?

Optimised bottom hole/hydraulics planning afforded? Constraints established, e.g. max ROP’s vs specific low end rheology.

Are friction factors known for field, well profile to be drilled, mud used etc.

Anticipated torque and drag modelling and charts generated for field use

Caliper logs, hole instability, in situ stress analysis, PWD/ECD management conducted and incorporated into drilling programme and drilling plans?

Bit/BHA selected and modelled to ensure max rotation while drilling (minimum sliding)?

Mud rheology. Compatibilty checked to ensure no cuttings or formations fluid/fluid or chemical reactions.

Mud inhibitive to prevent hole washout or enlargement. Optimised mud properties and flow regimes established for high angle and horizontal sections to ensure cuttings transportation.

Above parameters verified in hole cleaning simulations (both preplanning and during execution)

6 & 3 reading maintained above 12 & 10 throughout section.

Drilling practices Based on hydraulics modelling max instantaneous ROP established and controlled to avoid overloading annulus with cuttings

Rotations stopped after stand drilled down Stand wiped (no rotations) to establish drag trends in hole to monitor if hole is being cleaned. (see note1)

Down reaming applied if deviation from drag trends noted

Hydraulic modelling conducted by Drilling foreman daily based on actual parameters to indicate if problems are likely to exist

Trend analysis conducted, comparisons made, and discussed daily with drilling team to ensure optimised hole cleaning is constantly afforded

Tripping Mud loggers produced litholog for drill floor prior to trip?

Hole circulate clean prior to trip (may take 2-3 circulations).

Stand wiped back (no rotation) and reamed down with high rotation to disturb any cuttings beds that may have formed?

Stand laid out every 1/2hr while circulating to avoid undercutting hole?.

Torque and drag closely monitored to see if hole (drag and torque) conditions improve?

Drilling foreman on drill floor throughout trip in open hole?

Process established and used to differentiate between drag (ledge, dogleg, cuttings bed) and tight hole (reactive formation or hole restriction)? (see note 2.)

Stand wiped down and ensured free prior to breaking out and racking back.

If drag experienced, logs consulted to determine if it is formation related (ledge, interbedded, reactive formation, geopressured, faulted etc), wellbore/BHA geometry related (dogleg, period of prolonged sliding) or may be a result of a separated cuttings bed.

Drag wiped clean? Drag wiped and pumped clean? Drags accurately recorded and mechanisms accounted for in drilling reports, lessons learned?

If unable to pump and wipe through rotation required.? Drag eliminated once through resistant zone Pumping and/or wiping required Hole packing off while pumping out Hole circulated clean at casing shoe Casing shoe < 30degrees