7/27/2019 Well Control Calculations

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European Well Control Forum. Formulae ( Field Units.)

Kingdom dri ll ing services Ltd

Primary well control calculations.

Gradient ( Psi /ft.)

= Mud weight (PPG) x 0.052

Mud weight ( PPG)= Mud Gradient ( Psi/ft ) / 0.052

Formation pressure ( Psi )= Mud gradient ( Psi/ft ) x TVD of drillstring ( Psi ) + SIDPP ( Psi )

Equivalent Mud weight EMW ( PPG )= Bottom hole pressure ( Psi ) / 0.052 / TVD (ft )

Equivalent circulating density, ECD, ( PPG )

= Mud wt in use (PPG) + Annular pressure loss ( Psi ) / TVD / 0.052

Trip Margin / Safety factor ( PPG)= Kill weight mud ( PPG ) + [ Safety factor ( Psi ) / 0.052 / TVD ( Ft ) ]

Maximum Allowable Annular Surface Pressure. [ MAASP ( Psi.) ]= [ Form grad at shoe ( PPG) - mud gradient (PPG) ] x 0.052 x Csg shoe TVD (Ft)

Maximum allowable mud weight (PPG)= Test mud weight (PPG) + [Leak off press (Psi) /0.052/Casing TVD (Ft )]

Pressure drop per (Ft) tripping dry pipe ( Psi)= Mud grad (Psi/ft) x Metal Displ ( Bbls/ft) / Casing Capacity ( Bbls/ft) - Metal Displ ( Bbls/ft)

Pressure drop per (Ft) tripping wet pipe.=Mud grad (Psi/ft) x [Metal displ (Bbls/ft) + DP capacity ( Bbls/ft)]

Casing capacity ( Bbls/ft ) - [Metal Displ ( Bbls/ft) / DP Capacity (Bbls/ft)]

Kick tolerance (PPG)= [MAASP ( Psi) - Mud wt (PPG) x 0.052 x Height of Influx (Ft)] / TVD (Ft) /0.052

Circulation pressures.

Pump pressure / Pump strokes relationship ( Psi )= Present pressure ( Psi) x [New SPM / Old SPM ] 2

Pump output ( Bbls/min.)= Pump liner capacity ( Bbls/Stroke) x Pump speed ( SPM )

Annular velocity ( Ft/min.)= Pump output ( Bbls/min) / Annular Volume ( Bbls/ft.)

7/27/2019 Well Control Calculations

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European Well Control Forum. Formulae ( Field Units.)

Kingdom dri ll ing services Ltd

Secondary well control calculations.

Formation pore pressure.

= Mud gradient ( Psi/ft ) x TVD of the well ( Ft ) + SIDPP ( Psi )Kill weight Mud ( PPG)= Original mud weight (PPG) + [ SIDPP ( Psi) / TVD ( Ft ) of the well / 0.052 ]

Initial circulating pressure ( Psi )= Selected slow pump presure ( Psi) + SIDPP ( Psi)

Height of influx ( Ft )= Pit gain ( Bbls) / Drill collar / open hole volume ( Bbls/ft.)

Gradient of influx ( Psi/ft.)

= Mud gradient ( Psi/ft) - [ ( SICP-SIDPP) / influx height ( Ft )]Migration ( percolation ) rate ( Ft/hr)= Pressure increase per hour ( Psi/hr) / Mud gradient ( Psi/ft )

New MAASP ( Psi)= [ Max allowable mud wt (PPG) - mud wt (PPG)] x 0.052 x Casing TVD (Ft)

Barite required to raise mud weight ( Lbs/bbl.)= [1500 x ( Kill mud wt (PPG) - Old mud wt (PPG)] / [ 35.8 - Kill weight mud (PPG)]

Shut in casing pressure ( Psi)

= Mud gradient (Psi/ft) - [Influx grad ( Psi/ft) x Height of Influx (Ft)] + SIDPPor= Formation pressure (Psi) - [Mud grad x height + Influx grad x Influx height ]Where Gradients = Psi/ft , Heights = (Ft).

Gas Law equations

Boyles LawP1 V1 = P2 V2 ,

Therefore P2 = P1 x V1------------------------

V2

V2 = P1 x V1---------------------------

P2 I bbl

2 bbl

4 bbl

1500 psi.

3000 psi

750 psi.