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Kick tolerance worksheet, release 9, issued 19 August 2013. WORK version.

Kick tolerance definition; “A description of the volume and pressure of a gas influx that can be safely circulated out of the well“.

This worksheet calculates the volume of an influx taken from drilling into an overpressured formation that can be circulated out of the well without exceeding the assumed or tested strengths of the formations exposed just below the casing shoe. It does not account for gas migration or dispersion in the mud column and it also assumes that no heavy mud exits the bit before the top of the influx reaches the casing shoe. These calculations should not be used for diverter drilling, slimhole drilling (<6″), HPHT conditions or with oil muds where BHP exceeds 6000 psi. The default influx gradient is 1131 Pa/m or 0.05 psi/ft, which is a reasonable gas gradient to use at the pressures encountered at normal well depths.

A swabbed kick may also be calculated for but in this case, please review the JIT version first of all and note the common error that can result in a large overestimate of the kick volume that can be handled. Understanding this, feel free to use the work version afterwards for swabbed kicks.

All inputs can be made in metric or oilfield units. Outputs are given in both unit sets.

User input

Casing shoe TVD. L_Vshoe =

1.71

psi/ftSG or kg/lppglb/ft3ppbkPa/mpsi/m

Equivalent mud density for the casing shoe strength, estimated or FIT. ρemw =

100

psiPakPaMPa

Optional; safety margin for the casing shoe (reduces the maximum shoe pressure). Pshoe_s =

1.41

psi/ftSG or kg/lppglb/ft3ppbkPa/m

Drilling fluid density anticipated or in use for the section at casing point. ρmud =

0.1198

psi/ftSG or kg/lppglb/ft3ppbkPa/mpsi/m

Estimated influx gradient. ρinf =

1411

ftm

Planned hole section TVD. L_Vtd =

2173

ftm

Planned hole section MD. L_Mtd =

0

psi/ftSG or kg/lppglb/ft3ppbkPa/mpsi/m

Enter the required kick intensity (kick formation pressure gradient – mud gradient). 0 for swabbed influx. ρΔfm_mud =

50

FC

Enter the temperature at the casing shoe. Tfmg =

4.3

C per 100 ftC per 100 mF per 100 ftF per 100 m

Enter the geothermal gradient below the shoe (zero if not accounting for temperature). ZTm =

12.25

inmm

Enter the hole diameter. L_dhole =

5.6

inmm

Enter the drillpipe OD. L_Ddp =

76

Enter the inclination at the casing shoe. ΘΔ_Vcs =

Click here when any values are modified to update the result.

Results

Kick situation assumed;

Current Maximum Allowable Annular Surface Pressure

Leakoff shoe pressure

Bottom hole pressure after closing in the well

Maximum influx vertical length

Maximum influx volume (gas on bottom) after closing the BOP’s

Recommended Baryte reserve

NOTE – a negative value for the maximum influx volume shows that any kick taken would exceed the maximum shoe pressure.

For the data entered, the

Worksheet references

API RP59. Recommended Practices for Well Control Operations.

Drillers.com Incorporated. Practical Well Planning and Drilling Manual.

Horning, MR. Kick prevention, detection and control; planning and training guidelines for drilling deep, high pressure wells. IADC/SPE 19990.

Sedco Forex Schlumberger. Well Control Manual. Edition of March 1991.

Version 1 of this worksheet was released on 12 February 2008.

Version 6 was released after correcting the conversion factor for kPa/m.

Version 6a was changed for the JIT version, to display intermediate results in both metric and imperial units.

Version 6b was released after revising the variable names in line with the new DDC convention.

Version 6e was released after adding a specific warning if a negative kick intensity is used.

Version 6f was released after adding some more information in the Results.

Version 7 was released after correcting a small error, to account for any safety margin pressure in calculating the influx volume on bottom.

Version 8 was released after realising that there was a much easier way to calculate kick tolerance!

Version 9 corrected an error when calculating for hole inclination at the casing shoe.