Page 180 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 156

[ ] Well Programming
2.2.5

kick caused by drilling into an unexpected, overpressured zone is
unlikely. Hole cleaning is a much greater problem in horizontal wells
and this can increase swabbing. If possible, keep hole angle slightly
below 90°.
If the angle exceeds 90°, it may be difficult or impossible to circu-
late out a gas influx. A swabbed influx may stay in the horizontal well-
bore without migrating, causing a kick when the new BHA is run back
in and displaces out the influx.
Precautionary measures. The following precautions may be con-
sidered for inclusion in the well plan:

Pump out whenever moving pipe out in horizontal hole, on con-
nections, or when tripping out
Flow check at the shoe and before the BHA when pulling out, also
at the shoe and halfway in the horizontal section when tripping in
(if a long horizontal section is open)
Be particularly alert for a flow and “trip gas” after resuming drilling
If pressures and conditions allow, bullhead the influx back into the
producing formation
If the inclination is over 90° then bullheading, if possible, is preferable

2.2.5. References for Well Control

IADC Drilling Manual, eleventh edition. Published by the
International Association of Drilling Contractors.

Practical Well Planning and Drilling Manual on CD,
http://www.drillers.com.

“Unocal, Santa Fe Devise ‘Diverterless’ Drilling Method for Jack-
ups,” article in Drilling Contractor magazine, published by IADC,
July 1996.

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