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162 Part II Gas Drilling Systems

The importance of safety equipment can never be overemphasized in
H 2 S operations. Remember:
• Operational and equipment testing procedures must be established,
comprehended by all personnel, and enforced.
• Drilling should not continue if pressures exceed the maximum limits
established.
• Emphasis is placed on monitoring pressure while drilling, tripping, and
stripping.
• A blowout preventer (BOP) stack must be tested each time it is
reinstalled.
• Surface equipment should be regularly inspected and monitored.
• If H 2 S is detected, stop drilling.
• Inspect liquid/gas separators daily.
• Inspect diverter rubber elements several times a day.
• Check the diverter alignment with the rotary table.
• Have a contingency plan.
To prevent fires or explosions of natural gas at the surface, flaring gas is a
must.
• Flare lines should be adequately sized.
• Flare stacks should be properly positioned.
• Use of automatic flame igniters is preferred.
• Wind direction should be considered.
• Flare stack height should be adjusted for optimum performance.
• Flare lines should be adequately anchored.

When drilling with natural gas, liquid hydrocarbon separation and storage
facilities must meet API RP 500B, National Fire Protection Association
(NFPA) 70, and NFPA 496 guidelines.
Using float equipment is always a good practice in gas drilling to prevent
backflow. For optimum conditions, a good rule of thumb is to install a float
every 12 joints. Two floats should be placed close to the surface to minimize
the time required to bleed off pressure before making a connection.
Downhole fires and explosions can occur when hydrocarbons from
the formation are mixed with oxygen at high temperatures that result
from the mechanical friction between the drill string and the borehole
with a mud ring. Extreme caution must be exercised when air is used as
a drilling fluid. Although flammable conditions are well established in
terms of natural gas content in a mixture and the minimum oxygen