Download Hard Versus Soft Shut-In PDF

TitleHard Versus Soft Shut-In
File Size272.0 KB
Total Pages15
Table of Contents
Hard or Soft?
Hard Shut-In
Soft Shut-In
Simulated Results
Experimental Test Well
Surface Pressure Measurements
Downhole Pressure Measurements
Water Hammer Effect
Experiment Results Summary
When is Hard Shut-In Hard?
Field Implications
Defaults Choke Valve Arrangement
Possible Questions/Answers
Document Text Contents
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Sedco Forex

Research & Engineering

© Sedco Forex March '93

Technology Transfer
HARD - SOFT shut-in ?

Hard or Soft Shut-in ?
● Several shut-in procedures in use :

• variants of "Hard", "Soft"

● Historical approaches uncertain

● Varying preferences results in confused drill

● Require safety of personnel and well

• Several procedures to shut-in the well after detection of a kick are
in use today. Mostly these consist of small variations in one of two
main approaches - the "hard" or "soft" shut-in.

• Historically operators have had varying preferences for which
shut-inapproach is adopted. Often this has been based of dubious
assumptions for which there has been little supporting evidence.

• Even worse is the situation which often occurs in practice where
the operator and drilling contractor have conflicting procedures for
shutting in the well after detection of a kick.

• This results in added confusion to an already stressful situation.

• It should always be remembered that the final requirement is to
provide optimum safety of personnel while maintaining safety of
the well.

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• The downhole pressure measurements corresponding to the
surface measurements shown in the previous slide are shown here
at the casing "shoe" (708m) and at the bit (1430m).

• The water hammer pulse amplitude is reduced to a slight shoulder
on the pressure ramp at 130 seconds. This shoulder is about 36 psi
in amplitude and is less than the surface pulse amplitude due to
loss of energy of the wave as it travels down the annulus.

• The effect of the water hammer pulse is even less significant
compared to the normal annular pressure build than at surface.

• It could also be noted that there is a reduction in pressure at the
bit BEFORE the well is shut-in due to reduction in hydrostatic head
as gas enters the annulus.

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