Nomenclature
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A annulus: the annulus between the
tubing and production casing
B annulus: the annulus between the
production and surface casing.
C annulus: the annulus between the
surface casing and additional casing strings. If additional annuli are present,
continue down the alphabet.
LOP: "Lower Operating Pressure"
limit. While 0 psi is typically used, consideration should be given to:
- Possible introduction of air into the annulus, creating possible corrosion and
combustion potential,
- Inability to confirm casing integrity due to no pressure,
- Potential for annulus pressure buildup. High initial pressure in an annulus can
result in pressure exceeding burst/collapse of tubulars when the well heats to operating
tenperature
MOP: "Maximum Operating Pressure"
limit. This is the pressure that, if exceeded, would initiate a well integrity review.
This may not be a calculated value, but an easy to remember number to facilitate
use by Operations personnel.
MAP: "Maximum Allowable Pressure"
limit. This is normally the pressure some component in the system fails - tubing
collapses, casing bursts, casing shoe fails and fluid may be injected into a subsurface
formation. API RP90 has examples showing how to calculate this value.
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