Chapter 5: Choke Performance Flashcards
___ are used to limit production rates for regulations, protect surface equipment from slugging, avoid sand problems due to high drawdown, and control flow rate to avoid water or gas coning.
Wellhead Chokes
There are two types of well-head chokes. What are they?
Positive (fixed) chokes and adjustable chokes.
When the fluid flow velocity in a choke reaches the traveling velocity of sound in the fluid under the in situ condition, the flow is called…
Sonic Flow
Under ___ conditions, the pressure wave downstream of the choke cannot go upstream through the choke because the medium (fluid) is traveling in the opposite direction at the same velocity.
Sonic Flow
T/F The pressure discontinuity exists at the choke, that is, the downstream pressure does not affect the upstream pressure.
True, because the pressure discontinuity at the choke, any change in the downstream pressure cannot be detected from the upstream pressure gauge. either. The sonic flow provides a unique choke feature that stabilizes well production rate and separation operation conditions.
T/F Sonic flow exists at a choke depends on a downstream-to-upstream pressure ratio. If this pressure is less than the critical pressure ratio, sonic (critical flow) exists.
True
T/F If the downstream-to-upstream pressure ratio is LESS THAN OR EQUAL TO the critical pressure ratio, subsonic (subcritical) flow exists.
False, If it is greater than or equal to, then it exists.
T/F Pressure equations for gas flow through a choke are derived based on an isentropic process.
True, this is because there is no time for heat to transfer (adiabatic) and the friction loss is negligible (assuming reversible) at chokes.
T/F Temperature drop associated with choke flow is not an important issue for gas wells.
False, because hydrates may form might plug flow lines.
