This paper presents how to identify a hotspot, i.e. the most critical interval with a localized high gas rate and to determine the reliable maximum gas flow rate by interpreting production logging and calculating the fluid velocity at completion screen. This reliable characterization is highly important to prevent any failure of cased-hole gravel pack screens from fine particles.
Generally, operators manage the gas well within allowable pressure draw down range. The rule of thumb for restriction on maximum recommended drawdown ranged from 500 psi to 1000 psi. However wells completed through sand control equipment completion might encounter sand face completion failure in the occurrence of extremely high velocity flowing hotspot zone near the screen or liner. Therefore it is necessary to pay close attention to the detection of hotspot zone using production logging interpretation. Moreover, calculation of the maximum gas rate based on gas velocity profile through the screen would determine the allowable maximum flow rate with advanced method.
Normally In field cases, gas velocity higher than 1ft/s at the screen is considered as potential fluid velocity which could cause possible completion failure due to screen erosion accompanied by fine particles. One of the gas producing wells in SHWE project operated by Posco-Daewoo at Myanmar offshore, shows moderate mechanical skin damage and heterogeneous flow profile at the screen. Therefore rather than applying general drawdown criteria, calculating gas velocity at screen is recommended. To investigate the velocity profile at well bore, Production Logging was applied to Well-1 at SHWE field. By interpreting the Production logging, a highly biased flow profile was found out and reservoir interval showing highly biased flow would be suspected as of a hotspot zone.
Production logging interpretation results indicate that the flow rate of 500 psig drawdown is much higher than the flow rate correspondent of 1ft/sec velocity at hotspot zone due to highly biased flow profile. In this case, the general drawdown criteria will not guarantee the sustainable maintenance of screen however exposes potential erosion to screen. Therefore, the gas wells suspected to have biased flow profile required to detect any potential hotspot areas and should be operated with advanced criteria to prevent potential sand face completion failure.