Detection and interpretation of well test data distorted by phase segregation

The phenomenon of wellbore phase segregation occurs in a well which is shut-in with gas and liquid flowing simultaneously in the wellbore. This usually leads to an anomalous increase in wellbore pressure which may be large enough to cause a pressure hump in the early portion of the buildup curve, and make interpretation by conventional methods difficult or impossible. This paper presents a simple method of detecting and interpreting such buildup test data.