New Insights into Kerrobert Toe-to-Heel Air Injection (THAI) Production Analysis

The common practice in production data analysis usually utilizes instantaneous injection and production when seeking a relationship between them, but field experience in heavy oil field indicates that the liquid production can lag the injection by several weeks. Thus, the production lag effect should be taken into account in the process of determining the causal relationship. In this research, we have considered the time-lag effect when analyzing the Kerrobert Toe-to-Heel air injection (THAI) project and have observed two distinct recovery mechanisms: (1) oil production peaks right after the air injection; and (2) peak production occurs at a later time after the air injection. Based on these observations, the well performance profiles at Kerrobert THAI facility is classified into four distinct types. In addition, a mathematical model has also been proposed to represent the production mechanisms. The oil production is then approximated by accumulating the time-lag effect from previous air injection, which yields a better match with the actual cumulative oil production compared with the estimation using the cumulative air-to-oil ratio (cAOR) method.