Modesto Mercado, Carlos E. Perez, PEMEX; Mahmoud Asadi, ProTechnics; David R. Casas, O'Jeito S.A. de C.V.
A successful reservoir flood depends on a properly designed injection/production pattern. Knowledge of the flow pattern within a reservoir leads to a better design of the injection pattern, which in turn enhances overall recovery. To achieve this goal an interwell tracer program was used to characterize the flow stream within the current injection/production pattern of the central part of the Mesozoic Chiapas-Tapasco Basin. The field includes one injector and four producers. Due to production, the average reservoir pressure fell and approached the dew point at reservoir conditions. Natural gas was injected to maintain reservoir pressure and optimize condensate production. A chemical interwell tracer was also injected to detect and evaluate the magnitude of any communication between the injection and production wells and to track the areal flow pattern within the field. The study was designed for 18 months and commenced in December 2000. The results from the sample analyses provided information on the magnitude of highly permeable channels between the injector and producers as well as flow pattern within the field. Furthermore, the results provided valuable information on breakthrough time, which in turn shall lead to a more efficient gas injection design.