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C. Reyes-Lopez and M.A. Marhx-Rojano, Pemex; M. Asadi, SPE, ProTechnics; and D.R. Casas, SPE, O’Jeito S.A. de C.V.
A successful reservoir flood depends on prior knowledge of the flow stream within a reservoir and a proper injection/production pattern. A northern field formation in Mexico, which currently includes 44 injectors and more than 150 producers, has been under water flood since early 1965. Due to the loss of injection fluid and low sweep efficiencies a chemical interwell tracer program was designed and implemented to fully investigate the flow stream within the current injection/production pattern and to evaluate reservoir heterogeneity. However, based on the results of seismic and well test analysis and due to the large number of active injection and production wells, the entire field was divided into four sections for this interwell tracer study. This paper presents the interwell study results for the upper section of the north field, which includes seven injectors (A to G) and 36 producers (1 to 36). A detailed interwell study over a 10 month period indicated the existence of massive high-permeability channels as well the existence of a major fault initiating from this section and extending downward into the lower section of the field. Also, the results indicate the existence of several transverse faults along the main fault. Detailed graphical results to identify the flow stream, a comprehensive interpretation of the heterogeneity of the formation, and tracer travel time are also presented.