R. Perez

Methodology to Estimate the Optimal Production Rate and Owc Advance in Naturally Fractured Reservoir in the South of Mexico

A great problem of naturally fractured reservoirs is the abrupt irruption of water in wells. To predict this behavior, a methodology that uses numerical sector models and discrete fracture Network (DFN) was designed; so-called Pseudoradial models (PRM). These models were calibrated to match the water invaded wells production history and subsequently it was applied to proposed or new wells. This methodology was used successfully in Pijije field, Mexico. The first pseudoradial models were generated in the Pijije field due to the abrupt water irruption problem it presented. Three well models were built based on the calibration of the model built for the Pijije-101 well. The DFN was generated from average characterization of fractures obtained from FMI logs and general input from the field pressure and production behavior. Once the variables of uncertainty were analyzed, a conventional radial model was initially built and calibrated with the historical production and pressure profiles. To achieve this match, the values of porosity in both systems (matrix and fracture) were changed drastically and the water front advance resulting was homogeneous and only present a coning phenomenon when the OWC reaches a minimum distance of 200 meters from the well. The second part of the analysis was carried out with the pseudoradial model; in this case, the parameters with greater impact were the characteristics of discrete fracture network. The pseudoradial model managed to reproduce the well production and pressure history. Analyzing the results, it was concluded that both scenarios were acceptable. Reviewing the water advance fronts in both cases, the pseudoradial model did not have a uniform front of OWC advance and showed areas not drained (corresponding to present or absence of fractures) and the water moves through the preferential fracture channels represented by the DFN in the model.