In-situ combustion (ISC) is a promising enhanced oil recovery process for the vast heavy oil accumulation of the Orinoco Belt in Venezuela. Combustion tube tests were performed to assess the feasibility of the process in a reservoir of the area. Given the successful laboratory results, it was decided to proceed with the design of a pilot test. Along with the basic design calculations, a simulation model was built to aid in selecting optimum well locations and operating strategies of the pilot. This would also be used for history matching of the actual operation and further optimization. One of the features of the model is the inclusion of the foamy oil behavior exhibited by the oil. For the modeling of the combustion process, a kinetic model developed in-house by PDVSA Intevep using thermo-gravimetric and scanning calorimetry experiments from an analog field, was employed. The first stage of the study involved the characterization of the oil into the same pseudo-components utilized by the kinetic model. A match of relevant PVT data was done for this purpose. In the second stage, the field scale model was history matched with the new fluid model, which included the foamy oil behavior. The best agreement with field measured data was obtained with a dispersed-gas foamy oil model with velocity dependence of the reaction that converts the low-mobility dispersed gas into high-mobility free gas. The following stage consisted of the history match of the combustion tube test, which was partly achieved with an assisted-history-matching tool. In the last stage, the results obtained from the combustion tube match were applied to the field model. In order to determine the most appropriate locations of production and injection wells, several pilot configurations were studied combining vertical and horizontal wells. A sensitivity analysis was completed using operational parameters such as injection rates and distance between producers and injectors wells. Based on ultimate recovery, the best pattern configuration was selected along with the optimum operational parameters. This paper illustrates the application of a workflow for modeling ISC from laboratory experiments to the field scale.

Orocual is the most complex Field in Monagas, eastern Venezuela. Due to its complexity it has been divided vertically into two zones: shallow (heavy oil) and deep (light oil and condensate). The OOIP in shallow reservoirs is reported as 3500 MMSTB. The reservoir pressure is close to original conditions due to low historical production. Therefore, the current oil recovery factor is less than 1%. To date, cyclic steam injection pilot was applied to 5 wells and the initial oil rate showed to be as high as five times the cold production in vertical wells and six times the cold production for horizontal wells. According to the results of the pilot test, the future development of shallow Orocual will be mainly based on the application of thermal processes. This paper shows a methodology to design an exploitation plan through the application of thermal process. The first step involves analyzing the reservoir by sectors in order to determine which thermal process is appropriate to the reservoir; the second step is building sector models to simulate each process and optimize operational parameters. For the first time cyclic steam injection, steamflooding and steam assisted gravity drainage were simultaneously simulated in the same model. According to this study it is possible to maximize the production of these reservoirs, accelerate the exploitation of its reserves and optimize operational parameters in thermal recovery, as well as determine critical factors for each process. This study shows that numerical simulation of complex process can be efficiently carried out in FullField scale.