Simulation Study for Designing an In-Situ Combustion Pilot in the Orinoco Belt of Venezuela: From Laboratory Studies to the Field Scale

Abstract

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.

Impacts of Kinetics Scheme Used To Simulate Toe-to-Heel Air Injection (THAI) in Situ Combustion Method for Heavy Oil Upgrading and Production

“…The scheme does not take into account the induction period before coke formation. A significant number of simulation studies have used this kind of thermal cracking reaction scheme. ,,− A typical general representation is shown in Figure . Quite good matches were obtained using this scheme.…”

“…This is because oxygen has to bypass the combustion front before oil is burned. However, authors such as Lin et al and Anaya et al have included them in their model and their influence have not been reported.…”

Workflow of the In Situ Combustion EOR Method in Venezuela: Challenges and Opportunities

“…The modeling of reaction mechanisms in the ISC process ,− is one of the most complex tasks that could have an impact on the evaluation of the technology. The results reported by Amaro (2013) and Goncalves (2015) indicate that the addition of additives, nanoemulsions (based on surfactant and nanoparticles of a transition metal), or hydrogen donors improve the stability of the combustion front and the properties of the crude oil.…”

“…Figure illustrates the impact of the foamy oil effect on the overall field performance. It is reported that the foamy oil behavior helped in matching the gas production and in achieving higher and more realistic bottom hole pressures for the production wells in the evaluated reservoir zone …”

Forecasting of H2S Production due to Aquathermolysis Reactions

“…As highlighted by Gutiérrez et al (2011) and Zhu (2011), the fact is that, in reservoir engineering, the fluid modeling is usually based on cuts obtained by molecular weight splitting, and not on SARA fractions, because of the availability of well known methods/correlation for deriving component thermodynamic parameters (as critical coordinates for an EOS fluid model, or component correlation parameters) from their molecular weight. Hence, the approach followed by Anaya et al (2010) for building a consistent thermo-kinetic model usable for simulating in-situ combustion using a reservoir engineering software uses three heavy pseudo components (LO: Light Oil, MD: Medium oil, RC: short heavy residue) obtained from an arbitrary lumping of SCN (Single Carbon Number) components obtained from the splitting of the oil C11+ cut.…”