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In this work method to improve the efficiency of the development of shallow deposits of extra-heavy oil using cyclic team stimulation (CSS) technology together with injection of catalyst for in-situ upgrading and solvent was proposed. Oil-soluble catalyst has been developed. Efficiency of catalyst was proved in laboratory. Volume and conditions of catalyst and solvent injection together with steam were determined based on simulation results. Pilot tests of technology were carried out on extra-heavy oilfield in Tatarstan, Russia. The screening of catalysts and solvents together with injection of steam was studied in high pressure reactors under reservoir conditions. Heavy oil displacement coefficients in basic scenario of steam injection and second scenario of steam injection together with catalyst and solvent were measured on self-designed experimental steam injection apparatus. The technology was simulated with tNavigator softwarre (Rock Fluid Dynamics) version 18.2, STARS. Pilot tests were carried out in several stages: preliminary short-term injection of steam to pre-heat the reservoir, injection of catalyst solution and solvent, the subsequent full-scale stage of steam injection, imbibition, and production. The results of field tests confirmed laboratory and simulation data. According to the analyzed samples after six months of field tests, the viscosity at the first stage decreases as a result of dilution with a solvent. The effect of the catalyst, which particles are adsorbed on the reservoir rocks, clearly demonstrated later. It is shown that the combined use of in-situ upgrading catalyst and a solvent in CSS method allows to increase oil recovery factor. At the same time, the produced oil has better properties. Significant degree of conversion of resins and asphaltenes to light fractions was established. Field tests on Ashal'cha oilfield have shown that this technology is effective for the development of shallow deposits of extra-heavy oil.

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The settings, scale and geometry of lab facilities to simulate enhanced recovery methods play a significant role in the approximation of underground conditions of oil fields. The reliability more or less of the best replication of these conditions is a question of the reservoir engineer when forecasts are made for cases when enhanced recovery methods are applied. This paper presents the results of two experiments carried on in a steam flooding tube facility adding clay in one of them to assess the influence in temperature growth and production rates and onset times of a highly viscous oil field of the Tatarstan Republic. The results of the runs show that 4% (by weight) of clay content in the porous media has a strong effect on the overall oil recovery, reducing the temperature growth rate in average 73% when steam stimulation methods are used.

In-situ combustion (ISC) is an effective thermal enhanced oil recovery method. However, it is still not widely implemented in oilfields. One of the factors limiting the wide application of ISC is the challenge in its simulation and prediction. In this work, the oxidation experiments of maltenes and asphaltenes in reservoir rock were performed in the porous media thermo-effect cell (PMTEC) to establish a simplified reaction model based on non-isothermal measurements and to use it in numerical simulation of ISC process. It was found that the oxidation reaction process of oil fractions can be divided into different regions depending on generated self-energy rate and oxygen consumption rates that is up to the temperature. In order to propagate reactions from one mode to another, a specific oxygen consumption per unit mass of oil fractions is required. The average oxygen requirement for crossing LTOad (low temperature oxidation, oxygen addition reactions) boundary into LTC (low temperature combustion) mode was 64 mgO2/g(maltenes) and 10.4 mgO2/g(asphaltenes). To propagate reactions into HTO mode from the LTC mode, it requires about 646 mgO2/g(asphaltenes) for asphaltenes fraction. Moreover, this characterization seems to be a key tool when designing air injection in field pilots. Additionally, it was revealed that asphaltenes are more exothermic and require lower oxygen uptake per unit of temperature increment in comparison to maltenes. Furthermore, the mass conversion data obtained from non-isothermal measurements of oil fractions allow for the estimation of the stoichiometry coefficients of two low temperature oxidation reactions, i.e. oxidation and cocking processes, which can be included into a numerical simulation model to replicate combustion tube (CT) results. The numerical simulation model reveals that the simplified reaction model from a 6-step into a 3-step reaction scheme can reproduce ignition process, temperature profiles, combustion velocity, and fluid production, which thus makes it suitable for the upscaled modelling of ISC.