Investigation of forward in situ combustion have been carried out in a 7.3 cm diameter tube having a length of 0.869 m. Experiments at pressures up to 50 psig were made to study combustion characteristics and enhanced oil recovery of three different crude oils, namely North Sea Forties (36.6 °API), Maya Isthmus (32.4 °API) and Maya (22.1 °API). Sand packs were prepared with oil saturations in the range 38-44.32%. Close adiabatic control of the combustion tube was achieved for both dry and wet combustion modes. Detailed production history and overall mass balances are presented. Correlation in both graphical and tabular form is given for air-fuel ratio, oxygen utilisation and normalised combustion velocity. In this respect, the results of the present work show good agreement with those of other workers. Normal wet, partial quenched modes of combustion were produced using WARs up to 3.75 m3/Mm3 (STP). The combustion front temperature was not significantly affected by the cooling effect of the injected water. Under partially quenched conditions, high combustion-steam zone temperatures were achieved. For wet combustion, the oxygen utilisation generally improved slightly. Air requirement, air-oil ratio and fuel consumption all decreased with increased water-air ratio and increased with increased clay content. The velocity of the combustion front (normalised with respect to the air flux) increased in a linear manner as the WAR increased. Increasing the clay content, however, gave rise to a decrease in the combustion front velocity. High oil recovery, at 79.37%, was achieved during normal wet combustion of Forties oil. In sand mixtures containing amorphous silica powder, the combustion exhibited virtually 100% oxygen utilisation, with higher carbon burning rates compared with runs using clay addition. These effects are attributed to the nature and magnitude of the surface area of solid additives, which play an important role in the oxidation mechanisms.
|Date of Award||1985|