Heavy oil recovery has been an area of continuous research and improvisation. In Situ Combustion has been a technology full of promise and potential. The possibility of very high recovery makes this technique highly lucrative. However, the technical uncertainties and high cost poses a major problem. This paper suggests the use of sugar dust suspended in air as an alternative to water co-injected with compressed air/natural gas mixture used in In-situ combustion in order to overcome the above mentioned problems.
Sugar dust is a bi-product in the sugar industry and is treated as a waste material. Hence, its use will reduce the cost significantly. Another problem faced in implementing In-situ combustion is the occurrence of Low Temperature Oxidation (LTO) which creates many problems. However, Sugar dust suspended in air forms a highly combustible mixture and is capable of generating temperatures in the range of 800-1000°F which leads to occurrence of High Temperature Oxidation (HTO) only and thus eradicates any possibilities of LTO. An analytical study was undertaken of a dry combustion tube test data of a Louisiana heavy oil core. H/C ratio, oxygen to fuel ratio and air to fuel ratio was computed for the new suggested technique and compared with the existing values for the same. A similar analytical study was done for another combustion tube test data for a heavy oil core. Fuel requirement and air requirement was computed for the suggested technique and compared with the values observed for the normal ISC process. The comparison yielded positive results for all the parameter considered. Encouraged by those results an analytical and numerical case study was undertaken of a heavy oil field in Gujarat (India).The air requirement was seen to be reduced from 220sm3/m3 to 72.6sm3/m3. An economical analysis showed that the cost of oil production reduced by significant amount for that field.
Further, sugar dust concentration can be easily altered to facilitate auto ignition eradicating the need of artificial ignition. Combustion of sugar dust produces CO2 and steam. CO2 produced will be imbibed on oil surface and the viscosity will be reduced. Steam produced will aid in the displacement of the oil towards the producer well. Also, air requirement for the suggested technique would be very less. Hence, Sugar dust can revolutionize the in-situ combustion operation.