--> Enhanced Oil Recovery: From Innovative Approach to Optimize Liquid Hydrocarbon Recovery in a Depleted Reservoir, Rath, Surajeet, #90100 (2009)

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Enhanced Oil Recovery: From Innovative Approach to Optimize Liquid Hydrocarbon Recovery in a Depleted Reservoir

Rath, Surajeet1

1O.N.G.C Ltd., Kolkata, India.

Under an attractive reservoir pressure the reservoir fluid will be a mixture of liquid and gaseous hydrocarbon making it less viscous and more mobile through their onward migration from the deeper part of the reservoir overcoming the resistance offered by the forces like capillary pressure, surface tension, and heterogeneity to reach the exit with a high rate of recovery. Where as a depleted reservoir faces difficulties in recovery due to the separation of gaseous hydrocarbon from the parent fluid owing to drop in pressure and making it more viscous and less mobile to counter the resistance posed by overlying forces like capillary pressure and surface tension through its journey to the bore. Drop in pressure further enhances the problem by depositing finer particles in the migration path.

An innovative approach can be adopted in a depleting reservoir to overcome the resistances offered by different forces to obstruct the onward migration of liquid hydrocarbon to the bore effectively by decreasing the viscosity of the liquid hydrocarbon which will enhance its mobility and recovery.

The basic idea of this method is to exploit the natural physical and chemical properties of hot water underlying the liquid hydrocarbon zone of the reservoir with that of alkaline earth metal giving rise to liberation of enormous amount of gaseous hydrogen in their reaction process.
Through the reaction process liberated gaseous hydrogen being the lightest will moves upward through water to the overlying liquid hydrocarbon zone and owing to its high rate of miscibility will make the liquid hydrocarbon less viscous and more mobile only to accentuate its migration to the bore overcoming the above said resistances. Further the immiscible part of the liberated gas will move faster through oil zone to reach the bore ahead of fluid hydrocarbon and in the process will clear the finer particles deposited in the migration paths during drop in reservoir pressure .This will further smoothen the migration process of liquid hydrocarbon to the bore enhancing the oil recovery factor. As the reaction is exothermic, it will produce hues amount of heat giving rise to a thermal expansion effect of oil adding to its recovery factor.

The innovative approach can thus be implemented as an effective tool for Enhanced Oil Recovery ,Migration path clearance enhancing recovery and optimum recovery option in a heterogeneous reservoir.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil