Successful Foams EOR Field Pilot in a Naturally Fractured Reservoir by the Injection of the Foaming Agent Dispersed in the Gas Stream

Abstract

This work presents the concept, progression, execution and results for a successful field implementation for a new technique to create insitu blocking foams in a gas condensate naturally fractured reservoir by the injection of the foaming agent dispersed in the hydrocarbon gas stream. This new technique aims at simplifying the operation and reducing the footprint and costs for the deployment of EOR foams in gas injection based projects. It also helps to overcome the disadvantage of limited reservoir volume of influence obtained by the SAG technique. The selected field area for the pilot was confirmed to be naturally fractured dominated both by the production and gas injection performance. The field area had only one oil producer and one gas injector, so monitoring the results of the pilot was simplified. The operation was carefully planned so that a ramp up in foamer solution concentration could be implemented at the field, and the response of the gas injector well could be monitored in real time. Additionally, a gas tracer program was implemented to track the fly times of the gas prior and after the dispersed foam treatment. About 1000 Bbls of foaming solution were dispersed in the hydrocarbon gas stream in one gas injector of a gas condensate Piedemonte field, whose injectivity performance was confirmed to be highly influenced by the natural fractures. Base gas injection conditions were about 30 MM scfd at 3800 psi WHIP. Once the dispersed foamer injection started, the gas injectivity in the well was progressively reduced to the point of increasing the WHIP to ~5000 psi, and the final gas rate was half of the base. The oil production well influenced by this injector changed its performance showing an increasing ramp in oil production and a reduction of the gas oil ratio (GOR) after the dispersed chemical injection period. The tracking of the gas tracers evidenced a delay in the gas fly times between the injector and the producer wells of two fold (63 days Vs 28 days), as a consequence of the dispersed foam treatment. This is the first time a successful foam EOR field pilot is done in a naturally fractured reservoir by the injection of the foaming agent dispersed in a hydrocarbon gas stream. It is believed this new foams technique could also be extended to other non-condensable gases at field operating conditions like CO2, Nitrogen, Air, and Flue Gas.

Evaluation of Gas-Based EOR Methods in Gas-Invaded Zones of Fractured Carbonate Reservoir

“…Surfactant-alternating gas (SAG) combined with foams dispersed in gas injections leads to an increased treatment depth than SAG alone, and the foams block high-permeability fractures. This process increases the potential of inaccessible fractures until then [13][14][15]. Hence, implementing a proper process requires extensive laboratory work and simulation studies to be effective.…”