Research On The Application Of Nitrogen And Foam Flooding In Heavy Oil Reservoir

Cyclic steam stimulation is a main development method to heavy oil recovery at home. With the increase in cyclic steam stimulation cycle, the effect of the cyclic steam stimulation is getting worse, oil production is decreasing and productive cost is getting higher, and the economic benefits are getting worse. At the final phase of cyclic steam stimulation, seeking a more efficient development technique to further enhance oil recovery is so urgent in the oil field. As replace technique of cyclic steam stimulation, foam flooding shall nitrogen gas, hot water and foaming agent mixed and inject the mixture into wells. Using foam of air resistance effect and the characteristics of a substantial increase in displacement fluid of apparent viscosity, by means of controlling injection fluid fluidity, reducing gravity override and breakthrough of gas and water, pushing the displacement fronts evenly, broadening wept volume, these enhance crude recovery. Due to foam liquid with non-Newtonian rheological properties and foam fluid flow characteristics of strongly nonlinear, foam flooding by public is not deep enough understanding the people's understanding by public and there are still many difficulties in the implementation of industrialization, Therefore it is to be subjected to further study.This article from the drive mechanism of the foam flooding, laboratory experiments, field experiment and so on, foam flooding oil recovery techniques were studied. The displacement characteristics of foam fluid system depend primarily on foam stability, rheological properties and the ability to reduce interfacial tension. laboratory experiments show that: Foam system of surfactant can significantly reduce the interfacial tension between oil and water to enhance oil displacement efficiency; Higher apparent viscosity can effectively reduce oil/water mobility ratio , increase swept volume and finally result in the enhanced crude oil recovery. Adopting nitrogen foam flooding can effectively blank off lower oil saturation of high permeability zone. and enhance middle-low permeability layer of oil displacement efficiency.After five years field test, the Nitrogen foam flooding project in Jin-90th block have achieved larger technical breakthrough, and form a mature means of program design,dynamic regulation, allied injection/production technology, Reservoir dynamic monitoring data, effect analysis evaluation and so on. The field test proved: Nitrogen and foam flooding phase of the degree of reserve recovery was 11.2%, the average of oil recovery rate was 1.87%, enhanced oil recovery was more than water flooding by 6.2%, dynamic prediction final enhanced oil recovery was 9.3%and oil recovery rate enhances one time. The project achieved high benefit by 22.28 millions RMB per year, the unit operation cost of limited to 585 yuan per ton, the input-output ratio was 0.55, economic benefits are significant.