Study On The Identification Of Dominant Channel And Profile Control Of CO₂ Foam In 530 Well Area

The CO2 flooding test area of the conglomerate reservoir in the 530 well area of Xinjiang Oilfield has the characteristics of medium-low porosity-medium-low permeability reservoirs with serious heterogeneity.During the CO2 test injection,due to the serious heterogeneity of the reservoir,complex pore structure,development of dominant channels,and low viscosity and low density characteristics of C02,gravity overburden and viscous fingering are serious,causing premature breakthrough of CO2.Therefore,it is urgent to identify the dominant channel of the reservoir and explore suitable methods for suppressing the gas,so as to achieve the purpose of improving the development effect.In this paper,for the geological characteristics,development status and existing problems of the reservoir in the CO2 test area of the 530 well area,the dominant channel of the test area was studied,and the CO2 foam indoor experiment was carried out,and the following results and understanding were obtained.(1)Through the fuzzy comprehensive analysis of the dynamic and static indexes of the injection wells and production wells in the CO2 test area of the 530 well area,the development of the dominant channel in the test area is obtained:4 injection wells with strong dominant channels(80513 well,etc.).3 injection wells with weak dominant channel(80474 wells,etc.);12 production wells with strong dominant channels(80492 wells,etc.),and 6 production wells with weakly dominant channels(80576 wells,etc.).(2)Through the electron microscope scanning experiment and the physical sand filling model,the formation mechanism of the dominant channel of conglomerate reservoir is studied.The experimental results show that the more point-line contact between the rock skeleton particles,the denser the dissolution pores and micro-crack distribution,and the storage.The stronger the layer heterogeneity,the higher the viscosity of the crude oil,the higher the injection intensity,and the more pronounced the rhythmic deposition,the easier it is to form the dominant channel.(3)The formulation of CO2 foam system for controlling gas enthalpy was optimized,and the formula of CO2 foaming and displacing system suitable for the test area was selected:0.3%QP-1+0.1%QP-2+0.04%WP-3.The foaming volume of 100mL foaming liquid is 651mL,the foam half-life is 147min,the reservoir adaptability evaluation results show that the foam system has better salt tolerance.Properties,temperature resistance,stability and oil resistance.(4)The CO2 foam parallel core flow experiment was carried out to evaluate the CO2 foam plugging capacity.With the increase of injection volume,the resistance factor of high permeability core increased rapidly.The low permeability core resistance factor grew slowly in the early stage and increased faster after 0.8PV injection.Showing considerable fluidity control.The optimized injection parameters were obtained by CO2 foam core flow experiment:gas-liquid ratio 1:1,injection speed 0.05mL/min,slug size 0.1 PV gas+0.1 PV liquid.The CO2 foam flooding experiment was carried out.During the process of water and gas flooding,the core was not used uniformly.After the CO2 foam was adjusted,the low permeability core improved the recovery ratio by 7.7%,and the high permeability core enhanced the recovery ratio by 4.2%.The final recovery ratio is increased by 5.6%,which shows potential for enhanced oil recovery.