Experimental Study On Gas-phase Solid Deposition Of Flue Gas In HQ Reservoir

The average porosity of the HQ reservoir is 17.82%,the permeability is 57.81mD,the reservoir temperature is 42?,and the asphaltene content is 15.56%.The reservoir has a low temperature in the formation and a high content of colloidal material,which belongs to the medium-low permeability reservoir.During the development of gas injection,it can easily lead to deposition of organic solids such as waxes and asphaltenes,blocking pores and increasing flow resistance,thus affecting production.In this paper,based on a thorough investigation of the principle of enhanced oil recovery and solid-phase deposition of flue gas flooding,combined with the actual production data of the reservoir,the indoor physical simulation experiment was used to demonstrate the method of microscopic verification.The following conclusions and understanding were obtained:(1)Establish a test device and method for testing heavy oil solid-phase deposition point by laser method,grasp the influence rule of obtaining the gas drive of flue gas on the properties of crude oil and the solid-phase deposition point during gas injection.The injection of flue gas can make crude oil expand,reduce the viscosity of crude oil,improve the physical properties of crude oil and increase its fluidity;the injected gas mainly extracts the light components in crude oil,which leads to an increase in the density of crude oil,and increases with the increase of injected gas volume.The phase precipitation pressure increases,and the AOP is higher than the bubble point 2-4MPa.(2)Establish a multi-stage contact solid-phase deposition test method for gas-driving oils,and systematically test the changes in the composition of the flue gas and formation crude oil and the amount of solid-phase sedimentation in the current formation conditions:as the number of contact between flue gas and formation crude oil increases,The amount of sedimentation gradually increased.When the contact was made 13 times,the amount of solid phase precipitation reached a maximum of 2.5 mg/ml;the C02 in the flue gas was dominated by viscosity-reducing effect;N2 was mainly used to maintain the formation pressure and displacement;The multi-stage contact between gas and formation crude oil mainly extracts the intermediate hydrocarbon component C2?C6 of the crude oil in the formation.After the contact between the local layer crude oil and the flue gas for 13 times,the dissolved solid-phase capability and solid content of the crude oil are in equilibrium.Therefore it is inferred that during the actual gas injection process,the solid-phase deposition mainly precipitates out of the trailing edge of the gas-oil transition zone,and has little effect on the gas flooding front.(3)Using the general method of parallel gas injection,the influence rule of the low-viscosity conglomerate reservoir for the alternate driving of tail gas and flood water was evaluated,and the appropriate ratio of gas to water was selected to explore the influence rule of solid-phase deposition on the physical properties of the reservoir:Water flooding was low.The degree of utilization of the conglomerate reservoirs in the seepage control is relatively low,and the recovery rate of the long core water flooding test for the four groups is between 32.44 and 34.91%with an average value of 33.39%.The alternating water and gas flooding can significantly increase the degree of reservoir reserves,and water alternation can be achieved.The total recovery of the flooding is 54.45%?60.04%with an average of 56.83%.The alternating water and gas flooding is favorable to the utilization of low-conglomerate conglomerate reservoirs.Compared with water flooding,the average recovery rate is 23.44%;gas water The ratio of 1:1 and 0.1 HCPV for water slugs are the best for oil displacement,and the recovery rate reaches 60.04%.Therefore,the key to determining the effect of water vapor alternating flooding is the utilization of low permeability layer reserves,and the optimal ratio of gas to water is 1:1.Before and after gas injection,the physical properties of conglomerate reservoirs changed greatly.