Experimental Study On Deposition Of Solid Solution In Development Of Hydrocarbon Gas Injection In M Reservoir

With the maturation of hydrocarbon injection technology,the development of hydrocarbon injection has become one of the simplest and most practical measures in EOR development.The natural gas resources in the northwestern region of China are abundant.The major oilfields in the region have adapted to local conditions and have vigorously carried out pilot tests for hydrocarbon injection and gas flooding,and have achieved remarkable results.In recent years,domestic experts and scholars have been constantly advocating innovation,considering the establishment of gas storage at the same time as enhancing recovery,and maximizing the advantages of hydrocarbon injection gas extraction.Hydrocarbon gas extraction increases the crude oil recovery by improving the properties of crude oil,such as viscosity reduction,density reduction,and increasing the ratio of gasoline,but this process changes the composition of crude oil,and it may be possible for asphaltine and waxy reservoirs.Solid solution deposition occurs.If solid solution deposition occurs during gas injection,it will not only cause blockage of the wellbore,but it will severely block the pore throat of the reservoir and permanently damage the reservoir.As we all know,most oil fields in China have high crude oil content and poor physical properties.For the problems of solid solution deposition,the oil field should be studied clearly before its gas injection.This article takes the M reservoir in the northwest area as the target reservoir,takes the theory as the guide,the indoor test is the main method to study the deposition conditions of the solid solution in the reservoir in detail,and has obtained the following research results.(1)In the absence of a suitable solid-phase deposition analyzer,a solid solution deposition apparatus for testing the black oil of the reservoir under high temperature and high pressure was developed for the M reservoir crude oil.The existing PVT instrument is reformed to make it have the function of phase testing and solid-phase deposition testing at the same time,which greatly improves the experimental efficiency.(2)In-situ gas injection experiments were carried out using on-site oil samples,gas samples,and the three types of cores of high permeability,middle permeability,and low permeability in the reservoir.The experimental results of crude gas injection expansion show that under the current gas injection pressure,the viscosity and density of crude oil are reduced,the gasoline ratio is significantly increased,and the physical properties of crude oil are greatly improved.The results of long hydrocarbon gas flooding experiments show that the oil recovery efficiencies of high permeability,middle permeability,and low permeability cores are as high as 89.21%,81.82%,and 79.30%,respectively.On the aspect of enhanced oil recovery,hydrocarbon injection gas extraction can achieve remarkable results.(3)The experimental results of gas-expanding solid-phase deposition show that there is no solid solution deposition when the saturated pressure of the crude oil is increased by the injection gas to above the present formation pressure.This result indicates that the M reservoir will not produce solid solution deposition in the middle period before the development of hydrocarbon injection gas.(5)The results of multiple exposure experiments show that under the current formation pressure,when the gas injection volume is sufficient,the crude oil in the reservoir will produce solid solution deposition.On-line determination of the amount of solid solution deposited shows that the maximum amount of crude oil deposited is 0.549 mg/ml.This result shows that in the late stage of gas injection,there will be deposition of solid solution in the M reservoir.(6)The results of solid core sedimentation tests of long-term core hydrocarbon injection gas drive show that the permeability of the three types of cores of high permeability,middle permeability,and low permeability has dropped by 3.46%,6.17%,and 7.65%,respectively..This result shows that although there are solid solution depositions in the hydrocarbon-injection gas production of M reservoirs,the sediments have little effect on the pore structure of the formation,and there is no need to worry about solid solution deposition during the gas injection process.