Deep penetration slow plugging removal and injection technology for ultra-low permeability sandstone reservoir
In view of the problems of poor physical properties and large seepage resistance of ultra-low permeability sandstone reservoirs in HQ oilfield,oil layer blockage and poor water absorption are easy to occur after a period of time of injection well injection,which can not meet the water injection requirements for oilfield development,and the effect of conventional acidification is not ideal.In order to ensure enough water injection and good water injection,and promote the efficient development of reservoirs,the plugging removal and augmented injection technology of under-injection wells in ultra-low permeability sandstone reservoirs was studied.By analyzing the reasons for the unsatisfactory effect of conventional acidizing and augmented injection in the under-injection wells of the reservoir,combined with the geological characteristics of the reservoir,a deep penetration and slow plugging removal fluid was designed.The retarding performance,plugging removal ability,secondary damage inhibition and metal ion chelating ability of the plugging removal fluid were evaluated in laboratory.The plugging removal fluid was used to carry out on-site deep penetration and slow plugging removal and augmented injection process design and test work in HQ oilfield.Compared with the previous conventional acidizing augmented injection,the effective rate of augmented injection measures in test wells increased by 16.7％,the average single well water injection pressure decreased by 1.7MPa,and the average single well validity period was extended by 8 months.Through laboratory research and field test,a plugging removal and injection increasing process suitable for special reservoirs in HQ oilfield has been formed.
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