During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potent...During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery.However,carbon dots characterized of small size,high surface energy are faced with several challenges,such as self-aggregation and settling.The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation.In this work,we investigated the stability of hydrophilic carbon dots(HICDs)and hydrophobic carbon dots-Tween 80(HOCDs)nanofluids.The influences of carbon dots concentration,sorts and concentration of salt ions as well as temperature on the stability of CDs were studied.The results showed that HICDs are more sensitive to sort and concentration of salt ions,while HOCDs are more sensitive to temperature.In addition,the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88%and 26.14%,respectively.Hence,the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.展开更多
Profile control is utilized to redirect the injection water to low permeability region where a large amount of crude oil lies.Performed gel particles are the commonly used agent for redistributing water by blocking th...Profile control is utilized to redirect the injection water to low permeability region where a large amount of crude oil lies.Performed gel particles are the commonly used agent for redistributing water by blocking the pores in high permeability region.But the capability of deep penetration of performed gel particles is poor.Here,we formulate nanoparticle stabilized emulsion(NSE).The stability and the effect of NSE on the fluid redirection in a three-dimensional porous medium were investigated.By usingμ-PIV(particle image velocimetry),it was found that the velocity gradient of continuous fluid close to the nanoparticle stabilized droplets is much higher than that close to surfactant stabilized droplets.NSE behaves as solid particle in preferential seepage channels,which will decrease effectively the permeability,thereby redirecting the subsequent injection water.Furthermore,NSE shows high stability compared with emulsion stabilized by surfactant in static and dynamic tests.In addition,water flooding tests also confirm that the NSE can significantly reduce the permeability of porous media and redirect the fluid flow.Our results demonstrate NSE owns high potential to act as profile control agent in deep formation.展开更多
基金supported by the National Natural Science Foundation of China(51704313)the Chang Jiang Scholars Program(No.T2014152)。
文摘During the development of low or ultra-low permeability oil resources,the alternative energy supply becomes a prominent issue.In recent years,carbon dots(CDs)have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery.However,carbon dots characterized of small size,high surface energy are faced with several challenges,such as self-aggregation and settling.The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation.In this work,we investigated the stability of hydrophilic carbon dots(HICDs)and hydrophobic carbon dots-Tween 80(HOCDs)nanofluids.The influences of carbon dots concentration,sorts and concentration of salt ions as well as temperature on the stability of CDs were studied.The results showed that HICDs are more sensitive to sort and concentration of salt ions,while HOCDs are more sensitive to temperature.In addition,the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88%and 26.14%,respectively.Hence,the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.
基金supported by the National Natural Science Foundation of China(U1663206,51704313)the Taishan Scholar Climbing Program in Shandong Province(tspd20161004)the Fundamental Research Funds for the Central Universities(18CX02028A)
文摘Profile control is utilized to redirect the injection water to low permeability region where a large amount of crude oil lies.Performed gel particles are the commonly used agent for redistributing water by blocking the pores in high permeability region.But the capability of deep penetration of performed gel particles is poor.Here,we formulate nanoparticle stabilized emulsion(NSE).The stability and the effect of NSE on the fluid redirection in a three-dimensional porous medium were investigated.By usingμ-PIV(particle image velocimetry),it was found that the velocity gradient of continuous fluid close to the nanoparticle stabilized droplets is much higher than that close to surfactant stabilized droplets.NSE behaves as solid particle in preferential seepage channels,which will decrease effectively the permeability,thereby redirecting the subsequent injection water.Furthermore,NSE shows high stability compared with emulsion stabilized by surfactant in static and dynamic tests.In addition,water flooding tests also confirm that the NSE can significantly reduce the permeability of porous media and redirect the fluid flow.Our results demonstrate NSE owns high potential to act as profile control agent in deep formation.
