| Low permeability reservoirs are the important reservoirs of our country,which are the main areas of increasing production for oil field.Now water-flooding is the main development regime of low permeability reservoir.Low permeability reservoir are characterized bu low permeability,micro pore throats and low filtration rate,which caused the phenomenon of high water injection pressure and insufficient injection flow rate.The application of nanoparticle to enhance water injection had obtained some achievements.The character of the technique is marked effect,easy building and without pollution.In our study,we synthesized two diffirent modifieda-zirconium phosphate(hydrophobic and amphilic)as new nano injection agent to realize pressure reduction and injection stimulation.And we evaluated the performance of physics and chemistry,as well as the effect on ofaugmented injection and the affecting factor.(1)In this paper,the synthesis of ?-ZrP particles was refluxing method,which had simple preparation process,safe and pollution-free.And the ?-ZrP yield was high,can be prepared in large quantities.Through researching of synthesis process,we found that the a-ZrP particle size increased with longer refluxing time.Inorder to prepare smaller ca-ZrP particle,it was important to control refluxing time.The ?-ZrP was characterized by FT-IR,XRD,TGA,SEM and TEM,confirmed the successful synthesized layered ?-ZrP crystals,and the average of monodispersed ?-ZrP particles size was 70 nm,and thee thickness of particle was very thin.(2)Organically surface modified ?-ZrP(?-ZrP-?)was obtained buy reaction of the surface hydroxyl of ?-ZrP nanoparticles with octadecyl isocyanate(ODI).Surface fuctionalization of ?-ZrP with ODI was accomplised by one-step synthesis producing highly hydrophobic nanoparticle.The surface modified a-ZrP was characterized by FT-IR,XRD and TEM.And the amiphiphilic ?-ZrP(?-ZrP-?)were obtained by exfoliation ?-ZrP-? through tetra-(n-butylammonium)hydroxide.(3)Through DLS and SEM,we found that the full dispersed of ?-ZrP-? and ?-ZrP-?had an average particles size smaller than 100 nm,and with the concentrtion increasing,the allomeration of nano particales would be more serious.(4)The ?-ZrP-? was hydrophobic,which could adsorpted on the hydroated layer on the surface of reservoirs,formed ?-ZrP-? adsorption sheets.The contact angel of surface of rock slice wsa 115° when the ?-ZrP-? particles concentration was 200 mg/L.The cmc of?-ZrP-? was 2500 mg/L.(5)Evaluated the augmented injection performance of the new modified ?-ZrP based injection agent by core plugs displacement experiments.Study the injection process with the change of ?-ZrP-?I particles concentration and injection volume and adsorpted time.Determine that the optimal injection concentration was around 50 mg/L,the optimal injection volume was 1-2 times of the pore volume(PV),the optimal adsorpted time was 24 hours.After the ?-ZrP-? injected into cores,the subsequent water flooding pressure decreased 48.38%.And the weter flooding permeability was 2 times than before.But the ?-ZrP-?could not decreased the injected pressuer,injected different concentration of ?-ZrP-?,the subsequent injection pressure both increased.So,the degree of hydrophobic would affected the result of decompression and augmented injection.(6)The scouring properties of ?-ZrP-? was strong,when the accumulated injection reached to 200 PV,the permeability of core decreasing range was very small.Which indicated that the ?-ZrP-? had a good adsorption property,could be effectively adsorbed on the wall of the core channel. |
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