Interactions Between Nanometer Polysilicon Materials And Rocks

The pores and throats of low permeability reservoirs are very narrow, which results in the higher injection pressure and serious damage to casings. Well stimulation is a difficult problem which should be solved urgently for low permeability reservoir development. Nanometer polysilicon material (NMPM) is a material that is added by agents and activated byγ-ray for chemical modification, the main part of NMPM is silicon dioxide. In these years, NMPM has been used for well stimulation in low permeability reservoirs and achieved some progresses. Up to now, the mechanisms of NMPM for well stimulation are not clear and further investigations are needed. The size distribution of NMPM was measured and observed by laser particle analyzer and the transmission electron microscope (TEM). The viscosities of NMPM solutions were measured by the capillary viscometer. The interfacial tension between NMPM solution and water or air were measured by the automatic interfacial tension-meter. The static capability of restraining clay swelling by NMPM was evaluated by the clay swelling measurement under high temperature and high pressure and the dynamic capability of restraining clay swelling by NMPM was studied by core flow tests. The flow and distribution of NMPM solution in microscopic models was observed and recorded by the microcosmic observation system. Experiments show that NMPM is hydrophobic with particle size range between 5 and 40 nm. The densities and viscosities of NMPM solutions decreases with temperature increasing. The interfacial tension between NMPM solution and water is lower than that between diesel oil and water when the NMPM concentration reaches 1.0g/L. The interfacial tension between NMPM solution and water decreases with the measurement times. The swelling rate of the clay used increases with temperature and shorter time is needed to reach its equilibrium. The swelling rate and swelling speed of the clay treated by NMPM are lower than that of the clay untreated. The injection pressure of NMPM solution is lower than that of diesel oil and the later water flooding pressure in cores injected by NMPM solution is also lower than that of waterflooding of diesel oil, which shows that NMPM solution treatment can restrain the clay swelling in the cores. The NMPM can absorbed on the pore walls and increase the pore space for water flow, which maybe one of the mechanisms for the decrease of the injection pressure of water.