A method for preparing concentrated and stable nanoparticle organosols using phase transfer is disclosed. The method includes transferring nanoparticles from a hydrosol into a hydrocarbon carrier with the aid of a transfer agent. The transfer agent can be added before, during or after the reaction of nanoparticle preparation and can be added to the aqueous or the organic carrier. The nanoparticles may be prepared in situ, pre-prepared in-house or commercially available. At the optimum values of the different parameters; namely precursor concentrations, amount of transfer agent and concentration of nanoparticles in the organosol, complete transfer of the nanoparticles may be achieved. The approach employs room temperature, moderate mixing and minimum number and quantity of chemicals relative to prior art. The nanoparticles may be used in fluids used in oil and gas recovery including drilling, completion, and stimulation fluids.