The use of a preformed particle gel system has become an attractive option for water shutoff jobs and conformance control in oil fields. Preformed particle gels (PPGs) have several advantages over conventional chemical techniques of water shutoff treatments. This current research work talks about the effect of the reinforcement of two nanomaterials i.e., bentonite nanoclay and silica nanomaterial in the polymer matrix of NRPG (Nanomaterial-Reinforced Particle Gel). Nanomaterials were added and act as physical crosslinkers that enhance the thermal and mechanical properties of the developed gel. The nanomaterial's surface area will create an “interaction zone” when it is dispersed in the polymer matrix, altering the polymer's behaviour, morphology, space charge distribution, and bond dispersion. The NRPG is developed using Acrylamide (AM), Vinyl pyrrolidone (VP), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as a monomer, N, N-methylene bis acrylamide (NMBA) as a cross-linker. The equal concentration of two nanomaterials, bentonite nano clay and silica nanomaterial is used as a reinforcing agent via a free radical polymerization mechanism. Chemical characterizations such as Fourier Transform-Infrared Spectra (FT-IR), Powder X-ray Diffraction (P-XRD), Field Emission Scanning Electron Microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX), and Thermogravimetric Analysis (TGA) has carried out. In the current research work, tests were carried out to determine the effects of salinity, pH, multivalent ions, temperature, and nanomaterial concentrations, on the swelling of the NRPG. According to the findings, the NRPG swelling ratio decreased as salinity, pH, and nanomaterial concentration were increased. Moreover, there was a substantial increase in the swelling ratio at higher temperatures. Ampule sealing test has shown long-term thermal stability for more than 390 days at 120 °C. Rheological tests were performed to determine the mechanical strength of NRPG. In addition, the sandpack flooding experiment evaluates the plugging capacity of the NRPG to sandpack. These test results revealed that the plugging capacity of 0.5 wt % and 1 wt % suspension of NRPG is 96.03 % and 97.61 % and the residual resistance factor reaches 25.20 and 41.98 respectively. These findings suggest that the NRPG may be useful for water shutoff treatment in mature oilfields.