Oil and Gas industry is going through a phase where there is an increased demand of energy sources (particularly oil and gas) and reduced production due to mature oilfields. There is a need for new technologies which can help improve production from the reservoir and develop new fields. Nanotechnology offers promising solution for the same. Nanotechnology is the study of science of materials at nanoscale which help in enhancing the performance of processes. Nanoparticles are the nano-sized materials in the range of 1-100 nm. Nanoparticles have high specific surface area and unique properties, such as high adsorption potential and heat conductivity. These particles when mixed with base fluids, also called as nanofluids, and used for several application related to upstream oil and gas industry, help improve the performance of several processes. The use of nanoparticle in exploration and production is an attractive tool for petroleum engineers that have been improved by many researchers in recent years. This paper discusses about how the nanotechnology plays an important role in an upstream oil and gas industry which includes exploration, drilling, and completion, production and enhanced oil recovery operation. © (2013) Trans Tech Publications, Switzerland.