This chapter discusses nanoparticles can be produced by the “top-down” method, that is, crushing a bulk solid to nano size example by way of nanomilling. As the basic building block of nanotechnology is the nanoparticle, a tremendous variety of their synthesis methods have been developed, producing nanoparticles of different size, shape, composition, and internal structureto meet the requirements of the specific applications. The bottom-up methods form nanoparticles from different kinds of precursors mainly via a chemical reaction. Chemical modification involves covalent grafting of organic compounds of low molecular weight to the nanoparticle surface. The chapter explores the key objective of the nanoparticle surface coating for the upstream oil and gas applications is to make it survive the long-period, long-distance travel through the reservoir rock pores, so that it reaches the target location and carries out the design function.