An oilfield apparatus has a swellable elastomeric composition that includes a swellable elastomer and one or more nanosensors dispersed therein. An oilfield assembly for exploring for, drilling for, testing for, or producing hydrocarbons includes various oilfield elements such as tubing, jointed pipe, sucker rods, submersible pump motor protector bags, packer elements, blow out preventer elements, zonal isolation tool elements, etc; and one or more of the oilfield elements has a swellable elastomeric composition that includes a swellable elastomer and one or more nanosensors dispersed therein. A method of selecting one or more oilfield elements has a component of an elastomeric composition that includes a swellable elastomer and one or more nanosensors dispersed therein; and a method of using the one or more oilfield elements in an oilfield operation, thus exposing the oilfield element to an oilfield environment.