This invention is directed to a system for determining the position and depth of downhole equipment in a wellbore which includes an elongate spoolable composite coiled tubing for running the downhole equipment into the wellbore. The composite coiled tubing string has multiple layers of fibers arranged in a generally cylindrical shape, wherein each layer has a plurality of fibers arranged in a predetermined orientation to form a composite coiled tubing string having sufficient strength to be pushed into and pulled and out of the borehole. A plurality of detectable indicia (such as metallic, magnetic or encoded sections) overlay at least one of the layers of fibers and are integral to the composite coiled tubing string and spaced apart along the length of the tubing string at predetermined distances. As the tubing is raised and lowered in the wellbore, a detecting means detects the presence of the indicia in the composite coiled tubing string for determining the location of a particular point on the string relative to a particular position in the wellbore and can also be used for determining the composite coiled tubing behavior in relation to load and load deformation.