Without complete, high-quality petrophysical data, it can be difficult to acquire the formation and reservoir insight necessary to reduce geologic uncertainty, optimize completion design, mitigate costs, and enhance production in unconventional plays. The Weatherford Compact Spectral Gamma Ray tool is an efficient and cost-effective means of obtaining petrophysical data where conventional wireline tools are ineffective, including horizontal and high-angle wellbores. The 2.25-in. outside diameter of the tool enables advanced conveyance techniques in memory mode without the need for expensive and time-consuming wireline pipe-conveyed operations. The tool also reduces tool-string length and operates in small-diameter wellbores. By use of multiple high-resolution detectors, the tool delivers the precision and repeatability required by the most demanding applications. The tool measures potassium, uranium, and thorium—the three most common elements found in radioactive sands and shales—and total gamma radiation. These data are used to determine stratigraphic sequencing and correlation and to calculate porosity and clay volume. The spectral component of the tool helps to distinguish hot sands from shale, to identify organic carbon, and to differentiate clay types—a key factor in assessing formation permeability. All of these capabilities help to improve the identification of pay zones and to enhance well economics.