Reflectance spectra in the visible and near-infrared wavelength region provide a rapid and inexpensive means for determining the mineralogy of samples and obtaining information on chemical composition. Hydrocarbon microseepage theory establishes a cause-and-effect relation between oil and gas reservoirs and some special surface anomalies. Therefore the authors can explore for oil and gas by determining the reflectance spectra of surface anomalies. This determination can be fulfilled by means of field work and hyperspectral remote sensing. In the present paper, based on the analysis of reflectance spectra determined in the field of Qinghai X X area, firstly, a macroscopic feature of the reflectance spectra of typical observation points in the gas fields is presented. Secondly, absorption-band parameters of spectra such as the position, depth, width, and asymmetry are extracted. Based on the spectral absorption features of the spectra of 144 samples collected from the field, a spectral library for the Qinghai X X area is built to make the detection of the mineral alterations more rapid and reliable. Thirdly, two methods are improved and proposed to detect hydrocarbon microseepage using hydrocarbon absorption bands of reflectance spectra determined from the field. Finally, a linear unmixing model is studied based on the spectra of 144 samples so as to semi-quantitatively determine the abundance fractions of main minerals in the authors' studied area.