In the central Appalachian Basin, productive gas wells and dusters are often located close together with no general trends visible. In these highly heterogeneous reservoirs, hitting a fracture often makes the well productive. Some lineaments may be obvious, while others are more subjective. Significant differences in lineament maps for the same area may be caused by image factors and image types. Image factors include season or time of day, cultural disturbance, scale, and contrast and density.
Scale is the most important factor because, as the scale changes, so does the resolution.
For example, individual fractures in an aerial photograph may appear as a single lineament. Widely available image types include Landsat, US Geological Survey mapping photography, topographic maps, Digital Elevation Models, and Side-Looking Airborne Radar. Mapping techniques may be automated or based on visual analysis of images. In either case, the development of an exploration model using photolineament analysis requires finding a relationship between the value of a well and its spatial position with respect to lineaments. Most previous analyses have used simple linear relationships between well value and distance to lineament, lineament intersection, orientation, or lineament density.