Lineaments and Water Wells as Exploration Tools in Midway-Extra Gas Field, West Virginia: ABSTRACT

Abstract

A hydrogeologic characterization study was done in the Midway-Extra Devonian shale gas field of northern Putnam County, West Virginia. Lineaments were mapped and water wells were surveyed for physical and chemical parameters, for comparison to initial yield of nearby shale gas wells. Short, straight photolineaments are significantly associated with water-well yield in gallons per minute. Water wells located within 200 ft (60 m) of a lineament's center line have significantly higher yields, which indicates End_Page 1575------------------------------ that such lineaments probably represent anomalous zones of increased fracture permeability about 400 ft (120 m) wide at the surface. Gas wells located near short photolineaments oriented N60°W to N30°E and especially N60°W to N0°E had significantly higher initial open flows (both before and after stimulation) than wells located near other photolineaments. Gas wells also had significantly higher initial open flows when located in high-density areas of N60°W to N30°E photolineaments. Within lineament density zones exceeding 2.0 mi/sq mi (3.2 km/2.6 sq km), 71 and 100% of randomly located gas wells would have exceeded 100 Mcf/day before stimulation and after stimulation respectively. Gas wells located near class 1 (most certain) photolineaments had higher in tial open flows than wells near class 2 or 3 (less certain) photolineaments. Wells located within 0.25 mi (0.4 km) of a class 1 photolineament oriented N60°W to N30°E had significantly higher initial open flows than more distant wells. Landsat lineaments appear to be poor locations for gas wells, for they do not overlap the areas of high gas production. Certain water-well parameters are also associated with initial gas well yield. Water wells located within areas of high initial gas flow (over 100 Mcf/day after stimulation) have significantly higher bicarbonate and nitrate concentrations than wells in areas of low gas production. Optimum sites for high-yielding gas wells would be near water wells having at least 470 mg/1 bicarbonate or at least 1.75 mg/1 nitrate. Initial yields before stimulation were significantly greater for gas wells near high-yielding water wells compared to gas wells near low-yielding water wells; however, this trend is probably not useful for gas exploration, for it does not apply for initial gas flows after stimulation. End_of_Article - Last_Page 1576------------