Siting, Design and Construction of a Horizontal Well for Industrial Water Supply in the Ogallala Aquifer

The Ogallala Aquifer has been extensively pumped for decades and significant dewatering has occurred in many areas of Texas. In portions of the aquifer, decreased saturated thickness is becoming a limiting factor controlling the production capacity of vertical wells. While there is a finite volume of water in the aquifer, horizontal wells in deeper portions of the aquifer containing coarser sands might provide a more economically feasible approach to groundwater production for longer periods even as saturated thickness of the aquifer become smaller.

This paper presents the approach that was used for siting, designing, and construction of a horizontal well for industrial client. The industrial user has an extensive well field to provide cooling water for a facility but regional declines in water levels continues to reduce the capacity of most of the vertical wells. The approach to siting and designing a horizontal well entailed evaluation of estimated saturated thickness, permeability, and other strategic considerations as well as groundwater modeling. After the preliminary evaluation, approximately seven miles of geophysical resistivity lines were used to map the deeper portions of the Ogallala aquifer. Subsequent test borings were used to further refine the lithology and target the best channels. The horizontal well contains 500 feet of 12-inch screen placed about 190 feet below land surface and produced over 650 gpm with only 42 feet of initial saturated thickness at the well site. Water level measurements from four vertical wells are received daily by the groundwater conservation district for monitoring purposes.