Ground Water in West Texas and Southeastern New Mexico

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Introduction The area covered by this report, as shown on the map (Fig 1), extends from Latitude 30 deg. to 35 deg. north and from Longitude 101 deg. to 104 deg. west. This embraces the portion of western Texas lying between Colorado City on the east and the town of Pecos on the west and from Plainview on the north to Sanderson near the Rio Grande on the south. It also covers southeastern New Mexico east of the Pecos River and south of the town of Portales and comprises some 45,500 square miles, or an area slightly less than the State of Louisiana. As might be expected from its position in the subtropical barometric high belt, the climate in this vast region ranges from semi-arid on the eastern edge to arid on the west and south. The map (Fig. 1) shows that precipitation ranges from 20 inches per year in the northeastern portion to less than 10 inches on the southwestern edge. The surface elevation rises from 1700 feet at the extreme southeastern corner to 5000 feet at the northwest edge. Geographically, the region changes from rough brush covered mesas in the eastern and southeastern parts through steppes, whose native growth is short grass, to the sparsely vegetated Chihuahuan desert on the south and west borders. As might be expected from the rainfall and elevation, the region is strongly deficient in water supply for the native vegetation, as shown in Fig. 2. This deficiency ranges from one and one-half million gallons per square mile in the southwest, to one-half million gallons per square mile in the east. If this map were based on the needs of agricultural crops useful to man, the deficiency would become even more marked. Because of light rainfall the runoff from the area is negligible (Fig. 3). In spite of the fact that the Sacramento and Davis Mountains, which rise 7000 feet to 12,000 feet west of the region receive considerably greater quantities of rain. there is not any important runoff. Although in some districts the moisture supports dense stands of timber, the underlying rocks are either porous lavas or cavernous limestones.