interval immediately above the oil-water contact, and the wildcat was completed 

 as an excellent flowing oil well. 



Development Program 



Because Amprex had acquired leases covering all of what it thought to be 

 the potentially productive area, it could now plan an efficient development 

 program. Within the limits imposed by lease considerations and orders of 

 political regulatory bodies, the locations of the development wells were planned 

 to recover the maximum amount of oil with the natural producing mechanism 

 while employing the widest practical well spacing. 



Amprex's engineers and geologists realized that this discovery demanded 

 the planning of a sound well-spacing program to be initiated early in field de- 

 velopment. Proper well spacing for each of the productive reservoirs of the 

 field could be determined only through the technical appraisal of the physical 

 data accumulated for each reservoir, including structure, porosity, and perme- 

 ability of reservoir rocks, the nature of the contained fluids, and the recovery 

 mechanisms, i.e., dissolved-gas drive, water drive, expanding-gas drive, and 

 gravity drainage. The well-spacing program would be designed to permit efficient 

 secondary-recovery operations. Thus, it was necessary that the efforts of the 

 geologists and engineers jointly be directed toward the acquisition of adequate 

 technical evidence upon which a spacing program could be based. Amprex's 

 group decided to employ wide initial spacing to obtain a maximum of informa- 

 tion concerning the reservoirs, with a minimum number of wells. Early 

 knowledge of the physical characteristics of each of the reservoirs and their 

 individual behaviors would permit strategic location of infill wells where such 

 wells were shown to be needed. 



After a program of extensive coring, logging, and testing had been employ- 

 ed on an adequate number of wells to define the limits of each reservoir and 

 the characteristics and contents of each reservoir, Amprex's engineers and pro- 

 duction geologists would have the necessary factual data to develop the field 

 to proper well density, and to locate each completion interval to take advantage 

 of the most efficient driving mechanism in order to obtain high recoveries. 



The completion of the No. 1 Juan Cuervo and the subsequent development 

 of the Cuervo field, a name approved by the political regulatory bodies of the 

 area, marked a new era for the Arenoso Basin. The quiet, dusty basin became a 

 center of prosperity. Several of Amprex's competitors, through their scouting 

 sections, had followed the geological, geophysical, and leasing activities of 

 Amprex with considerable interest. They had scouted the drilling of the strati- 

 graphic tests and of the No. 1 Cuervo; and, although they had no detailed infor- 

 mation as to exactly what these tests had encountered, they were aware of the 

 total depths of the wells and had observed the formation tests. The depths of 



857 



