diverse ownership of leases. Secondary recovery operations, where applicable, 

 are more efficient where the field is controlled by one owner or operator. 



Amprex recalls an outstanding example of progressive exploration, the 

 Cuyama Valley of California, where a large lease block was tested by a wildcat 

 well drilled in 1948. Approximately 300 million barrels of new oil was dis- 

 covered by this wildcat drilled in an area that had been condemned for many 

 years by some competitors. Valuable concessions in the Middle East, Near East, 

 Indonesia, and South America follow the same pattern of large rewards resulting 

 from optimistic thinking. It was with this objective that Amprex first began 

 investigating a barren desert waste in the western part of the United States, an 

 area known to the marginal farmers and ranchers as the Arenoso Valley or 

 Basin (fig. 41-2). 



THE ARENOSO BASIN — Little was known of the Arenoso Basin region 

 A POTENTIAL OIL- when a geologist of Amprex's exploration 



PRODUCING REGION group first visited the area. He wondered 



what lay beneath the nearly 5000 square miles 

 of alluvial-covered lands which composed the floor of the basin. Early mapping 

 by geologists of government agencies had indicated that the rocks exposed in 

 the hills and mountains that bordered the basin to the southwest and west were 

 composed of Paleozoic sediments. A fairly complete, although thin, Paleozoic 

 sequence of carbonate and clastic sediments with many extrusive and intrusive 

 igneous rocks was reported. However, there had been no detailed mapping of 

 either facies or stratigraphy and the structural aspect of the area was very 

 generalized. A discouraging fact relating to the basin was the presence of two 

 wildcat tests drilled in 1923 by Arido Oil Company, which had reported "base- 

 ment rock" at relatively shallow depths. 



During the years subsequent to the drilling of these tests, probably many 

 geologists had viewed the intrusive igneous outcrops and the shallow "basement 

 tests" with pessimism and had condemned the Arenoso Basin area. Amprex's geol- 

 ogist, however, recalled the great oil fields of the Tampico region of Mexico and 

 their close association with outcropping igneous intrusives, and at the same time, 

 he considered the possibility that the two reported "basement tests" were 

 abandoned in extrusive igneous rocks, perhaps late Tertiary or Recent lava 

 flows, rather than basement rocks. He knew that, in the infancy of oil explora- 

 tion, men untrained in geology often described the rocks encountered by the 

 drill and, therefore, the rocks were sometimes improperly identified. Moreover, 

 he was reluctant to condemn a basin of more than three million acres with only 

 two shallow dry holes. With this initial optimistic thinking, Amprex began its 

 attack on the Arenoso Basin. 



819 



