Perhaps the most significant result of the initial phase of investigation was 

 the discovery that a set of cuttings from one of the two early wildcat wells was 

 available for study. Fortunately, these samples had remained undisturbed in 

 the storehouse of a university for more than thirty years. These cuttings and 

 cores were studied by the company's geologists and paleontologists. A petro- 

 grapher examined cuttings from the subsurface section referred to as "base- 

 ment" by the operator, and described these igneous fragments as "hard, dark, 

 fine-grained igneous rock composed of plagioclase feldspar, pyroxene, and fine, 

 opaque ore minerals, with an occasional phenocryst of coarser pyroxene." This 

 description, typical of extrusive basalts that were found in the Black Peak area 

 to the south, convinced Amprex's geologists that this old wildcat had not en- 

 countered basement, but instead had been abandoned in extrusive igneous rock 

 lying beneath a section of late Tertiary or Recent alluvial fill. It seemed reason- 

 able to assume that a Paleozoic section lay beneath this old flow. 



With this encouraging information, the company geologists contacted their 

 management and presented the facts. Both the law and land groups of the 

 company indicated that there were no serious problems in either operating or 

 leasing which would deter exploration in the area. The preliminary regional 

 thickness maps, although based on limited information, suggested that several 

 of the Paleozoic formations were thickening toward the center of the Arenoso 

 Basin. The regional facies maps supported this observation by indicating a 

 progressive change from light-colored carbonates and coarse elastics typical of 

 shelf facies to darker carbonates and fine-grained elastics suggestive of basin 

 facies. Structural trends mapped in the outcropping formations plunged basin- 

 ward and, therefore, could be expected to persist into the "deeper" parts of the 

 Arenoso Basin. The photogeologists mapped several anomalous patterns in the 

 alluvium which appeared to be reflections of structures at depth. Petrographers, 

 studying the extrusive and intrusive igneous rocks of the area, concluded that 

 the metamorphism of the sediments surrounding these areas was local and not 

 regional. All of the facts seemed to suggest that the Arenoso Basin or Valley 

 might be a Paleozoic sedimentary basin with potential source and reservoir 

 rocks and that favorable structures offering possibilities for production occur 

 within the basin. 



RECONNAISSANCE After the management group of Amprex's 



EXPLORATORY PROGRAM Exploration Department had reviewed and 



studied this information, they recommended 

 to the Board of Directors of the company that additional money be budgeted to 

 conduct an extensive reconnaissance geological and geophysical exploration 

 program for further evaluation of the area. 



821 



