Pre-Permian Paleozoics of Las Animas Arch--New Oil Province: ABSTRACT

Abstract

The Las Animas arch has been the site of intermittent exploration during nearly 40 years but still is virtually untouched. Despite two recent, significant discoveries, the arch is a cold area. The writers believe that this is the result of a lack of careful study of the rocks and the total absence of a planned exploration program. Detailed analysis of the Pennsylvanian and Mississippian sections indicates that parts of the arch are more favorable than others, although sparcity of control in large areas of the arch precludes eliminating any part of it from consideration. The results of recent drilling have provided new evidence on the structural history of the Las Animas arch and indicate that it is considerably more complex than has been considered previously. The arch actually is a compound structure with an older axis considerably east of the present axis which originated during the Laramide orogeny. Each of the five series of the Pennsylvanian System (Virgilian, Missourian, Desmoinesian, Atokan, and Morrowan) is productive on or adjacent to the Las Animas arch, but none of the discoveries to date has been of sufficient magnitude to provide impetus for a concerted exploration effort. Two discoveries, both producing oil from the Osagean (Mississippian), are very significant, though neither is, of itself, sufficiently large to excite much attention. The significance lies in the fact that both are productive beneath a younger Mississippian rock cover (i.e., within the Mississippian). Heretofore, it was believed that a productive Mississippian reservoir had to be in subcrop contact with overlying Pennsylvanian in order to produce. However, discoveries during the past 6 years in southwestern Kansas and End_Page 2033------------------------------ northern Oklahoma have proved this to be false. The afore-mentioned discoveries indicate that similar potential for the Mississippian exists along the Las Animas arch. The authors conclude that a carefully planned exploration program will prove, during the next few years, that the Las Animas arch truly is a New Oil Province. End_of_Article - Last_Page 2034------------