dolomite was recovered. A formation test made opposite this interval indicated 

 excellent productivity of 37 degree gravity oil; the gas-oil ratio was approxi- 

 mately 1100:1; and the flowing and shut-in formation pressures were considered 

 normal for this depth. A very slight drawdown or drop from shut-in formation 

 pressure to flowing formation pressure indicated that the reservoir rock probably 

 possessed excellent permeability. An additional 460 feet of permeable dolomite 

 was continuously cored and tested before salt water was encountered. Later 

 studies by company petrographers and paleontologists indicated that this 

 dolomite section was reef facies of Devonian and Silurian ages. 



After the reef was drilled though at 4970 feet, Silurian shales and sandy 

 shales were drilled and cored to 5850 feet, where a hard drilling break was 

 noted. Although the mud-logging unit had not recorded an increase in either 

 gas or oil, the section was cored for 30 feet. Core recovery from this interval 

 consisted of highly fractured, dense, sandy dolomite; only scattered, very faint 

 fluorescence was noted on a few of the fracture surfaces. However, Amprex's 

 geologist decided to make a precautionary formation test of this interval. He 

 realized that, frequently, fractured formations which carry high-gravity oil or 

 condensate may be flushed during drilling and coring operations. On a formation 

 test this interval flowed gas and condensate at a calculated rate of 4.5 million 

 cubic feet of gas and 405 barrels of 57 degree gravity condensate per day through 

 a 14 -inch bottom choke and a i/8" mc h top choke. Gas-condensate ratio was 

 approximately 11,000:1. Coring and testing were continued for the next 460 

 feet before salt water was encountered. Drilling and coring were then continued 

 until granite was encountered at 6801 feet. Fifty feet of fractured granite was 

 cored; and, although no shows were noted, a precautionary test of this fractured 

 basement was made, for Amprex geologists today were becoming aware of 

 the potential of fractured basement reservoirs. A formation test opposite this 

 interval flowed salt water with no trace of oil or gas. An additional 150 feet of 

 granite was drilled and cored and, when no shows of hydrocarbons were noted, 

 drilling was stopped. 



Electric-log surveys and gamma ray-neutron logs, which were run at 

 different stages during the drilling of the well, added detailed information to 

 the stratigraphic section and were particularly helpful in analyzing the non- 

 cored intervals and those intervals where core recoveries were poor. They 

 aided in the definition of oil-water contacts and were invaluable as a continuous 

 record of the stratigraphic section. 



Casing was set to a depth of 6600 feet and cemented. After studying the 

 results of the formation tests, the core analyses, and the different "logs", 

 Amprex's Exploration and Production Departments decided to complete this 

 well opposite the lower part of the Siluro-Devonian reef, although consideration 

 was given to dually completing this well. Casing was perforated opposite an 



856 



