Evaluation of Norwegian Wildcat Wells (Article 1)

Abstract

This paper describes the objectives, organisation, datatypes and some selective results from the project: Evaluation of Norwegian Wildcat Wells. The project was initiated by the Norwegian Petroleum Directorate in 1996. Twenty oil companies participating in exploration on the Norwegian Continental Shelf have taken part in the project. The evaluation is a comparative of well prognoses versus results in order to use the past experience in future exploration. The project comprises 195 wildcat wells, including all those drilled on the Norwegian Continental Shelf between 1990 and 1997. Ten of the wells were drilled in the Barents Sea, 40 in the Norwegian Sea and 145 wells in the Norwegian part of the North Sea. The data types — a total of 114 parameters — are considered to be critical factors for future exploration success. For each well one or several prospects — and one or several cases — have been reported. This means that one well may have several prognoses, but only one result. The different companies' assessments of their dry wells were also reported. The results show that hydrocarbon pore volume (HCPV) in 60% of the technical discoveries proved to be lower than the minimum probability estimate prior to drilling. The risked volume for all oil prospects is 2.5 times greater than the discovered volumes for oil discoveries. A similar comparison for all gas prospects and discoveries shows that the difference in the gas case is minor. The average discovery probability was 23% compared to the average technical finding rate that is 36%. The average discovery rate, excluding technical discoveries was 27%. In order to monitor future developments and improvements the project will be continued, incorporating new analyses in the future.