A Statistical Analysis of the Mature Oil Province of the U.K. North Sea

WESTON, JOHN RONALD, Gaffney, Cline and Associates, Alton, U.K.

Historical success rates (up to end 1989) are described and analyzed for a defined set of nine core play types within the Mature Oil Province of the United Kingdom North Sea. The dataset comprises almost 900 exploration wells located within 18 quadrants of the Viking Graben, Moray Firth, and Central Graben structural provinces. Only significant discoveries of equal to, or greater than, tested rates of 1000 stbopd or 1000 mmscfgd are included.

The statistical analysis of this historical performance data and the use of trends in a predictive model is well established (e.g., Meisner and Demirmen, 1981). In this study the forward exploration program is specifically tailored to perceived opportunities. The decline formulae and constants are derived from observations in mature petroleum provinces worldwide and describe the general trends of decreasing success ratio and decreasing reserve size versus the cumulative number of exploration wells drilled.

An in-house, predictive computer model takes the relationships for success probability and reserves distribution, together with a postulated exploration program (up to the year 2020), and generates a probability distribution of likely outcomes in terms of a discovery profile and a development profile with time. Twelve cases are selected as being potentially suitable for predictive modeling. The potential

of particular area/play combinations indicates both quantifiable, relatively low risk upside, unquantifiable, high risk upside, and "played-out" combinations.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)