About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 42 (1958)

Issue: 11. (November)

First Page: 2549

Last Page: 2566

Title: Economics of Drilling for Cretaceous Oil on East Flank of Denver-Julesburg Basin

Author(s): J. J. Arps (2), T. G. Roberts (3)


After a brief review of the results of the past drilling activity and the production history of the Denver-Julesburg basin to date, the merits of this play are discussed from an economic viewpoint. An analysis of the relative importance of stratigraphy and structure in forming the Lower Cretaceous traps is presented.

The cost of drilling dry holes and producers in the basin is discussed and its effect on the economics of producing marginal wells analyzed.

The Denver-Julesburg basin at present with its hundreds of Lower Cretaceous fields and thousands of wells represents a unique opportunity for statistical analysis. A "sample area" of 5,700,000 acres was chosen on the east flank and a statistical correlation prepared of the estimated ultimate recovery per field and the number of delineating dry holes per field as a function of the productive field area.

This correlation shows some well defined trends from which significant conclusions can be drawn. A frequency-density distribution of the fields found was then prepared and plotted versus ultimate field recovery, which again indicated a well defined pattern.

A mathematical relation is presented, relating the number of fields of a given size found after drilling a known number of wildcats to the total number of fields of that size originally occurring in the sample area for the assumptions of: (a) random drilling in the productive trend; (b) pattern drilling in the productive trend; and (d) drilling on geophysical and geological leads in the trend.

After computing the frequency-density of occurrence from the frequency-density distribution of fields found, it is shown how this mathematical relation can also be used to make a forecast of the average results to be expected from future drilling.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].