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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 51 (1967)

Issue: 3. (March)

First Page: 465

Last Page: 465

Title: Quantitative Analysis of Prospect to Determine Whether It Is Drillable: ABSTRACT

Author(s): Vito A. Gotautas

Article Type: Meeting abstract

Abstract:

Thirty-one models were constructed in an attempt to represent all conceivable types of structural, stratigraphic, and structural-stratigraphic traps. Combinations of 52 parameters constitute these traps and define their proximity to hydrocarbon accumulation.

A trap is defined with 100 per cent certainty where all parameters necessary for its constitution can be demonstrated. Where only a part of the total parameters can be demonstrated, the per cent chance that a trap is present is reduced in a linear manner according to equations and graphs prepared by the writer. The same relation applies in defining the chance that a hydrocarbon accumulation exists, provided a trap is present.

The Composite Chance Factor (CCF) is the product of the Percentage Chance for a Trap and Percentage Chance for Hydrocarbon Accumulation. It is mathematically related to economics by the following formula:

[EQUATION]

A graph was prepared showing the interrelations of the parameters in the above formula.

The statistical number of wells that must be drilled to find at least one economically successful prospect for a particular CCF, based on the minimum desired return, was calculated using probability equations and tables.

A summary sheet was designed to record all the data pertinent to the analysis of a prospect. A formula on this sheet yields a numerical prospect grade. These grades can then be used to select objectively the required number of drillable prospects commensurate with the allocated drilling budget.

By using the proposed system, the user can reduce considerably the monetary speculation when prospecting for oil, and he can invest, fully expecting to realize at least the desired minimum return on his investment.

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Copyright 1997 American Association of Petroleum Geologists