American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Society of Petroleum Engineers of AIME, Regional Secondary Recovery Symposium, to be held in Pampa, Tex., Oct. 26–27, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract

To apply techniques available in the literature for interpretation of individual well drawdown test data for reservoir boundary conditions and performance predictions properly, it is necessary that the pressure data be observed at constant flow rates. This paper presents a method which takes into account the variation of flow rates that are generally observed during most drawdown tests.

In one example cited, the drawdown test analysis b:, conventional methods suggested that connected oil in place would amount to more than 1 million bbl of oil. Actual production history and analysis by the multiple transient method indicates oil in place to have been on the order of 200,000 bbl. This latter technique provides a very useful tool for short-term drawdown reserve determinations, when coupled with the permeability variation of the reservoir, which tends to make calculated short-term drawdown tested reserves conservative or less than actual. In addition, wellbore conditions and formation capacity within the test volume can be more accurately determined for better well performance predictions.

With successful interpretation of pressure drawdown and buildup data, an engineer can save his company substantial investment by preventing unnecessary development, especially in areas of relatively deep, one-or two-reservoir fields. On the other hand, he can provide the necessary information to justify an accelerated development program at minimum risk to improve the present value of an undeveloped property.

METHOD OF ANALYSIS

The multiple-transient equation for continuous succession of steady states can be set up for simultaneous solution of several pressure-time relationships which can be measured at the well.[1]

for oil flow. The pw and pi terms are squared for gas flow.

[2]

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