PUBLICATIONS RIGHTS RESERVED PUBLICATIONS RIGHTS RESERVED THIS PAPER IS TO BE PRESENTED AT THE INTERNATIONAL TECHNICAL MEETING JOINTLY HOSTED BY THE PETROLEUM SOCIETY OF CIM AND THE SOCIETY OF PETROLEUM ENGINEERS IN CALGARY, JUNE 10 TO 13, 1990. DISCUSSION OF THIS PAPER IS INVITED. SUCH DISCUSSION MAY BE PRESENTED AT THE MEETING AND WILL BE PAPER IS INVITED. SUCH DISCUSSION MAY BE PRESENTED AT THE MEETING AND WILL BE CONSIDERED FOR PUBLICATION IN CIM AND SPE JOURNALS IF FILED IN WRITING WITH THE TECHNICAL PROGRAM CHAIRMAN TO THE CONCLUSION OF THE MEETING.

Abstract

General minifrac analysis curves for analysis of heterogeneous formations have been developed and are presented in this paper. These type curves apply to a wide variety of formations including coalbeds and naturally fractured formations. The new type curves have been developed for the Perkins and Kern model. The paper presents the development of equations and type presents the development of equations and type curves, and discussion of the technique and criteria for their application.

Conduct and results of a minifrac test in a coal seam are presented in this paper. The test is analyzed using the developed technique. The data in this case fits the new type curve extremely well. The match with existing type curves was poor.

Introduction

A minifracture test is essentially the creation of a small fracture without using any propping agent. It is performed a few hours to propping agent. It is performed a few hours to several days prior to the main fracturing treatment. The objectives of a minifrac are to gain knowledge of fluid-loss and fracture geometry. For design purposes, the most important parameter calculated from a minifrac test is the leakoff coefficient. Fracture length and width, fluid efficiency, and closure time may be also calculated.

Techniques for analyzing a minifrac test have been developed. In the initial paper introducing minifrac analysis, Nolte presented the technique employing the Perkins and Kern model. In developing the technique, it was assumed that fracture length relates to time as a power law function.

L=Lo (t)a
(1) (to)

In SPE 8341, Nolte, assumed that the exponent, a may be 0.50 or 1.0. He showed that error with the use of either exponent is less than 16%. Lee re derived the equations for minifrac analysis for K-Z and radial models using probably the more realistic exponent of 2/3. Modifications of these techniques to account for effect of fluid compressibility and temperature change during the minifrac test were also presented in the literature.

P. 5-1 P. 5-1

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