1 - Evaluating Fractured Reservoirs: Introduction

• Published in: Geologic Analysis of Naturally Fractured Reservoirs pp. 1 - 100
• Main Author: R.A. Nelson
• Format: Book Chapter
• Language: English
• Published: Elsevier Inc 2001
• Edition: Second Edition
• ISBN: 9780884153177; 0884153177; 9780080507293; 9781493303472; 0080507298; 1493303473
• DOI: 10.1016/B978-088415317-7/50004-X

This chapter presents the critical attributes that must be evaluated to quantify fractured reservoirs in a logical, workable sequence: origin, properties, fracture/matrix interaction, reservoirs typing and, eventually, well placement and completion. The most frequent and often most critical fracture evaluation is that performed early in the exploration phase of a hydrocarbon play to better define the properties of interest and to determine or predict the gross reservoir quality of a discovery. The origin of the fracture system is postulated from data on fracture dip, morphology, strike, relative abundance, and the angular relationships between fracture sets. Three fracture types are observed to form at consistent and predictable angles to the three principal stress directions during laboratory compression, extension, and tensile tests. All brittle fracture in rock must conform to one of these basic fracture types: shear, extension, and tension fractures. Once the origin of a fracture system has been determined in a reservoir, the petrophysical properties of the rock-fracture system must be considered. This involves characterization of the fracture system in terms of physical morphology, distribution, and estimation of the reservoir properties resulting from the fracture system characteristics.