The appendix contains four sections. Section 1 defines the term "fracture" as we have used it in this book. Section 2 contains definitions of terms used to describe fracture surface structures and a general discussion of mechanisms governing their development. Section 3 deals with hackle plume geometry and its relation to the distribution of relative fracturing stresses and propagation velocities. Section 4 discusses stress fields developed during drilling and coring operations.
Figures & Tables
The characterization of naturally fractured reservoirs should include core analyses that encompass interpretation of natural and induced fractures. Unfortunately, to date, the differentiation of induced fractures from natural ones in core has been somewhat speculative and often is based on improper techniques. Consequently, bad interpretations have been made and useful information contained in both natural and induced fractures is overlooked. This book addresses the problem of distinguishing natural fractures from induced fractures in both oriented and unoriented core. Natural fractures include any cored fracture that existed in a volume of rock prior to initiation of drilling or coring-related stresses. Induced fractures in core are those that develop during drilling, coring, and subsequent handling. Many of the procedures for distinguishing between the two are based primarily on recognition of fracture surface structures and fracture traces that differ between natural fractures and induced fractures.