James Fergusson

PREFACE TO SECOND EDITION

Since the fi rst publication of this work, our industry has progressed. Whereas formerly production of hydrocarbons was from predominantly conventional reservoirs using vertical wells, it is now more common to produce from unconventional reservoirs using high angle or horizontal wells. This has resulted in a need for innovative methods for conveying measurement devices to the ends of the non-vertical wells. It has also called for design changes to the measurement devices themselves in order to properly monitor segregated fl ow regimes in non-vertical pipes. Our industry has also progressed in the design of new measurement devices that considerably enhance our ability to perform formation evaluation through casing and to monitor tri-phasic fl ow in production strings. Data recording methods have also progressed and now offer a number of alternatives to conventional real-time wireline logging methods. In particular it is now common to leave permanent sensors in wells to provide continuous measurements of key parameters of reservoir performance. Hopefully this revised second edition of Cased-Hole Log Analysis and Reservoir Performance Monitoring will bring the reader some useful insights to assist in daytoday improvement in the task of economical hydrocarbon production. It is sobering to note that the time taken to drill and complete a new well is measured in weeks or months but the life of a producing well is measured in years or decades. Every year the number of old wells in need of remediation grows and worldwide is numbered in the millions. The tools and techniques described in this work constitute a vital, but often underrated, resource for tapping hydrocarbons that have already been found and they deserve to be more widely understood and used.