Breathing New Life Into Postmortem Analysis: the Testing And
BREATHING NEW LIFE INTO POSTMORTEM ANALYSIS: THE TESTING AND FORMALIZATION OF A METHODOLOGY FOR THE IDENTIFICATION OF KEY FAILURE MODES IN DRY HOLES by Jack M. Samis A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Master of Science (Geology). Golden, Colorado Date __________________________ Signed: __________________________ Jack M. Samis Signed: __________________________ Alexei V. Milkov Thesis Advisor Golden, Colorado Date __________________________ Signed: __________________________ Dr. Steve Enders Professor and Head Department of Geology and Geological Engineering ii ABSTRACT The petroleum exploration industry relies on various subsurface data and interpretations to minimize risk and uncertainties and maximize gains. Dry holes provide a wealth of useful subsurface information. However, far too often a company drills a dry hole and either does not conduct a postdrill analysis (postmortem), or incorrectly determines the failure mode. The purpose of this study is to formalize and test the applicability of a postdrill methodology (a decision tree) that helps identify the main failure mode for dry segments tested by conventional wells. Use of this decision tree allows the interpreter to evaluate and identify specific failure modes such as reservoir presence, reservoir deliverability, structure, seal, source maturity, and migration. The decision tree was tested on three exploration wells drilled in the Taranaki Basin, offshore New Zealand. Each segment’s key failure mode was identified based on the comprehensive, integrated evaluation of both pre- and postdrill reports, seismic data, well logs, geochemical analysis of gases and source rocks, and other materials freely available through the New Zealand government.
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