Technology Focus: Well Testing (February 2011)

Abstract

Technology Focus Often, the trial-and-error method is viewed as an imperfect surrogate for systematic scientific research. Yet, great advances never would have taken place without such an approach. Take shale gas, for example. Despite scarce research conducted by only a few companies, shale-gas plays have undergone massive development and have progressed techniques (e.g., horizontal drilling and multistage fracturing) that enabled resources unavailable less than a decade ago. According to a US Department of Energy report, US shale-gas production is expected to increase from 1.4 Tcf in 2007 to 4.8 Tcf in 2020. That same year, 64% of the total US gas production will come from unconventional gas. Well testing is no exception. Although transient-linear-fluid-flow and dual-porosity concepts for fractured horizontal wells have been available for many years, painstaking trial and error has been the key to accommodating such extremely-low-permeability ranges in current prefracture- and post-fracture-well-test designs. Similarly, many if not all operators have diligently re-evaluated their appraisal programs in an effort to collect data needed for critical parameters (e.g., gas-in-place and initial pressure) in a cost-effective manner while accounting for varying relationships between matrix and natural- and hydraulic-fracture networks. It is undeniable that trial and error should not be used to replace the rigor and thoroughness of systematic scientific research. However, the expanded range of environments that we encounter (from unconventional, to multilayered, to high-pressure/high-temperature reservoirs) requires rapid learning and adaptation, and, therefore, experimentation. The papers selected for this issue are clear examples of best-in-class knowledge development in well testing through first principles and an old familiar approach—trial and error. Well Testing additional reading available at OnePetro: www.onepetro.org IPTC 13912 “A Novel Analysis Procedure for Estimating Thickness-Independent Horizontal and Vertical Permeabilities From Pressure Data at an Observation Probe Acquired by Packer/Probe Wireline Formation Testers” by M. Onur, Istanbul Technical University, et al. (See JPT, September 2010, page 56.) SPE 134534 “Practical Use of Well-Test Deconvolution” by A.C. Gringarten, SPE, Imperial College, London. SPE 131675 “Pressure-Falloff-Test Interpretation for Leakage Detection During CO2 Injection in a Deep Saline Aquifer” by C.A. Ehlig-Economides, Texas A&M University, et al.