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The LOP Revisited

Abstract

The Extended leak-off test, XLOT, is a main tool for obtaining minimum stress data during drilling operations. If performed according to a proper protocol, it is perhaps the most cost-effective and robust method for determining the minimum stress. The low cost of the test means that a lot of data can be collected, allowing for efficient regional analysis. A widely reproduced figure by Gaarenstrom et al. (1993) has become a classic in the industry. It shows the pump-in phase as two distinct linear segments. The point of change in slope is denoted the Leak-off Point or the Leak-off Pressure (LOP). It is sometimes argued that the LOP is a good measure of the in-situ stress, and it is sometimes argued the LOP marks the initiation of a fracture. We analyze this hypothesis and show by basic theoretical considerations and several examples of high quality field data that this is not necessarily the case. The nonlinear behavior during initial pump-in may be due to leak-off to a permeable formation or through a poorly cemented casing shoe.

Category

Academic chapter

Language

English

Author(s)

  • Arne Marius Raaen
  • Jamie Stuart Andrews
  • Trygve Gullestad Fintland

Affiliation

  • SINTEF Industry / Applied Geoscience
  • Equinor

Year

2022

Publisher

American Rock Mechanics Association (ARMA)

Book

56th U.S. Rock Mechanics/Geomechanics Symposium

ISBN

9780979497575

View this publication at Norwegian Research Information Repository