Understanding XLOTs

Alexander Heger, Hermann F. Spoerker

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

2 Citations (Scopus)


Leak-off Tests (LOTs) are a common procedure during the drilling process and have been performed for decades. Still the pressure vs. volume curve seems to be not fully understood, and slightly different explanation theories exist. The paper discusses these theories together with the commonly applied leak-off testing procedure and attempts to explain the curve from a stress calculation standpoint. Theories are presented about fracture initiation at the wellbore wall, SH determination from extended leak-off tests (XLOTs) and the change of the pressure vs. volume curve by repeating pressure cycles. Industry estimates put the contribution of wellbore stability to non-productive time at approximately 40%, costing the industry approximately $8 billion dollars per year1. In addition wells are becoming more and more difficult to drill as complex trajectories are required and smaller drilling margins are encountered to discover new oil and gas deposits. The authors advocate that fundamental understanding of geomechanic principles by all the engineers involved is required to efficiently and successfully drill complex wells. Better understanding of and familiarity with these phenomena will minimize inappropriate decisions which might cause down time or even a loss of the well.

Original languageEnglish
Title of host publicationSociety of Petroleum Engineers - SPE/IADC Drilling Conference and Exhibition 2011
Number of pages11
Publication statusPublished - 13 Jun 2011
Externally publishedYes
EventSPE/IADC Drilling Conference and Exhibition 2011 - Amsterdam, Netherlands
Duration: 1 Mar 20113 Mar 2011


ConferenceSPE/IADC Drilling Conference and Exhibition 2011

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