Tfds paPIJr was~lW waenfafion at h SWSRMEurti 'W hatd in T~m, -y, 8-10 Juty 1996 s paper w =bded & Pfewnfatiin by an SW Program Ccinmillee foflwi~revi.awof .9fti d~~h M Wafracf *KOd by W aul~($) Contents Of Ihe paper, as ti~. ha~~~n C*VW by the SWbtY of pairohw Ew!neers ati are subtecl tõ by tha adti(s) W material, as Ws.nred dws no! n.ussarily re~any wsillon of tha Smty d Petroti Ew-rs, its ofhcart, w membrs Papers wesenled @ SPE m-s w s~I~10 tir~cw mvk by Etitwial Committees of tfw Swiely of Petroleum =ti E~ic~M, distr~ti, or storaga of any pan of !hIs w for wifhouf fha written -sent of the Scciety of Petroleum Eng-rs is Pemi$sti 10 m~m m ml is restricted lo an abstract of mt mcfe than 3C0 -s,~alis may w m IXQM Ttm abstrna must mntam WSPIWOUS acknowld~wt of whom d by % the pqr was pesen!ed WTife L!brar!an SPE, P O Box 833836 Rti~, TX 7SC33.SJ3SSU S A fw Ilf-972-952-9435 AbstractThe principal finction of leak-off tests is to assess casing integri~, but the test data are commonly used beyond this original purpose, for stress estimations in exploration and drilling, The value of Ieak-off test data for stress estimation is questionable and extended leak-off tests have been proposed as a more appropriate method for stress estimation. The paper for the fwst time compares leak-off test (LOT) and extended leakoff test (ELO~data from two areas, the North West Self of AustraIia and the Norwegian North Sea. Standard LOTS have a chrrracteristicaIly large scatter associated with the leak-off pressures (~. ), minimum stress and fracture gradient estimates in both areas. However, the minimum stress determined from ELOTS are consistent and form a lower bound to the standard fio data in both areas. The ELOT takes about an hour to perform, but provides far superior data than that obtained from a LOT. and is recommended where stress data are required.

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