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In-situ stress characterization and applications (view source)
Revision as of 13:11, 31 May 2022
, 13:11, 31 May 2022→Extended Leak-off Test (XLOT)
====Extended Leak-off Test (XLOT)====
====Extended Leak-off Test (XLOT)====
The extended leak-off test (XLOT) is an extension of LOT and it is similar to fracking which involves propagating of a fracture by pumping fluids. However, XLOT does not determine the stresses orientation. Figure 13 shows the recorded pressure during XLOT. The horizontal stresses values can be estimated as follow:
The extended leak-off test (XLOT) is an extension of LOT and it is similar to fracking which involves propagating of a fracture by pumping fluids. However, XLOT does not determine the stresses orientation. [[:File:GeoWikiWriteOff2021-Tayyib-Figure13.png|Figure 13]] shows the recorded pressure during XLOT. The horizontal stresses values can be estimated as follow:
:h = Plo
:h = Plo
:H = 3Plo– Pr – Po
:H = 3Plo– Pr – Po
Where Plo is the leak-off pressure.
Where Plo is the leak-off pressure.
[[File:GeoWikiWriteOff2021-Tayyib-Figure13.png||center|framed|{{Figure number|13}}Recorded pressure during the extended leak-off test (XLOT) (from Kartevoll, 2009) [9]]]
[[File:GeoWikiWriteOff2021-Tayyib-Figure13.png|center|framed|{{Figure number|13}}Recorded pressure during the extended leak-off test (XLOT) (from Kartevoll, 2009) [9]]]
====Overcoring Method====
====Overcoring Method====
Overcoring method is used to determine in-situ stresses from a rock sample extracted from shallow depths, and released to expand freely. This method involves a sequence of steps illustrated in Figure 14. The process of cutting the hollow cylindrical rock, using the tool shown in figure 15, is called overcoring and the resulting change in shape is measured using a device called stressmeter. In general, the maximum expansion of the rock sample occurs in the direction of the maximum horizontal stress (σH).
Overcoring method is used to determine in-situ stresses from a rock sample extracted from shallow depths, and released to expand freely. This method involves a sequence of steps illustrated in Figure 14. The process of cutting the hollow cylindrical rock, using the tool shown in figure 15, is called overcoring and the resulting change in shape is measured using a device called stressmeter. In general, the maximum expansion of the rock sample occurs in the direction of the maximum horizontal stress (σH).