Changes

====Geophysical Method (Borehole Breakouts)====

====Geophysical Method (Borehole Breakouts)====

Borehole breakout is the breaking zone of the wellbore’s wall, causing the hole to have an irregular elongated shape, from which the orientation of the horizontal stresses can be inferred. The breaking of fragments is assumed to occur parallel to the minimum horizontal stress and perpendicular to the maximum horizontal stress (see Figure 19).

Borehole breakout is the breaking zone of the wellbore’s wall, causing the hole to have an irregular elongated shape, from which the orientation of the horizontal stresses can be inferred. The breaking of fragments is assumed to occur parallel to the minimum horizontal stress and perpendicular to the maximum horizontal stress (see Figure 19).

[[File:GeoWikiWriteOff2021-Tayyib-Figure19.png|framed|center|{{Figure number|19}}Breaking of rock fragments gives information about the orientation of the horizontal stresses (from Fossen<ref name=Fossen />).

[[File:GeoWikiWriteOff2021-Tayyib-Figure19.png|framed|center|{{Figure number|19}}Breaking of rock fragments gives information about the orientation of the horizontal stresses (from Fossen<ref name=Fossen />).]]

The shape of the hole is identified using four-arm caliper tools or well imaging tools (see Figure 20). These tools are used during the drilling of the well for petroleum exploration and production. The four caliper arms push against the wall as they move along the wellbore, recording the shape of the hole, from which the orientation of the horizontal stresses can be inferred.

The shape of the hole is identified using four-arm caliper tools or well imaging tools (see Figure 20). These tools are used during the drilling of the well for petroleum exploration and production. The four caliper arms push against the wall as they move along the wellbore, recording the shape of the hole, from which the orientation of the horizontal stresses can be inferred.

[[File:GeoWikiWriteOff2021-Tayyib-Figure20.png|framed|center|{{Figure number|20}}(a) Four-arm Caliper tool used to identify the shape of the well. (b) Well imaging tool used to detect breakouts. (from Heidbach et al.<ref name=Heidbachetal />).

[[File:GeoWikiWriteOff2021-Tayyib-Figure20.png|framed|center|{{Figure number|20}}(a) Four-arm Caliper tool used to identify the shape of the well. (b) Well imaging tool used to detect breakouts. (from Heidbach et al.<ref name=Heidbachetal />).]]

==Applications of In-situ Stress==

==Applications of In-situ Stress==