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The following subsections showcase the different methods of in-situ stress determination:  

The following subsections showcase the different methods of in-situ stress determination:  

====Conventional Hydraulic Fracturing (Fracking)====

====Conventional Hydraulic Fracturing (Fracking)====

Hydraulic fracturing can be used to measure the maximum and minimum horizontal stresses at great depths below the surface. This method involves pumping fluid into an isolated target formation, until the fracture breakdown pressure is reached and the fracture is created. The fracture will propagate perpendicular to the minimum horizontal stress as shown in figure 11. Then, the well is shut-in (pumping stops), causing the pressure to subside until it reaches the fracture closure pressure and the fractures will start to close. The pumping of fluid starts again until the fracture reopening pressure is reached and the previously closed fractures reopen. Multiple pumping cycles (minimum of three) are required to measure the reopening pressure. After the last pumping cycle, the shut-in pressure (Ps) is recorded and is considered equal to the minimum horizontal stress (σh). Then the maximum horizontal stress (σH) can be calculated as follows:

Hydraulic fracturing can be used to measure the maximum and minimum horizontal stresses at great depths below the surface. This method involves pumping fluid into an isolated target formation, until the fracture breakdown pressure is reached and the fracture is created. The fracture will propagate perpendicular to the minimum horizontal stress as shown in [[:File:GeoWikiWriteOff2021-Tayyib-Figure11.png|Figure 11]]. Then, the well is shut-in (pumping stops), causing the pressure to subside until it reaches the fracture closure pressure and the fractures will start to close. The pumping of fluid starts again until the fracture reopening pressure is reached and the previously closed fractures reopen. Multiple pumping cycles (minimum of three) are required to measure the reopening pressure. After the last pumping cycle, the shut-in pressure (Ps) is recorded and is considered equal to the minimum horizontal stress (σh). Then the maximum horizontal stress (σH) can be calculated as follows:

:H = 3Ps– Po - Pr

:H = 3Ps– Po - Pr

::Po is the pore pressure, which is the pressure of fluid inside the rock.

::Po is the pore pressure, which is the pressure of fluid inside the rock.

:::Pr is the reopening pressure.

:::Pr is the reopening pressure.

[[File:GeoWikiWriteOff2021-Tayyib-Figure11.png|thumbnail|Figure 11 The direction of fracture propagation is perpendicular to the minimum horizontal stress. (from Hoeksema, 2015) [7]]]    

[[File:GeoWikiWriteOff2021-Tayyib-Figure11.png|framed|center|{{Figure number|11}}The direction of fracture propagation is perpendicular to the minimum horizontal stress. (from Hoeksema, 2015) [7]]]

====Hydraulic Testing of Pre-existing Fracture (HTPF)====

====Hydraulic Testing of Pre-existing Fracture (HTPF)====