Geomechanics and FracturingIn-Situ Stress and Rock Mechanics

Maximum Horizontal Stress from Wellbore Breakout Width Formula

S_{hmax}=\frac{C_o+2P_p+P+\sigma_t-S_{hmin}(1+2\cos\theta_b)}{1-2\cos\theta_b},\quad \theta_b=(\pi-w_b)/2

Maximum Horizontal Stress from Wellbore Breakout Width calculates maximum horizontal stress from breakout width for in-situ stress and rock mechanics workflows in geomechanics and fracturing.

Calculate

How engineers use this formula

Use this formula when the listed inputs (C_o, P_p, P_drawdown, sigma_t, w_b, S_hmin) are known and the assumptions behind the cited in-situ stress and rock mechanics relationship match the engineering case being checked.

Assumptions

Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
The declared units match the field-unit constants used in the formula.
The cited formula applies to the selected petroleum engineering workflow.

Limitations

The calculation does not replace a full engineering model or operating procedure.
Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.

Common mistakes

Mixing unit systems without converting the inputs.
Using default example values as field recommendations.
Applying the formula outside the source assumptions.

Default example

Using the default inputs, S_hmax equals 18,024.166673 psi.

C_opsi

10000

P_ppsi

3500

P_drawdownpsi

500

sigma_tpsi

300

w_bdeg

S_hminpsi

6000

Inputs

C_o

psi

Wellbore Compressive Strength

P_p

psi

Pore Pressure

P_drawdown

psi

Drawdown Differential Pressure

sigma_t

psi

Thermally Induced Stress

w_b

deg

Wellbore Breakout Width

S_hmin

psi

Minimum Horizontal Stress

Outputs

S_hmax

psi

Maximum Horizontal Stress from Breakout Width

C_o

psi

Wellbore Compressive Strength

S_hmin

psi

Minimum Horizontal Stress

Source and review

reviewed

Zoback, M.D. 2007. Reservoir Geomechanics, Cambridge University Press, Page 223.

Source