ParaGeoInv can be used to search for the optimal boundary conditions that are consistent with target observations at defined history points. In this particular case, we have a 7-layer model including reservoir. The main structure consists of a two-way anticline with a fault intersecting the southern limb. The target measurements used to perform the optimization procedure consist of stresses in X, Y and Z directions at nine locations within the reservoir. The objective of this optimisation procedure is to search for optimal normal displacement subject to the target measurements.
In this synthetic case the target solution is set using a simulation whereby a 25m displacement is applied to the North boundary. Consequently, both the target stress set at the well locations and the target boundary displacements are known a priori allowing an exact assessment of the accuracy and efficiency of the procedure.
The location of history points are located along the three notional well paths specified for this problem. In this case, a super-element approach has been used to decrease the number of freedoms in the solution to achieve economical computational cost.
The algorithm approaches optimal boundary displacement as misfit reduces.
Geomechanical Boundary Optimisation
The misfit value generally reduces as the algorithm converges to optimal boundary displacement (25.05m). This value differs from the target value (25.00m) by 0.2%, which corresponds to a misfit value of 0.5732E-03 against the target measurements. Also, the optimum model recovers the stress contours that compare favourably with the reference model.
Stress YY comparison with reference solution
Stress XX comparison with reference solution