Numeric Investigations on Frac Propagation in Tight Gas Reservoirs with the FDM Program FLAC3D

The main objective of the third phase of the project 680 was to develop a more phys-ics based numerical approach to simulate the proppant transport with the considera-tion of settling effect in the 3D FDM program “FLAC3D”. Through the adaptive calculation and the comparison with the calculated results of the analytical model the new computing concept was validated. Then the fracture closure in the developed model was also verified. After the verification, two numerical applications are illustrated. The first one is the numerical modelling of a hydraulic fracture operation in a tight gas borehole in the North German Basin, in which the fracturing treatment was done in the 1980s. As the conclusion of this simulation, it could be said, that the stable state of the proppant placement is achieved. The second numerical example is the fracture operation at Frac5 in the tight gas reservoir XYZ2. As introduced in the report of the second phase, the hydraulic fracturing was operated in 2009 with four stages respectively: perforation, injection test, data and main fracturing. Both issues caused problems on the tight gas fracture/wellbore connections.