NUMERICAL SIMULATIONS OF HYDRAULIC FRACTURING IN TIGHT GAS RESERVOIRS

摘要

In the framework of DGMK research project 680-I, the FDM-Program FLAC3D was used for the simulation of fracture propagation in an in-situ scale model, based on field data of the North German Rotliegend tight gas reservoir. This reservoir was treated hydraulically by a massive fracturing in 1983. The results regarding the fracture propagation were compared to those in the analytical P3D simulator FracPro. It was noticed that the original code FLAC3D was unsuitable for the applications of hydraulic fracture. In further investigations, our own developed algorithm with a moving boundary condition based on discontinuum mechanics was implemented in FLAC3D. The results showed a relatively good agreement with those of FracPro. The advantage of the algorithm is above all that irregular fracture front can be realistically simulated, which in turn reflects the stress states in multi-layers and their different rock mechanical properties.