Two-dimensional simulation of controls of fracture parameters on fracture connectivity

Abstract

Two-dimensional fracture simulation is conducted to analyze the controls of different fracture parameters (variations in fracture orientation, density, and length) on fracture network connectivity. Three different scenarios, which are commonly encountered in natural fracture systems, are analyzed: (1) a single fracture set; (2) two fracture sets, with one primary through going set; and (3) two fracture sets with approximately equal parameters. The modeling reveals that certain parameters are more dominant in controlling the connectivity for each of the settings. For a single set of fractures, increases in length and dispersion and a decrease in spacing all result in higher fracture-parallel connectivity, but the decrease in spacing is the most important in increasing fracture-normal connectivity, especially where the dispersion in fracture strike is very low. Simulations of two sets of fractures reveal that the density, length, and angle between the two sets are important factors in producing complete connectivity. In cases where one set of fractures is a systematic throughgoing set, a critical combination of length of the second set and the angle between the two sets results in complete connectivity. Where both sets of fractures have varying length and density, the influence of increasing density of one set has a great effect on connectivity when the other set is short and a more subtle to insignificant change when the other set is long. The network also shows higher connectivity with increasing angles (up to 90°) between the two sets.