FORMATION PERMEABILITY DETERMINATION BY MICROHYDRAULIC OR MINIHYDRAULIC FRACTURING

This paper presents a theory and its application for post-fracture pre ssure-transient analyses. The proposed procedure, known as ''impulse f racture test,'' is an injection/falloff test designed for the determin ation of formation permeability and reservoir pressure. The hydraulica lly induced fracture can pass the near wellbore damaged zone and expos e a larger formation area to flow. The permeability and reservoir pres sure determined are therefore more representative of the reservoir. Th e theory is based on the distribution of sources with variable intensi ty along the fracture trajectory. For field applications, asymptotic s olutions are derived to give the ''type-curve'' capability for the est imation of formation permeability and reservoir pressure. Assorted slo pe behaviors, such as -1, -2, +1/2 and + 1 slopes, are predicted from various pressure and pressure derivative plots. Analyses of data from two wells which were inadvertently fractured support these behaviors.