Aquifers with flow controlled simultaneously by intergranular and planar porosity applied to metasedimentary rocks of the Alto Paraguay Region, Mato Grosso State, Brazil

ABSTRACT

Groundwater reservoirs with flow controlled simultaneously by intergranular and planar porosity are popularly known as double porosity aquifers. Research studies on these aquifers are important to understand the hydraulic behavior of reservoirs with this type of flow. The Raizama and Diamantino aquifers consist of deformed, low grade metamorphic sediments, distributed along a northeast-southwest belt with southeast concavity. Saturated zones flow is controlled by anisotropy, with low permeability, and the storage is conditioned by fracture and intergranular porosity. In double porosity aquifers the predominance of one or another type of porosity can be observed. When compared to fractured aquifers, double porosity systems present lower drawdown and higher specific capacity values. The transmissivity and hydraulic conductivity hydrodynamic parameters are respectively on the order of 10^-5 m²/s and 10^-7 m/s for the the Raizama Aquifer, and 10^-6 m²/s and 10^-7 m/s for the Diamantino Aquifer.

Keywords:
Double porosity Aquifer; groundwater flow; Raizama Formation; Diamantino Formation