THE EFFECT OF FRACTURE TREATMENT PARAMETERS ON DIAGNOSTIC FRACTURE INJECTION TESTS (DFIT)

Resumo

In-situ stresses and permeability of the rock media has a significant role in predicting the
production rate of oil and gas reservoirs. Hydraulic fracturing is a widely used technique to increase the
rock formation permeability in oil and gas reservoirs. The diagnostic fracture injection test (DFIT) is a
commonly used and reliable technique executed prior to a hydraulic fracture stimulation process. Its
main objective is to break a small fracture in the rock formation around the wellbore, in order to evaluate
the closure of the fracture system. This test provides the parameters necessary for hydraulic fracturing
planning, such as minimum horizontal stress, fracture closure pressure, fracture gradient, fluid leak-off
coefficient, fluid efficiency, and formation permeability. These parameters play an important role in
determining the operation window for stability and planning of secondary recovery operations. This
work presents the numerical simulation of a DFIT in a carbonate reservoir of a Brazilian oil field.
Coupled hydro-mechanical continuum elements and coupled cohesive interface elements represent the
porous media and the hydraulic fracture in the numerical model, respectively. This paper aims at
investigating the effect of fracture treatment parameters on the hydraulic fracture geometry before- and
after-closure response of the DFIT. The methodology reproduces numerically all stages of a DFIT.
Therefore, the comparison of the measured bottom-hole pressure and those obtained numerically show
good agreement. The right combination of minimum in-situ stress and permeability estimation was
essential to obtain a good closure response after shut-in.