| dc.description.abstract | Unconventional oil and gas reservoirs have low recovery rates and to increase
productivity, hydraulic fracturing is used. Hydraulic fracturing allows increased flow of
oil and gas to the well. The extended production from these reservoirs and the economic
value of the well is controlled by certain qualities of the reservoir and the hydraulic
fractures. A sensitivity analysis allows us to understand how various petrophysical and
completion factors affect cumulative production from these fractures. By understanding
which factors affect production, we can optimize completions to enhance productivity
further. The simulation model used for this study is a single fracture well. A compositional
equation of state (multi-component multi-phase) fluid transport reservoir simulator is
used. The reservoir model considers the matrix consisting of organic and inorganic
components, the fracture is imbedded into this matrix as a discreet feature describing a
discontinuity. The matrix porosity is made of organic nanopores and inorganic stress-dependent
cracks. The experimentation on the sensitivity is split into two phases, where
phase 1 is a 15 variable fractional factorial design of experiment model with a resolution
4 and phase 2 is a refined experiment using the top 10 variables from the 1st phase based
on Central Composite Design of experiment. The cumulative production was noted after
1 and 3 years of production. From the results, it was found that the maximum confining
stress needed to close the inorganic microcracks completely, the parameter indicating the
resistance of microcracks to close, and the fracture geometry (more precisely the fracture
half-length) were the most influential. These effects amplify over time during the production. Operationally, the bottom hole pressure is identified the most important wellbore condition with potential to affect the cumulative production. | |
