Effects of Fracture Properties on Oil Recovery in Tight Reservoirs

Abstract

Unconventional reservoirs, characterized by low permeability are gradually becoming a force to reckon with in today’s world owing to the rapid depletion of conventional resources. However, low oil production from tight reservoirs can be mitigated by implementing hydraulic fracturing. In this study, Schlumberger’s eclipse-100 simulator was used to simulate various scenarios in order to determine the best fracture geometry and the effects of fracture properties on oil recovery. The properties considered were fracture half-length, width and number. Oil recovery from the tight reservoir was found to be 0.47% OIP and the application of hydraulic fracturing increased the recovery to 4.78%. OIP sensitivity analysis was carried out by varying well trajectory, porosity, permeability and wettability. It was found out that, fracture geometry of 300 ft half-length, 1 inch width and a fracture number of 15 is ideal for this reservoir, both technically and economically. An increase in the fracture number affected the spacing greatly. As the number increased, initial production from the reservoir increased. However, cumulative production declined with continued increase in fracture number as spacing decreased. The fracture half-length had a more significant impact on the early time behavior as a result of the fractures reaching further into the reservoir. Increase in fracture width impacted on the late time production behavior of the well by maintaining production for a longer duration. Variations in the reservoir properties after obtaining the optimum case show that hydraulic fracturing is applicable to tight reservoirs.

Keywords: Hydraulic fracturing, fracture geometry, recovery factor, oil recovery