Evaluation and Hydraulic Fracturing Design for Optimization of Effective Conductivity in Multilayer Reservoir

Abstract

The HI-68 is an existing well carried out by the fracturing program in layer A1 at an interval of 1254 – 1260 m. In this work, the fracturing fluid was pumped at a rate of 17 bpm and an average tubing pressure of 2000 psi, using 70 klbs carbolite proppant size 20/40 at a concentration of 1 to 8 ppa ramp and followed by a 30 bbl flush (under displacement 4 bbl) using slickwater. Hydraulic fracturing in the HI-68 was carried out 2 times, but the well did not experience a significant increase in oil, but there was an increase in watercut. This condition occurs as a result of hydraulic fracturing which results in low fracture conductivity. This is due to the problem of low fluid efficiency and the type of completion of the multilayer reservoir which results in unwanted early screen outs. Furthermore, the HI-68 well was modified for a limited entry multilayer completion in order to easily control fracture initiation which aims to reduce fluid loss into the rock, fracture initiation is a modification of the conventional method of hydraulic fracturing which is initiated by pressure, not velocity. Using rate to create pressure (as a consequence of Darcy's law). As the pressure increases, fracturing will begin as the pressure rises above the breakdown pressure of the weakest point along the hollow interval. The perforation interval 1254 – 1270 m has different price values and is divided into three areas, first interval area 1254 – 1260 m, second interval area 1260 – 1265 m and third interval area is 1265 – 1270 m, if the three areas are carried out hydraulic concurrent fracturing, it is possible for an early screen out to occur due to narrowing in the second interval area due to the stress load generated from the first and third areas which suppresses the second interval area so that fracture initiation does not develop. Using medium to high density proppant will be advantageous, because it is expected to form short and wide fractures with high conductivity around the wellbore. Results of sensitivity the proppant size larger than mesh size of proppant, resulting greater retained permeability, it will affect fracture conductivity value. From the economic aspect, the net present value for 1 year obtained depends on the fracture conductivity, so the combination of proppant type and proppant size is adjusted to the formation permeability conditions.