Abstract
The technique of employing specialized particulates for far-field diversion is well-established during hydraulic fracturing treatments in unconventional formations and is being investigated for use in conventional formations. Far-field diverters (FFD) divert fluid away from the wellbore far into the formation. The injection of FFD at the beginning of the treatment provides an additional stress barrier between the producing interval and adjacent layers by depositing at the layer boundaries where higher leak-off is encountered. The ensuing restriction in height growth maximizes fracture extension within the producing zone, optimizing geometry for increased hydrocarbon production while limiting excess water. Polylactic Acid (PLA) polymer is self-degradable, compatible with reservoir fluids, and has a variety of compositions for different temperature applications. Blending proppant with PLA has been seen to significantly improve the strength of the deposited far-field diverter. Therefore, PLA powder and silica proppant are blended to develop Generation-1 far-field diverter (FFD-Gen1). However, many silica proppants have greater density than PLA, leading to separation during transport which prevents these two components from depositing evenly at the upper fracture boundary. This results in a situation in which excessive downward growth is prevented while upward growth is left unchecked. For this reason, both components need to be simultaneously deposited in order to develop an effective seal. Generation-2 far-field diverter (FFD-Gen2) is developed by replacing silica proppant of FFD-Gen1 with a deformable proppant having a density nearly equal to the polymer, which enables uniform deposition on all adjacent formation boundaries where leakoff is encountered. The deformable characteristic improves the pressure withstanding capacity of the diverter pack.
The deposition and degradation behaviors are investigated in the laboratory by performing HTHP filter press and plug stability experiments. Experimental findings suggest that the primary selection criteria for acceptable performance are the material's mechanical properties. This methodology is used to select the appropriate FFD materials to optimize fracture geometry in carbonate reservoirs. Successful applications prevent excessive water production and substantially increase hydrocarbon production as illustrated in a three well case studies.
Numerical Simulation of a Single-Phase Flow Through Fractures with Permeable, Porous and Non-Ductile Walls
