Hydraulic Fracturing Process in Tight Base Shale of Asmari Formation in Ahwaz Oilfield

Over the years, unconventional reservoirs have not received attention in Iran in light of easy oil. The most significant oil reservoir in Iran is Asmari formation of Ahwaz oilfield which has been producing oil by natural flow potential. Due to the gradual pressure drop of Asmari formation and oil price increment, production from the base shale of this formation has been considered. However, due to the low permeability of this layer, oil production has not been achieved, and it has still remained a challenge. Production of petroleum from tight/shale rocks has become possible by hydraulic fracturing. This study has hired Asmari formation base shale as case study for hydraulic fracturing simulations. This paper is focused on a scientific process to construct a lithology-dependent one-dimensional geomechanical model in an oil well which is completed in Asmari formation. Moreover poro-elastic formulation has been used for in-situ stress determination. In addition, the tectonic stress regime has been identified as normal faulting. Afterwards, a hydraulic fracturing operation has been designed by the FracCADE simulator. During hydraulic fracturing operations, an uncontrolled-height fracture may occur due to the absence of stress-barriers in bounding layers. A hydraulic fracture was designed for a sublayer of the Asmari base shale based on the constructed profile of in-situ stresses to constrain the vertical growth. Ultimately according to the results of the simulation, it was illustrated that the designed fractures did not cross the bedding interfaces of Asmari base shale.

Keywords:

Fracture migration , Unconventional reservoirs , in-situ stresses , Geomechanical model