On-site Fracturing Fluid Damage Mechanism of Shale Reservoirs in Chai 204 Well Area
The shale reservoir in the Ganchaigou Group,located in the western part of the Qaidam Basin,is rich in oil and gas.The adaptability of the fracturing fluid currently in use at this site to the reservoir is not clearly defined,and the existing industry standards are not completely applicable to the evaluation of damage to tight shale reservoirs.Consequently,a combination of various imaging techniques has been employed to ascertain the extent and mechanism of damage caused by the fracturing fluid to this reservoir.The reservoir's pore permeability characteristics and mineral composition were determined through experiments.Displacement damage experiments were also integrated with nuclear magnetic resonance,computed tomography(CT)and microscopy automated particle scanning(MAPS)to conduct an in-depth analysis of the fracturing fluid's invasion depth and damage mechanisms.Research results show that the reservoir matrix has extremely low porosity and permeability,with a high content of clay minerals and strong heterogeneity.Both guanidine gum and slickwater cause significant damage to the core's permeability.The amount and depth of invasion by the fracturing fluid are not significant,with the damage mainly occurring at the core's fluid entrance end face,where pore damage is severe.The damage to the reservoir by fracturing fluids is primarily due to the sealing of fracture surfaces.Slickwater fracturing fluid mainly causes liquid phase damage,while guanidine gum fracturing fluid leads to both liquid phase damage and solid phase blockage,resulting in greater damage to the pores compared to slickwater.The research results provide a comprehensive set of research methods for assessing the damage of fracturing fluids to shale reservoirs,offering a reference for evaluating shale reservoir damage.
tight oil reservoirformation damagenuclear magnetic resonancecomputed tomography(CT)scanning electron microscope
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