Development directions of formation damage evaluation and fracturing fluids in tight and shale oil reservoirs

Tight and shale oil reservoirs are characterized by small pore throats, low porosity, and low permeability, which must be stimulated to increase production. Fluid flow experiences a multi-scale transport process, starting from the matrix pore throats, extending to the natural fractures, and reaching the hydraulic fractures. Initially, tight and shale oil wells exhibit high production rates after hydraulic fracturing. However, this rapidly decreases due to insufficient energy in the reservoir, as well as formation damage to the reservoir, which impedes the multi-scale transport process. Consequently, effective systems for low-damage slickwater fracturing fluids and clean fracturing fluids to ensure the scale and effective development of tight and shale oil reservoirs after volume stimulation have been widely used. The pressure decay method and high back pressure displacement method have provided the valuable foundations for selecting fracturing fluids for tight and shale oil reservoirs. Nonetheless, challenges such as slow fluid transfer unpropped fracture closure, and water-phase trapping damage in tight and shale oil reservoirs need to be addressed urgently. Therefore, integrating fracture preservation, energy enhancement, and damage removal concepts will be essential for successful reservoir stimulation in tight and shale oil reservoirs. Additionally, exploring matching formation damage evaluation and fracturing fluid optimization technologies is crucial to achieving the efficient development of tight and shale oil reservoirs. These will all improve fracture stimulation effects and reservoir recovery, ultimately maximizing the reservoir potential.