Study on the Imbibition Damage Mechanisms of Fracturing Fluid for the Whole Fracturing Process in a Tight Sandstone Gas Reservoir

Tight sandstone gas is a significant unconventional natural resource, and has been exploited economically mostly through the application of hydraulic fracturing technology in recent decades. However, formation damage occurs when fluid percolates into pores inside sandstones imbibition driven by capillary pressure during operations. In this work, resulting from whole operation process composed fracturing, well shut-in flowback, degree at different moments were investigated core flow experiments low-field Nuclear Magnetic Resonance (NMR) technique. The results show that starting contact surface between fluid, which penetrates an increasingly deep position with time down to certain depth. T2 spectra NMR indicates initially enters small pores, followed large due larger former. Thus, cores low permeability incur higher their stronger capability retaining compared high-permeability cores. front moments, along damage, characterized one-dimensional encoding processing signal. These underlie effective strategy relieve