Characteristics of Oil Production by Fracturing Fluid Additive-Assisted Displacement in Tight Oil Reservoirs

The concept of integrating fracturing and flooding has gained widespread recognition for its role in advancing the development of unconventional oil and gas resources. Nonetheless, there exists a relative scarcity of research investigating the impacts of fracturing fluid additives on oil production in tight formations during the displacement process of fracturing fluids. This study endeavors to address this gap by conducting fracturing fluid displacement experiments, employing a combination of nuclear magnetic resonance (NMR) technology and microscopic visualization displacement systems, and seeks to quantitatively characterize the extent and patterns of oil production, residual oil distribution, and occurrence characteristics facilitated by fracturing fluid additives. The findings indicate that fracturing fluid additives effectively reduce the interfacial tension between the fracturing fluid and crude oil, thereby altering the rock wettability. Notably, the oil production efficiency of guar gum fracturing fluid surpasses that of carbon nanoimbibition (CNI) nanovariable viscous slick water fracturing fluid. To assess the contribution of pores of varying scales, an oil production index (η) is introduced. The study reveals an increase in the oil production index following the addition of additives with a markedly higher index for small pores. Microscopic visualization systems unveil that the cocoamidopropyl hydroxysultaine (CHSB) additive effectively reduces the area of residual oil distribution and exhibits favorable oil displacement effects. Residual oil occurrence is influenced by the pore structure and additive characteristics. This study is of great significance for the elucidation of the mobilization and occurrence states of oil by fracturing fluid additives in tight reservoirs.