Huff-n-puff methods using nanofluids and/or CO₂ are most promising methods for enhancing oil recovery in the Mahu Oilfield, Xinjiang, China. Six tight glutenite reservoir samples were conducted the huff-n-puff experiment using different displacement fluids (i.e. D₂O, supercritical CO₂ and D₂O/nanofluid) following saturation with oil. The results of T₂ NMR spectra of the samples show that D₂O can readily enter the larger pores stripping the oil with smaller pores remaining relatively untouched. Furthermore, the oil recovery initially fast before quickly tapering with the final average oil recovery over samples using D₂O huff-n-puff alone being only 14.89%. However, CO₂ could effectively enter both small and large pores with the oil recovery efficiency from small pores being greater than 20% and from the large pores being even higher with the final average recovery over two samples using CO₂ huff-n-puff alone being 40.44%. Relative to D₂O alone, the nanofluid improved the oil recovery in small pores by more than 10%. There appears to be a synergistic effect combining CO₂ and nanofluid huff-n-puff; both CO₂ followed by nanofluid huff-n-puff or nanofluid followed by CO₂ huff-n-puff achieved similar final recoveries close to 50% of the overall oil.