Experimental Investigation on Cyclic Huff-n-Puff with Surfactants Based on Complex Fracture Networks in Water-Wet Oil Reservoirs with Extralow Permeability

The injection from a well to other wells can be difficult in extralow-permeability oil reservoirs. In order address this issue, method of cyclic huff-n-puff with surfactants based on complex fracture networks for single horizontal was proposed and then investigated terms the effects parameters recovery water-wet models. Firstly, interfacial tension (IFT) contact angle different surfactant concentrations were measured determine basic properties surfactants. Then, experiments at threshold pressures soaking time carried out increasing analyze pore-scale (micropores, mesopores, macropores) mechanisms by combining technology nuclear magnetic resonance (NMR), which showed that increased pressure mostly mesopores macropores, while micropores. Eventually, distributions conducted six plate-fractured models investigate surfactants, primary fracture, secondary each cycle huff-n-puff. Cyclic assisted including both fractures would bring higher recovery. However, methods should taken after several cycles due rapid reduction cycle. findings provide meaningful guide development