Visualization the Surfactant Imbibition at Pore Scale by Using of Fractured Micromodels

Abstract

Recovery in low permeability oil reservoirs is challenging because they are often high fractured and oil-wet. Microemulsion-forming surfactant solutions, which can replace oil from tight matrix by imbibition, have been verified as effective enhanced oil recovery fluids for tight reservoirs. To better understand the mechanisms of oil recovery from oil-wet, fractured rocks using microemulsion-forming surfactants, microfluidic experiments including single channel micromodel tests and fractured micromodel imbibition tests which could visualize the in-situ phase changes were conducted in this work. Through on our study, the priority of wettability alteration and phase change with a function salinity was clarified. Besides, the imbibition dynamics of microemulsion-forming surfactants at different salinities were provided, and further understanding about the equilibrium process of microemulsion during imbibition was obtained. Based our studies, we suggest a moderate salinity for microemulsion-forming surfactants enhanced imbibition recovery.

Experimental Study of Imbibition Within Core Chips of Shale in Ordos Basin

“…In the field, surfactant solution is injected as pad fracturing fluid, which is then filtered into the matrix during the fracturing process, after that imbibition equilibrium is achieved by a shut-in well, and oil is recovered under normal formation energy. Hence an imbibition runs experiment consists of an imbibition cell with a photographic camera system to record and present each seepage step [10]. Two face-to-face pieces of glass are used to fix the core chips, with one end left on each side to connect the fluid, and both sides are vacuumed synchronously to ensure that the bond layer between glass and rock chip is as dense as possible.…”

Micromodel Studies of Surfactant Flooding for Enhanced Oil Recovery: A Review

“…Moreover, the formation of microemulsions is competitive with the wettability alteration. As the salinity approaches the optimum value, the time required for wettability alteration is longer …”

“…As the salinity approaches the optimum value, the time required for wettability alteration is longer. 24 Wettability is one of the most important factors determining oil−water displacement patterns in porous media. Experimental studies indicate that the displacement efficiency is low in strongly oil-wet micromodels, and the displacement efficiency is much higher in weakly water-wet or neutral micromodels.…”

Experimental Study on the EOR Performance of Imbibition and Huff and Puff in Fractured Tight Oil Reservoirs

“…At present, there have been a lot of studies on the stimulation mechanisms of imbibition fluids and CO 2 in tight oil reservoirs [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Imbibition is one of the main methods of oil production in tight oil reservoirs, and the main driving force of imbibition is capillary force.…”

“…How to use the existing imbibition theory to develop tight oil reservoirs effectively is an important research topic. The current researches about fluid imbibition in tight oil reservoirs are mainly focused on the imbibition mechanism in the fracture network system at a microscale [13][14][15][16][17] as well as the screening and synthesis of excellent additives to improve the EOR function of fracturing fluids [18][19][20][21][22]. For the selection of imbibition fluids, nanoparticle fluids have excellent performance and good application prospects.…”