Experimental Study of Effective Amphiphilic Graphene Oxide Flooding for an Ultralow-Permeability Reservoir

Abstract

Current displacing agents for enhanced oil recovery (EOR), i.e., water, gas, foam, and common nanofluid, suffer plenty of problems in ultralow-permeability reservoirs, with a limited oil recovery. A novel agent, amphiphilic graphene oxide (H−GO), is confirmed to be effective in EOR under such unconventional conditions. We present the fundamental mechanisms for the improved performance by H−GO. Specifically, the effectiveness of H−GO is experimentally verified from multiple perspectives, including emulsifying ability, interfacial activity, and wettability alteration action. Experimental observations show that H−GO has excellent emulsifying ability that the amphiphilic Janus nanosheet is inclined to move onto the oil−water interface. Pickering emulsion formed by H−GO and oil, with an average droplet diameter of only 2.66 μm, is considerably stable, which can be maintained for at least 30 days. Besides, H−GO reduces the oil−water interfacial tension to 0.493 mN/m, 1 order of magnitude lower than that between the common nanoparticle and oil. H−GO shows better wettability alteration efficiency compared to a common nanoparticle. Consistently, micromodel tests show that H−GO gives a promising sweep and displacement efficiency to oil. As a result of these advantages of H−GO, the oil on the rock surface can be separated and form the emulsion or oil zone easily, leading to the incremental recovery of 10.83% using only H−GO (1 mg/mL) in an ultralowpermeability core. The study provides a novel approach for EOR in ultralow-permeability reservoirs. The high performance, convenient operation, and environmental protection make H−GO flooding have great potential for oilfield practice.

Investigating the Influences of Pore-Scale Characteristics on Tight Oil Migration by a Two-Phase Pore Network Model

“…However, for the low-permeability reservoir (e.g., tight reservoir and shale reservoir), whether both the steady oil migration and episodic oil migration can be identified to explain the flow phenomena in low-permeability media is still a question. A common consensus is that the effect of buoyancy on fluid flow can be neglected because of the extremely small size of pores in tight formations [61,62]. Due to the same reason, the effect of capillary pressure becomes significantly important, which means the fluid flow in tight media is more likely to follow the steady migration mode.…”

A review of development methods and EOR technologies for carbonate reservoirs

“…A considerable number of new temperatureand salt water-resistant gel polymers have been prepared to reduce syneresis during the displacement process. Although several novel acrylamide polymers have been reported in the literature, only a few have been industrialized (Singh and Mahto 2016;Chen et al 2018). Partially hydrolyzed polyacrylamide (HPAM) is the most widely used polymer for chemical EOR due to its high water solubility (Sheng 2010;Zhang and Seright 2013).…”

Design and characterization of oil-in-water nanoemulsion for enhanced oil recovery stabilized by amphiphilic copolymer, nonionic surfactant, and LAPONITE® RD

“…[15][16][17][18] The performance of polymer and nanoparticle mixing systems obtained by polymerization or blending can be improved by increasing the viscosity, temperature tolerance, and salt resistance. [19][20][21][22] Layered nanoparticles, including nanoclay 23,24 and grapheme oxide, 25,26 have also been used in EOR.…”