Role of chemical additives and their rheological properties in enhanced oil recovery

Abstract

<jats:title>Abstract</jats:title> <jats:p>A significant amount of oil (i.e. 60–70%) remains trapped in reservoirs after the conventional primary and secondary methods of oil recovery. Enhanced oil recovery (EOR) methods are therefore necessary to recover the major fraction of unrecovered trapped oil from reservoirs to meet the present-day energy demands. The chemical EOR method is one of the promising methods where various chemical additives, such as alkalis, surfactants, polymer, and the combination of all alkali–surfactant–polymer (ASP) or surfactant–polymer (SP) solutions, are injected into the reservoir to improve the displacement and sweep efficiency. Every oil field has different conditions, which imposes new challenges toward alternative but more effective EOR techniques. Among such attractive alternative additives are polymeric surfactants, natural surfactants, nanoparticles, and self-assembled polymer systems for EOR. In this paper, water-soluble chemical additives such as alkalis, surfactants, polymer, and ASP or SP solution for chemical EOR are highlighted. This review also discusses the concepts and techniques related to the chemical methods of EOR, and highlights the rheological properties of the chemicals involved in the efficiency of EOR methods.</jats:p>

Perspectives in Nanocellulose for Crude Oil Recovery: A Minireview

“…72 In chemical EOR, a flooding liquid, typically watercontaining additives, such as polymers, surfactants, and caustic compounds, is injected at a high pressure. 73 The presence of these compounds increases water viscosity, reduces surface tension, or alters the surface wettability of the reservoir, improving oil recovery. 72 Two characteristics qualify the performance of a chemical flooding agent: the macroscopic sweep/displacement efficiency of the reservoir and the microscopic oil displacement efficiency.…”

“…where k is the effective permeability of porous media to displacing liquid, μ is the displacing liquid viscosity, k 0 is the effective permeability of porous media to crude oil, and μ 0 is the crude oil viscosity. 72,73,75,76 Efficient oil recovery occurs when M is less than 1 (favorable number). Values higher than 1 (unfavorable number) indicate better flow of the displacing fluid, by either channeling or bypassing residual crude oil.…”

“…Values higher than 1 (unfavorable number) indicate better flow of the displacing fluid, by either channeling or bypassing residual crude oil. 72,73,75,76 Figure 3 shows a cartoon depicting the process of enhanced oil recovery. 75 Chemical EOR by Polymer Flooding.…”

“…Increasing viscosity is typically achieved by injecting water-soluble polymers in dilute brines into the reservoir. 73,78,79 Salinity is fundamental to maintain the integrity of the mineral, particularly on sandstone. Synthetic polyacrylamides (PACs), partially hydrolyzed polyacrylamides (HPACs), and acrylamide copolymers are usually the compounds of choice as a result of price, versatility, and availability.…”

Surfactant screening to generate strong foam with formation water and crude oil

“…Therefore, the sulfonate surfactant molecules have a high stability against the hydrolysis reaction. Recently, AAS surfactants have been used commonly in EOR processes (Tackie-Otoo et al 2020;Machale et al 2020). Generally, it is preferred to use these anionic surfactants on sandstones and clays due to their low adsorption on their surfaces.…”