An overview of chemical enhanced oil recovery: recent advances and prospects

Abstract

Despite the progress made on renewable energy, oil and gas remains the world's primary energy source. Meanwhile, large amounts of oil deposits remain unrecovered after application of traditional oil recovery methods. Chemical enhanced oil recovery (EOR) has been adjudged as an efficient oil recovery technique to recover bypassed oil and residual oil trapped in the reservoir. This EOR method relies on the injection of chemicals to boost oil recovery. In this overview, an up-to-date synopsis of chemical EOR with detailed explanation of the chemicals used, and the mechanism governing their oil recovery application have been discussed. Challenges encountered in the application of the various conventional chemical EOR methods were highlighted, and solutions to overcome the challenges were proffered. Besides, the recent trend of incorporating nanotechnology and their synergistic effects on conventional chemicals stability and efficiency for EOR were also explored and analysed. Finally, laboratory results and field projects were outlined. The review of experimental studies shows that porescale mechanisms of conventional chemical EOR is enhanced by incorporating nanotechnology, hence, resulted in higher efficiency. Moreover, the use of ionic liquid chemicals and novel alkaline-cosolvent-polymer technology shows good potentials. This overview presents an extensive information about chemical EOR applications for sustainable energy production.

Evaluation of Polymeric Materials for Chemical Enhanced Oil Recovery

“…Additionally, the anions on the carboxyl groups promote polyelectrolyte behavior, which increases viscosity and controls adsorption within the reservoir. The oil recovery efficiency of a particular polymer is dependent on the degree of hydrolysis (which typically ranges from 15% to 35% [7]), as well as the molecular weight (which can be varied up to about 30×10 6 g/mol, as reported by [15]). Polymer flooding is of particular interest, because it is a developing field that still has significant room for improvement.…”

“…However, most of these biopolymers are also susceptible to biodegradation (more so than synthetic polymers), which limits their usefulness in the EOR application. Several reviews of biopolymers that have been investigated for polymer flooding have been compiled recently (including [7,18]), and key points are summarized in Table 2. Table 2.…”

“…Polymer flooding is arguably the most common form of chemical EOR [4] and tends to be more widely used than alkali or surfactant flooding. Alkalis can be problematic, as they introduce scaling and plugging [4], and both alkalis and surfactants become less efficient as they flow through porous media due to adsorption effects [7].…”

“…Although the addition of polymeric materials improves the sweep efficiency through the reservoir, it can also cause pore plugging if an inappropriate polymeric material is selected for the application (or if the reservoir geology is not suitable for polymer flooding). The other major deterrent is related to polymer stability; many of the materials used for polymer flooding (especially acrylamide-based polymers) are known to degrade under the harsh conditions that are characteristic of oil reservoirs [7,11,12]. Thus, it is critical that these shortcomings (related to plugging and instability) be addressed.…”

“…As natural resources are being consumed, it is more important than ever to focus on overall (long-term) oil recovery rather than "easy" (immediate) oil recovery. Concerns for long-term applications have motivated many researchers, and many detailed overviews of enhanced oil recovery [3,4,13,14] and polymer flooding [7,10,[15][16][17][18][19][20][21][22][23] have been published in recent years. Therefore, the purpose of this overview is not to rehash the same contents as prior sources of information but rather to provide background for researchers as they continue to pursue optimally designed materials to be used in enhanced oil recovery (specifically, polymer flooding).…”