1. Introduction
The oil production processes from a reservoir are grouped into three classes: primary, secondary, and tertiary [
1]. In the primary stage, oil is produced due to natural drive mechanisms, for example, water, gas cap, solution gas, etc. The secondary process is launched after the weakening of natural energy. Waterflooding and pressure maintenance are common secondary recovery methods. The tertiary oil recovery, known as the enhanced oil recovery (EOR) method, is introduced when the second technique is no longer economically feasible [
2,
3]. The common EOR methods are chemical, gas, thermal, and others [
4,
5,
6]. The chemical EOR method involves injecting surfactant, polymer, alkaline, and alcohol chemicals to alter interfacial tension (IFT), wettability, phase behavior, and boost oil recovery. In the gas EOR method, gases such as CO
2, N
2, CH
4, and Flue gas are injected into the reservoir to reduce viscosity, IFT, increase the crude’s mobility, and improve oil recovery. This is achieved due to gas mixing with the oil which results in expansion and thus pushes the oil toward production outlets. In the case of the thermal EOR methods, the temperature of the reservoir region is raised to heat the crude oil in the formation to reduce its viscosity, vaporize part of the oil, increase the mobility of the oil, and finally boost oil recovery. Common examples of thermal processes include hot water, steam, and in situ combustions, which are suitable for heavy crude oil.
Microbial enhanced oil recovery (MEOR) falls under other EOR methods [
1]. MEOR technology is an eco-friendly enhanced oil recovery method that involves the injection of microorganisms to produce surfactant, polymer, alcohol, ketone, acids, and gas in situ, to enhance the recovery of residual oil [
7,
8,
9,
10,
11]. In 2013, Haq [
12] introduced an environmentally friendly oil recovery method known as green enhanced oil recovery (GEOR). GEOR is a nature-friendly EOR process that injects specific green fluids, such as surfactants, polymers, alcohols, acids, ketones, and gas (N
2, CO
2), which boosts macroscopic and microscopic sweep efficiencies, as a result, this then increases residual oil recovery [
9,
10,
11]. The GEOR method is divided into two types: in situ and ex-situ [
11]. MEOR falls under the in situ category, whereas green chemicals (i.e., surfactant, polymer, and alcohol), smart water, gas (carbon dioxide and nitrogen), and hybrid (water alternating gas (WAG), and (FOAM)) are grouped in the ex situ process.
In green surfactant flooding, the eco-friendly surfactant is injected into the reservoir to reduce interfacial tension, alter phase behavior properties, and wettability alteration to improve oil recovery whereas smart water flooding (SWF) is a developing technology that utilizes modified water chemistry in terms of salinity and composition of the ions to prepare a more suitable brine composition for a specific brine/oil/rock system to achieve better recovery. The mechanisms of SWF are fine migration, pH increase, multi-ion exchange, salting-in, and wettability alteration.
In the last decade, nanoparticles have received several applications ranging from emulsion stability [
13,
14] and EOR [
15,
16,
17]. Particularly, carbon nanoparticles including carbon nanotubes (CNT), single-walled CNTs, multi-walled CNTs, and carbon dots were tested mainly in the laboratory for EOR potential. Recently, there was one test conducted in the field. While these carbon-based nanoparticles are promising, they are expensive, thus, making field applications uneconomical. As a result, the development of a cost-effective and environmentally friendly carbon nanomaterial is highly desirable. So far, date-leaf carbon nanoparticle (DLCNP) application does not extend to GEOR. This work, therefore, aims to develop carbon nanomaterial from the date-leaf via ball milling and the pyrolysis technique (the different methods of preparation are described in detail in
Section 2.2) and examines its potential in GEOR. The objectives are achieved through experimental processes.