Date-Leaf Carbon Particles for Green Enhanced Oil Recovery.

Green enhanced oil recovery (GEOR) is an environmentally friendly enhanced oil recovery (EOR) process involving the injection of green fluids to improve macroscopic and microscopic sweep efficiencies while boosting tertiary oil production. Carbon nanomaterials such as graphene, carbon nanotube (CNT), and carbon dots have gained interest for their superior ability to increase oil recovery. These particles have been successfully tested in EOR, although they are expensive and do not extend to GEOR. In addition, the application of carbon particles in the GEOR method is not well understood yet, requiring thorough documentation. The goals of this work are to develop carbon nanoparticles from biomass and explore their role in GEOR. The carbon nanoparticles were prepared from date leaves, which are inexpensive biomass, through pyrolysis and ball-milling methods. The synthesized carbon nanomaterials were characterized using the standard process. Three formulations of functionalized and non-functionalized date-leaf carbon nanoparticle (DLCNP) solutions were chosen for core floods based on phase behavior and interfacial tension (IFT) properties to examine their potential for smart water and green chemical flooding. The carboxylated DLCNP was mixed with distilled water in the first formulation to be tested for smart water flood in the sandstone core. After water flooding, this formulation recovered 9% incremental oil of the oil initially in place. In contrast, non-functionalized DLCNP formulated with (the biodegradable) surfactant alkyl polyglycoside and NaCl produced 18% more tertiary oil than the CNT. This work thus provides new green chemical agents and formulations for EOR applications so that oil can be produced more economically and sustainably.

Modification of Xanthan Gum for a High-Temperature and High-Salinity Reservoir.

Tertiary oil recovery, commonly known as enhanced oil recovery (EOR), is performed when secondary recovery is no longer economically viable. Polymer flooding is one of the EOR methods that improves the viscosity of injected water and boosts oil recovery. Xanthan gum is a relatively cheap biopolymer and is suitable for oil recovery at limited temperatures and salinities. This work aims to modify xanthan gum to improve its viscosity for high-temperature and high-salinity reservoirs. The xanthan gum was reacted with acrylic acid in the presence of a catalyst in order to form xanthan acrylate. The chemical structure of the xanthan acrylate was verified by FT-IR and NMR analysis. The discovery hybrid rheometer (DHR) confirmed that the viscosity of the modified xanthan gum was improved at elevated temperatures, which was reflected in the core flood experiment. Two core flooding experiments were conducted using six-inch sandstone core plugs and Arabian light crude oil. The first formulation-the xanthan gum with 3% NaCl solution-recovered 14% of the residual oil from the core. In contrast, the modified xanthan gum with 3% NaCl solution recovered about 19% of the residual oil, which was 5% higher than the original xanthan gum. The xanthan gum acrylate is therefore more effective at boosting tertiary oil recovery in the sandstone core.

Comparative Study of Green and Synthetic Polymers for Enhanced Oil Recovery.

Several publications by authors in the field of petrochemical engineering have examined the use of chemically enhanced oil recovery (CEOR) technology, with a specific interest in polymer flooding. Most observations thus far in this field have been based on the application of certain chemicals and/or physical properties within this technique regarding the production of 50-60% trapped (residual) oil in a reservoir. However, there is limited information within the literature about the combined effects of this process on whole properties (physical and chemical). Accordingly, in this work, we present a clear distinction between the use of xanthan gum (XG) and hydrolyzed polyacrylamide (HPAM) as a polymer flood, serving as a background for future studies. XG and HPAM have been chosen for this study because of their wide acceptance in relation to EOR processes. To this degree, the combined effect of a polymer's rheological properties, retention, inaccessible pore volume (PV), permeability reduction, polymer mobility, the effects of salinity and temperature, and costs are all investigated in this study. Further, the generic screening and design criteria for a polymer flood with emphasis on XG and HPAM are explained. Finally, a comparative study on the conditions for laboratory (experimental), pilot-scale, and field-scale application is presented.

Challenges of trachoma control: an assessment of the situation in northern Nigeria.

Over the last three decades, a lot has been achieved in the control of trachoma worldwide. New assessment techniques, effective evidence-based control strategy with new methods and drugs, and an aggressive global partnership for the control of the disease have evolved. As such the number of people with the disease and blindness due to the disease had drastically reduced. Trachoma is now only responsible for about 4% of blindness worldwide down from 12% some few decades ago. Some countries are on the verge of eliminating the disease as a public health problem. Despite these achievements numerous challenges remain for achieving trachoma control in endemic communities. This article highlights the challenges faced in one of the known trachoma endemic areas - northern Nigeria. Aspects on the dearth of complete situational data on trachoma, fragmented implementation of the SAFE strategy, community apathy, difficulties faced in ensuring safe, and quality lid surgery in the most difficult terrain where the disease thrives are discussed here. Other unique challenges like managing children with severe trichiasis, curbing the high rate of early-onset recurrence of trichiasis after lid rotation surgery and challenges to maintain supply of antibiotics and implementation of facial cleanliness and environmental improvement components of the control strategy are presented along with the learnt experiences and recommendations. These challenges and their remedies are likely to be shared by other trachoma endemic areas in Africa.

Rapid assessment of cataract surgical services in Birnin-Kebbi local government area of Kebbi State, Nigeria.

PURPOSE: To provide baseline data for cataract surgical services in Birnin-Kebbi Local Government Area (LGA) of Kebbi state, Nigeria for effective planning of services in the LGA and the state. METHODS: People aged 50 years and above were enrolled in the study using stratified cluster sampling with probability proportional to size procedures. Subjects were assessed based on the WHO (World Health Organization) RACSS (Rapid Assessment of Cataract Surgical Services) methodology. RESULTS: Out of the 2,589 enumerated subjects, 2,424 (93.6%) were examined 51.7% of whom were male. The overall prevalence of bilateral blindness was 4.5% (confidence interval (CI) 95% 3.7%-5.3%). The prevalence of bilateral cataract blindness was 2.1% (CI 95% 1.5%-2.7%). The prevalence of operable cataract in the study was 9.5% (CI95% 8.3%-10.7%). The cataract surgical coverage was 28.9%, but couching coverage was 32.9%. The presenting vision was poor in 100% of non-intraocular lens (IOL) operated eyes, 90.6% of couched eyes and only 6.9% of pseudophakic eyes. The major barriers to services were 'old age and no need for surgery' (29.6%), 'cannot afford operation' (16.9%), 'waiting for cataract surgery' (12.7%). CONCLUSION: Despite the recently introduced free cataract surgical services the prevalence of operable cataract is high. Accessibility of existing services needs to be improved and other barriers should be overcome by appropriate health education on cataract services.