Sudanese Oil Research Articles

Development of Prediction Model for Oil Formation Volume Factor for Sudanese Crude Oil

Understanding Oil Formation Volume Factor βo is crucial for effective oil field development, impacting well performance analysis, reservoir simulation, and production engineering calculations. Traditionally, βo is determined through costly and time-consuming laboratory tests, prompting the need for accurate mathematical correlations. Existing correlations such as Vasquez-Beggs, Standing-Glaso, and others have been widely used but show varying degrees of accuracy across different operating conditions. In this study, these correlations were evaluated against 95 datasets of experimental βo data for Sudanese crude oils. Statistical analysis revealed that Vasquez-Beggs and Standing- Glaso models performed best, with average absolute errors of 3.4219 and 3.4477, and correlation coefficients of 0.7563 and 0.7213 respectively. Motivated by the limitations of existing correlations, a new ap- proach using Polynomial Neural Networks (PNN) was developed. This model utilized reservoir temperature, gas gravity, gas oil ratio, and API as input parameters, trained on 70% of the dataset and tested on the remaining 30%. The PNN model exhibited superior predictive performance with a relative average absolute error of 2.8607 and a correlation coefficient of 0.9080. This study contributes a robust predictive tool for estimating βo in Sudanese oil fields, offering enhanced accuracy over traditional correlations and facilitating more reliable reservoir management decisions.

An Artificial Lift Selection Approach Using Machine Learning: A Case Study in Sudan

This article presents a machine learning (ML) application to examine artificial lift (AL) selection, using only field production datasets from a Sudanese oil field. Five ML algorithms were used to develop a selection model, and the results demonstrated the ML capabilities in the optimum selection, with accuracy reaching 93%. Moreover, the predicted AL has a better production performance than the actual ones in the field. The research shows the significant production parameters to consider in AL type and size selection. The top six critical factors affecting AL selection are gas, cumulatively produced fluid, wellhead pressure, GOR, produced water, and the implemented EOR. This article contributes significantly to the literature and proposes a new and efficient approach to selecting the optimum AL to maximize oil production and profitability, reducing the analysis time and production losses associated with inconsistency in selection and frequent AL replacement. This study offers a universal model that can be applied to any oil field with different parameters and lifting methods.

Mathematical modeling of thermal enhanced oil recovery method

The demand for petroleum is increasing steadily, with the International Energy Agency (IEA) projecting that the world's petroleum expenditure will rise from 3564 Million Tonnes of Oil Equivalent (MTOE) in 2007 to as much as 5471 MTOE in 2015 and 6301 MTOE in 2030. More than two-thirds of the oil discovered around the world remains unrecovered; 40–70% of the original oil is still left in place after using conventional production techniques, namely, primary and secondary recovery techniques. This paper is based on the use of the Thermal Enhanced Oil Recovery (TEOR) method in a Sudanese oil field, the Orion field. There are two types of thermal EOR methods, namely In-Situ Combustion (ISC) and Hot Fluid Injection Process. The selection of a specific thermal EOR method is crucial for economic production. Also the challenges faced, such as depth limitation, conventional completion problems, reservoir heterogeneity, etc. are discussed. In order to get maximum recovery from the field, it is necessary to select a shallow depth so that heat loss does not occur inside the formation.

A comparative study of thermal enhanced oil recovery method

The world's petroleum consumption is projected to increase steadily, with most of the oil discovered worldwide remaining unrecovered. Thermal Enhanced Oil Recovery (TEOR) techniques have been found to be effective in increasing the oil recovery from mature reservoirs. This paper compares the two most commonly used TEOR methods, In- Situ Combustion (ISC) and hot fluid injection, in the Sudanese Oil Field, Orion Field. The reservoir properties, operating conditions, production performance, technical challenges, and opportunities, including depth limitations, conventional completion problems, and reservoir heterogeneity, were analyzed for each method. Economic feasibility and environmental impacts are also discussed, including factors such as capital and operating costs, oil recovery rates, and carbon emissions. This study offers valuable insights into the practical aspects of implementing TEOR projects in the Sudanese oil field and can inform decision-making in the oil and gas industry, particularly in reservoir engineering, production optimization, and environmental management.

Determination of the Gas-Oil Ratio below the Bubble Point Pressure Using the Adaptive Neuro-Fuzzy Inference System (ANFIS).

Determining the solution gas–oil ratio (Rs) below the bubble point is a vital requirement that aids in multiple production engineering and reservoir analysis issues. Currently, there are some models available for the determination of the solution gas–oil ratio under the bubble point. However, they still may prove unreliable due to the applied assumptions and their specification to operate only under a particular range of data. In this study, the neuro-fuzzy, i.e., the adaptive neuro-fuzzy inference system (ANFIS) approach, is utilized to develop an accurate and dependable model for determining the Rs below the bubble point pressure. A total of 376 pressure–volume–temperature datasets from Sudanese oil fields were used to establish the proposed ANFIS model. The trend analysis was applied to affirm the proper relationships between the inputs and outputs. Furthermore, using different statistical error analyses, the developed model was benchmarked against widely used empirical methods to evaluate the proposed method’s performance in predicting the Rs at pressures below the bubble point. The proposed ANFIS model performs with an average absolute percent relative error of 10.60% and a correlation coefficient of 99.04%, surpassing the previously studied correlations.

Evaluation of Chemical Application as Pilot to Improve Oil Production from High Viscous Oil in Sandstone Reservoir

Chemical injection stimulation is one of worldwide proven technologies for viscosity reduction and mobility enhancement. The principle mechanism is to reduce heavy oil viscosity by injecting of active chemical agent solution into reservoir as huff and buff practice, the agent solution is act at near wellbore area by remove plugging of heavy organic material, Energy support due to large quantity of stimulation liquid being injected into the formation, viscosity reduction by emulsification and micro-emulsion which will greatly enhance oil mobility; therefore, accelerate oil recovery and reduce interfacial tension (IFT); therefore, increase oil recovery. as global oil industry many technologies introduced to Sudanese oil fields such as chemical which had been implemented in 2018 to increase oil production by developing high viscous oil reservoirs. The pilot was done in two wells in Moga and Fula fields; they are located at southern part of western escarpment trend of Fula sub-basin, Main oil-bearing distributes in Aradeiba, Bentiu and Abu Gabra formations. Bentiu formation was selected for pilot, it is consolidated medium productive sand stone reservoir as per well test interpretation productivity index is 0.05 to 0.2 bbl/day/psia, PVT features: low bubble point pressure, low gas oil ratio (GOR), viscosity at initial pressure between 396–5902 mPa.s and 8986–13880 mPa.s at surface pressure and 29°C, permeability lab test results show strong heterogeneity formation. This paper discusses the chemical injection as enhanced oil recovery (EOR) application in block-6, investigate and evaluate pilot results, then discuss lesson learned from this pilot. Basic reservoir engineering principles and lab test result had been used to calculate production and reservoir parameters before and after implementation. The results of first well shows instantaneous downhole fluid level (DFL) raising about 129 m and remain stable while same pump speed was maintained after the chemical injection, the water cut dropped from 64% to 42% and Oil rate jumped from 95 BOPD to 204 BOPD. second well shows bad performance post the chemical injection and the oil rate decreased from 60 to 40 BOPD and WC increased from 70% to 93% due to well located in the down dip close to OWC and strong reservoir pressure support.

Sudanese Oil Field Production Performance by Nodal Analysis Technique

The study has evaluated production performance of oil well by using nodal analysis for entire production system. The goal of this study is to analysis one of the Sudanese oil field using nodal analysis and to review the field completion strategy for the respective field. The study starts by collecting the data from oil Company and takes the X Field as case study. The X field consist of 18 well and four of them were selected for theanalysis namely X NW-1, X NW-2, X NW-3 and X NW-4. Operating pressure for each well are 2409, 2455, 2550 and 2420 psia, and operating flow rate are 3925.4, 1110.4, 2255.7, and 1387.2 STB/D respectively. Wellfl modeling used for this task, which permits the production optimization of oil well using the concept of nodal analysis.
 Several sensitivity analyses were conducted in order to get the production forecast. If assumed thatthe depletion in the pressure occur within 1 year, the pressure reduced to 2000 and 1000psia for each well; as can be seen, the production reduced rapidly inXNW-2 and XNW-4. However, 1000psia the production becomes zero for the four wells.

Sudanese Oil Field Production Performance by Nodal Analysis Technique

The study has evaluated production performance of oil well by using nodal analysis for entire production system. The goal of this study is to analysis one of the Sudanese oil field using nodal analysis and to review the field completion strategy for the respective field. The study starts by collecting the data from oil Company and takes the X Field as case study. The X field consist of 18 well and four of them were selected for theanalysis namely X NW-1, X NW-2, X NW-3 and X NW-4. Operating pressure for each well are 2409, 2455, 2550 and 2420 psia, and operating flow rate are 3925.4, 1110.4, 2255.7, and 1387.2 STB/D respectively. Wellfl modeling used for this task, which permits the production optimization of oil well using the concept of nodal analysis.
 Several sensitivity analyses were conducted in order to get the production forecast. If assumed thatthe depletion in the pressure occur within 1 year, the pressure reduced to 2000 and 1000psia for each well; as can be seen, the production reduced rapidly inXNW-2 and XNW-4. However, 1000psia the production becomes zero for the four wells.

Examining the relationship between soft total quality management (TQM) aspects and employees' job satisfaction in “ISO 9001” Sudanese oil companies

PurposeSoft total quality management (TQM) aspects are the facets of TQM that mainly concern with the management of human resource in a way to achieve the results of employees' job satisfaction. Based on this approach, the objective of this research is to examine the relationship between the most popular five soft TQM aspects and employees' job satisfaction in “ISO 9001” certified Sudanese oil companies.Design/methodology/approachData were collected through questionnaires from employees across a total of five Sudanese oil companies owned by the government, and adopting an ISO-9001 quality program. The total population of the study consists of 1,505 permanent employees, while the sample size was 253 employees, determined by adopting a stratified random sampling technique. The multiple regression model was adopted for data analysis.FindingsThe results showed that the construct of soft TQM aspects including “top management commitment”, “employee empowerment”, “teamwork”, “training and education” and “employee involvement” explain 74% in the variance of employees' job satisfaction. Results showed positive association between soft TQM aspects and employees' job satisfaction at the 5% significance level. It was also found that each individual variable of the five soft TQM aspects has a significant positive association with employees' job satisfaction. Meanwhile, the results indicated that the most important soft TQM aspect in explaining the variability of employees' job satisfaction was the “employee empowerment” with the highest correlation coefficient (β) of (0.189).Practical implicationsThe study recommends that in order to achieve their primary goal of employees' satisfaction, HR practitioners within organizations adopting total quality programs should align their practice in such a way to enhance soft aspects of TQM. Policy makers and top management in order to gain long-term infrastructural benefits obtained from employees' job satisfaction should show a visible support to TQM programs and allocate necessary resources to train their staff in the quality management system that enhance their empowerment and involvement. The study also recommends that since soft aspects of TQM raise their job satisfaction, employees should support and conform to quality management systems within their organizations.Originality/valueThe paper focuses on soft TQM aspects’ practical implementation. The findings make a significant contribution by using ISO-certified governmental Sudanese oil companies and tested the hypothesized model entails the impact of soft TQM implementation and employees' job satisfaction.

Effects of Garlic Oils on the Fecundity and Hatchability of Callosobruchus maculatus L. (Coleoptera: Bruchidae)

Laboratory experiments were conducted to evaluate the efficacy of the three types of garlic oils; Sudanese, Chinese and Egyptian on the eggs of cowpea beetle Callosobruchus maculatus. Volatile oils from Sudanese and Chinese garlic were obtained by steam distillation and Soxhlet extraction using ethanol correspondingly, whereas Egyptian garlic oil was bought as a ready-made product. The oils were tested at concentrations of 0.01%, 0.1%, 1%, 5% and 10%, at exposure periods ranging from 24-72 hrs. Respective average number of eggs laid after exposure to the lowest concentration of Sudanese, Chinese and Egyptian oils were; 5.4, 4.0, 4.1 after 24 hrs; 0.7, 0.1, 0.1 after 48 hrs 0.2, 0.5, 0.5 after 72 hrs. The oils from the three garlic cultivars significantly reduced number of eggs laid with the highest dose (10%) caused complete inhibition of egg laying. Average number of eggs hatched when exposed to the lowest concentration (0.01%) were; 0.25 after one day and 1.00 after 7 days of exposure to Sudanese oil vapours, 0.00 after one day and 0.75 after 7 days of exposure to Chinese oil vapour and 0.00 after one day and 0.75 after 7 days of exposure to Egyptian oil vapour.

Investigation on the Benefits of Steam Adsorption and Distribution during Cyclic Steam Injection to Improve Oil Recovery - FNE Case Study, Sudan

One of the main types of Enhanced Oil Recovery (EOR) methods is thermal stimulation method which is an increasingly common method of extracting heavy oil. there are different forms of the technology of thermal method Cyclic steam stimulation, Steam flooding and In-situ combustion “Fire flooding” are commonly applied to oil reservoirs, which are relatively shallow very viscous oil at the reservoir temperature, the most widely used steam injection methods for heavy oil recovery is Cyclic Steam Stimulation “steam soak or huff and puff” method. Most of commingle thermal wells has a problem in steam intensity distribution among the layers, which will lead to inconsistency in steam adsorption and some layers would adsorb more than double of the designed steam injected volume. This phenomenon will lead to low productivity and negatively impact the distribution of water cut in the different layers. Steam adsorption and distribution represent one of the main challenges of heavy oil production from Sudanese oil fields, very limited studies have been conducted in this field in Sudan oil fields, and this study is focused on addressing this challenge to maximize recover factor from each well and each field. In this paper the challenge facing Bentiu reservoir in Fula North East (FNE) located in heavy oil zone with target of production around 85% of the total reserves will be highlighted. The field has shallow depth ranging between 520m and 700m and low pressure gradient 1.09 psi/m, and with reservoir temperature around 44 o C. The study covers an investigation on the benefits of steam adsorption to enhance the oil recovery focusing on the distribution of the steam inside the layers, also cover the analyzing and reviewing the actual steam intensity distribution among each layer in the two wells that are later compared with the designed ones. In a later stage, we designed a pilot model that has been designed using advanced thermal EOR Simulator to understand the effect of commingle injection and production (Steam adsorption and distribution) using data from single layers. An optimum steam injection protocol that will maximize the recovery factor from these oil zones has been designed and the results show that the injection rate has significant effect in steam distribution. Keywords: Cyclic Steam Stimulation, Enhanced Oil Recovery (EOR), Steam-Assisted Gravity Drainage (SAGD), Hot water flooding and In situ combustion,

The Effect of Produced Water from Heglig Oil Field on Chemical Additives for Fracturing Fluids

Produced water is the water produced with oil or gas during well production as a result of different operations. Recently, many Sudanese oil fields suffer from the massive amount of water production; the most water production problems in Sudan were observed in Heglig oilfield. The Heglig oilfield is located in Muglad Basin in the southeast and middle of Block 2 in Sudan. The oil production from Heglig oilfield was reported to have peaked in 2006, however it has been declined now and the water cut was reached 95%. Due to many environmental impacts, several studies were conducted for treating the produced water from Heglig oilfield to be used in irrigation; no work was presented to study the effect of Heglig oilfield produced water on chemical additives for fracturing fluids. However, this work analyzes and treats the produced water from Heglig oilfield and evaluates the possibility of the treated water for the re-using in water base fracturing fluids. Samples were collected from two different ponds in the field and analysed according to the American Public Health Association (APHA) and the results were compared with (National Recommended Water Quality (EPA)) to identify the required treatments for the collected water. The analysis was done in Rheine Waal University of Applied Science-Kamp-Lint fort-Germany. In this study, the effect of produced water from Heglig oil field on fluid formulation was studied as management processes of produced water prior to reuse for petroleum operation (Hydraulic Fracturing and Injection) or to be safe in environment. The pH effect on fluids viscosity was investigated for (6, 7, 8, 9 and 10). The results showed that the cross-linking ability of the fracturing fluid presented that better cross-linking system were achieved with 0.48 g CMHEC at pH of 8 and temperature of 40°C for HEC and 60°C CMHEC.

The Effect of CO2 on Wax Appearance Temperature of Crude Oils

Wax deposition makes up one of the main problems in the petroleum industry. Different types of techniques and treatments have been used to inhibit wax deposition. In this work, crude oils from Malaysian oil fields and Sudanese oil field are studied to determine their wax formation tendency for flow assurance purposes. In addition, effect of CO2 injection on the wax appearance temperature (WAT) for these crude oils is studied. In this paper, the high pressure micro differential scanning calorimetry (HPμDSC) has been employed in order to assess the WAT of the crude oils. Results showed that all these crude oils have a WAT ranging from 26.46 to 53.67°C. This suggests a likelihood of wax production in the reservoir and transportation pipelines. Experimental results showed that the injection of CO2 reduced the WAT of the crude oils to about 8.53°C below its original value.

Phenolic compounds of three unconventional Sudanese oils.

The total amount and content of phenolic and flavonoid compounds using the Folin-Ciocalteu and Aluminum chloride methods of the methanolic extracts of Sclerocarya birrea oil (SCO), Melon bug oil (MBO), and Sorghum bug oil (SBO) were studied. Dry samples of Sclerocarya birrea, Aspongopus vidiuatus and Agonoscelis pubescens were used in this study. The oil was extracted using n-hexane following AOCS method. The phenolic compounds were extracted following a well known method and the total amounts of phenolic and flavonoids were determined using Folin-Ciocalteau and aluminum chloride methods, respectively and were identified by HPLC. The concentration of total phenolic compounds was determined as 3.3, 20.7 and 0.9 mg/100 g oil, in SCO, MBO and SBO, respectively, calculated as gallic acid equivalents. The polar fraction of the three oils was separated using solid phase extraction method. The variation of simple and complex oils phenols studied by high-performance liquid chromatography with diode-array detection (DAD) using sephadex eluted by acetone revealed six phenolic compounds which were identified as vanillic acid, callistephin, sinapic acid, t-cinnamic acid, epicatechin, and luteolin in SCO, and four phenolic compounds were identified as vanillin, sinapic acid, o-coumaric acid, and quercetin, in SBO, while in MBO four phenolic compounds were identified as t-cinnamic, syringic acid, quercetin and pelargonin. The phenolic compounds found in SCO, SBO, and MBO can be divided into phenolic compounds and flavonoids.

Sudan Looks East: China, India and the politics of Asian alternatives ed. by Daniel Large and Luke Patey

Reviewed by: Sudan Looks East: China, India and the politics of Asian alternatives ed. by Daniel Large and Luke Patey Gerard McCann Daniel Large and Luke Patey (eds), Sudan Looks East: China, India and the politics of Asian alternatives. Woodbridge: James Currey (pb £16.99 - 978 1 84701 037 7). 2011, 203 pp. From its very outset, the welter of academic literature on resurgent Africa-Asia relations has had a broadly corrective feel. Scholars rightly attempt to interrogate reductive and tendentious Western representations of vulnerable African nations [End Page 518] and rapacious Chinese neo-colonialism. They disaggregate the opportunities and challenges for Africans that emerge from the competitive interest of a range of Asian suitors. They emphasize the power of African agency in shaping this brave new world. The nuances of this politics of choice - 'an Africa that can say no' in the words of Chris Alden - are debated with increasing sophistication in academia and African civil society fora, if not yet in the media outlets on which many of the dominant panoramic studies are based. Nevertheless, one might have detected a certain waning of momentum in much of this literature, given the relative lack of empirical case studies testing the speculations painted at the macro level. In this sense, this excellent volume makes one of the most telling interventions of the last few years. The book comprises ten detailed and judicious chapters, many of which naturally concern the politics of Sudan's oil relations with Asian rising powers. But, crucially, the volume also highlights the wider gamut of Chinese, Indian and Malaysian contact with Sudanese citizens, markets and political economy. Perhaps most rewarding is the fashion in which much of the book, particularly the tight introduction, looks to the history of 'South-South' relations as a meaningful driver of today's political practice. This sympathetic and sustained view of the longer historical durée better enables readers to engage the tapestry of dynamic relations between various Asian rising powers and Sudanese elites. It also convincingly demonstrates how all such liaisons are powerfully conditioned by the imperatives of Sudan's political economy. This line of argument is not new, but the skilful way in which historical complexities are laid out in the introduction provides one of the most significant examples of this scholarship to date. It is especially pleasing that several authors have also been able to fire the opening analytical salvo on South Sudan's Asian frontier, for example in reflecting on changing discourses of historical conviviality between China and the SPLM/A since the 2005 Comprehensive Peace Agreement and subsequent independence. The book makes the point that, despite the growing visibility of Sudan's relations with China, with all the accompanying anxieties over Darfur and executive authoritarianism, the actual mechanisms of Sudan's relations with China (and other Asian partners) are paradoxically relatively neglected. The rallying call here is to delve below elite state-to-state relations and remedy the fact that 'local perspectives across the country are lost in the flurry of international debate' (p. 2). It is here that the book falls a little short of its elegant introductory argumentative promise, despite making some substantial leaps. After encyclopaedic and generalist overviews of Sudan's historical foreign policy and oil industry, the book treats readers to a highly interesting window into the local impacts of oil production on Dinka and Shilluk communities in Southern Sudan after the CPA. This is based on copious local interview material, but greater analytical rigour emerging from the intriguing descriptive material would have been welcome. The author should, however, be commended for bringing such rare research to the public eye. One should also praise the book for looking beyond China. Like some of the author's previous work, the chapter on India provides a rich account of how the Indian government negotiated access to Sudanese oil in the context of Chinese competition and domestic political constraint, deliberately eschewing the 'prism of Sudanese politics' (p. 88) on this occasion. The following chapter, by contrast, looks into political thought and the trajectories of 'Islamization' within Malaysia and Sudan, as opposed to the minutiae of economic relations. The chapter contains suggestive passages on the Islamic...

Physico-chemical properties, fatty acid and tocopherol composition of oils from some Sudanese oil bearing sources

Seven oils, obtained from seven Sudanese oil bearing sources that are Albizia lebbek Oil (ALO), Cassia obtusifolia Oil (COO), Cassia occidentalis Oil (CCO), Abutilon pannosum Oil (APO), Mitracarpus villous Oil (MVO), Ipomea indica Oil (IIO) and Sesamum alatum Oil (SAO), were investigated. The seeds were collected in Sudan from Ghibaish, North Kordofan state. In addition to the oil content, the fatty acid was determined by capillary gas chromatography and the tocopherols were evaluated by highperformance liquid chromatography. The oil content of the seven seeds amounted to 12.8, 7.0, 3.2, 7.1, 11.5, 8.8, and 21.3%, respectively.The oils contained 16.4, 20.0, 14.3, 16.8, 19.4, 19.9 and 10.9 % palmitic acid and 21.0, 24.4, 22.1, 10.9, 27.7, 34.0, 45.1 % oleic acid, and 43.8, 38.2, 45.0, 63.9, 34.6, 33.5, 36.3 % linoleic acid and traces of linolenic acid, respectively.The tocopherol content of these oils amounted to 85.6, 48.2, 32.7, 163.5, 52.5, 30.9, and 26.4 mg/100 g oil, respectively. Alpha-tocopherol was the predominant tocopherol in the oil of Albizia lebbek, Cassia obtusifolia, Cassia occidentalis , and Abutilon pannosum , while gamma-tocopherol was the predominant tocopherol in the oil of Mitracarpus villous, Ipomea indica and Sesamum alatum .

Commentary: China and Africa

Six Years After the turn of a new century, Africa finds itself courted with an intensity of interest unrivalled perhaps since the turn of the last century. To go back a century in time, of course, puts one roughly in the era of the great scramble for Africa, a euphemism for what might more properly be called an invasion mounted on a continental scale by rival European nations eager to expand their mercantile interests, to compete with one another strategically on a global checkerboard and, where they saw fit, to impose their values, religious or otherwise. With China rediscovering Africa, and expanding its interests there at a breathtaking pace, malicious tongues have not hesitated to call what is happening today a new invasion of the continent. The statistics on what China has accomplished in very little time in Africa speak eloquently of the vast scope of the world’s incipient superpower’s undertaking. China recorded $40 billion in trade with Africa in 2005, a four-fold increase since 2001. In the process, it surpassed the United Kingdom to become the continent’s third leading commercial partner, after the United States and France. Just as suddenly, Chinese can be seen almost everywhere in Africa. With about 100,000 nationals living and working in the continent, the newcomers have become more numerous than Britons in places such as Nigeria, long London’s most prized West African possession. This year, China has committed $8.1 billion in lending to Nigeria, Angola, and Mozambique alone. By comparison, the World Bank has committed $2.3 billion to all of sub-Saharan African in the same time span. By one tally, China currently has about 900 investment projects on the continent. These range from the highly controversial, such as China’s 40% controlling participation in the Sudanese oil company, Greater Nile Petroleum, and mining projects in Zimbabwe, to the construction of a new national rail network in Angola.

Synthesis of Alkyl Esters from Three Unconventional Sudanese Oils for Their Use as Biodiesel

Biodiesel is a renewable, biodegradable, and nontoxic fuel that can be derived from vegetable oils by transesterification. In this study, Sclerocarya birrea oil (SCO), melon bug oil (MBO), and sorghum bug oil (SBO), three long-term stable oils from Sudan, were transesterified using methanol or ethanol in the presence of sulfuric acid; the obtained biodiesel characteristics were studied in accordance with the DIN EN 14214 specifications for biodiesel. Most of the biodiesel characteristics met the DIN specifications (water content, iodine number, phosphorus content). The kinematic viscosity values of all samples were higher than those of biodiesel standard limits. Concerning the oxidative stability, only SCO has an induction period higher than the required limit. It was possible to prepare the methyl and ethyl esters catalyzed by H2SO4 from the three unconventional Sudanese oils. Under the described transesterification conditions, SCO seems more suitable for biodiesel than MBO and SBO.

Effects of processing on the quality and stability of three unconventional Sudanese oils

AbstractIn a refining experiment, on a laboratory scale, crude oils from Sclerocarya birrea (SCO), sorghum bugs (SBO), water‐extracted melon bugs (MBO H2O) and solvent‐extracted melon bugs (MBO SOL) were processed by alkali refining. Quality changes were characterized by the determination of free fatty acids (FFA), peroxide value, tocopherols, sterols, phosphatides and stability against oxidation (Rancimat test). In addition, the fatty acid composition was determined. It is clear that the contents of phosphatides, peroxides, tocopherols, sterols as well as oxidative stability were reduced during processing, while FFA were nearly totally removed. The content of phosphorus was reduced in SCO, SBO, MBO H2O and MBO SOL by 26, 19, 12, and 78%, respectively, while complete oil processing removed 95, 99, 96 and 99% of the FFA in crude oils, respectively. The level of total tocopherols decreased during processing by 38.7, 83.8, 100, and 33.3%, respectively. The color decreased through the processing steps up to bleaching; then, in the deodorization step, it darkened sharply in all samples. No change in the fatty acid composition was observed. The order of oxidation stability was crude > degummed > deodorized > neutralized > bleached, in SCO; and crude > degummed > neutralized > bleached = deodorized, in MBO H2O; and crude > degummed > deodorized > neutralized > bleached in MBO SOL; while in SBO, the order of oxidative stability was deodorized > crude > degummed > neutralized = bleached. Total sterols decreased by 42–92% in the processed oils, compared with crude oils.

IMPROVING THE OXIDATIVE STABILITY OF SUNFLOWER OIL BY BLENDING WITH SCLEROCARYA BIRREA AND ASPONGOPUS VIDUATUS OILS

ABSTRACT Improvement of the oxidative stability of sunflower kernel oil (SKO) by blending with highly stable unconventional edible Sudanese oils was investigated. Blends (9 : 1, 8 : 2, 7 : 3, 6 : 4, w/w) of sunflower oil with Sclerocarya (Sclerocarya birrea) oil (SCO) and melon bug (Aspongopus viduatus) oil (MBO), respectively, were studied with respect to the fatty acid composition, the oxidative stability (Rancimat 120C) and stability at 70C using peroxide value. By increasing the proportion of SCO and MBO in SKO, the linoleic acid content decreased from 46.3 to 31.2% (SCO) and 30.1% (MBO), respectively, while the oleic acid content increased from 41.3 to 51.0% (SCO) and 43.9% (MBO), respectively. As a result of blending SKO with SCO and MBO, respectively, the oxidative stability in the Rancimat test was improved from 47 to 147% in (SCO) and from 5 to 68% (MBO) compared to the SKO as control, with increasing parts of SCO and MBO, respectively. Storage of the blends at 70C showed that the increase of the peroxide value as a measure of oxidation was remarkably lower for the mixtures of MBO and SCO with SKO than for pure SKO. This study demonstrated a means for improving the stability of sunflower oil by blending with SCO and MBO.