Adewale Project Proposal PDF

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IMPROVING OIL RECOVERY FACTOR WITH BIO-CHEMICAL A GGREGATES

PROJECT PROPOSAL BY

JOLAADE ADEWALE AHMED 15/ENG07/026

SUPERVISED BY DR. ADENIYI, A.T.

DEPARTMENT OF CHEMICAL AND PETROLEUM ENGINEERING, AFE BABALOLA UNIVERSITY, ADO-EKITI

IN PARTIAL FULFILLMENT FOR THE AWARD OF THE DEGREE OF BACHELOR OF ENGINEERING IN PETROLEUM ENGINEERING

OCTOBER, 2019. 1|Page

TABLE OF CONTENTS INTRODUCTION BACKGROUND OF THE STUDY STATEMENT OF THE PROBLEM AIM OF STUDY OBJECTIVES OF THE STUDY PROJECT HYPOTHSES JUSTIFICATION OF THE STUDY SCOPE OF THE STUDY LIMITATION OF THE STUDY EXPECTED CONTRIBUTION TO KNOWLEDGE LITERATURE REVIEW MATERIALS/SOURCE BRIEF METHODOLOGY ORGANIZATION/PLAN OF STUDY SAMPLE PREPARATION TEST EQUIPMENT AND LOCATION COST ESTIMATION OF STUDY FUNDING PLAN DISSEMINATION PLAN WORK PLAN TERMS AND DEFINITIONS REFERENCES 2|Page

PROJECT PROPOSAL 1.0 INTRODUCTION Despite the diversification into renewable energy, the ever-rising global demand for fossil energy cannot be over emphasized. Even the renewable fuels have a foundation built on fossil fuels. As a result of this, maximizing oil recovery from previously under exploited reserves becomes crucial to meet the everrising energy demand. By nature, crude oil is a limited resource. Nevertheless, the amount of crude oil available has to meet the worldwide demands. From time to time, oil production has been intentionally reduced, and this has resulted in serious oil crises accompanied by a general increase in the oil price. This in turn has forced the oil industry to recover oil from more complicated areas, where the oil is less accessible meaning that recovery techniques are constantly advanced. This has contributed to the development of techniques for enhanced oil recovery, (EOR), which while used today, also constantly undergo further advancement and development. Up to two thirds of the crude oil remains trapped in the reservoirs after primary and secondary recovery in an average oil reservoir. EOR is then required to optimize the depletion, as the remaining oil is trapped in the pore structure inside the reservoir. Enhance oil recovery methods are used throughout the world as a means of increasing energy supply after the depletion of conventional mechanism of recovery original oil in place (OOIP). It is known that primary and secondary oil recovery processes achieve on a worldwide basis an average recovery of 33% of the original oil in place (OOIP); while the unrecovered oil (67%) might be retained in the reservoir by viscous and/or capillary forces. Conventional chemicals, such as solvents and surface-active compounds (surfactants) are used during chemical EOR applications. Solvents reduce the oil viscosity to improve the oil mobility by overcoming viscous forces; while surfactants reduce the interfacial tension between oil and rock or oil and water overcoming capillary forces. These chemicals are added to the injection water and transported within the reservoir during water flooding, however, the chemicals reach only the places where oil has already been displaced by water; furthermore, the chemicals could be partially consumed and/or retained within the rock formation before they reach the target area in the reservoir for their intended use. The injection of solvents and surfactants into some reservoirs have yield unsatisfactory results because the chemicals failed to contact the residual oil for the required time period, which is needed to achieve a long-term effect. Another problem is the natural heterogeneity of the reservoirs; therefore, the injected chemicals inevitably flow along the paths of least resistance (i.e., high permeability zones, natural fractures, etc.) 3|Page

where the saturation of residual oil is usually the lowest. It has been known for decades that specifically selected microorganisms are capable of metabolizing hydrocarbons producing organic solvents, such as alcohols, aldehydes, surface active fatty acids, and other metabolites which can interact with the crude oil improving its fluidity. Other oil production issues such as the presence of paraffin, emulsions, and corrosion problems can also be controlled using microorganisms. For instance, extensive research has been conducted on the use of biosurfactants (BS) for enhanced oil recovery applications. The injection of surfactants into oil reservoirs can improve oil recovery by mobilizing the oil stranded by capillary forces. The most commonly used method is to inject a high-concentration surfactant solution into the formation to create an ultra-low interfacial tension between the surfactant bank and the residual oil, hence mobilizing trapped oil. Another method uses a low-concentration surfactant solution to change the wettability of the reservoir rock to a more water-wet state, promoting the spontaneous imbibition during waterflooding. This method can be very useful in fractured carbonate reservoirs where the wettability change can improve oil recovery by accelerating the spontaneous imbibition process.

1.1 BACKGROUND TO THE STUDY Biosurfactant is a structurally diverse group of a surface-active molecule synthesized by microorganisms. Their capability to reduce surface and interfacial tension with low toxicity and high specificity and biodegradability, lead to an increasing interest on these microbial products as alternatives to chemical surfactants. The interest in biosurfactant has been steadily increasing in recent years due to the possibility of their production through fermentation and their potential applications in such areas as the environmental protection. The uniqueness with unusual structural diversity, the possibility of costeffective ex-situ production and their biodegrability are some of the properties that make biosurfactant a promising choice for use in environmental application. All living cells produce amphipathic molecules. These molecules which consist of both hydrophilic and hydrophobic moieties are called surface-active compounds or surfactants. In many cases, they exhibit surface-active characteristics such as dramatic lowering of surface tension at the air/water interface, lowering interfacial tension at the oil/water interface, and micelle or pseudomicelle formation. Such characteristics confer excellent detergency, emulsifying, foaming, and dispersing traits, which make surface-active compound, some of the most versatile process chemicals. Microorganisms utilize a variety of organic compounds as the source of carbon and energy for their growth. When the carbon source is an insoluble substrate like a hydrocarbon (CxHy) microorganism facilitate their diffusion into the cell 4|Page

by producing a variety of substances, the biosurfactants. Some bacteria excrete ionic surfactant, which emulsify hydrocarbon substrates in the growth medium. In recent years industries have generated a large amount of tropical agricultural residues. Their disposal causes several environmental problem therefore there has been an increasing trend towards more efficient utilization of agro industrial residues like oil cakes, wheat bran, soya bean waste, banana peel, orange peel, sesame waste, coconut waste, bagasses etc. These residual by-products serve as an ideal substrate for fermentation processes to produce biosurfactant. Mostly agricultural products are utilized as source of raw material as they are produced in large quantities, contain large amount of usable proteins and carbohydrates with some amount of oil residues, no storage problem, easily available and cheap. Surfactants are molecules that concentrate at interfaces and decrease surface and interfacial tension. These compounds find applications in an extremely wide variety of industrial processes involving emulsification, foaming, detergency, wetting, dispersing or

solubilization.

However, naturally

occurring

surface-active

compounds

derived from

microorganisms, also called biosurfactants, are attracting attention as they offer several advantages over chemical surfactants, such as low toxicity, inherent good biodegradability and ecological acceptability. Biosurfactants are amphiphilic biological compounds produced extracellularly or as part of the cell membranes by a variety of yeast, bacteria and filamentous fungi from various substances including sugars, oils and wastes. The unique properties of biosurfactants allow them to be preferably used than the chemically synthesized surfactants in a number of industrial operations. Biosurfactants reduce surface tension, Critical Micelle Concentration (CMC) and interfacial tension in both aqueous solutions and hydrocarbon mixtures. This study will encompass the production of biosurfactant from agricultural or agro waste as an alternative cheap cost over its chemical counterpart to increase the recovery of residual oil. The recovery of residual oil depends on the capillary number and bond number. The higher the capillary number the higher the residual oil recovered. Capillary number is given as: NC = µ.v / σ. cosϴ Altering any of the above properties will either increase or decrease the capillary number. Where µ is the viscosity of displacing fluid, v is the Darcy’s velocity of displacing fluid, σ is the interfacial tension of displaced fluid and displacing fluid and ϴ is contact angle of displaced fluid indicating the degree of wettability. Increasing the viscosity of displacing fluid will lead to increase in capillary number and thus increase in oil recovery. For this study, polymer will be added to know it effect on oil recovery in 5|Page

comparison with the use of biosurfactant to reduce interfacial tension which in turn increases the capillary number. However, chemical surfactant will be added to form a bio-chemical surfactant aggregate mixture in order to improve upon the performance of biosurfactant. Biosurfactants are known to be non-toxic and specific in nature thereby altering the interfacial tension that exist between fluid-fluid interface and solidfluid interface and also altering the wettability of reservoir rock surface. The crux of this study is to investigate the effect of biosurfactant and/or chemical surfactant in increasing residual oil recovery by altering the interfacial tension and wettability of reservoir rock by series of core flooding experiments. The interfacial tension after secondary flooding by hot water and after tertiary flooding by BS will be measured using the Tensiometer. Also, the wettability alteration will be determined using Amott wettability index test. The adsorption rate of biosurfactant will be determined by introducing alkaline to reduce the adsorption of biosurfactant in the core plug. At the end of the experiment, results will be collated to make proper analysis on the effectiveness of biosurfactant on the alteration of interfacial tension, wettability and its adsorption rate.

1.2 STATEMENT OF THE PROBLEM Increasing residual oil will help curb the increasing demand for crude oil production. In order to achieve this, the mobility of residual oil must be greatly increased. Even after the conventional methods (Primary and secondary mechanism) of oil recovery, some oil are still trapped in the pore spaces of the reservoir rock by capillary pressure. The oil in these pore spaces has to be recovered in order to meet the increasing demand for oil production. Capillary pressure (P c) is the pressure difference across the interface between two immiscible fluids arising from the capillary forces. Biosurfactant produced from agro waste will be used to reduce the interfacial tension between displacing fluid and the displaced fluid thus decreases the capillary pressure holding residual oil to the pore spaces and thereby increases the mobility of residual oil. Also, biosurfactant alters the wettability of reservoir rock surface from oil wet to water wet by decreasing the adhesive force of capillarity and increasing the oil permeability of the reservoir. The wettability will be measured using the Amott wettability index test. Increasing mobility of residual oil increases the production of crude oil.

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1.3 AIM OF THE STUDY The aim of this study is to improve residual oil recovery with the use of bio-chemical surfactant aggregates using core flooding equipment.

1.4 OBJECTIVES OF THE STUDY The specific objective of this study include: 1. To produce biosurfactant from agro waste. 2. To investigate the effects of biosurfactant on wettability alteration using Amott wettability index test. 3. To estimate the tendency to loss of biosurfactant caused by adsorption. 4. To investigate the effect of chemical surfactant in increasing biosurfactant performance. 5. To investigate the effect of biosurfactant on interfacial tension alteration.

1.5 RESEARCH HYPOTHESES In order to achieve the objectives of this study, the study would be guided by the following research hypothesis which will be investigated. Hypothesis I H0: Capillary forces are responsible for trapped oil in the small pore spaces in the reservoir rock. H1: Residual oil are assumed to be trapped in the small pore spaces making the reservoir rock surface oil-wet. Hypothesis II H0: Interfacial tension is directly proportional to the capillary pressure. The lower the interfacial tension, the lower the capillary pressure. That is Pc = 2σcosɵ / r H1: Interfacial tension is inversely proportional to the contact angle which is a measure of wettability.

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Hypothesis III H0: Adsorption of biosurfactant is caused by strong affinity of reservoir rock to biosurfactant solution as a result of unlike charges attraction. H1: Alkaline are used to reduced adsorption of biosurfactant. Hypothesis IV H0: Polymer as co-surfactant increases the recovery of oil by increasing the viscosity of displacing fluid. H1: Increasing the viscosity of displacing fluid increases the capillary number. Although polymer increase of capillary is less when compare with biosurfactant increase of capillary number.

1.6 JUSTIFICATION OF THE STUDY Improving oil recovery is recognized as the major target and challenge at different stages of an oil field development. Among several methods in oil recovery, microbial oil recovery which involves the injection of biosurfactant which react with reservoir fluids has been used to increase the mobility of residual oil. Biosurfactants are complex molecules comprising different structures which react with residual oil to form surfactant. The surfactant helps lowers the interfacial tension of oil brine system and also alters the wettability of reservoir rock surface thereby mobilizes residual oil in the pore spaces. Biosurfactant flooding improves pore-scale displacement efficiency through the mechanism of interfacial tension reduction, or wettability alteration, or a combination of both mechanisms. During secondary recovery via waterflooding, it is practically impossible for water to displace all the oil in the pore scale due to trapping of oil by capillary forces. This capillary force is measured by a dimensionless capillary number. Capillary pressure is closely related to residual oil saturation and oil recovery and increases as residual oil saturation decreases. Consequently, a higher NC will result in a higher oil recovery. A typical brine flooding has an NC in the range of 10^-7 to \ 10^- 6. Increasing NC from this value to a range of 10^- 2 reduces the residual oil saturation to the barest minimum and result in an increase of the oil recovery factor. This can be achieved in three ways: (1) increasing the displacing fluid viscosity; (2) increasing the injection fluid velocity; (3) reducing the IFT. Increasing the injection fluid velocity may cause the injection pressure to be greater than the fracture pressure of the reservoir, thereby, fracturing the reservoir rock. Meanwhile, increasing the displacing fluid viscosity using polymer solutions increases the capillary number by less than 100 times. Practically, only the method of reducing 8|Page

IFT can be used to increase NC by 1000 times. This is achieved with the aid of surfactants. When surfactant solutions are injected along with brine into oil reservoirs, the hydrophilic head reacts with water while the hydrophobic tail interacts with the components of the crude oil. An adsorbed film occurs as a result of the interaction between the oil and alkyl tail of the surfactant, hence, lowering the IFT at the oil/water interface. Reduction of IFT at the oil/water interface weakens the capillary forces withholding the trapped oil, thereby, causing oil droplets to flow with ease from the pore throats of the rock to form an oil bank downstream. Altering the wettability of a surface from oil-wet to water-wet diminishes the adhesive force of capillarity and increase the oil permeability of the reservoir. The biosurfactants have attracted attention because of their low toxicity, biodegradability, and ecological acceptability; furthermore, low cost raw materials, such as agricultural and industrial waste can be used as substrates to the biosurfactant production. In addition to the surface-active properties, biosurfactants produced by some microorganisms have exhibited antimicrobial activity and anti-adhesive activity against several other microorganisms.

1.7 SCOPE OF THE STUDY The areas which this research will be limited to include: 1. Production of biosurfactant from agricultural waste through fermentation and centrifugal extraction in order to enhance residual oil recovery. 2. Aggregate mixing of biosurfactant with chemical surfactant to increase biosurfactant performance using series of core flooding experiments. 3. The determination of interfacial tension and wettability alteration using tensiometer and Amott wettability index test respectively. 4. Assuming relatively constant porosity and permeability for all core plugs. 5. Investigating loss of biosurfactant by adsorption and the use of alkaline to reduce it.

1.8 LIMITATION OF STUDY As a result of time constrain, this study will be limited to: 1. The investigation of interfacial tension and wettability alteration by aggregate mixture of biosurfactant and chemical surfactant. 9|Page

2. The determination of interfacial tension using tensiometer only and the determination of wettability using only Amott wettability index test only. 3. Controlling adsorption of biosurfactant using alkaline solution only. The interfacial tension and wettability alteration can be determined by other method other than the methods listed in this study. Biosurfactant has effect is influenced when rocks of different porosity and permeability is used. Using core plugs for different porosity and permeability influences the performance of biosurfactant. Due to time constrain, core plugs will assumed relatively constant permeability and porosity. There are other properties that influences the performance of biosurfactant such as pressure, temperature, salinity of formation brine, P H of formation brine, rock heterogeneity, critical micelle concentration etc. But for the purpose of this study due to time constrain, rock heterogeneity will only be accounted for while other factors are assumed constant. Reservoir rock heterogeneity causes adsorption of biosurfactant as a result of the unlike charge that exist between the reservoir rock and formation fluids. This study will be limited to the preventive measure used to curb the adsorption of biosurfactant by reservoir rock using alkaline solution.

1.9 EXPECTED CONTRIBUTION TO KNOWLEDGE On successful completion, this project is expected to: 1. Reveal how biosurfactant alters interfacial tension between displacing fluid and displaced fluid. 2. Reveal how biosurfactant alters wettability of rock surface. 3. Reveal how biosurfactant is been adsorbed by rock surface.

1.10 LITERATURE REVIEW Extensive literature survey on previous works related to the project topic from journals, text books, internet and other sources will be carried out.

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1.11 MATERIALS/SOURCE The starting material that will be used in the c...