Petroleum Engineering Journal Full Paper A REVIEW: APPLICATION OF BIOSURFACTANT IN ESTER BASED MUD Muhammad Razzin bin Rosilan 23rd July 2020 *Corresponding author muhammadrazzin97@gmail.com School of Chemical & Energy Engineering, Engineering Faculty, UTM, 81310, Skudai, Johor, Malaysia Graphical abstract Abstract This paper provides a review on application biosurfactant in ester-based drilling fluids. A proper formulation of drilling fluid will enable to enhance penetration rates, reduce hole problems and minimize damages of formation and operator will able to drill into a desired geological aim at low cost. Choosing ester-based mud (EBM) as a proper formulation drilling fluid already common in petroleum industry. In fact, its among promising alternatives as its environmentally friendly due to its biodegrability attributes instead of other types of drilling fluids. Even though, EBM has biodegradable and lubricity properties to begin with but there are several constraints as high kinematic viscosity, low thermal stability and prone to hydrolysis either in acidic or base condition that can lead to detrimental impacts on the drilling fluid performances. Different type of surfactants can be added and affect the changes in rheology properties of EBM and also increase the performance of EBM as drilling fluid. Hence, the application of bio-surfactant are used for environmental purpose and at the same time can be use as additive in drilling fluids. The present review describes the potential applications of biosurfactants in ester-based mud. Keywords: ester-based drilling fluid, biosurfactant, rheological properties, performance EBM green energy, Abstrak Kertas ini menyediakan kajian semula tentang aplikasi biosurfaktan dalam cecair penggerudian berasaskan ester. Rumusan yang sesuai untuk cecair penggerudian akan membolehkan untuk meningkatkan kadar penembusan, pengurangan masalah telaga dan kurangkan kerosakan kepada pembetukan telaga dan pengendali akan dapat menggerudi ke arah tujuan geologi yang diinginkan pada kos yang rendah. Memilih cecair peggerudian berasaskan ester sebagai satu rumusan yang sesuai telah menjadi kebiasaan dalam industry petroleum. Dengan itu, ia adalah salah satu daripada alternatif yang meyakinkan daripada cecair peggerudian yang lain kerana ia mesra alam disebabkan sifat biodegrasinya. Walaupun EBM mempunyai sifat biodegrasi dan pelinciran sebagai sifat asli tetapi terdapat beberapa kekangan seperti kelikatan kinematic yang tinggi, kestabilan terma yang rendah dan terdedah kepada hidrolisis sama ada dalam keadaan yang berasid ataupun asas yang bole membawa kepada kesan buruk kepada prestasi cecair penggerudian. Jenis surfaktan yang berbeza boleh ditambah dan memberi kesan dalam sifat reologi EBM dan juga boleh meningkatkan prestasi EBM. Oleh itu, aplikasi biosurfaktan digunkan untuk tujuan alam sekitar dan pada masa yang sama, ia boleh digunakan sebagai bahan tambahan dalam cecair peggerudian. Ulusan ini menerangkan tentang potensi aplikasi biosurfaktan dalam cecair penggerudian berasaskan ester. 85:1 (2020) 1–5 | www.jurnalteknologi.utm.my | eISSN 2180–3722 | 2 Azizul, Elmi & Muhammad Zaim / Jurnal Teknologi (Sciences & Engineering) 85:1 (2020) 1–5 Kata kunci: cecair penggerudian beasaskan ester, biosurfaktan, tenaga hijau, sidat reologi, prestasi EBM © 2020 Penerbit UTM Press. All rights reserved 1.0 INTRODUCTION The ever-increasing demand for oil and gas is pushing the global discovery and exploitation of new resources in unexplored areas and deeper formations. Drilling fluids also known as drilling muds are hydraulic fluids used in the drilling industry for maintaining hydrostatic pressure, cooling the drill bit, providing wellbore stability and hanging the formation cuttings. Common and frequent instances of spills and blowouts of hydrocarbons are common accidental situations experienced during drill operations. Such incidents can be managed fairly effectively by shutting down in the well with the aid of the blowout preventers and by adjusting the drilling fluid's physical properties. Recent progress in deep water exploration has exposed complex geological and environmental conditions. Water Based Muds (WBM) which are widely used in the current scenario are found to be highly unsuitable for shale formations and deep-water drilling. Water based muds are cheap and can be formulated with easily available ingredients. When it comes to drilling through shale formations, waterbased muds cannot be used due to very high filtration loss. Shale formations are fine grained sedimentary rocks made of clay minerals, calcite and quartz. These rocks show high fissility and are mainly composed of silt sized particles of clay. Often, wellbore instability issues are encountered in these formations which is due to the dispersion of the clay into ultra-fine colloidal particles and this has a direct impact on the drilling fluid properties. (Mohamed Khodja, 2010) Oil base muds (OBM) are highly effective due to their low fluid loss and high temperature and pressure tolerance. OBMs rules the industry for a long time until the environmental problem caused by their disposal was realized. Abidance by the Environmental Protection Agency (EPA) and cost has been a major concern which sojourns the usage of oil-based muds (Mohammed Mokhtar Said, 2018). Low aromatic mineral oils as well as synthetic oils have been replacing the highly aromatic oils (e.g. diesel) in the oil and gas industry. However, as environmental legislation become more stringent, even the newer and less polluting mineral and synthetic oils in vogue now may be pronounced unsuitable because of their non-biodegradability. This led to the breakthrough in the field of drilling fluids research when researchers began to study the use of different materials which could abide by the EPA standards but also possess the excellent physical properties of OBMs during the 1990s. Therefore, ester-based drilling fluids (EBDF) is being used to overcome this trouble. EBDF have biodegradability, bio-accumulation, minimal toxicity and superior lubricity attributes to become alternatives for oil-based mud and water-based mud (Ikodiya Orji, 2018). This type of drilling fluids created to lessen the limitation of drilling fluids such as environmental issues, toxicological and associated health aspects due to oil-based mud. Using biogradable substance as base for drilling fluid is better instead of using oil such as diesel and mineral oil. Thus, ester fluid provides similar shale stabilization and superior lubricity to mineral oil-based mud, and yet also satisfies environmental parameters (Prasad, 2014). Many companies using ester-based drilling fluids as alternative drilling fluids instead of oil-based mud and water-based mud due to its biodegradability and lubricity property. Hence, high biodegradability and relatively low toxicity have long made esters universally recognized as the best base fluids for synthetic-based muds in regards to environmental performance. Despite of the characteristics, hydrolysis of esters can be occurred when water is added to ester in the presence of an acidic or basic environment. Hydrolysis is triggered by higher temperature but would also occur at normal room temperature at lower rates. This also increases the viscosity of the material. Hence, very high viscosity is also not desirable since it will cause high equivalent circulating density (ECD).(Prasad, 2014) Hence, different kinds of surfactant were added to ester-based mud and to maintain the properties of ester-based mud to lease the problem contained in EBM.. Biosurfactant have been introduced due to their versatility and proven efficiency such as such as emulsifying/demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Biosurfactants are often presented as valuable versatile tools (Darne G. De Almeida, 2016). The main purpose of this paper is to review on the application of bio-surfactant in ester-based mud. 3 Azizul, Elmi & Muhammad Zaim / Jurnal Teknologi (Sciences & Engineering) 85:1 (2020) 1–5 2.0 METHODOLOGY 2.1 Synthesis of ester The research and development of EBDF mainly focus on the synthesis of ester from fatty acids of vegetable oils. Esterification or transesterification is used to modify the chemical structure of vegetable oil (Songtham Photaworn, 2017). Vegetable oils are eco-friendly, cheap and readily available potential alternative to conventional mineral oils as based fluids (Aliyu A. Sulaimon, 2017). From the understanding, viscosity of vegetable oils is about 4 or 5 higher than diesel oil and make them unsuitable as base fluid for mud formulation (Prof. Adewale Dosunmu & Nigeria, 2010). Hence, esterification and transesterification has been applied to overcome such problems such as high viscosity of vegetable oils and become popular chemical process of reducing viscosity by reacting vegetable oil with alcohol in the presence of catalyst. Moreover, the purpose of acid esterification is to reduce the free fatty acids (FFA) content while the purpose of trans-esterification was to convert the vegetable oil to methyl ester so that can be used as base fluid for drilling mud. At table 1, there are different types of ester are produced from these methods because each of ester can give different result in various properties of drilling mud. stipulated “RP 13B-1 Recommended Practice for Standard Practice for Field Testing Water-Based Drilling Fluids, 2009” as a guide for laboratory works in formulate the drilling fluids. Moreover, other drilling fluids samples will be prepared in order to measure the change in properties such as density, plastic viscosity, gel strength and filtration loss as compared to the base case and there are also studies compare the base case with commercial drilling fluids. Hence, there are different kinds formulation of drilling fluids with addition of several surfactants in order to contain the desire performance. Figure 1 and 2 show that different sample of formulation EBM with different oil water ratio (OWR).In this study, they choose 80/20 as the best candidate and continue to compared with other type of drilling fluids. Figure 3 show the formulation of Palm Fatty Acid Methyl Ester (PFAME) and later to be compared with commercial drilling fluid (Escaid-110). Figure 1 & 2: Formulation of EBM and other drilling fluid to be compared (Arina Sauki, 2015) Table 1: List of synthesis of ester Figure 3: Formulation of PFAME (Mohammed Mokhtar Said, 2018) 2.2 Drilling fluids preparation Drilling fluids formulation is important in every drilling operation because it’s can impact the performance of drilling fluids. Most of studies used the standard 4 Azizul, Elmi & Muhammad Zaim / Jurnal Teknologi (Sciences & Engineering) 85:1 (2020) 1–5 2.3 Measrument of rheological properties of mud Rheology refers to the action of deformation and flow of all kinds of matter. Some rheological measurements on fluids, such as viscosity, gel strength, yield point and so on, help to determine how this fluid can flow under a range of different conditions. This knowledge is essential for the design of the circulation systems required for the achievement of certain desired objectives in drilling operations (Radzlan, 2013). The common rheological properties that been measured in various studies are density, plastic viscosity, yield point, gel strength, and filtration loss. Table 2: The rheological properties and its purpose Figure 4: API specififications for rheology properties at 300oF (Aliyu A. Sulaimon, 2017) Table 3: Rheology properties of PME based mud (Aliyu A. Sulaimon, 2017) Rheology properties Plastic viscosity (PV), cP Yield point (YP), lb/100 ft2 10' sec gel strength, lb/100ft2 10″ gel strength, lb/100 ft2 Electrical stability (ES), volts HPHT filtration loss, ml BHR T8 AHR Sarapar147 BHR AHR 20 36 13 14 5 8 7 8 8 11 3 4 11 12 4 6 1624 1355 608 528 - 5.4 - 4.5 Figure 5 : Effect of addition Thinner solvent (Aliyu A. Sulaimon, 2017) 3.0 RESULTS AND DISCUSSION 3.1 Rheology properties and performance of EBMs Based on (Aliyu A. Sulaimon, 2017), they using palm methyl ester (PME) as base fluid through synthesis of ester from crude palm oil using estrification and transesterification process to reduce viscosity. In their study, the mud weight used is 12.5 ppg and used ratio 85:15 as water oil ratio(OWR) for formulation drilling fluids. They find that the different before hot rolling (BHR) and after hot rolling (AHR) are significant. Moreover, at table 6, PME mud sample T8 with addition of thinner solvent which is toluene reached the API requirement for PV, GS, ES but not for YP, filtrate loss, and mud cake thickness while Sarapar147 reached the target values by API specifications. Azizul, Elmi & Muhammad Zaim / Jurnal Teknologi (Sciences & Engineering) 85:1 (2020) 1–5 5 Next, palm-based ethylhexyl ester as base oil for EBM. Using same process as before which is transesterification by using palm oil methyl ester react with 2-ethylhexanol and sodium methaxide as catalyst. F2 sample gave 11.6 lb/gal as mud weight and used 80:20 as OWR for formulation mud. Table 7 shows that F2 sample gave the best rheology properties because its closed to API range while the present of Versagel additive in mud make F4 sample showed the worst rheology properties but its showed the best in HPHT filtration test because the additive excellent in improving fluid loss property in drilling fluids.(Nor Saiful Hafiz Abdul Habib, 2014) Table 4: Rheology properties for samples and API standard (Nor Saiful Hafiz Abdul Habib, 2014) Rheology properties Plastic viscosity (PV), cP Yield point (YP), lb/100 ft2 10' sec gel strength, lb/100ft2 10″ gel strength, lb/100 ft2 Electrical stability (ES), volts HPHT filtration loss, ml F2 F4 API 13B Specification 35 90 25-40 4.5 95 15-45 7 25 8-20 40 36 8-30 120 715 100-400 9.8 5 <10 ml Moreover, (LINA JASSIM, 2016) make a studied about lauric acid methyl ester as base oil in EBM. With 2-Ethylhexanol as alcohol in trasesterification process and sodium methaxide as catalyst produce the lauric acid methyl ester. Formulation mud including mud weight at 12 ppg and 85:15 as OWR gave superior rheologcal properties as shown at table 8. With this new formulation, electrical stability stay the same before and after hot rolling which showed excellent thermal stability. In fact, the filtrate was clear without any water means no hydrolysis occurred. Table 5: Rheology properties for sample (LINA JASSIM, 2016) Rheology properties Plastic viscosity (PV), cP Yield point (YP), lb/100 ft2 10' sec gel strength, lb/100ft2 10″ gel strength, lb/100 ft2 Electrical stability (ES), volts HPHT filtration loss, ml BHR 25 20 14 17 1999 - AHR 26 21 13 19 1999 2 Thus, studies from (M.M. Dardir, 2014) make two esteramides as base fluids for their EBM and also make comparison between their formations of EBM with commercial synthetic-based mud. N-(2 hydroxy ethyl) N-(ethyl linolineate) hexanamide as MT1 samples, N,N-Bis(ethyl linolineate) hexanamide as MT2 sample and commercial synthetic-based mud as MR sample. The samples had been aging for 16hr at 350oF, hydrostatic pressure and continues circulation to measured thermal stability property. Table 6 illustrates that new formation of EBM samples in this study showed superior rheological properties results compared to commercial synthetic-based. Samples of EBM are stable at high temperature and pressure with continuous circulation (thermal stability). Table 6: Rheological property of EBM samples with commercial synthetic-based mud after 16hr aging (M.M. Dardir, 2014) Rheology properties Plastic viscosity (PV), cP Yield point (YP), lb/100 ft2 10' sec gel strength, lb/100ft2 10″ gel strength, lb/100 ft2 HPHT filtration loss, ml MT1 73 17 11 12 7.5 MT2 45 11 10 15 5 MR 50 32 15 21 9 Based on all the studies on EBM, its shows great rheological properties with new formulation of mud, addition of additive and modify the parameters either to be compared with commercial drilling fluids or API standards. 3.2 Application bio-surfactant in drilling fluids Petroleum industry uses substantial amounts of petrochemical-based synthetic surfactants in its activities as mobilizing agents to increase the availability or recovery of hydrocarbons as well as many other applications related to extraction, treatment, cleaning, and transportation. However, biosurfactants have several potential applications for use across the oil processing chain and in the formulations of petrochemical products such as emulsifying/ demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Due to their versatility and proven efficiency, biosurfactants are often presented as valuable versatile tools (Darne G. De Almeida, 2016). The development of high performance and environmentally-friendly clay stabilizers is still crucial to the drilling industry. Wellbore instability is typically caused by chemical or mechanical changes (or both).The drilling process may encounter serious operational problems such that the drilling operation might be permanently stopped before reaching the targeted oil layers. From (Aghil Moslemizadeh, 2017), studied about mulberry leaf extract (MLE), a biosurfactant as clay stabilizer. Biosurfactant exhibit an environmentally friendly characteristic which an asset for this biosurfactant. The present study assesses the capability of MLE to inhibit the clay hydration in aqueous phases. Moreover, MLE considerably improve the performance of drilling operations and boost the oil recovery factor in an enhanced oil recovery process due to reducing the oil-brine interfacial tension (Mohammad Ali Ahmadi, 2014). 6 Azizul, Elmi & Muhammad Zaim / Jurnal Teknologi (Sciences & Engineering) 85:1 (2020) 1–5 Other studies using non-ionic surfactant glycyrrhizin that was obtained as Glycyrrhiza glabra rootextract (GGRE) as a clay swelling inhibitor and compared it with synthetic surfactant (TX-100). The compatibility with the drilling fluid formulation was investigated through the rheological and fluid loss analysis.They also found that GGRE compatible with the commercial drilling fluids additives as they investigated the inhibition mechanism. The inhibition mechanism probably relies on the adsorption of hydrophilic group through hydrogen bonding on Mt's surfaces and ori entation of the hydrophobic group toward the aqueous phase whereby a hydrophobic shell could be made on Mt's surfaces. Despite having good performance, features such as cost-effective, biodegradability,and low toxicity are great merits for GGRE.(Aghil Moslemizadeh, 2017). emulsification, phase separation, solubilization, foaming, de-emulsification, corrosion inhibition, and viscosity reduction of heavy crude oils (Zhifeng Liu, 2017). Main application of biosurfactant is MEOR, the tertiary recovery of oil in which microbes or their metabolic products are used to enhance recovered residual oil. It usually is less-expensive when compared to chemically enhanced oil recovery particularly when microorganisms are used to produce sufficient products such as polymers and biosurfactants starting with low-cost substrates raw materials. Biosurfactants enhances the formation of stable water-oil emulsions and the breakdown of the oil film in the rocks which is important for a maximizing oil extraction ultimately extending the reservoir life time (Robert Thomas Bachmann, 2014). 3.3 Other Application bio-surfactant 4.0 CONCLUSION Biosurfactants are mainly produced by microbial cultures grown on water immiscible substrates, therefore allowing access to these hydrophobic substrates (such as hydrocarbons) and are generally classified into low molecular-mass molecules (lipopeptides, glycolipids) and high molecular-mass polymers (polymeric and particulate surfactants)(O. L. Matvyeyeva, 2014).These molecules offer several advantages over chemical surfactants, such as environmental compatibility, low toxicity, biodegradability, and maintained activity under extreme conditions of temperatures, salinity and pH values(Rita de Cássia F. S. Silva, 2014). Figure 6: List of application of biosurfactants relevant to the petroleum industry.(Zhifeng Liu, 2017) In this study, biosurfactants appear to have reached a critical stage in their commercial exploitation; after many years in which interest in them was at a low level, they have now come to the top of the agenda of many companies as a result of the sustainability initiative and green agendas. However, the recent advances in the applications of biosurfactant in drilling fluids especially in EBM. The world growth toward environmentally friendly in everything due too much of pollutant that destroying our environment. This work systematically reviewed the source and properties of biosurfactant and ester based mud. This is not only because of the biosurfactants’ excellent characteristics, but also their environmental and economic benefits. 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