A team of researchers at Khalifa University has discovered a way to use elemental sulphur to enhance the refractive index of polymer materials.��

The refractive index, which is the measure of how fast light moves through a material, is an important optical property. It determines the focusing power of lenses, the dispersive power of prisms, the reflectivity of lens coatings, and the light-guiding nature of optical fibers. High refractive index materials are particularly sought for applications requiring high transmission of light.

Inorganic materials—chemical compounds that contain no carbon-hydrogen bonds—usually possess a high refractive index, but their lower flexibility and high densities can limit their applications. Polymeric materials, or plastics, overcome these issues with low weight, excellent impact resistance, easy processability and low cost, but their refractive index is��

A team of researchers including Dr. Vijay Wadi, Postdoctoral Fellow, Dr. Kishore Jena, Research Scientist, Kevin Halique, Research Assistant, and Dr. Saeed Alhassan, Associate Professor and Acting Senior Director of the Petroleum Institute, all from the Department of Chemical Engineering at Khalifa University, has discovered a way to use elemental sulphur to enhance the refractive index of polymer materials. Their findings were published in .

Previous research has focused on using inorganic or metal nanoparticles to produce polymer composites with a high refractive index, but manufacturing these is more difficult, and the dispersion of the nanoparticles in the polymer matrix is inconsistent, impacting the transparency of the materials and limiting their applications.

Elemental sulphur is a national resource for the UAE, with production coming from the refining and processing of oil and gas. Sulphur atoms can increase the refractive indices of materials. The amount of sulphur and the degree of molecular packing in the polymers play an important role in controlling the refractive properties.

However, elemental sulphur is difficult to incorporate into polymers on its own due to its low solubility and incompatibility with the majority of organic chemicals. Additionally, the resultant polymers produced with heat treatment are highly brittle and unstable at room temperature, making them less than effective for use during polymer processing.

Dr. Alhassan and the research team made stable polymers by reacting elemental sulphur with 1,3-diisopropenylbenzene (DIB) cross-linker inside a polystyrene matrix where it diffuses into the matrix, ensuring even dispersion of the sulphur. The refractive index of the final polymer can be tuned as needed by varying the amount of cross-linkers.

“Directly using elemental sulphur to produce high refractive index polymers is limited by sulphur’s low solubility in most organic solvents and chemicals,” explained Dr. Alhassan. “However, the inverse vulcanization technique is one way to overcome this.”

Inverse vulcanization is a process where sulphur reacts with unsaturated hydrocarbons to form polymers with linear sulphur in their molecular structures. The polymers are synthesized with no solvent as sulphur itself acts as a solvent, making the process highly scalable at the industrial level. The sulphur-rich composite polymers made using this technique are characterized by a high refractive index, and the optical properties can be tuned by simply modifying the chemical formulation.

“The main advantage of these composites is their ability to be scaled up and processed into a variety of different objects,” explained Dr. Alhassan. “Molded objects and films made using these composites are transparent and uniformly colored, showing the stability of the composites. They can be processed into any shape and size without altering transparency. Plus, since they are highly soluble in most organic solvents, they can be made into ultra-thin films that are clear and stable.”

This manufacturing method means high refractive index composite materials can be produced at low cost and high scale, using an easily obtained waste product from the UAE’s petroleum industry for myriad applications in various fields.

Jade Sterling
Science Writer
2 November 2020

The post Khalifa University Researchers Produce High Refractive Index Materials Using Sulphur appeared first on Khalifa University.

Researchers from Khalifa University have developed a simple method to produce catalysts more efficiently and precisely, which could help accelerate the development of super effective catalysts for numerous industries.

A team of researchers led by Dr. Yasser Al Wahedi, Assistant Professor of Chemical Engineering at Khalifa University and a member of the Center for Catalysis and Separations (CeCaS), and Dr. Georgia Basina, Post-Doctoral Fellow in the same department, have developed a new way of making catalysts that is more precise and effective. This simple and effective method involves embedding nanoparticles in a material dotted with ultra-small pores, known as the ‘NEMMs’ approach. The team recently published their work in.

A catalyst is a substance that can be added to a reaction to increase the reaction rate without being consumed in the process. They typically speed up a reaction by reducing the energy needed to activate the process by providing an alternate reaction pathway.

Heterogeneous catalysts, commonly used in the oil and gas industries, are catalysts that exist in a different state than the reactants—for example, the catalyst may be in a solid state, while the reactants are liquid or gas.

“Heterogeneous catalysts are crucial in many industries such as oil, gas, petrochemicals, and pharmaceuticals,” explained Dr. Al Wahedi. “A typical heterogeneous catalyst is composed of an active phase, which performs the catalytic function, and a support which enhances the active phase and its stability.”

One such example is the catalytic converter in a gasoline or diesel-fueled car. Transition metal catalysts are embedded on a solid phase support, which comes into contact with gases from the car’s exhaust stream, increasing the rate of reactions to produce fewer toxic products from pollutants in this exhaust stream. The catalytic converter is also an example of surface catalysis, where the reactant molecules are adsorbed onto a solid surface before they react with the catalyst. The rate of a surface-catalyzed reaction increases with the surface area of catalyst in contact with the reactants, and so the solid support is designed to have a very high surface area with a porous structure and honeycomb-like appearance.

“Typically, the support structure accounts for 60 to 99 percent of the weight of the total catalyst, while its role is limited to stabilizing the active component nanoparticles,” said Dr. Al Wahedi. “To enhance the catalytic performance, we need to increase the amount of active component in the structure, while keeping particle size and state optimal.”

Conventional methods to prepare catalysts often start with the support structure and then introduce the active ingredient via insertion methods such as impregnation, chemical vapor deposition or ion exchange. When manufacturers want to increase the amount of the active ingredient using these methods, it often results in poor dispersions, or a lack of control over the size of the ingredient particles.

“To overcome this issue, we can encapsulate the active nanoparticles in a mesoporous matrix comprised of the supporting material to produce a structure we term the NEMMs,” explained Dr. Basina. “This approach allows us to develop catalysts with high active component loadings while keeping the size optimal for efficient catalysis.”

The NEMMs approach involves growing a porous support material around nanoparticles of the active ingredient. They use nanoparticles that are the perfect size to serve as nucleation centers, around which a mesoporous silicon oxide (a material containing pores with diameters between 2 and 50 nanometres) matrix grows. The approach also uses surfactant molecules to create a ‘crown’ around the active component particles, which is removed after the matrix has been grown in order to leave an empty space between the active component and the mesoporous material. It is in this empty space that the catalysis reactants can be adsorbed.

The research team tested their catalyst on the selective oxidation of hydrogen sulphide, an important industrial reaction whereby toxic hydrogen sulphide is oxidized to produce sulphur.

“Our approach circumvents the limitations rooted in conventional catalyst design by allowing complete independent control over the active component nanoparticle shapes and size,” said Dr. Al Wahedi. “ We have investigated this approach on the selective oxidation of H2S reaction (commercially denoted as SuperClausTM). Compared with previous studies, our catalysts achieve near complete conversions and more than 95 percent selectivity at a fraction of the catalyst mass required.”

The ease of this synthesis method and the stability and efficiency of the resulting catalyst promise a wide spectrum of applications beyond the selective oxidation of hydrogen sulphide in myriad industries.

Jade Sterling
Science Writer
29 September 2020

The post Turning Catalyst Production Inside Out appeared first on Khalifa University.

Khalifa University researchers developed a model to overcome the challenges natural gas plants face due to fluctuations in processed natural gas quality and quantities demanded by markets.��

Researchers at Khalifa University have used artificial intelligence to investigate the optimal allocation of natural gas for maximum operating efficiency.

Satyadileep Dara, MSc in Chemical Engineering, and Dr. Yasser Al Wahedi, Assistant Professor of Chemical Engineering, along with Haytham Abdulqader from the Department of Petroleum Engineering and Dr. Abdallah Berrouk, Associate Professor of Mechanical Engineering, detailed their model using an evolutionary algorithm in a published this month in the journal Energy.

Natural gas is one of the most commonly used fuels and the fastest growing component of worldwide primary energy consumption.

“A key challenge faced by many governments lies in the optimal allocation of resources,” explained Dr. Al Wahedi. “The market is experiencing dynamic changes that have to be taken into account.”

“Natural gas has always been a focal point due to its pivotal impact on the world economy,” added Dr. Berrouk. “The economies of many countries across the globe rely on gas because of its versatility across sectors.”

Gas plants are often challenged by fluctuations in processed natural gas quality and quantities demanded by markets. Even more challenging is the rapid variation in the demand for natural gas products across the gas supply chain. To adapt a product portfolio to the changes in the market, a supply chain needs high operational flexibility.

The KU researchers developed a unified optimization model that envelops all supply chain components starting from reservoirs to the various downstream industries. The model aims to maximize the net profit of the gas network through optimum allocation of gas across the supply chain, which is defined as the network of suppliers, producers and consumers.

By taking into account the technical, contractual and economic aspects of a gas supply chain, the optimization exercise resulted in a large-scale model comprising 446 decision variables and 190 constraints. The researchers employed an evolutionary algorithm to solve the model and determine the optimum gas allocation matrix for a country’s gas network in any particular operating scenario.

“We focused on a large-scale gas value chain typical to the Middle East given that gas is a primary catalyst for economic growth and diversification across the region,” explained Dr. Al Wahedi.

“A system is grouped into three blocks: two onshore gas development blocks and one offshore. Each of these blocks comprises a number of gas reservoirs, stabilization trains and processing plants. Their key products include sales gas, ethane, propane, butane, sulphur, naphtha and condensate. These products are then routed to various consumer industries that include cement, power, polymers, steel, fertilizers and aluminium. Gas used for reservoir pressure maintenance is also considered.”

The natural gas supply chain network contains several combinations of gas pathways because there are many destinations for the products developed at each gas complex. Therefore, there are multiple possibilities of allocating the gas from the wells to the stabilization facilities, and then from these facilities to NGL units. The simplest and most convenient way to allocate the gas is to base it on previous experience, informal obligations, or constraints evolved over years of operation.

“Such practices can only offer a sub-optimum allocation of gas since they do not pay any attention to overall supply chain benefits or account for the gas consumers,” said Dr. Berrouk. “At a country level, the scope for optimization extends to identifying the most efficient gas allocation network in terms of energy consumption across the supply chain ranging from reservoirs to consumers.”

“We validated our model using real operating data from 2015, with results showing that our model predictions lie within 3 percent of the real data,” said Dr Al Wahedi. “Not only that, but we used our model to investigate the optimum allocation of gas across the supply chain for sixteen operating scenarios.”

The results found that a minimum 3 percent increase in aggregate supply chain net profit can be obtained using the optimized allocation matrix.

“It’s clear that a comprehensive optimization model can benefit the government for overall gas allocation and value generation.” said Dr. Berrouk.

Jade Sterling
News and Features Writer
5 April 2020

The post Optimizing a Country’s Natural Gas Supply Chain from Wells to Consumers appeared first on Khalifa University.

Also Hosting SPE ADIPEC University Program, to Welcome 19 Teams from Middle East and North Africa Region

Khalifa University of Science and Technology is showcasing research innovations in the strategic oil and gas sector, presenting research papers and leading dedicated knowledge-sharing sessions at the Abu Dhabi International Petroleum Exhibition and Conference (ADIPEC) 2019.

The 35th edition of ADIPEC, one of the world’s largest, most important and influential oil and gas events, is being organized from 11-14 November at the Abu Dhabi National Exhibition Center (ADNEC).

The Khalifa University stand (No: 9412) is displaying projects including an external non-contact smart monitoring system for inspecting oil pipelines, while the faculty and researchers will present five papers about their scientific contributions in the discovery of new technologies in petroleum exploration, production and distribution. In addition, Khalifa University will host the SPE ADIPEC University Program, welcoming a total of 19 teams from universities in the Middle East and North Africa (MENA) region.

Dr. Arif Sultan Al Hammadi, Executive Vice President of Khalifa University, said: “The oil and gas sector remains strategically vital for the UAE and therefore requires closer monitoring and inspection to ensure longevity of the industry assets. With our cutting-edge research, our faculty experts continue to train students and guide them into focusing on developing new technology solutions in both downstream and upstream areas. The projects presented at our stand and the papers to be presented by our research strongly illustrate the extent and depth of our involvement in this industry, as we continue to lead with pioneering innovations that benefit industry and government sector stakeholders.”

The Khalifa University research papers will cover scientific explorations focusing on black powder that helps in ensuring smooth supply and distribution in oil pipelines, design of improved oil recovery from tight carbonate reservoirs in UAE oil fields, and drill-in fluid and wellbore cleanup fluid that facilitate full capacity production in an oil well while minimizing corrosion of downhole tools.

Another research paper will focus on Autonomous Robotic Inspection System (ARIS) – a cost-effective inspection tool for non-contact external detection of defects in highly vulnerable aging oil supply pipelines. A paper on photovoltaic (PV) array shades, which can reduce thermal load on the labor working at extreme weather conditions, especially at oil rigs during long working hours, will also be presented.

Khalifa University researchers are also working on a data-driven workflow, combining deep learning, rock imaging and modeling, which offers great potential in accurately estimating the properties of oil reservoir for reservoir management and enhanced oil recovery strategy.

For the SPE ADIPEC University Program, Khalifa University will host a total of 19 teams from the MENA region. The program aims to benefit the best undergraduate geosciences and engineering students from the MENA region, offering them an insight into the industry and an opportunity to interact with a number of major industry employers through field trips as well as an onsite visits.

Clarence Michael
News Writer
10 November 2019

The post Khalifa University Showcasing Research Innovations in Strategic Oil and Gas Sector at ADIPEC 2019 appeared first on Khalifa University.

Modern oil geologists examine surface rocks and terrain, using sensitive gravity meters to measure tiny changes in the Earth’s gravitational field that could indicate flowing oil, and electronic noses to “sniff” for the smell of hydrocarbons. Most commonly, they use seismology, creating shock waves that pass through the rock layers and interpreting the waves that are reflected back.

Finding oil beneath the Earth’s surface is one thing; extracting it is another. Hydrocarbon exploration is an expensive, high-risk operation. Hydrocarbons formed in source rock migrate to a reservoir rock, commonly a porous limestone or sandstone. The hydrocarbons collect in the pores in the rock (the more porous, the more oil) and extracting them requires the reservoir to be permeable so hydrocarbons can flow to the surface during production.

If a potential area lacks sufficient porosity or permeability, it may not be economically viable to extract the contained hydrocarbons.

Accurate estimations of petrophysical properties are critical for oil reservoir characterization with direct impact on reservoir management and enhanced oil recovery strategies. In work presented at the Abu Dhabi International Petroleum Exhibition and Conference (ADIPEC) 2019, KU’s Dr. Moussa Tembely, Research Associate, applies advanced artificial intelligence (AI) techniques to predict the petrophysical properties of complex carbonate rock. Once trained on thousands of high-resolution images, the AI-based model was able to reduce the computation time into seconds instead of days for classical direct simulations.

Reservoir models are built upon measured and derived petrophysical properties to estimate the amount of hydrocarbons present in the reservoir, the rate at which that hydrocarbon can be produced to the Earth’s surface through wellbores, and the fluid flow in rocks. Geological descriptions are normally obtained from thin-section photomicrograph analysis, but in carbonates like limestone and dolomite, which make up the geological landscape of the Middle East, reservoir heterogeneity complicates efforts to establish rock types.

The mineralogy, organic content, natural fractures, and other properties vary from reservoir to reservoir in this region.

“Characterizing complex rocks, such as carbonate, is still very challenging due to intrinsic heterogeneities occurring at all scales of observation and measurement,” explained Dr. Tembely.

A major application of petrophysics is in studying reservoirs for the hydrocarbon industry. The rock properties of the reservoir are investigated, particularly how pores in the subsurface are interconnected and control the accumulation and migration of hydrocarbons.

“The permeability is one of the most significant petrophysical properties for reservoir rock,” explained Dr. Tembely. “It is essential in targeting a desired commercial oil and gas production rate.”

Permeability is a measure of the ability of a rock to allow fluids to pass through it and relates to pore interconnectivity. If a rock has sufficient porosity and permeability that oil or gas can flow through it, it can potentially serve as a reservoir.

Apart from core analysis, formation testing is so far the only tool that can directly estimate a rock formation’s permeability. Where this is absent—as in most cases­—an estimate for permeability can be derived from empirical relationships with other measurements such as porosity, nuclear magnetic resonance and sonic logging.

“Correctly predicting subsurface flow properties is critical in many applications, ranging from water resource management to the petroleum industry,” explained Dr. Moussa Tembely. “To address this, we apply machine and deep learning to quickly and accurately compute petrophysical properties based on micro-CT images without any computationally intensive procedures.”

Digital Rock Physics (DRP) allows reservoir rock characterization to take place away from the reservoir site. High-resolution images of the rock’s pores and mineral grains are obtained and processed, and the rock properties are evaluated at the pore scale. Micro-plugs are drilled and high resolution micro-CT images are recorded, processed and analyzed to generate 3D digital rock models. Users of DRP look for total porosity and absolute permeability, among other reservoir properties.

Simulations at the pore scale can be classified into two categories: pore-networking modeling (PNM), and direct modeling, which includes the lattice Boltzmann method (LBM).

“The pore network modeling approach is widely used for fast computation of flow properties, albeit with less accuracy due to the inherent simplification of the pore space,” explained Dr. Tembely. “Alternatively, direct simulation using computational fluid dynamics, such as the lattice Boltzmann method, is very accurate. However, its high computational cost prevents this approach from including all the relevant flow physics in a single simulation.”

Innovations in machine learning accelerate the pace of any sector and artificial intelligence has already been applied to petroleum engineering. Previously, most applications were concerned with rock typing, production, and drilling optimization, while few works were devoted to the direct prediction of petrophysical properties using 3D micro-CT images. One model has been used to predict permeability using the PNM approach, which is not reliable enough to provide an accurate estimation.

“After assessing numerical techniques ranging from PNM to the LBM, we established a framework based on machine learning for fast and accurate prediction of permeability directly from 3D micro-CT images of complex Middle East carbonate rock,” said Dr. Tembely. “We used thousands of samples from which engineered features are fed into both shallow and deep learning algorithms to compute the permeability. In addition, we have a hybrid neural network accounting for both the physical properties and 3D raw images. Our model is accurate and much faster than the lattice Boltzmann method.”

Using images of complex carbonate rock from the Middle East, Dr. Tembely and Dr. Ali Alsumaiti from the Abu Dhabi National Oil Company (ADNOC) compared three numerical techniques used to simulate flow properties: PNM, the finite volume method, and a voxel-based method of the LBM. The PNM technique was used to extract porosity and permeability data, while LBM direct simulations were performed to compute the permeabilities of all samples. This data was then fed into supervised shallow and deep learning models to train the machine learning technique to compute permeability.

Despite only being trained on a small subset of 3D images, the machine learning technique was able to estimate the permeability of a larger sample in less than a second—in very good agreement with the result obtained by LBM in a day of simulation. Dr. Tembely’s algorithm accurately estimated complex and heterogeneous rock petrophysical properties within a 3 percent margin of error.

“With our data-driven workflow, simulations that could take days would only need a few seconds when a trained network is used,” said Dr. Tembely. “Combining deep learning and rock imaging and modeling has great potential in reservoir simulation and characterization to swiftly and accurately predict petrophysical properties of porous media.”

Jade Sterling
News and Features Writer
14 November 2019

The post Predicting Permeability in Middle Eastern Carbonate Using Machine Learning appeared first on Khalifa University.

Model Helps Make Better Predictions about Mechanics of Acid Fractured Horizontal Wells and Oil Flow

Fracturing, commonly known as fracking, is frequently used to enhance oil and gas production from underground hydrocarbon reservoirs. Fracking allows access to vast quantities of previously unreachable unconventional hydrocarbon resources and therefore is being adopted by regional oil and gas producers to unlock oil and gas deposits. For instance, the Abu Dhabi National Oil Company (ADNOC) saying fracking will be critical to future production.

To support ADNOC’s ambition to explore new sources of oil and gas, researchers at Khalifa University, Dr. Talal Al Hajeri and Dr. Mohamed Motiur Rahman, have developed a new computer model that could potentially boost oil production from unproductive, or ‘tight’, carbonate reservoirs by making better predictions about the mechanics of acid fractured wells and how oil flows through them.

The model was described recently by Dr. Talal Al Hajeri, Director Engineer of the UAE Navy Task Force and PhD student from KU, during a technical seminar at the 2019 Abu Dhabi International Petroleum Exhibition and Conference (ADIPEC).

“The main objective of this work is to study the behavior of injected hydrochloric acid and oil flow from a horizontal well with multi-stage acid fractures,” explained Dr. Al Hajeri.

Horizontal wells, which are created by horizontal drilling, combined with acid fracturing, allow oil companies to access previously non-viable reservoirs. In conventional vertical wells, a single acid fracture is used, but in horizontal wells, multiple acid fractures are required.

“Our research looks at the acid flow behavior in multiple fractures created hydraulically in horizontal wells, and the flow of the oil after the fracturing. We have created an integrated model that simulates five different stages of fractures, along with other dimensions, such as well geomechanics and operational constraints. The model then generates the post-fractured oil flow and production yields,” Dr. Al Hajeri said.

Because fracturing takes place underground, using advanced computer models to simulate the fracturing mechanics is critical to understanding and improving the process. Dr. Al Hajeri and Dr. Rahman’s work will contribute to advanced well simulation techniques of acid fracturing that are representative of actual field applications.

Acid fracturing is one of two types of fracturing methods used to exploit tight and ultra-tight (or low permeability) oil formations underground. In carbonate rock formations, such as limestone and dolomite, which make up the geological landscape of the Middle East, acid fracturing is common. Whereas in sandstone formations, hydraulic, or proppant, fracturing in used.

Both techniques involve injecting high-pressure liquids into an oil or gas rock formation to create a flow channel through which hard-to-reach hydrocarbons trapped in porous rocks can flow to the surface.

Hydraulic fracturing involves pumping high-pressure liquids (like water) mixed with a proppant (such as sand) into a well to crack the rock open (the proppant is used to keep the cracks open). While acid fracturing involves pumping high-pressure acids (like hydrochloric acid) into a well to etch channels in the rocks (in acid fracturing, the acid keeps the channels open).

Before fracking can begin, reservoir modelling is key to improving productivity, as it allows operators to better understand their resources, the area they’ll be working in, and the best locations to drill. Even more helpfully, whether acid fracking or hydraulic fracking should be used can also be determined digitally.

“Determining the type of stimulation technique for a formation is completely dependent on instinct, logic, and experience,” said Dr. Al Hajeri. “Moreover, choosing between hydraulic or acid-based fracturing may be subject to regulations, environmental, or even geological criteria.”

Modelling can help make this decision. Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems involving fluid flows. Computers are used to perform the calculations required to simulate the free flow of the fluid, and the interaction of the fluid with surfaces defined by boundary conditions. The researchers used the Autodesk Fusion 360 software to initiate the vertical and horizontal fractures before using CFD to model the flow inside the fracture itself. There are several studies using various CFD software to investigate hydraulic fracturing but these involve the application of proppant, not the use of an acid.

“The issue with using CFD software for acids compared to proppant is that the properties of acid are normally not included in the CFD directory compared to the mechanical properties which can be added for solid flow,” explained Dr. Al Hajeri.

The researchers focused on a preliminary simulation to model acid fracturing in a carbonate formation. They combined two of the most common hydraulic fracture models: the 2D fracture geometry model known as the Perkins-Kern-Nordgren (PKN) model and the pseudo 3D fracture geometry model. The outcomes of this combined model will assist in upscaling simulations to 3D models with field values from existing wells, adding validity. Further developments with fracture simulation can be carried out for horizontal fractures to understand how the area around the fracture will be affected.

“One of the challenges of acid fracturing in carbonates is related to layering where it is important for the induced fracture not to propagate into adjacent undesired layers,” said Dr. Al Hajeri. “The CFD simulation gives a visual representation of acid and oil flow inside a fractured formation and how fluid flow properties affect the development of acid turbulence inside the fracture and along the fracture walls. Additionally, the fracture widening for a horizontal fracture is simulated to model the stress intensity on fracture growth and the displacement of the mesh elements.”

“Our simulation can show the behavior of two fracture models and their relative geometries where most realistic formation constraints and requirements are incorporated. If the model is integrated properly with production models for designing an acid fracture, this can predict the production profile in a much better way than any existing model in the industry.”

Jade Sterling
News and Features Writer
18 November 2019

The post New Computer Model Could Help Boost Oil Production from UAE’s Tight Oil Wells appeared first on Khalifa University.

A new approach to drilling oil wells that combines novel drill-in fluids with enzymatic wellbore cleanup fluids could lead to more productive oil and gas reservoirs.

Research led by Dr. Samuel Osisanya, Professor of Petroleum Engineering at Khalifa University, with Ismail AlCheikh, former KU Graduate Research and Teaching Assistant, Dr. Bisweswar Ghosh, Associate Professor of Petroleum Engineering, and Dr. Debayan Ghosh, President and Founder of Epygen Biotech, has led to the development of a new drill-in fluid and non-corrosive cleanup solution to maximize oil well productivity.

Drilling fluid is an essential component of any rotary drilling operation—no drilling can be performed without it. In geotechnical engineering, drilling fluid is used to aid the drilling of boreholes into the earth. Drilling fluid provides hydrostatic pressure to prevent formation fluids from entering the wellbore, keeps the drill bit cool and clean during the process, carries out drill cuttings, and suspends said cuttings while drilling is paused and the assembly is moved.

The drilling fluid for any job is selected to avoid formation damage – the general term to describe the reduction in permeability to the wellbore area – and limit corrosion. To a great extent, the successful completion of a borehole depends on the properties of the drilling fluid.

“Drilling fluids have undergone significant development since they were first used,” said Dr. Osisanya. “As drilling operations progressed, new conditions were encountered and new functions were required. Despite the usefulness of drilling fluids with regards to any rotary drilling operation, there are several aspects that require critical attention and control.”

Dr. Osisanya’s work focuses on minimizing formation damage to the wellbore. There are many ways this area can be damaged, including solid particles from the drilling fluid physically plugging pores in the formation and chemical reactions between the drilling fluid and the formation rock precipitating solids that line the borehole as a sludge.

“Drilling fluids with improper particle size distribution result in the plugging of the formation pores,” explained Dr. Osisanya. “This is due to the act of the invading filtrate into the pores, known as internal damage. Internal damage causes a decrease in the porosity or permeability of the formation and therefore lowers its productivity.”

One approach to minimizing formation damage is to use drill-in fluids specially formulated to avoid damage to the formation.

“For a drilling fluid to be used as a drill-in fluid, several modifications to the composition and properties must be made,” said Dr. Osisanya. “The addition of sized bridging particles such as calcium carbonate and sodium chloride is an example of such a modification.”

One of the critical factors in designing a drill-in fluid is to prevent the solids and filtrate present from the drilling process from invading the pores, effectively sealing the formation surface. What is known as Abram’s Rule can be used to formulate a drill-in fluid as it specifies a bridging agent to be equal to or slightly greater than one third of the medium pore size of the targeted formation. However, this rule only addresses the particle size that initiates a bridge and does not address the best packing sequence for minimizing fluid invasion and optimizing sealing.

Instead, Dr. Osisanya applied Ideal Packing Theory by determining the maximum, median and minimum pore sizes of a given core plug to provide the full particle size distribution required to quickly bridge all sizes of pore openings.

Because each reservoir is unique, each drill-in fluid must be tailor-made. Laboratory tests on core samples characterized the reservoir rock and then a polymer-based drill-in fluid was formulated using calcium carbonate bridging particles.

Results from core flood tests showed that effective filter cakes – impermeable layers of built-up solids used to prevent filtrate loss during the initial drilling – were deposited on the core face, reducing permeability by more than 99 percent.

While blocking the pores in a wellbore is necessary during the drilling process, once the well is complete, the reservoir rock needs to be returned to its original permeability so the sought-after hydrocarbons can flow to the surface during production. If sufficient permeability cannot be restored, it will not be economically viable to extract the hydrocarbons.

“Homogenous and effective cleanup operations must then be performed to remove any residual filter cake (known as external damage) and to restore the well’s original permeability,” said Dr. Osisanya. “The second objective of this work was to develop a non-corrosive wellbore cleanup fluid to remove the external filter cakes and bring the skin close to zero prior to well completion.”

A zero-skin well refers to a well in which the permeability around the wellbore is unaltered after drilling takes place.

To maximize the production rate and economic value of the well, the filter cake needs to be removed as uniformly as possible from the entire borehole. Historically, acid, particularly hydrochloric acid, has been used to remove calcium carbonate in filter cakes. While strong acids can give good results in wells with short production intervals, the very fast reaction rate results in the consumption of the acid before a homogenous cleanup is achieved. Plus, strong acids tend to also react with downhole equipment and tubulars causing severe corrosion. Conversely, weak acids have improved efficiency due to their slow reaction but are unable to dissolve a filter cake’s polymer content and are also corrosive to the downhole tools.

“Normally, wellbore cleanup fluids are highly acidic and need a corrosion inhibitor,” explained Dr. Osisanya. “But this new formulation is effective in minimizing corrosion of downhole tools without the use of corrosion inhibitors.”

Dr. Osisanya’s work combines acid precursors and enzymes into one cleanup solution. Organic acid precursors are esters which generate weak acids downhole at various rates, which minimizes corrosion as they are pumped downhole in a non-acidic phase. These clean the carbonate content of the filter cake. To tackle the polymer content, specific enzymes such as alpha-amylase are used. The combination leads to effective and uniform removal of the filter cake while also limiting corrosion of the tools and equipment.

“The corrosion rates were found to be significantly below the industry limits. Meaning, the use of acid corrosion inhibitor is not necessary,” said Dr. Osisanya. “The industry accepted corrosion limit is 4.6mm per year. The average corrosion rate from our solution was 0.327mm per year.

Corrosion inhibitors are usually inorganic salts of heavy metals and extensive use of these materials is restricted in many areas due to their impact on personnel and the surrounding area. Strong acids also pose significant health and safety risks as well as environmental concerns. A corrosion free breaker chemical is key to mitigating these issues.

Not only is Dr. Osisanya’s cleanup solution minimally corrosive, it is also very efficient. Return permeability for all tests was around 95 percent. As a common acceptable return permeability is around 60 percent, this is a remarkable improvement.

“The combination of our designed drill-in fluid and the cleanup solution saw us achieve a ‘near zero-skin,’ which was the objective of this research.”

Jade Sterling
News and Features Writer
18 November 2019

The post Towards a ‘Zero-Skin’ Well with New Drill-In Fluids and Non-Corrosive Cleanup Solution appeared first on Khalifa University.

Beyond just providing cover, PV panels can be part of a hybrid electrical generating system, with storage batteries and diesel generators. The PV panels reduce the need to operate the generators and reduce carbon dioxide emissions.

Heat stress is a common phenomenon in the UAE. During the harsh summer months, residents across the country suffer from the heat, but for outdoors workers, like those on oil rigs, summer can be a potentially dangerous time of year. To keep workers safe, a team of researchers from Khalifa University have investigated using a system of photovoltaic (PV) panels to provide shade for the workers, significantly reducing the temperatures in which the employees are working.

Dr. Clarence Rodrigues and Dr. Rodney Simmons, both Associate Professors of Industrial and Systems Engineering supported Abdul Hasib Siddique, graduate student from the M. Eng. in Health, Safety and Environmental Engineering (HSE) program, with his efforts conducted for the 1-credit research course requirement for the program.

“Excessive heat in an oil or natural gas drilling environment can have negative effects on workers, production levels and work efficiency,” explained Siddique. “The summer temperature in the UAE can reach as high as 51⁰ C, which is extremely high for continuous outside work, especially considering that a 12-hour work shift is normal on the rigs.”

Heat stress is a common, yet often ignored hazard in the workplace. Research shows that working in hot environments is linked with lower mental alertness and physical performance, and subsequently, more injuries. When elevated body temperature and physical discomfort are added to the mix, it’s understandable that workers may divert their attention from hazardous tasks and overlook common safety procedures.

“In occupational settings, heat stress is the thermal load to which a worker is exposed, and heat strain is the body’s physiological response to that stress,” explained Siddique. “The body has coping mechanisms that allow it to function in very hot environments, but in extreme conditions, these coping mechanisms can be overwhelmed. As the UAE has long hot summers, heat stress becomes an issue for every worker who is outside in the sun.”

“With the establishment of the new ADNOC campaign ‘100% HSE’, a stricter personal protective equipment (PPE) policy has been implemented,” explained Siddique. “Workers wear more protective gear, like helmets, masks, safety shoes, gloves and other job-specific PPE, and wear them more consistently than they once did. As a result, high workplace temperatures make the same task more stressful and exhausting.”

Siddique’s work proposes area cooling on drilling rigs by providing photovoltaic shades as a roof cover. His system covers the entire mud tank area with PV panels to reduce radiant load and provide shade, reducing direct radiation. Each panel is movable to prevent delaying operation during rig moves and has a minimum headroom of 10 feet to accommodate free movement beneath them.

“Out in the open sky, a person feels hotter because the sun’s rays landing on the skin adds energy to the body in the form of heat,” explained Siddique. “As the radiant heat load on the body is reduced or eliminated under the shade, it will always feel cooler in that shaded area. The body usually loses or gains 60 percent of heat exchange from radiant heat gain or loss, so it’s evident it will be much better for workers if a PV array is implemented as shade in the tank area.”

Shade generated from roofs covered by PV panels significantly reduces surface temperatures below the covered areas in both moderate and high temperature conditions and although a cooling effect may be relatively small, it can improve the thermal comfort of the affected humans significantly.

The Thermal Work Limit (TWL) is an indication of how long a person can do work in a certain environment—it predicts the maximum work that can be carried out without a worker’s body temperature exceeding 38.2⁰ C or a safe sweat rate. The TWL is assessed by measuring temperature, wind speed, radiation, and relative humidity, as human performance is directly impacted by these factors.

“Companies have been trying to come up with engineering and administrative controls to reduce the effect of summer heat in this region,” said Siddique. “We proposed photovoltaic array shades to improve conditions for the workers and help reduce thermal stress.

“Due to global warming, average ambient temperatures in the summer are now generally higher than experienced in the past,” said Siddique. “Although the differences are of only a few degrees, these small differences can make a big change in the work environment.”

Beyond just providing cover, PV panels can be part of a hybrid electrical generating system, with storage batteries and diesel generators. The PV panels reduce the need to operate the generators and reduce carbon dioxide emissions.

The UAE receives an average 9.7 hours of sunshine each day, with one of the highest solar exposure rates in the world, giving the country tremendous potential for renewable energy supply.

“According to the World Wildlife Fund (WWF) Living Planet Report 2010, the UAE is one of the leading countries contributing towards the per capita carbon footprint,” said Siddique. “A photovoltaic system will help reduce the country’s greenhouse gas emissions and we calculated a total reduction of about 135 kilotons per year. Installing solar panels will decrease the heat stress experienced by workers while also producing energy and contributing to a decrease in greenhouse gas emissions.”

Jade Sterling
News and Features Writer
19 November 2019

The post The Impact of PV Shades in Reducing Heat Stress in Oil and Gas Industry appeared first on Khalifa University.

Global energy consumption is on the rise, driven by a robust global economy and higher heating and cooling needs in some parts of the world. This increase is led by the demand for natural gas, which accounts for nearly 45 percent of the increase in total energy demand. Transporting gas from the well to the consumer requires a journey of miles of pipelines that need to be maintained in excellent condition.

In a paper presented at the 2019 Abu Dhabi International Petroleum Exhibition and Conference, Vidya Sudevan, Research Assistant at Khalifa University, introduced an autonomous robotic inspection system (ARIS) as a solution to the currently expensive and time-consuming process of gas and oil pipeline inspection and maintenance. Sudevan collaborated with Dr. Hamad Karki, Arjun Sharma, and Vishnu Bhadran also from Khalifa University, and Amit Shukla from the Indian Institute of Technology in Mandi, for this work.

“Middle Eastern countries have the most complex and extensive oil and gas pipeline network in the world and are expected to have a total length of more than 24,000km of pipelines by 2022,” said Sudevan. “Routine inspection and active maintenance of these structures is therefore high priority in oil and gas operations.”

Since oil and gas pipelines are an important asset to the economy of almost any country, the safety of these pipelines, both intrinsically and to the surrounding population and environment, is of paramount concern. Various technologies and strategies are implemented to monitor pipelines, from physically walking the lines to satellite surveillance.

Pigging is the current internal inspection method, and uses devices known as pigs or scrapers to clean and inspect the pipeline without stopping the flow of the product. This is expensive and time-consuming and requires strict adherence to pre-installation procedures, while external inspections are conducted manually by a group of operators who traverse the buried pipeline structures. The data collected along the pipelines is then analyzed manually to identify and locate any possible anomalies, which leads to potential discrepancies in accuracy depending on the experience of the operators. This kind of inspection is a tedious task, compounded by extreme environmental conditions such as the high temperatures and uneven terrain across the region.

“In Abu Dhabi, many oil and gas facilities are still using infrastructure that is at least four decades old to carry expensive and sensitive fluids through metallic pipes,” explained Sudevan. “But unfortunately for such aging and vulnerable pipes, there is no way of externally inspecting them for various defects creeping in. These pipes are subjected to extreme weather conditions and may have not been inspected for a long time, which can lead to unexpected failures causing loss of revenue and environmental pollution.

“The current inspection procedures in use are expensive and somewhat inefficient. Buried oil and gas pipelines that are exposed to severe environmental conditions will be adversely affected by corrosion, erosion, cracks, joint-failures and shock loading, to name a few.”

In the UAE, oil and gas pipelines are mostly buried under a berm, a raised trapezoidal structure made up of sand over the buried pipeline structure. Pipelines are generally laid underground to avoid temperature fluctuations and reduce the expansion and shrinkage that can occur in the metal. They are also shielded from ultraviolet rays, photodegradation, airborne debris, electrical storms, natural disasters, the flora and fauna of their surroundings and accidental damage or intentional sabotage. However, their routine inspection is still vital to their operation.

“Among Middle Eastern countries, the UAE alone has roughly 9000km of pipelines,” explained Sudevan. “Out of these, almost 90 percent is buried under the berm, around 2 to 3 metres underground for safety, economic and environmental reasons.”

To obtain information about the integrity of the pipeline, the exact location of the buried pipeline needs to be known beforehand. A precise buried pipeline locating device is therefore a critical component of any ARIS. In the UAE, pipelines are buried under the berm as either a single pipeline in the middle of the berm or as two pipelines buried on the two edges.

“The challenges in the current manual inspection methods can be tackled by using a robotic platform equipped with various sensors that can detect, navigate, and tag the buried oil and gas pipelines,” explained Sudevan. “An autonomous robotic inspection system would offer the ability to locate, inspect and navigate the buried pipeline structure above the ground without any failure even in the most extreme situations.”

Inspection robots are used in the oil and gas industry already, and help reduce human intervention, increase operational efficiency and improve safety. However, autonomy would automate the process of externally inspecting and geo-tagging the buried pipelines as an autonomous mobile platform would have the ability to identify the target, navigate along the pipeline structure, inspect the structure and geotag it. Automation of this process would result in more comprehensive and efficient inspections, especially in potentially dangerous inspection sites, while also negating the need for breaks.

However, this autonomous robotic inspection system would need to detect and inspect pipeline structures from the surface irrespective of the terrain.

“The objective was to design a novel hierarchical controller that can track the buried pipeline and navigate along the berm without failure even in extreme conditions. The controller should track the pipeline when the pipeline is in the middle of the berm, and also when the pipeline is at the extreme edge of the berm. The ARIS should be able to identify the precise location of the pipeline and navigate exactly along the center of the berm.”

The robotic system used by Sudevan and team involved the Husky A200, a rugged, 4-wheel drive all-terrain unmanned ground vehicle, equipped with various non-contact sensors to perform the autonomous inspection and tagging operation. A target detection sensor determines the location of the pipeline while ultrasonic sensors continuously monitor the distance between the berm and the vehicle.

The team developed a hierarchical controller based on this data for the ARIS to autonomously detect and track the buried pipeline structure in any extreme condition without any fail or skid. The hierarchical controller generates required velocity commands which it feeds to the vehicle controller to navigate over the berm. When the pipeline is buried in the center of the berm, these commands suffice, but when the pipeline is buried on the extreme edge, and the vehicle is at risk of toppling over, a further Sliding Mode Controller (SMC) generates the required angular velocity to navigate the ARIS safely over the berm.

Based on its pipe locator-based tracking controller and its ultrasonic-based anti-topple controller, the hierarchical controller performed well under experimental conditions, showing the ability of ARIS to detect and track buried pipelines and navigate along the berm without failure. The advanced control algorithm is under development for even better tracking accuracy in extreme conditions and a real field test will be conducted to validate the results.

“This research will help the Abu Dhabi National Oil Company (ADNOC) develop its own reliable tool for the continuous inspection of its buried oil and gas pipelines,” said Sudevan. “Since complete development is done at the research facilities within Khalifa University, it will be very cost effective and any new inspection tool can be customized according to the needs of the various ADNOC operations.”

Jade Sterling
News and Features Writer
25 November 2019

The post Keeping Oil and Gas Pipeline Inspection on Track appeared first on Khalifa University.

New simulations of the interactions between oil, water and rock at the quantum level could help solve giant reservoir problem

Over half of the oil in the UAE’s hydrocarbon reservoirs is trapped underground in tiny rock pores. Despite the millions of barrels of oil produced every day in the UAE, extracting this crude oil efficiently and sustainably has proven extremely difficult.

Now, researchers at Khalifa University have discovered a way to analyze how this oil and water interacts with reservoir rock at the quantum level, providing detailed information about how multiphase fluids – fluids with a combination of liquids, like oil and water – move along mineral surfaces, revealing the key role of temperature and a characteristic called wettability.

This new understanding might improve productivity of the UAE’s oil wells and help Abu Dhabi reach its goal of increasing oil recovery rates to 70%.

The new results are published in the Journal of Physical Chemistry C in a by Dr. Tiejun Zhang, Associate Professor of Mechanical and Materials Engineering, with first authors Dr. Jin You Lu and PhD student Qiaoyu Ge, as well as Research Scientist Dr. Aikifa Raza.

“Crude oil is a complicated mixture. While it’s mostly hydrocarbons, crude oil has a range of hydrocarbon fractions, and it interacts with both formation water and reservoir rock, which have a variety of minerals. How this diverse oil-water mixture flows through carbonate rock pores has been difficult to observe and capture in scientific detail, until now,” Dr. Zhang said.

His team developed a density functional theory (DFT) simulation technique as a way to reveal what’s happening in these subterranean fluid flows down to their molecular interactions with rock. DFT is an important research tool that allows chemists to calculate the electronic structure of atoms, molecules and solids on computers, rather than in a lab. The KU researchers used the DFT technique to examine the electronic structure of multiphase liquids on a crystalline surface, or more specifically, on calcite – the main composite of carbonate rocks in hydrocarbon reservoirs.

Traditionally, scientists have used the DFT approach for understanding solid-state physics. Dr. Zhang pointed out that by analyzing solid-fluid quantum interfaces, their work adds critical new knowledge to the field of DFT. “Our work is unique. We’re looking into complicated solid-fluid interactions – their mechanism becomes neat at the quantum level,” he said.

They successfully simulated and quantified the chemical bonding that occurs between molecules of different liquids – like water and oil – and calcite or dolomite surfaces, at varying temperatures. Their results reveal how polarity and temperature impact the calcite’s wettability, or its preference to be in contact with one fluid more than others. Essentially, it is the molecular bonds – covalent and ionic bonds – which are controlled by a substance’s polarity, coupled with the temperature, that determines the wettability of the calcite solid and interfacial behaviors among fluids.

“Quantifying the effects of surface polarity and temperature is valuable in providing fundamental understanding for sophisticated wetting phenomena in multiphase systems, which would be a step forward to understand the complex geological nature of oil reservoirs of this region,” shared Qiaoyu Ge.

With these new insights, scientists can now predict how different multiphase fluids and solids will interact under high temperatures, deep underground, directly from their lab.

Being able to predict the polar and thermal effects on wetting properties of crystalline, or in other words, being able to see what’s happening at the molecular level in the microscopic pores of underground rocks – will help scientists understand the mechanism behind why the oil is trapped and how to develop more effective solutions for oil recovery.

The work has important implications beyond oil reservoirs, however. Multiphase liquid flows in porous rocks or other media occur in a range of real-world applications, from oil and gas recovery and groundwater management to geothermal energy production and carbon sequestration.

“Understanding the surface wettability and interfacial interaction of liquid−liquid−solid multiphase systems is essential for many applications, such as condensation for optimized cooling systems, enhanced oil recovery, carbon dioxide mineralization and geothermal energy utilization,” Dr. Zhang said.

The work was enabled by recent advances in high-performance computing from Alibaba Cloud, which make it possible to compute such an enormous amount of data. The team simulated 400 different atomic combinations, and they are now working to scale it up for an even larger sample size with machine learning-assisted atomic modeling approaches.

This research was supported by the Abu Dhabi National Oil Company (ADNOC) R&D Department, and also by High Performance Cloud Computing Platform of Alibaba Cloud.

Erica Solomon
Senior Editor
23 May 2019

The post Quantum Predictions of Flow may be Key to Freeing Up More Oil appeared first on Khalifa University.