Microscopic Study on Size and Roundness of Some Malaysian Sand for Proppant

The significant of proppants are really important in oil and gas operations worldwide. Proppants will always be needed in any hydraulic fracturing job. However, currently in Malaysia there is no local proppants producer exists although there are a lot of oil and gas field being operated. Besides, the sands in Malaysia also were not fully characterized for proppants. There is an opening to look for a suitable material to be used as a proppants in Malaysia. This is because the most of the material or sand that are currently being used for proppants exist in Malaysia. Hence, this project aims to characterize some of Malaysian sand in term of its size and roundness. At the same time, to provide any suggestion in order to improve the quality of sand for proppant if there is any. Comprehensive literature review have been conducted to identify the concept and scope of study to be consider to achieve the objectives, which are; i) hydraulic fracturing, ii)selection of proppants, iii) physical characteristic of proppants, iv) location of suitable sand sample considering its type and mineralogy of sand. On the other hand, to conduct this project successfully, the author also did searches through journal paper and technical books to identify the methodology. By utilizing the methods that have been mentioned by several literatures, the author will first collect sample from an area identified to have suitable sands which is Terengganu. The sample then will be used in laboratory experiment to determine its characteristic. The laboratory experiments involve sieve analysis, roundness and sphericity test and permeability. The experiments aim to characterize the sand samples that have been collected. Ultimately, suggestion for further study on related matter is made based on the finding especially in the area of standard proppant testing and improvement of proppant properties

Microscopic Study on Size and Roundness of Some Malaysian Sand for Proppant

The significant of proppants are really important in oil and gas operations worldwide. Proppants will always be needed in any hydraulic fracturing job. However, currently in Malaysia there is no local proppants producer exists although there are a lot of oil and gas field being operated. Besides, the sands in Malaysia also were not fully characterized for proppants. There is an opening to look for a suitable material to be used as a proppants in Malaysia. This is because the most of the material or sand that are currently being used for proppants exist in Malaysia. Hence, this project aims to characterize some of Malaysian sand in term of its size and roundness. At the same time, to provide any suggestion in order to improve the quality of sand for proppant if there is any. Comprehensive literature review have been conducted to identify the concept and scope of study to be consider to achieve the objectives, which are; i) hydraulic fracturing, ii)selection of proppants, iii) physical characteristic of proppants, iv) location of suitable sand sample considering its type and mineralogy of sand. On the other hand, to conduct this project successfully, the author also did searches through journal paper and technical books to identify the methodology. By utilizing the methods that have been mentioned by several literatures, the author will first collect sample from an area identified to have suitable sands which is Terengganu. The sample then will be used in laboratory experiment to determine its characteristic. The laboratory experiments involve sieve analysis, roundness and sphericity test and permeability. The experiments aim to characterize the sand samples that have been collected. Ultimately, suggestion for further study on related matter is made based on the finding especially in the area of standard proppant testing and improvement of proppant properties

EXPERIMENTAL STUDY OF EFFECT OF PROPPANT CONCENTRATION, TYPES, SIZES, ROCK MINERALOGY AND OVERBURDEN STRESS ON FRACTURE CONDUCTIVITY

Hydrocarbon production from unconventional reservoirs, particularly shales, requires massive hydraulic fractures to expose the large surface areas within the formation and provide a conduit to the wellbore. Proppants are pumped along with the fracturing fluids during hydraulic fracturing to keep the fractures open. For the economic production of hydrocarbon, maintaining the conductivity of such fractures is critical. However, there are different mechanisms such as proppant crushing, fines migration, proppant embedment and proppant diagenesis etc., which can lead to the significant reduction in fracture conductivity with time. The severity of each mechanisms varies substantially depending on the rock mineralogy, proppant type, proppant concentration, proppant size and overburden stress. Field observations reveals the overall performance of well productivity depends on fracture conductivity which is influenced by the combination of these factors. Lab experiments conducted under simulated reservoir conditions can help to systematically evaluate the effect of different parameters on fracture conductivity. This study focuses on the effect of proppant concentration, proppant type, proppant size, rock mineralogy and overburden stress on the propped fracture conductivity under simulated reservoir conditions. Different damage mechanisms including proppant crushing, embedment and diagenesis and their severity to the conductivity reduction have also been evaluated. Experiments were conducted with shale platens machined from Eagle Ford and Meramec formations. Proppants with different concentration (varying form 1.5 lb/ft2 to 4 lb/ft2), different sizes (20/40, 40/70, 60/100), different types were placed between the two platens and propped fracture conductivity is measured over the period of 7-60 days. Axial stress of 5000 psi was applied to simulate the closure stress which was also varied from 1500 to 7500 psi in different experiments to evaluate the effect of overburden stress on conductivity. The brine composed of 3% NaCl, 0.5% KCl was flowed at a constant rate of 3 ml/min throughout the experiment. In some experiments, 0.05 molar Na2CO3 was added to raise the pH of the brine up to 10. Testing was done to study the effect of proppant concentration using 60/100 mesh Ottawa sand placed between metal platens; result shows significant reduction in permeability at lower concentration of 2 lb/ft2 compared to higher concentration of 4 lb/ft2. Within a unit drop in porosity, permeability declines up to 98% with 2 lb/ft2 concentration while conductivity decline of 80% and 60% observed with increased concentration of 3 lb/ft2 and 4 lb/ft2 respectively. Particle sizes analysis showed 13% fines generation at lower concentration compared to 8% at higher concentration. Effect of particle size evaluated at different closure stress by placing the Ottawa sand (20/40 and 60/100 mesh) between metal platens shows higher crushing and proppant width reduction with higher stress. However, finer mesh (60/100) mesh shows relatively higher compaction and crushing compared to coarser sand (20/40) at each compaction pressure. Effect of particle size on conductivity evaluated using long term flow through conductivity tests with Meramec formation platens shows higher decline in conductivity with finer (60/100 mesh) sand compared to coarser (20/40 mesh sand). Compaction up to 17% observed with 20/40 sand compared to 25% compaction with 60/100 sand over the flow period of 10 days. Experiments with different types of proppant shows higher initial permeability with ceramic proppant compared to Ottawa sand under similar conditions. Over the period of 8 days, experiment with Ottawa sand shows up to 60% fracture width reduction compared to 30% with ceramic proppant. Ceramic proppant also shows uniform distribution of embedded grains and formation extrusion. However, significant diagenetic growth is observed with ceramic proppant. Over the life of a well, due to the production, pore pressure decreases leading to increase in effective stress on fractures. To study the effects of different stress condition on conductivity, experiments were conducted at 1500, 3000 and 7500 psi closure stress keeping all other test conditions the same. Conductivity was observed to decrease significantly at higher stress. Over the flow period of 10 days, fracture width reduces up to 50% at 7500 psi whereas up to 18% and 21% fracture width reduction observed at 1500 and 3000 psi respectively. Surface scans and SEM images shows higher degree of proppant crushing and embedment with increased closure stress. Exit brine composition also shows higher silica concentration at 7500 psi throughout the period of experiment indicating significant proppant crushing and dissolution. Experiments with different rocks machined form Meramec, Vaca Muerta and Eagle Ford suggests higher decline in conductivity with higher clay and lower quartz content formations. Assuming the matrix permeability of (50 nd) and fracture half-length (100 ft), the dimensionless fracture conductivity (FCD) observed to decline at a very high rate and goes below 20 after 18 days in Eagle Ford, 35 days in Vaca Muerta and 75 days in Meramec

Graphene Aerogel Epoxy Sphere used as Ultra-Lightweight Proppants

Hydraulic fracture is a well-developed and widely used technology across petroleum upstream operations. The process involves the high-pressure injection of ‘fracking fluid’, mainly water containing proppants and thickening agents, into wells to form underground artificial fractures. The fracking fluid extends forward and supports those fractures to create diversion channels which lead to increased production. Therefore, it is of great significance to improve the permeability of the fractured formation, which leads to increased oil and gas production, and improved efficiency of oil and gas wells. Due to the importance of conductivity in such operations, the quality of s proppants are a critical factor affecting the fracturing efficiency and stimulation. For improvement of proppant, high strength often comes at the cost of increased density. During fracturing stimulation, it demands a higher flow rate, viscosities, and pumping pressure. It also results in the consumption of a significant amount of power, fresh water and produces more greenhouse gas and chemical pollution in the formation and the well site. This study investigated the production of an Ultra-Lightweight Proppant made by Graphene Aerogel (GA) and Epoxy Resin (ER) composite. GA with graphene as the basic structural unit is a low-density solid material with a high specific surface area, abundant nanoporous structure and good mechanical properties. Cured ER has the characteristics of small deformation and shrinkage, good dimensional stability, and high hardness. ER is one of the commonly used substrates in resin matrix composites. The main research contents of this study are as follows: 1. Using graphene oxide solution as a precursor to prepare graphene hydrogels, then make graphene aerogels through supercritical drying or freeze-drying. The graphene aerogel was placed in ER, followed by immersion in a vacuum environment, and then thermally cured to obtain a graphene aerogel-epoxy composite. The prepared GA has a network microstructure; the ER combined with the aerogel, and the composite material have good mechanical properties, strength is about 50 MPa. Specific gravity is 1.2, 55% lighter than silica sand and 63% lighter than ceramic proppant. 2. Spherical GA were produced using a droplet freezing method, which was combined with ER to create spherical fracturing proppants. The graphene aerogel-epoxy resin composite compressive strength is about 30 MPa, which is significantly higher than silica sand. The sphericity is about 0.9, better than silica sand (0.6-0.8) and same as ceramic proppant (0.9). its crushing rate is better than intermediate-density ceramic at 50, 70, and 100 MPa. The conductivity test showed that this new proppant was 30% and 50% higher than traditional silica sand and ceramic. 3. In the Field study, collecting core sampling and fluid analysis results to evaluate the porosity formation, permeability, fluid density and oil viscosity. Analyzation of the fracturing treatment data for the pressure testing data within the current field. Using the test results of the graphene aerogel spherical epoxy proppant (GAS-EP) modelling conducted for fracturing half-length and fracturing width, the result showing the new proppant can improve the fracturing length by 35% and increase oil Estimated ultimate recovery (EUR) volume about 10K bbl. 4. Based on field data and modelling results, horizontal well decline curve were generated for each scenario, using economic indicators, such as NPV value, payback time and others estimated that the break-even price of GAS-EP will be $2800/t. 5. Discuss the environmental benefits, using GAS-EP could reduce chemical additives by 4600L, reduce freshwater consumption 190m³ and reduce CO₂ emission 1.3 tons for a single fracturing stimulation. The study resulted in the production of a novel proppant with improved properties compared to the conventional materials. The results of this study provide a better understanding of the novel proppant properties and concluded that the novel proppant could safely use in the petroleum industry for enhance hydrocarbon recovery and significant environmental and economic benefits

Development of an ultra-lightweight coconut shell-based proppant for hydraulic fracturing of subterranean formations

Hydraulic fracturing (HF) has seen a considerable increase in interest for the purpose of improved oil recovery. HF creates high conductive conduits between wellbores and reservoirs by a pressurized fluid mixed with proppants. The problem of most popular fracturing fluid (i.e., slickwater) is the high settling rate of common proppants, e.g. sand, which results in small effective propped fractures. Ultra-lightweight (ULW) proppants are easily transported by slickwater and can cover further fracture area. However, ULW proppants cannot provide enough strength at high closure pressure. This study developed a moderately high strength, chemically modified and reinforced composite proppant (CMRCP) which is composed of chemically modified coconut shell, composite material, and epoxy resin. Investigating the performance of new ULW proppant was conducted using laboratory and simulation works such as characterization, quality and mechanical evaluation, simulation mechanical response of particles under compression, fracture conductivity, and HF design. Characterization indicated that the coating layers of CMRCP provide thermal stability of 297.5 °F. Also, quality tests revealed that CMRCP is a neutral buoyant proppant with lower bulk density than frac sand, glass beads, ULW-1.75, and ceramic. Desirable strength (i.e., 8,000 psi) and conductivity (i.e., 791 mDft) from mechanical tests and fracture conductivity were observed, respectively. The results showed an improved performance than Brady sand and its counterpart (i.e., ULW-1.25). The results of strength tolerance and fracture conductivity of CMRCP were 25% and 77% higher than ULW-1.25. Furthermore, experimental and simulation of proppant’s mechanical response with different geometries approved that round geometry provides further strength. Finally, HF design shows that the new product can realise high cumulative production, net present value, and return on investment. This study introduced a new ULW proppant that has moderately high strength, resistant to high temperature, easy to get, light, and cost effective, and it can be used as proppant for HF of subterranean formations

High macroscopic neutron capture cross section ceramics based on bauxite and Gd2O3

The effect of the addition of Gadolinium oxide (Gd2O3) up to 10 wt.% in bauxite was studied and its thermal behavior compared with pure bauxite. The incorporation of Gd2O3 is of technological interest for the design of smart traceable ceramic proppants used for unconventional gas and oil well stimulation. These high macroscopic neutron capture cross section proppants are used to obtain relevant information, such as the location and height of the created hydraulic fractures, through a neutron based detection technology. The study comprised a set of thermal and sintering behavior analyses up to 1500 °C of mixtures up to 10 wt.% addition of Gd2O3. The developed texture and microstructure was also assessed. A simple mechanical characterization was performed as well. Fully-dense pore-free microstructures were developed, with alumina and mullite as the main crystalline phases. Gadolinium secondary and ternary alumino-silicate phases were also observed after thermal treatment. These present a needle morphology that might result in reinforcement mechanisms. No important glassy phase was detected; although sintering was enhanced, the Gd2O3 oxide main role was found to be as a sintering aid rather than a strict flux agent. The mechanical behavior remained fragile with the rare oxide addition. In fact, the mechanical resistance increased up to 20 wt.% for the 10 wt.% added sample. The oxide addition together with the bauxite dehydroxilation mass loss resulted in materials with up to 1.5 x 105 (c.u.) macroscopic neutron capture cross section materials. The obtained results permit to define design strategies of high macroscopic neutron capture ceramic materials for wellbore and developed fractures description.Fil: Hernández, Maria Florencia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Herrera, Maria Silvia. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Anaya, Ricardo Javier. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martinez, Juan Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Cipollone, Mariano Enrique. YPF - Tecnología; ArgentinaFil: Conconi, María Susana. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Rendtorff Birrer, Nicolás Maximiliano. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentin

COMPARISON BETWEEN EULERIAN-EULERIAN NUMERICAL SIMULATION AND EXPERIMENTS ON SINGLE NARROW CHANNEL MIXTURE FLOW

Currently, many engineering challenges addressing the flow of mixtures exist. Slickwater hydraulic fracturing is an economical method of unconventional resource extraction that can accelerate mixture flow. For this thesis, the flow of a sand-water mixture and its dune shape were observed. The aim of this study is to investigate similarities between simulated and experimental results by comparing peak height and volume ratios. The flow described above is also called a "proppant flow" or "frac sand flow", one of the ways of enhancing shale gas production. After horizontal drilling, solid material is used to keep an induced hydraulic fracture open. The permeability of a proppant with cracks developed during production can endure high closure stress by the mantle. An example of this was expressed by the following experiment and simulation of the study. An experimental study was conducted by a single narrow channel with the flow of a mixture. Particle size and volume injection rate are the main parameters that we controlled. Sand concentration as well as density were restricted for the experiment. Also, the total particle number and inlet speed of the mixture for the simulation were calculated with certain parameters. Among numerous models, the standard K-ε turbulence model was employed as a tool for analyzing solid and fluid materials for this task. We tried to verify the accuracy of these Eulerian-Eulerian methods by comparing the sand particle’s diffusion and deposition results between a simulation and experiment. Comparison of both results was conducted by a post image processing tool on each step, time by time. The study contains specific cases of hydraulic fracturing, and with this, validation of the turbulence model simulation accuracy is one of the aims. The comparison of each result is not only important regarding cost and time saving aspects, but also in showing that a simulation of each case is more efficient than time by time experiments

High Macroscopic Neutron Capture Cross Section Ceramics Based on Bauxite and Gd₂O₃

The effect of the addition of Gadolinium oxide (Gd₂O₃) up to 10 wt.% in bauxite was studied and its thermal behavior compared with pure bauxite. The incorporation of Gd₂O₃ is of technological interest for the design of smart traceable ceramic proppants used for unconventional gas and oil well stimulation. These high macroscopic neutron capture cross section proppants are used to obtain relevant information, such as the location and height of the created hydraulic fractures, through a neutron based detection technology. The study comprised a set of thermal and sintering behavior analyses up to 1500 °C of mixtures up to 10 wt.% addition of Gd₂O₃. The developed texture and microstructure was also assessed. A simple mechanical characterization was performed as well. Fully-dense pore-free microstructures were developed, with alumina and mullite as the main crystalline phases. Gadolinium secondary and ternary alumino-silicate phases were also observed after thermal treatment. These present a needle morphology that might result in reinforcement mechanisms. No important glassy phase was detected; although sintering was enhanced, the Gd₂O₃ oxide main role was found to be as a sintering aid rather than a strict flux agent. The mechanical behavior remained fragile with the rare oxide addition. In fact, the mechanical resistance increased up to 20 wt.% for the 10 wt.% added sample. The oxide addition together with the bauxite dehydroxilation mass loss resulted in materials with up to 1.5 x 105 (c.u.) macroscopic neutron capture cross section materials. The obtained results permit to define design strategies of high macroscopic neutron capture ceramic materials for wellbore and developed fractures description.Centro de Tecnología de Recursos Minerales y Cerámic

Image-Based Modeling of Porous Media Using FEM and Lagrangian Particle Tracking

The study of fundamental flow and transport processes at the pore scale is essential to understanding how the mechanisms affect larger, field-scale, processes that occur in oil and gas recovery, groundwater flow, contaminant transport, and CO2 sequestration. Pore-scale imaging and modeling is one of the techniques used to investigate these fundamental mechanisms. Although extensive development of pore-scale imaging and modeling has occurred recently, some areas still need further advances. In this work, we address two areas: (1) imaging of bulk proppants and proppant-filled fractures under varying loading stress and flow simulation in these systems and (2) nanoparticle (NP) transport modeling in porous media. These are briefly explained below. Rock fracturing, followed by proppant injection, has been used for years to improve oil and gas production rates in low permeability reservoirs and is now routinely used in low-permeability resources such as a shales and tight sands. While field data makes clear the effectiveness of this technique, there is still much room to improve on the science, including how the proppant-filled fracture system responds to changes in loading stress which affect permeability and conductivity. Here, we use high-resolution x-ray computed tomography (XCT) to image two unsaturated rock/fracture/proppant systems under a series of stress levels typical of producing reservoirs: one with shale, one with Berea sandstone. The resulting XCT images were segmented, analyzed for structural and porosity changes, and then used for image-based flow modeling of Stokes flow using both finite element (FEM) and Lattice Boltzmann methods. NPs have been widely used commercially and have the potential to be extensively used in petroleum engineering as stabilizers in enhanced oil recovery operations or as tracers or sensors to detect rock and fluid properties. %In spite of a wide range of applications, many NP transport details are still unknown. In this work, we describe a Lagrangian particle tracking algorithm to model NP transport that can be used to better understand the impact of pore-scale hydrodynamics and surface forces on NP transport. Two XCT images, a Berea sandstone and a 2.5D micromodel, were meshed and used for image-based flow modeling of FEM Stokes flow. The effects of particle size, surface forces, flow rate, particle density, surface capacity, and surface forces mapped to XCT-image based mineralogy were studied

Improvement of fracture conductivity through study of proppant transport and chemical stimulation

During hydraulic fracturing treatments, proppants – usually sand – are placed inside fractures to improve fracture conductivity. However, a large portion of the generated hydraulic fractures often remain unpropped after fracturing treatments. There are two primary reasons for this poor proppant placement. First, proppants settle quickly in common fracturing fluids (e.g., slickwater), which results in unpropped sections at the tip or top of the fracture. Second, a large number of the microfractures are too narrow to accommodate any common commercial proppant. Such unpropped fractures hold a large potential flow capacity as they exhibit a large contact area with the reservoir. However, their potential flow capacity is diminished during production due to closing of unpropped fractures because of closure stress. In this study, fractures are categorized as wider fractures, which are accessible to proppant, and narrower fractures, which are inaccessible to proppant. For wider fractures, proppant transport is important as proppant is needed for keeping them open. For narrower fractures, a chemical formulation is proposed as there is less physical restriction for fluids to flow inside across them. The chemical formulation is expected to improve fracture conductivity by generating roughness on fracture surfaces. This dissertation uses experiments and simulations to investigate proppant transport in a complex fracture network with laboratory-scale transparent fracture slots. Proppant size, injection flow rate and bypass fracture angle are varied and their effects are systematically evaluated. Based on experimental results, a straight-line relationship can be used to quantify the fraction of proppant that flows into bypass fractures with the total amount of proppant injected. A Computational Fluid Dynamics (CFD) model is developed to simulate the experiments; both qualitative and quantitative matches are achieved with this model. It is concluded that the fraction of proppant which flows into bypass fractures could be small unless a significant amount of proppant is injected, which indicates the inefficiency of slickwater in transporting proppant. An alternative fracturing fluid – foam – has been proposed to improve proppant placement because of its proppant carrying capacity. Foam is not a single-phase fluid, and it suffers liquid drainage with time due to gravity. Additionally, the existence of foam bubbles and lamellae could alter the movement of proppants. Experiments and simulations are performed to evaluate proppant placement in field-scale foam fracturing application. A liquid drainage model and a proppant settling correlation are developed and incorporated into an in-housing fracturing simulator. Results indicate that liquid drainage could negatively affect proppant placement, while dry foams could lead to negligible proppant settling and consequently uniform proppant placement. For narrower fractures, two chemical stimulation techniques are proposed to improve fracture conductivity by increasing fracture surface roughness. The first is a nanoparticle-microencapsulated acid (MEA) system for shale acidizing applications, and the second is a new technology which can generate mineral crystals on the shale surface to act as in-situ proppants. The MEA could be released as the fracture closes and the released acid could etch the surface of the rock locally, in a non-uniform way, to improve fracture conductivity (up to 40 times). Furthermore, the in-situ proppant generation technology can lead to crystal growth in both fracking water and formation brine conditions, and it also improves fracture conductivity (up to 10 times) based on core flooding experimentsPetroleum and Geosystems Engineerin