bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Molecular Composition on the Electro-Deposition of Asphaltene
Authors: Xia Shunxiang , Kostarelos Konstantinos 
Published: March 2019

Abstract
Asphaltene deposition and plugging of pipelines during oil production and transportation is considered a challenging flow assurance issue. Instead of adding dispersants, the concept proposes to remove asphaltenes from the flow stream by means of electro–deposition prior to transportation to prevent later deposition. This study mainly examined the effect of molecular composition on the efficiency of electro-deposition. Two sources of asphaltene, namely asphaltenes from coal tar ("AS-C") and asphaltenes from bitumen ("AS-B") with different molecular composition were collected in this study. Elemental analysis revealed that both AS-B and AS-C possessed transition metals (V and Ni) and heteroatoms (O, N and S). The effect of oil components on the stability of two asphaltenes was studied. After conducting the electro–deposition of both asphaltenes with various oil components and electric field strength, the deposition charge and recover rate was recorded and compared. During stability test, the amount of precipitated AS-B decreased with increasing aromaticity of solvent, while that of AS-C was constant. For electro–deposition, the electro–kinetic behavior of AS-C reveals strong sensitivity to the oil components. Interestingly, both asphaltenes exhibited a change in the net charge, which occurred under 6000 V/cm and 12000 V/cm for AS-B and AS-C respectively, as evidenced by a change in the electrode upon which deposition ocurred. Based on the results, the efficiency of electro–deposition is confirmed to depend upon the metal and heteroatoms of asphaltenes; in addition, and by interaction with these elements, the oil composition and electric field affected the stability, net charge, and electro–kinetic behavior of apshaltene. However, our study is the first to show that the current density plays a role in the net charge of the asphaltene molecule and offers an explanation to the controversy over the polarity or the charge sign of asphaltenes, which gives a clue to understanding the microstructure of asphaltenes. In addition, this is the first study to include the effect of oil components and electric field strength on the performance of deposition, which makes further optimization of the proposed process possible.
A New Up-Scaled Wormhole Model Grounded on Experimental Results and in 2-Scale Continuum Simulations
Authors: Palharini Schwalbert Mateus , Hill A. Daniel , Zhu Ding 
Published: March 2019

Abstract
The optimum design of matrix acidizing treatments in carbonate reservoirs requires accurate modeling of wormhole propagation. While there are several wormhole correlation models available, most are developed based on small core scale experiments, and result in significant deviation when upscaled to field treatment design. There also exists simulation models (e.g. Two-Scale Continuum or Pore Network models). These models are not practical for field design because of the extensive computation effort involved. Large variations in the wormholing behavior are observed in laboratory experiments using different core sizes and geometries (radial flow versus linear flow). This variation is not captured in the previous models. This work proposes a new multiscale wormhole model that represents the physics of wormholing behavior in matrix acidizing of carbonates both at core and field scales.
The derivation of the new semi-empirical model is formulated to represent the experimental data for different core dimensions and flow geometries, as well as field results. In core flooding experiments with different core sizes, the obtained pore volumes to breakthrough and optimal injection velocity are different for each core size. The same behavior is observed in numerical simulations using the Two-Scale Continuum model. That behavior is correctly calculated with the proposed model, which accounts for the dimensions in a function with dependence of the correlation parameters on the wormholed region scale and geometry. Upscaling procedures to linear, radial, elliptical, spherical, and ellipsoidal geometries are presented.
The model's results are validated by the Two-Scale Continuum numerical simulations for both linear and radial flow and verified with experimental results with different core sizes and geometries (both linear and radial flow). We further developed the model for field application, and procedure of using the model is illustrated in the paper. The different flow geometries allow predicting the acidizing behavior in common completions, such as openhole, cased and perforated, and limited entry. The model prediction compares very well to the outcome of field cases.
The new model reproduces the fractal behavior of the dominant wormhole growth above optimal injection rate, and predicts the injection pressure dependence on time as measured experimentally. The model correctly captured the physics of wormhole propagation phenomenon.
Multifunctional Chemical for Simultaneous Dissolution of Iron Sulfide, Corrosion Inhibition, and Scale Inhibition
Authors: Rodgers Patrick , Lundy Brian , Ramachandran Sunder , Ott James , Poelker David , Lee Dong , Stevens Corey , Bounds Christopher , Sullivan Matthew 
Published: March 2019

Abstract
Operators producing hydrocarbons from conventional and unconventional wells often encounter interconnected production-related challenges that exacerbate one another. Challenges during production include the corrosion of steel caused by acid gases, as well as the precipitation and accumulation of iron sulfide, calcium carbonate scale, and barium sulfate scale. The accumulation of solids on pipe walls can facilitate under-deposit corrosion and plugging. Each of these issues can lead to failures and costly workovers. To address these issues, current treatment approaches require multiple chemical applications, frequent batch treatments, mechanical intervention, or a combination of approaches. In certain scenarios, these approaches can be impractical, ineffective, and/or uneconomical. The objective of this study was to develop a solution to overcome the aforementioned production challenges simultaneously and continuously with a single chemical application. The design strategy was to formulate chemicals that included a variety of chemistries to inhibit multiple corrosion mechanisms, as well as an iron sulfide dissolver, and a scale inhibitor to inhibit the formation of calcium carbonate and barium sulfate scales. Laboratory tests were conducted to demonstrate that the formulations could function in the aforementioned areas. One formulation was then applied in the field under different production scenarios: oil wells equipped with either a gas lift mechanism or an electrical submersible pump. Data from those situations are presented to demonstrate the field performance of the new formulation. Compared to the benchmark chemical treatment efforts, application of the formulation improved or maintained similar corrosion control, reduced or eliminated the accumulation of iron sulfide solids in the well, and improved scale control in each of the production scenarios. This paper presents a viable option for effectively treating common production challenges simultaneously and with one chemical application, which is particularly useful when it is impractical or uneconomical to employ multiple chemical treatments.
A New Class of Permanent Clay Stabilizers
Authors: Assem Ahmed I. , Nasr-El-Din Hisham A. , Harper Thomas L. 
Published: March 2019

Abstract
A new class of permanent clay stabilizers has been developed inorganic based on an aluminum/zirconium-based compound. The increased charge density of the molecule allows it to bind more strongly to swelling clays, while its relatively low molecular weight allows it to stabilize the clay permanently without causing formation damage by blocking the pore throats and reducing permeability.
The most commonly used clay stabilizers are organic and inorganic chloride salts including trimethylammonium chloride, potassium chloride, and choline chloride. These salts have been used for years, are effective in most wells, and are both cheap and abundant. However, their high water solubility and the relatively small size of the cation means that these products are highly mobile and thus are quickly washed away during flowback. Several chemical derivatives were made from a tri-functional amine by reacting it with organic and inorganic acids such HCl, acetic acid, and formic acid; as well as alkylating agents, including chloromethane, benzyl chloride, diethyl sulfate, and paraformaldehyde.
Certain cationic polymers have also proven useful as clay stabilizers. These much larger molecules are not as easily washed away due to steric hindrance and a much higher charge density per molecule. These products have proved useful as long-term clay stabilizers, but their high molecular weights can lead to formation damage by causing them to be filtered out on the rock face.
In this research, several laboratory tests were carried out on the new clay stabilizer. These tests included coreflood experiments conducted on Berea sandstone cores to assess the stabilizer at high temperatures and the influence of different acids on its performance. Coreflood effluent samples were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES) to measure the concentrations of aluminum and zirconium.
This new permanent clay stabilizer improved productivity from formations that have high clay content by minimizing clay swelling and thus preventing formation damage caused by clogged pore throats and subsequent loss of permeability. It worked well at temperatures up to 250°F and with 15 wt% HCl and regular mud acid (12 wt% HCl, 3 wt% HF).
Rducing Backpressure and Enhancing Throughput of Saltwater Disposal Wells with Chlorine Dioxide and Complex Nano Fluids: Optimization and Case Studies
Authors: Pagel Ryan , Tindall Trey , Pursley Tom , Sweeney Tim , Li Zack , Lathrop Tim , Sullivan Bob , Simpson Greg 
Published: March 2019

Abstract
Oilfield produced waters are usually returned to the ground by either reinjecting into underground reservoirs for enhanced oil recovery or injecting in saltwater disposal wells (SWDW) for final disposal. SWDWs often receive waters from production wells with comingled brines. These brines contain residual oils, suspended solids, and additives (such as friction reducers, partially broken gels, biocides, scale and corrosion inhibitors). SWDWs experience declined well injectivity, due to damages from downhole buildup of particles, oils, and biofilms clogging well casing and tubing and plugging a well's perforations and the near wellbore matrix. To fix these problems, chemical treatments are often performed to restore the injectivity of the formations and reduce the injection pressure. Acids and solvents are frequently used to clear blockages of the wells and restore the permeability of the rock formation. Existing chemical treatments of SWDWs still face some challenges, including asphaltene and iron oxide and iron sulfide precipitation, and H2S formation from acid reaction with iron sulfides.
Herein, we report the development and optimization of an innovative field SWDW chemical treatment program. We have successfully developed and optimized the new treatment method including three treating chemicals: hydrochloric acid (HCl), chlorine dioxide (ClO2), and a proprietary Complex nano Fluid (CnF®). Typically, CnF®, HCl, and ClO2 solutions are pumped sequentially downhole into the well formation, with the specific flush volumes of each chemical varying from well to well based on the wellbore configuration. The field application data collected from SWDWs in Haynesville Play and Permian Basin clearly demonstrate remarkable improvement in injectivity and pressure reduction parameters. In all cases, the new treatment combination provides great economic value, with investment payout time within a few weeks. The novel chemical treatment program is expected to have broad application in the treatment of SWDWs across a variety of geological formations in almost all basins.
Effect of Network Parameters of Preformed Particle Gel on Structural Strength for Water Management
Authors: Baghban Salehi Mahsa , Mousavi Moghadam Asefe , Jarrahian Khosro 
Published: March 2019

Abstract
Preformed Particle Gel (PPG) is an appropriate solution for conformance control and managing water production in low permeable reservoirs. Rheological behavior evaluation of these deformable particles is a key factor in designing composition to achieve the best conformance control treatment due to the viscoelastic behavior of these particles along with their swelling. The purpose of this paper is to evaluate the network parameters of PPGs through swelling tests, rheology and determining its role in maintaining their structural strength. Several PPG hydrogels were prepared by varying the concentrations of polyacrylamide and Cr(OAc)3 as copolymer and crosslinker, respectively. The characterization of these hydrogels was performed using Scanning Electron Micrographs (SEM), Electron Dispersion X-ray analysis (EDX), Environmental Scanning Electron Microscopy (ESEM), ThermoGravimetric Analysis (TGA), and Differential ThermoGravimetry (DTG). The correlation between reaction conditions and network parameters of polymer networks such as, molecular weight of the polymer chain between two neighboring crosslinks, crosslink density, and size fraction have been determined. The swelling of the hydrogels was found through the Fickian diffusion mechanism. In this case, the diffusion rate of water in the 3D structure of the hydrogel is less than the relaxation of the polymeric chain, resulting in a significant increase in the PPG particles volume. As PPG was invaded such as in the reservoir by formation water or oil, repeatedly, the sensitivity factor was measured to ensure the swelling in the electrolyte solution. Based on rheological tests, the dynamic modulus of the swelled PPG was strongly dependent on the concentration and consequently network parameters. Also, through the optimization of the network parameters, the appropriate composition from the point of view of strength (complex modulus of 4×104 Pa) and salt sensitivity of 0.5 was presented. In addition, the results of the TGA/DTG test demonstrated the thermal stability of the sample was in temperature range 245 to 340°C. The determination and analysis of the network parameter is the novel technique for predicting the hydrogel performance in porous media and investigating its strength under harsh reservoir conditions. In other words, determination of the network parameter can be a shortcut to ensure the success of the gel performance in porous media.
Relation Between Chemical Composition of a Green Nanofluid and Its Foam Film Stabilization For Robust Foam Injection EOR
Authors: Wei Bing , Wang Yuanyuan , Chen Shengen , Mao Runxue , Ning Jian , Wang Wanlu 
Published: March 2019

Abstract
Foams were introduced to enhanced oil recovery (EOR) for the purpose of improving sweep efficiency via mitigating gas breakthrough. In prior works, well-defined nanocellulose-based nanofluids, which can well stabilize foam film as a green alternative to reduce the environmental impact, were successfully prepared in our group. However, due to the costly manufacturing process, its field scale application is restricted. In order to further simply the manufacturing process and minimize the cost, in this study, we proposed another family of functional nanocellulose, in which lignin fraction was remained as well as carboxyl groups. The primary objective of the present work is to investigate the synergism between the lignin-nanocellulose (L-NC) and surfactant in foam film stabilization. Particular attention was placed on the relation between the chemical composition of L-NC and its stabilizing effect. Direct measurements of foamability, drainage half-time, foam morphology, foam decay, etc., were performed. The results showed that after the contents of lignin and carboxyl group were well tailored, the resultant L-NC can significantly improve the stability of foam either in the absence or presence of crude oil. The flooding dynamics observed in core plugs indicated that the L-NC stabilized foams could properly migrate in porous media and generated larger flow resistance accross the cores than surfactant-only foam.
Development of Structure-Property Relationships for Steam Foam Additives for Heavy Oil Recovery
Authors: Nguyen Thu , Raj Ajay , Rommerskirchen Renke , Fernandez Jorge 
Published: March 2019

Abstract
Low steam viscosity during steam injection can cause steam override and channeling issues for heavy oil recovery, resulting in high operating cost and low oil recovery. One of the common methods to increase the viscosity of steam is by co-injecting surfactants that generate stable foams with steam. The objective of this research is to develop structure-property relationships for surfactants in order to identify surfactant candidates as the steam foam additives for heavy oil recovery.
In this study, alkyl propoxy ethoxy ether carboxylate (alkyl PO EO ECA) surfactants were evaluated. Surfactant solutions at 1 wt% prepared in 1 wt% NaCl were aged at up to 250 °C in Parr reactors for up to 2 weeks. The degradation of the surfactants was quantified based on High Performance Liquid Chromatography profiles of the surfactants before and after the aging process. The foaming performance of the surfactants was evaluated at 1 wt% concentration at varied temperatures from 100 to 250 °C in a high temperature high pressure visual cell. Sand-packed columns were performed to evaluate the ability of the surfactant to increase the apparent viscosity of steam.
The results showed that alkyl PO EO ECA surfactants exhibit excellent chemical stability at up to 250 °C. However, the chemical stability of these surfactants are dependent on the hydrophobe structure as well as the numbers of PO and EO units of the surfactants. Among the studied surfactants, only ECA surfactants with specific structures were able to generate stable foam at 250 °C. It was found that the ECA surfactants with both PO and EO units and a long branched hydrophobe demonstrated to be excellent foaming agents that were able to increase the apparent viscosity of steam by three orders of magnitude at 250 °C in sand-pack columns. In the presence of bitumen, these surfactants were able to increase the steam apparent viscosity by two orders of magnitude. This increase in the steam apparent viscosity is sufficient to overcome the steam override and channeling during steam injection.
Past research has randomly identified some sulfonate and ether carboxylate surfactants as foaming agents for steam EOR processes. This work, however, evaluated these surfactants systematically in order to develop the structure-property relationships that can be used to optimize surfactants as steam foaming agents for thermal EOR processes at up to 250 °C.
Modeling/Forecasting Reservoir Souring in a Field Rajasthan, India with an Extremely Low Indigenous Volatile Fatty Acid VFA Concentration
Authors: Burger Edward , Venkat Panneer Selvam , Mittal Saumya 
Published: March 2019

Abstract
The Rajasthan Field has been undergoing waterflood with produced water reinjection (PWRI) using makeup water with a moderate sulfate (≈500 mg/L) and negligible organic content since 2010. Initial analyses of the formation water indicated that the volatile fatty acid (VFA) content was quite low (≈ 20 mg/L), suggesting a priori that the levels of H2S biogeneration and production would not be problematic. However, after less than four years the H2S production rate from the field was over 1000 kg/day and the H2S concentration in the composite separator gas was about 200 ppmv. Consequently, studies were carried out using the H2S forecasting model previously discussed in four SPE papers to determine the cause for the high level of souring and to estimate future levels and trends of H2S production in the field.
The mechanistic reservoir souring model considers H2S biogeneration due to water-soluble VFAs and/or primarily oil-soluble organics such as BTEX components, the effects of H2S-siderite geochemical reactions within the reservoir to scavenge H2S, flow of H2S (and other components) through the reservoir to the surface, and partitioning of H2S into the oil, water and gas phases within the reservoir and in the surface separators. Also included in the Rajasthan model were the use of power water to lift the well production since it affects partitioning at the surface; and, the effect of chemical H2S scavengers added in selected well flowlines to maintain H2S partial pressures at safe levels.
The model determined that the observed H2S production was not possible even with complete consumption of the indigenous VFAs by sulfate-reducing bacteria and that only with the majority of their organic nutrients being provided by the BTEX-type components were the historical H2S production levels able to be matched. The model results have indicated that H2S production rates have already peaked in the field, primarily due to the reduction in makeup water which provides most of the sulfate being injected into the reservoir. Sulfate is the limiting microbial reactant since the oil-soluble organic supply is essentially infinite.
This study has shown even in non-seawater waterfloods and with minimal organic acids in the formation water that reservoir souring can occur, resulting in the need to handle significant levels of H2S on the surface. The significance of oil-soluble organics as a potential SRB nutrient must be considered when planning a waterflood if sulfate is injected.