bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection and Application of Scale Inhibitor for Application in Oxygenated Produced Water, Norwegian Sector, North Sea
Authors: Marlow D. , Madden A. , Sutherland L. , Jordan M. M. , Sorhaug E. 
Published: April 2009

Abstract
Scale control within produced fluids both topside and downhole in oil/gas production facilities is critical to the effective production of hydrocarbons in a safe, economic and environmentally acceptable manner.
This paper will focus on the scale challenges associated with production of produced water that contains significant amounts of barium, sulphate and dissolved iron ions. While this challenge is not unusual in production operations the presence of dissolved oxygen in the topside process just prior to discharge has resulted in a very challenging environment for barium sulphate scale inhibition.
This paper will outline the challenge of scale control in the presence of ferrous and ferric ion. The inhibitor selection program undertaken will be outlined as well as the critical factors that had to be taken into account given this application was for offshore Norway where environmental characteristics of production chemicals can restrict the choices of chemical suitable for this application.
The development of an application strategy for the selected environmentally acceptable chemical will be outlined along with the monitoring program to ensure not only that the chemical is applied at the correct treatment rate but that it performs as expected from the laboratory performance testing results and can be optimised as brine composition changes with time.
Core Flood Investigation Into Asphaltene Deposition Tendencies in the Marrat Reservoir, South East Kuwait
Authors: Rahmani N. H. G. , Gao J. , Ibrahim M. N. , Bou-mikael S. , Al-Matar B. S. , Al-Ruhaimani F. 
Published: April 2009

Abstract
Asphaltene precipitation can have profound effects on oil production during miscible flooding, heavy oil recovery, or even primary depletion. Even though asphaltene precipitation and eventual deposition have been known to have strong effects on permeability reduction (Turta et al., 1997; Minssieux et al., 1998), quantitative analysis of the process has not been studied extensively. This paper describes experimental work conducted to study the precipitation and deposition tendencies of asphaltenes within the rock material in the Marrat reservoir, South East Kuwait. Live asphaltenic reservoir fluids and carbonate cores of the Marrat reservoir were recovered and used at reservoir pressure and temperature conditions during core flood experiments. The live Marrat reservoir fluid was fully characterized, and subjected to pressure depletion tests to determine the asphaltene onset point at various temperatures.
The results reveal preferential deposition of the precipitated asphaltenes with respect to the rock material. The characterization of the rock materials by CT-Scans had indicated the presence of local occluded porosities. These occluded sites were found to be the main influence on the pattern of deposition seen in the core samples. The study shows clearly that although asphaltenes may precipitate and deposit from the Marrat reservoir fluid, the propensity for permeability damage is in fact determined by the nature of the rock material. In addition, the tendency of the precipitated asphaltenes to aggregate into larger flocs that are generally friable influences the rock damage potential.
Handling and treatment of asphaltenic fluids will continue to impact on reservoir operations, project costs and recovery efficiencies. Understanding the nature of asphaltenes and how they impact on the sub-surface behaviour of reservoir fluids will become more pertinent, as global oil demand forces a move towards heavy oils and / or highly asphlatenic fluids.
Forecasting the Effects of Reservoir Souring From Waterflooding a Formation Containing Siderite
Authors: Burger E. D. , Jenneman G. E. 
Published: April 2009

Abstract
A computer model has been developed to investigate the potential effects of water injection in an offshore oilfield on H2S biogeneration and its subsequent production from the reservoir. The model is based on mechanistic algorithms employed in previous reservoir souring models developed for the Prudhoe Bay and Kuparuk River Fields (Alaska) and the Ekofisk Field (Norway). These mechanisms include the biogeneration of H2S, the partitioning of H2S between oil and water in the waterflooded portions of the reservoir, the reaction of dissolved H2S with siderite to form immobile iron sulfides, and the transport of H2S, oil, water, and gas to producing wells.
The reservoir is currently being seawater flooded although produced water reinjection (PWRI) will soon be initiated. In mid-2006, after less than three years of waterflood at relatively low injection rates, H2S was detected in the gas of several producing wells located close to injectors. It is known that PWRI will result in increased H2S production.
The model was initially calibrated via history match to determine algorithm coefficients associated with siderite scavenging and microbial nutrient availability within the reservoir during seawater flooding. This calibration required historical produced water sulfate concentrations and H2S mass production rates in order to ascertain actual biogenic sulfate reduction levels and the remaining amount of H2S scavenged by the siderite following its partitioning to reservoir fluids. Results indicate that while scavenging by the siderite is likely occurring at a relatively high level, the H2S production rate will increase significantly once water injection rates are increased and PWRI begins.
This paper presents insight as to the importance of water geochemistry in the reservoir souring process and the potential for siderite reactivity, distribution and availability to affect H2S production.
47Ca-Aided Studies of CaCO3 Scaling Rates at Low Saturation Ratios
Authors: Hassfjell S. , Haugan A. , Bjørnstad T. 
Published: April 2009

Abstract
An improved method for continuous on-line measurement of calcite scaling rate in a porous medium at very low saturation ratios based on the radiotracer 47Ca2+ is described. The technique utilizes ?-detectors which measures the precipitation by detection of the g-rays from 47Ca. 47Ca is produced in IFE's nuclear reactor by neutron irradiation of CaCO3, isotopically enriched in 46Ca to 4.1 %. Pressure difference (Dp) and pH is also measured. Several experiments with varying brine-composition, temperature and saturation ratio (SR) have been carried out. Large data sets of relative scaling rates as a function of position and time have been generated. A method for converting these relative scaling rates into absolute scaling rates has been devised. Masses of scale as a function of position at the end of the experiments have been calculated.
Development of Environmental Friendly Iron Sulfide Inhibitors for Field Application
Authors: Chen Tao , Montgomerie Harry , Chen Ping , Hagen Thomas , Kegg Stuart 
Published: April 2009

Abstract
The inhibition of iron sulfide mineral scale formation in oil and gas production is notoriously difficult. High concentrations of scale inhibitors are always needed to provide limited inhibition performance. In addition, it is extremely difficult to test the iron sulfide formation and inhibition in the laboratory.
In this paper, a novel iron sulfide test method has been developed to test the performance of iron sulfide inhibition. Compared with the traditional static jar test and dynamic loop test, this novel developed test method shows good reproducibility and provides a quick and effective way to evaluate the performance of iron sulfide scale inhibition.
An environmentally friendly iron sulfide scale inhibitor has been developed based on this novel developed test method. It provided good performance on iron sulfide inhibition in synthetic field water. The mechanism of iron sulfide inhibition will be addressed.
This paper will give a comprehensive study of iron sulfide formation and inhibition, including iron sulfide prediction,development of test method and development of inhibitors for field application.
Understanding the Mechanisms of Halite Inhibition and Evaluation of Halite Scale Inhibitor by Static and Dynamic Tests
Authors: Chen Tao , Montgomerie Harry , Chen Ping , Jackson Tim , Vikane Olav 
Published: April 2009

Abstract
The inhibition of halite mineral scale formation in oil and gas production is notoriously difficult. High concentrations of halite inhibitors always provide limited inhibition performance. In addition, it is extremely difficult to test halite formation and inhibition in the lab.
In this paper, the dynamic halite loop has been developed to test halite formation and inhibition. Halite formation and inhibition were tested under both traditional static conditions and newly developed dynamic conditions. The results showed inconsistencies based on static jar tests and dynamic loop tests. The possible mechanisms of halite inhibition are discussed.
The following conclusions have been drawn: Compared with the traditional static jar test, dynamic halite loop tests are more representative of halite formation in the field conditions and showed good reproducibility.The newly developed scale inhibitor demonstrated dynamic inhibition performance towards halite formation. Efficiency loop tests showed that the minimum inhibitor concentration (MIC) is less than 200ppm to inhibit halite formation effectively under the test conditions.
Physico-Chemical Interactions Perturbing the Effectiveness of an ATBS-Based Fluid Loss Polymer Used in Oil Well Cementing
Authors: Plank Johann , Lummer Nils Recalde , Dugonjic-Bilic Fatima 
Published: April 2009

Abstract
Water-soluble acrylamide tert-butylsulfonic acid (ATBS)-based copolymers are commonly used to provide fluid loss control for oil well cement slurries. In our study, we investigated the behavior of a CaATBS-NNDMA copolymer synthesized by aqueous radical polymerization with respect to its fluid loss performance in presence of sulfate, chloride and Welan gum and at high temperature (80°C).
First, we found that CaATBS-co-NNDMA adsorbs in high amounts on both cement and silica flour. Its effectiveness relies exclusively on high adsorption onto these mineral surfaces. FLA adsorption may, however, be perturbed by several physico-chemical effects.
Inorganic anions present in high concentrations such as e.g. chloride, as well as organic anionic admixture molecules such as Welan gum, can negatively impact the effectiveness of CaATBS-co-NNDMA. They were found to compete with the polymer for adsorption sites on the surfaces of cement and silica. This way, they reduced the adsorbed amount of the ATBS copolymer. Their impact on the ATBS copolymer generally depends on their anionic charge density, the quality of their anchor group to the cement/silica surface and their concentration.
Elevated temperature (80°C) causes a significant increase in the concentration of solved sulfate present in cement pore solution. As a result of the higher ionic strength, the ATBS copolymer changes its solved conformation from stretched to coiled. Coiling of the macromolecule, however, results in lower adsorption. Through this mechanism, higher temperature reduces effectiveness of the FLA.
Comparative Study of the Working Mechanisms of Different Cement Fluid Loss Polymers
Authors: Plank Johann , Lummer Nils Recalde , Dugonjic-Bilic Fatima , Sadasivan Deependra 
Published: April 2009

Abstract
Oil well cementing uses a variety of chemically different fluid loss polymers, depending on the specific well conditions. In this study, the working mechanisms of polyvinyl alcohol (PVA), polyethylene imine (PEI) and CaATBS-co-NNDMA cement fluid loss additives were investigated. These polymers were selected due to their distinctively different chemical structures.
PVA works by reducing filter-cake permeability through coalescence of hydrated PVA microgel particles which then form a polymer film. At temperatures &gt; 38°C, non-crosslinked PVA starts to dissolve in water. Thus, above this temperature, film formation is no longer possible and fluid loss control is not achieved. Addition of AFS dispersant extends the temperature range at which PVA works from 38°C to about 60°C. The reason behind is that the more anionic and higher soluble AFS prevents PVA from dissolving.
PEI, when used on its own, provides only poor fluid loss control. Its effectiveness is greatly enhanced by the addition of a minor amount of AFS dispersant. Charge titration experiments demonstrate that, when combined in the proper ratio, PEI and the AFS dispersant form a insoluble polyelectrolyte complex which effectively plugs the pores of the filter cake. To achieve optimum performance, PEI and AFS need to be pre-dissolved in the mixing water of the cement slurry to allow the complex to form quantitatively.
In contrast to PVA and PEI, CaATBS-co-NNDMA works by adsorption onto the positively charged surfaces of cement hydrate phases, especially ettringite. Other anionic compounds, e.g. AFS dispersant or even sulfate released from the cement, can interfere with its adsorption and thus reduce its effectiveness through a competitive adsorption mechanism. Therefore, CaATBS-co-NNDMA should not be combined with admixtures which possess high anionic charge density.
Formate Brines for HPHT Well Control—New Insights into the Role and Importance of the Carbonate/Bicarbonate Additive Package
Authors: Howard Siv , Downs John D. 
Published: April 2009

Abstract
This paper describes new research into the role and importance of the carbonate/bicarbonate pH-buffer added to formate based well construction fluids along with a newly developed field method for determining buffer concentrations.
For many years it has been recommended practice to buffer formate brines with carbonate and bicarbonate for corrosion control. Bicarbonate is also the product of the dominant thermal decomposition reaction in formate brine. Since this is an equilibrium reaction, according to Le Chateliers Principle, this additive should cause the equilibrium to establish sooner. Past attempts to demonstrate this have been unsuccessful because it has been difficult to accurately reproduce downhole hydrothermal conditions in laboratory autoclaves. This challenge has now been overcome with specialist equipment that has made it possible to accurately simulate downhole conditions and prove that chemical equilibria do indeed establish downhole. Test results have shown that the equilibrium favors high formate concentrations, meaning that the presence of only relatively small amounts of carbonate/bicarbonate is required for the equilibrium to establish.
Along with the growing understanding of the importance of the carbonate/bicarbonate buffer, there has been a growing demand for a field method to accurately measure carbonate and bicarbonate concentrations as the standard API method for determination of alkalinity does not work in formate brines. The newly developed, simple field method consists of an accurate pH-determination combined with a standard phenolphthalein titration. The method has been extensively tested in the laboratory, and should be reviewed by API for possible inclusion in the API recommended practices.
This new understanding of the roles of the carbonate/bicarbonate buffer has provided us with a better basis for making recommendations as to how to buffer the brine and maintain the appropriate buffer levels for different applications. Combined with the new field method for determining buffer levels, these new insights provide the oil industry with a robust technology to meet the well challenges of the future.
Surfactant-Assisted Synthesis of Metal-Phosphonate Inhibitor Nanoparticles and its Transport in Porous Media
Authors: Zhang Ping , Shen Dong , Fan Chunfang , Kan Amy T. , Tomson Mason B. 
Published: April 2009

Abstract
A surfactant-assisted synthesis route was developed to form nanometer sized metal-phosphonate particles to expand its use in the delivery of phosphonate inhibitors into porous media for scale control. Aqueous solutions of calcium chloride and zinc chloride were mixed with basic solution containing phosphonate scale inhibitors, such as diethylenetriamine-penta (methylene phosphonic acid) (DTPMP) or BHPMP in the presence of sodium dodecyl sulfate (SDS) and/or tetradodecylammonium bromide (TTAB) surfactants. The physical and chemical properties of the fabricated nanoparticles have been carefully evaluated. A large number of fabrication procedures are screened and only those that yield the metal-phosphonate particles in the diameter of 50-200 nm with various shapes are further evaluated. Furthermore, these nanoparticles should meet the criteria of forming stable suspension over 12 hours at 70°C and up to 2% KCl. The nanoparticles are capable of traveling through the porous media and depositing into the formation during a shut-in period. After that, production is resumed and the inhibitor nanoparticles are dissolved into the produced fluid to prevent scale formation. The potential application of synthesized nanoparticles in inhibitor treatment in oil fields was tested by laboratory squeeze simulations, where the nanoparticles can be placed at distance away from the injection port and retained by the porous media and returned slowly as flow back with synthetic brine. The retention and long term flow back performance of metal-phosphonate particles will be reported.
Molar Ratio of Ca2+ to Fe2+ in the Supersaturated Solution of Iron Carbonate and Calcium Carbonate and in the Precipitate: Relation and Interpretation
Authors: Alsaiari H. A. , Kan A. , Tomson M. B. 
Published: April 2009

Abstract
Calcium and iron ions are commonly observed in treated waters. Their carbonate salts are widely found in production lines of separation plants and gas and oil wells. Extensive studies have been made on calcium carbonate salts. On the other hand, little attention has been paid to ferrous iron carbonates and iron sulfide [Tomson et al., 1991; Jonson et al., 1991; Braun, 1991; Greenberg et al., 1992, Yean et al., 2008]. This is probably attributed to the reactivity of ferrous iron and the difficulty in the laboratory to completely prevent the reactions of ferrous iron from oxygen. Several experimental designs and sampling procedures are proposed in the literature. Nonetheless, none of them guarantee complete avoidance of oxygen. In addition, little information is available about ferrous iron carbonate, no reports have been found in the literature focusing on the interaction of iron/calcium carbonate common to nearly all oil field systems. Most of the reports found in the literature focus on the topic in terms of impurities and their influence in crystal structures and/or in their geochemical interaction at low temperatures (20-30°C) [Langerak, et al., 1999; Meyer, H.J., 1984; Herzong et al., 1989].
This work has the following objectives; 1) to study the interaction between ferrous iron and calcium ions simultaneously toward carbonate ions in supersaturated solution in a continuous stirred tank reactor (CSTR), 2) to establish an acceptable experimental design as a preparation step to study the behavior of iron sulfide salts. The experiments were conducted in 0.5 M NaCl solution at 55 °C. The pH values were between 6.2 and 7.8. It was found that calcium ions have a strong influence in increasing the solubility of iron carbonate. On the other hand, ferrous iron did not significantly affect the solubility of calcium carbonate. This might be due to increasing the stability of ferrous iron carbonate complexes in the presence of calcium. Also the molar ratios of calcium to iron in the solution were compared with their molar ratios in the precipitated salts solid. It was found that the relation was greater than unity; Rsolid/Rsolution = 2.39. Although calcium carbonate has higher solubility and also the saturation index of calcium carbonate was lower than that of ferrous iron carbonate during the experiment, however, calcium carbonate has a preference to precipitate. This result seems to be in agreement with water dissolution rates of divalent ions and also with reaction rate constants of iron carbonate and calcium carbonate reported in the literature.
Self-Healing Cements that Heal without Dependence on Fluid Contact
Authors: Reddy B. R. , Liang Feng , Fitzgerald Rocky 
Published: April 2009

Abstract
Oilfield-cement compositions capable of self-healing cracks/fractures in set cement without depending on contact with a fluid, such as water or oil, have been developed. Traditionally, such compositions include additives that are capable of swelling when exposed to fluids like water or oil, for example. Presumably, if the cement develops cracks/fractures or flow channels caused by shrinkage or debonding and allows fluid flow, the swelling additive exposed to such fluids will swell, thereby healing the flow path. The current technology employs additives that swell either in water or oil, but not both. Such additives do not swell when exposed to gas, irrespective of whether the gas is carbon dioxide or a hydrocarbon. Dependence on additives to swell and block flow channels after contact with a specific type of fluid hinders the self-healing effectiveness of the cement composition. As a result, designing cement compositions for field applications requires prior knowledge of the type of fluids that the cement may come into contact with, not only through the productive lifetime, but also after abandonment of the well. Alternately, multiple additives that will swell and seal in both water and oil might need to be included in the initial cement design. Even in the latter case, the compositions still cannot offer protection against gas flow.
A new class of elastomeric additives that do not depend on the nature of fluid to seal cracks is presented in this paper. Performance of these additives in a variety of self-healing tests based on flow studies through cracked cement cores will be presented. In addition, the importance of specific structural features of the additives that render them suitable for inclusion in self-healing cement compositions will be discussed.
Enhanced Effect of Transition Metal Ions on Inhibitor Squeeze Treatments
Authors: Fu Gongmin , Kan Amy T. , Tomson Mason B. 
Published: April 2009

Abstract
Scale inhibitor squeeze treatment is often used to prevent scaling in the oil field. However, some inhibitors show poor retention in the conventional squeeze treatment, where less than 50% of the inhibitors are retained in the formation. It has been shown that the addition of transition metal ions, such as Zn2+, and Cu2+ significantly increases inhibitor retention and effectiveness. In this study, calcite and oil field core material were used in laboratory squeeze simulations to test the squeeze efficiency of phosphonate and polymeric scale inhibitors. Three squeeze procedures, whereby transition metal ions are added into inhibitor pill, overflush solution, and preflush solution were compared. It was demonstrated that over 90% of BHPMP and PPCA were retained when Zn2+ and Cu2+ were added in the pill, overflush and preflush solution. Simulation indicates that squeeze life may be improved by a factor of 60 or greater if these new squeeze procedures are used. The mechanism of enhancing inhibitor retention is also discussed in the paper. It is probably due to the formation of transition metal-inhibitor and Ca-inhibitor co-precipitate, and more stable complex of transition metal ion with inhibitor. Zn2+ displacing Ca2+ from the calcium containing rock and forming a new solid phase ZnCO3 have been evidenced. This solid will enhance the inhibitor depositing in the formation and probably also serve as a sulfide scavenger to remove hydrogen sulfide from conate brine in the formation.