bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Injection Into Stratified Gas-Condensate Reservoirs
Authors: Sänger P. J. , Bjørnstad H. K. , Hagoort Jacques 
Published: December 2007

Abstract
Nitrogen injection is an attractive recovery process for gas condensate reservoirs. It maintains the reservoir pressure and thus prevents condensate drop-out as a result of pressure depletion. A disadvantage is that liquid drop-out occurs in the mixing zone between the injected nitrogen and the gas condensate. This occurs not only at the displacement front, but, due to bypassing, also at the boundary between layers of different permeability.
This paper presents the results of a detailed, high resolution simulation study of nitrogen flooding of a stratified reservoir. The reservoir simulator used is a fully compositional simulator, based on the Peng Robinson EOS. The gas condensate is a 3 component hydrocarbon system that is representative of a North Sea reservoir.
The main result of the study is that in stratified systems severe drop-out (up to 50 percent) may occur at the layer boundaries, in particular just downstream of the trailing displacement front. The latter can be explained by crossflow caused by an unfavourable mobility ratio. It is shown how this mechanism is affected by permeability contrasts, dispersion, aspect ratio and gravity.
Treating of Produced Water for Surface Discharge at the Arun Gas Condensate Field
Authors: Madian S. , Moelyodihardjo Tarwanto , Snavely E. S. , Jan R. J. 
Published: December 2007

ABSTRACT
Mobil's Arun Field in northern Sumatra produces natural gas, hydrocarbon liquids and water condensate. Purification of the water for surface disposal is the subject of this paper.
The Arun waste water contains about ppm of liquid hydrocarbons in the form of a very stable oil-in-water emulsion. Stability of the emulsion is enhanced by the small diameters of the oil droplets, low salt content of the water and low pH. The water is saturated with carbon dioxide and hydrocarbon gases which bubble from the water when pressure is released. Returns of acids, surfactants, emulsifying agents and corrosion inhibitors from acid fracturing operations also contribute to the composition of Arun waste water.
Increases in waste water production, now about 32,000 BPD, and relatively high concentrations of BOD, phenols and ammonia have prompted Mobil to upgrade the Arun waste water treating facilities to protect the receiving bodies of water from contamination.
The upgrade focused on two areas of water treating: 1). removal of suspended liquid hydrocarbons from the water; and, 2). biological oxidation of dissolved organics.
Demulsifier chemical and a skim tank were added to the oil removal facility; the decarbonator and caustic addition before air flotation were eliminated. Without added caustic, the gas flotation unit remove acid gases from the water very effectively. The new skim tank removes over 90% of the suspended hydrocarbons.
The biological oxidation ponds were upgraded by adding barriers to improve plug flow, increasing dispersed air flow, increasing sludge recycle volume, lowering the oil input and by adding nutrients and biological seeding.
Results of the biological pond upgrades are not yet available because increased sludge recirculation and the optimization of biological seeding are not yet completed. Tests of the use of locally-produced biological sludge are planned.
Viscosified CO2 Process: Chemical Transport and Other Issues
Authors: Bae J. H. 
Published: December 2007

ABSTRACT
Supercritical CO2 viscosified by two orders of magnitude using a commercial silicon polymer and toluene as cosolvent, was used in the laboratory corefloods and the results reported previously. More corefloods in Berea cores with pressure taps along the core were conducted to investigate the transport of chemicals in the core. In an attempt to reduce the chemical costs, different silicon polymers and hydrocarbon cosolvents were tried. The effect of methane on the solubility of polymers was also investigated. Scoping economic runs were made by modifying an actual economic analysis of a field CO2 project, which showed that chemical costs have to be reduced significantly for the process to be economic.
Permeability-Dependent Propagation of Polyacrylamides Under Near-Wellbore Flow Conditions
Authors: Zitha P. , Chauveteau G. , Zaitoun A. 
Published: December 2007

ABSTRACT
A new type of polyacrylamide flow-induced retention has been observed in core experiments simulating near-wellbore flow conditions. The retention is due to the bridging of pore throats by adsorbed macromolecules previously stretched under elongational flow. It occurs in low-to-medium permeability granular packs (up to k = 1000 mD in our test conditions) and leads to progressive but severe plugging. The present paper shows that polymer placement in the reservoir surrounding the wellbore can be very different from what is predicted from stable values of polymer mobility. In heterogeneous reservoirs, polymer penetration in low-permeability layers is expected to be strongly reduced, thus allowing a deeper penetration into higher permeability zones. The polymer can thus improve reservoir conformance around the wellbore when injected directly through the entire opened interval. Near-wellbore polymer or gel treatments may thus not require zone isolation to be efficient.
New Chemistry for Chromium-Free Bentonite Drilling Fluids Stable at High Temperatures
Authors: Burrafato Giovanni , Miano Fausto , Carminati Stefano , Lockhart T. P. 
Published: December 2007

ABSTRACT
The broad substitution of aqueous drilling fluids for oil-based muds will require that the performance limitations of current aqueous muds be overcome. The research described in this paper is focused on the most commonly-used aqueous drilling fluids, lignosulfonate (LS03)-dispersed bentonite muds, and addresses two important issues that restrict their wider use: their limited stability at elevated temperature, and their reliance on chromium-containing additives (Cr-LSO3 and Cr-lignite) for control of their rheological properties.
In this paper, new hypotheses regarding the mode of action of Cr(VI) and Cr(III) in Cr-LSO3/bentonite muds are formulated on the basis of new and published experimental observations. Of primary importance are the ideas that (1) LSO3-bound Cr(III) is the form which enhances the thinning power of LSO3 and (2) Cr(VI) stabilizes LSO3/bentonite muds primarily by acting as a latent source of Cr(III). Acting on these hypotheses, it has been found that Cr(III) complexes of appropriate kinetic stability can duplicate the rheology-stabilizing function of Cr(VI). Further pursuit of this coordination chemical approach has led to the identification of a family of Zr(IV) complexes with which chromium-free drilling fluids of outstanding rheological stability can be prepared. The general chemical factors influencing the rheology-stabilizing activity of metal ion complexes are examined. Finally, the unexpected and remarkable thinning power of the Zr(IV) citrate complex is described and its implications for the formulation of novel drilling fluids are briefly discussed.
An Improved Viscosity Equation to Characterize Shear-Thinning Fluids
Authors: Allen Elise 
Published: December 2007

Abstract
An improved viscosity equation is proposed for shear-thinning polymer solutions, using a kinetic approach to model the rate of formation and loss of interactive bonding during shear flow. The bonds are caused by temporary polymer entanglements in polymer solutions, and by coordination bonding in metal ion cross-linked gels. The equation characterises the viscosity of shear-thinning fluids over a wide range of shear rates, from the zero shear region through to infinite shear viscosity.
The equation has been used to characterize fluid data from a wide range of fluids. Recent work indicates that a range of polymer solutions, polymer-based drilling fluids and frac-gels do not have a measurable yield stress, and that the equations which use extrapolated values of yield stress can be significantly in error. The new equation is compared with the Carreau and Cross equations, using the correlation procedure of Churchill and Usagi. It gives a significantly better fit to the data (by up to 50%) over a wide range of shear rates. The improved equation can be used for evaluating the fluid viscosity during the flow of polymeric fluids, in a range of oilfield applications including drilling, completion, stimulation and improved recovery (IOR) processes.
Determination of the Chemistry of HF Acidizing with the Use of 19F NMR Spectroscopy
Authors: Shuchart Chris E. , Buster Douglas C. 
Published: December 2007

Abstract
A more thorough understanding of the chemistry of HF acid and its reaction products on silica and alumino-silicates is essential to the design and optimization of HF acidizing treatments. So far, results from laboratory flow tests and HF acid well returns have not been explained readily by traditional theories. To more clearly define the chemistry of HF acidizing, an indepth investigation of the reaction of HF and H2SiF6 with alumino-silicates was undertaken using 19F Nuclear Magnetic Resonance (NMR) spectroscopy.
In addition to the fluosilicic acid (H2SiF6) and A1F2+ predicted by traditional theories, 19F NMR spectroscopy shows a complex mixture of silicon and aluminum fluoride species in reacted HF acidizing solutions. During a secondary reaction of silicon fluorides with alumino-silicates, a constant F/Al ratio was maintained until the silicon fluorides had reacted completely. The distribution of the fluoride species depends on the HC1 concentration.
In this investigation, a tertiary reaction of HF acid on alumino-silicates was identified. When the silicon fluorides have reacted completely to give silica gel, the aluminum fluoride complexes continue to react on fresh alumino-silicates. The reaction causes the aluminum content to increase and the F/Al ratio and acid concentration to decrease. The final F/Al ratio is dependent upon acid strength and temperature.
Numerous HF acidizing well returns have been analyzed to verify the reactions conducted in the laboratory. The extent of the reaction of HF acid can be determined with the use of 19F NMR spectroscopy. In wells with temperatures of 150 to 200°F, the reaction of H2SiF6 is complete. Silicon content was quite low, and pH levels were 2 to 3. The F/Al ratios of the returns were 0.5 to 1.3, depending on the concentration of HC1 and HF used in the treatment. In wells less than 100°F, the secondary reaction did not go to completion. Silicon and aluminum fluoride complexes were present in the returns along with live HC1.
A Comprehensive Approach for Stimulating Produced Water Injection Wells at Prudhoe Bay, Alaska
Authors: Fambrough J. D. , Lane R. H. , Braden J. C. 
Published: December 2007

Abstract
The paper presents a three-component approach to removing damage from produced water injection wells of Prudhoe Bay Field, Alaska: 1) identification of plugging material, 2) evaluation and selection of potential treatment chemicals, and 3) design and implementation of a well treatment and placement method. Plugging material was sampled anaerobically and kept frozen prior to identification and evaluation. Appropriate treatment chemicals were determined through a series of solvation, filtration, and weight-loss tests. Field treatments were designed so that the treating chemicals entered the formation under normal operating conditions, i.e., at pressures and rates similar to those present during produced water injection. A number of treatments improved injection rates and profiles, but continued injection of oil- and solids-laden water caused deterioration of well performance at rates that precluded general application of the treatment at Prudhoe Bay.
Laboratory Study and Subsequent Field Results of Chemical Stimulation for Use in Open Hole Environments
Authors: LaFontaine-McLarty Jackie , Ali S. A. , Sanclemente L. W. , Sketchier B. C. 
Published: December 2007

Abstract
This paper describes the results of a two-year study conducted to optimize cleanup systems in open hole environments. Specifically, the study originated from problems encountered in the design of a series of open hole horizontal completions and the effort to improve well productivity.
Effects of Oxygen on Fracturing Fluids
Authors: Walker Michael L. , Shuchart Chris E. , Yaritz Joseph G. , Norman Lewis R. 
Published: December 2007

Abstract
The stability of polysaccharide gels at high temperature is limited by such factors as pH, mechanical degradation, and oxidants. Oxygen is unavoidably placed in fracturing fluids through dissolution of air. To prevent premature degradation of the fracturing fluid by this oxidant, oxygen scavengers are commonly used.
In this paper, the effects of oxygen and various oxygen scavengers on gel stability will be presented. Mechanical removal of oxygen resulted in surprisingly stable fracturing gels at 275°F. However, chemical removal of oxygen gave mixed results. Test data from sodium thiosulfate, sodium sulfite, and sodium erythorbate used as oxygen scavengers/gel stabilizers showed that the efficiency of oxygen removal from gels did not directly coincide with the viscosity retention of the gel, and large excesses of additives were necessary to provide optimum gel stabilization. The inability of some oxygen scavengers to stabilize the gel was the result of products created from the interaction of oxygen with the oxygen scavenger, which in turn, produced species that degraded the gel. The ideal oxygen scavenger should provide superior gel stabilization without creating detrimental side reaction products. Of the materials tested, sodium thiosulfate appeared to be the most beneficial.
Chemical Characterization of Fluids and Their Modelling With Respect to Their Damage Potential in Injection on Production Processes Using an Expert System
Authors: Thomas L. G. , Albertsen Manfred , Perdeger Asaf , Knoke H. H. K. , Horstmann B. W. , Schenk Dietmar 
Published: December 2007

Abstract
Deep groundwaters, esp. oil field waters, from different sedimentary basins in Germany were characterized and evaluated with respect to their damage potential in production and injection processes. Geochemical modeling with different computer programs (PHREEQE, PHRQPITZ, SOLMINEQ etc.) was used to evaluate fluid-rock-interactions as well as their damage potential during operation processes. The geochemical program PHREEQE was integrated in an expert system (XPS FROCKI) for the evaluation of operational problems (scaling, fines mobilization, reduced permeabilities) in production or injection wells.
Thermodynamic Modelling for Prediction of Asphaltene Deposition in Live Oils
Authors: Cimino Roberto , Correra Sebastiano , Sacomani P. A. , Carniani Carlo 
Published: December 2007

ABSTRACT
Original phase equilibria data on asphaltenic mixtures show that the principal modellistic approaches described in the literature do not accurately reproduce asphaltene phase behaviour. A new, more reliable modellistic approach is proposed in this paper, and a procedure for predicting the stability of asphaltene solutions is outlined. Application of the new model to two oils gives satisfactory results when compared with field observations.
Development and Application of Accurate Detection and Assay Techniques for Oilfield Scale Inhibitors in Produced Water Samples
Authors: Graham G. M. , Sorbie K. S. , Boak L. S. , Taylor K. , Blilie L. 
Published: December 2007

ABSTRACTIn the application of chemical inhibitors in field squeeze treatments for the prevention of sulphate and carbonate mineral scale formation, it is very important that the chemical species involved can be accurately assayed. When the inhibitor concentration drops below a predetermined threshold level for scale inhibition (Ct) then the well may need to be resqueezed. The accurate assay of scale inhibitors down to concentration levels of a few ppm in real field brines can be a difficult task.In this paper, we examine a number of interferences which often make assay techniques very difficult to apply in field produced brines. The inhibitors examined in this work include phosphonates (PH), polyacrylates (PAA) and phosphino-polycarboxylates (PPCA). The main objective of this work is to develop suitable pre-treatment/purification techniques which allow the standard wet chemical techniques to be applied effectively after appropriate modification. Successful techniques - all based on careful modification of existing methods - have been developed by which these common inhibitors can be assayed very accurately at ppm and sub-ppm levels in a variety of North Sea field produced waters. This paper examines some of the major problems and interferences associated with poor analysis and introduces modified methods which can be applied in the field without the use of expensive equipment. It is also shown that different detection methods can often be employed in order to avoid more extensive clean-up strategies. Finally, instrumental methods such as ICP analysis (commonly used for phosphonates) are examined and pre-treatment methods are developed which allow phosphino-polycarboxylic acid based inhibitors to be assayed very accurately by this method. The results from an independent assessment by a North Sea operator, using spiked field produced water, are also presented as an independent verification of the accuracy of the techniques which have been developed in this work.
Hydrophobically Associating Terpolymer and Its Complex With a Stabilizer in Brine for Enhanced Oil Recovery
Authors: Lijian Dong , Biao Wang 
Published: December 2007

Abstract
This paper relates to tertiary recovery employing a polymer thickened aqueous drive fluid or mobility control fluid, more particularly, this paper relates to a novel type of thickening agent named AST agent for drive fluid composed of a hydrophobically associating terpolymer (PAAE) and a stabilizer (AN).
AST thickening agent exhibits good thermal stability (at 100°C, thermal aging in 33000 mg/l brine) and electrolytic tolerance (salinity ranging from 16500mg/l to 66000 mg/l) and good resistance to shear relative to the conventional water-soluble polymers such as polyacrylamide, acrylamide/acrylic acid copolymer etc., and furthermore, AST agent has some surface activity.
Many laboratory experiments have been shown that AST thickening agent could be considered as an advanced one in comparision with the conventional water-soluble polymers. Especially AST thickening agent is more suitable for a mobility control fluid in the hostile environment in subterranean formations such as in high salinity and high temperature formations.
Development of a Flow Injection Analysis Method for the Determination of Acrylamide Copolymers in Oilfield Brines
Authors: Taylor K. C. , Burke R. A. , Nasr-EI-Din H. A. , Schramm L. L. 
Published: December 2007

Abstract
An automated method for the determination of acrylamide polymers by flow injection analysis (FIA) has been developed and optimized for routine use. The method has been extensively tested for interferences common in oilfield brines. Potential interferences were examined from Na+, Ca2+, Cr3*, Al3+, Zr3*, NH4+, Cl-, OH-, CO32-, sample coloration, and commonly used surfactants. The analysis is specific for amides, and the sensitivity to concentration of amide groups in the polymer was shown to be constant as the degree of polymer hydrolysis was varied. The range of the method is 0.1 to 100 mg/L. Sample throughput is 30 samples/h with triplicate analysis. Relative standard deviations of 0.2% are readily obtained from standard solutions and 0.5% from complex samples (at 50 mg/L). The method is applicable to the determination of aqueous, acrylamide-based polymers in process streams, surface waters and oilfield brines.
A Study on Synthetical Relieving Plug Agent for Steam Huff-puff Wells in the Watersensible Formation
Authors: Biao Wang , Yunxin Cheng , Yinxue Jian , Zimian Hu 
Published: December 2007

Abstract
A great quantity of crude is heavy crude oil which has been produced by using steam huff-puff method in Liaohe Oil Field. This kind of crude contains a lot of resin-asphaltene and possesses the property of very high viscosity (4537 mPa. s at 50°C) and specific gravity (0.9568 — 0.9611). The formation is not only very sensible to water, but also damaged by fluids of drilling mud. Through injecting steam, the production rate was still very low and duration of steam huff-puff was very short because of plugs which were formed by clay swelling and the residual hydrocarbon that produced by volatilization of light fraction of heavy crude around wellbore.
This paper offered a synthetical relieving plug agent which is a mixed fluid, containing organic mixed solvent, inorganic acid, surfactant and other additives. The synthetical relieving plug agent (ARP — 8801 and BJ — 30) has been successfully used in 37 wells in Shuguang No. 48 union, Liaohe Oil Field since April 1989.
According to the statistical data, obtained from 33 experiment wells, it has been sown that the ARP — 8801 and BJ — 30 synthetical relieving plug agent has excellent relieving plug ability for the heavy crude wells of using steam huff-puff method in watersensible formation. The production rate per well was increased on an average from 0—8.6tons/day (before treatment) to 6.0 — 26.7tons/day (after treatment). The duration of steam huff-puff was increased on an average from 121 days (before treatment) to 218 days (after treatment). The oil/steam ratio increased from 0.41 (before treatment) to 1.17 (after treatment). The cumulative incremental oil production has reached 41704 tons.
The application in oil field proved that the method, offered by this paper, is a very nice stimulation treatment for heavy crude wells of injecting steam in the watersensible formation.
The mechanism of relieving plug is discussed in this paper also.
Research On the Preparation of Sodium Asphalt Sulfonate and its Mechanism of Fluid Loss Control for Drilling Fluids
Authors: Shen Qin-chang , Xian Tao , Yu Banje 
Published: December 2007

Abstract
A process for producing sodium asphalt sulfonate with gaseous sulfur trioxide has been developed with a systematic study of the main parameters which have influence on the performance of the products. After a description of a spectrophotometric method. The content of asphalt sulfonate in aqueous solutions and the adsorption of those products on British evaluation clay have been determined. The measurements of electric conductivity and surface tension for aqueous emulsions of the asphalt sulfonate have also been conducted. It is concluded that the adsorption on clays as well as the emulsification in aqueous solution are the two essential factors for asphalt sulfonate to reduce fluid loss.