bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Successive Squeezes on Treatment Lifetime and Well Productivity: Laboratory and Field Evidence
Authors: Fleming Niall , Ramstad Kari , Nelson Alex , Graham Gordon 
Published: May 2008

Abstract
Over the lifetime of a well it is possible that several squeeze operations will be performed depending on scaling severity. Downhole squeeze operations have been performed for many years and have on the whole been an effective scale management tool. However, the long term impact that successive squeezing has on treatment lifetime and well productivity has received little attention. This paper will address these issues by comparing the results from a unique sequence of long term corefloods that were designed to replicate five successive treatments on the kaolinite rich, Middle Tarbert core from the StatoilHydro operated field, Oseberg Sør. Relatively few squeeze treatments have been performed on this field, and the coreflood results have been up-scaled to provide a potential prediction of the effects of long term squeezing and well productivity on Oseberg Sør. Furthermore, the laboratory results have been cross-checked by comparing with the Heidrun field that has been squeezed for many years. Heidrun is an analog of Oseberg Sør with kaolinite rich producing intervals and similar productivity issues related to kaolinite mobilisation.
Managing Radioactive Scale: Strategic Approach and Success Story
Authors: Ghosh B. , Al-Bemani Ali. S. , Najim Kitany , Al-Hajri Said , Clark James , Boukadi F. H. 
Published: May 2008

Abstract
Radioactive material contaminated, hard crystalline scale deposition on ESP & downhole equipment was resulting in frequent breaking of ESP shaft in a multilateral openhole producer. Extremely high workover cost in frequent replacement of downhole equipment and associated radioactive hazards, necessecitated a strategic MDT approach. Software usage and extensive laboratory backup helped finding the best possible option to mitigate this problem. Three possible well treatment options were investigated. Scale inhibitor squeeze option was studied through reservoir condition core flow and rejected because of probable formation impairment and placement difficulties in a complex well and reservoir geometry. Periodic soaking of ESP with scale dissolver was considered a viable option because of economics and operational ease. Laboratory studies were conducted to design the placement strategy. We developed a xanthan based high viscous self degrading polymer gel coushion which would support the scale inhibitor solution around the ESP for the necessary soaking period to prohibit flow into the pressure depleted formation. However this concept had to be abandoned because of flipping over of the fluids in laboratory observation and uncertainty of optimum soaking period downhole. The last and final option was to wait for the running ESP to fail and during workover the well could be completed with a macroni line for continuous injection of scale inhibitor. Judicial selection and optimization of inhibitor, continious monitoring of well treatment and well behavior has resulted in phenomenal success which is demonstrated by the fact that the ESP run life has been exceeded 700+ days against &lt;100 days average runlife prior to treatment. The treatment also took care of radiation hazard and contaminated equipment disposal problem to a large extent.
Deployment of Real-Time Scale Deposition Monitoring Equipment to Optimize Chemical Treatment for Scale Control During Stimulation Flowback
Authors: Emmons D. , Smith S. A. , Weathers T. , Jordan M. M. , Feasey N. D. 
Published: May 2008

Abstract
A series of three fixed platforms off the California coast produce fluids sourced from sandstone and carbonate formations that individually produce brines with substantial amounts of calcium and bicarbonate, respectively. These fluids are sent to a central facility onshore for processing, requiring that the combined fluids be treated for calcium carbonate scale. During acid stimulation treatments of wells, the fluid flowback from the wells initially has very high calcium levels that greatly increase risk of scale formation for a short period of time. To better understand the dynamic scale risk created during stimulation flowback, a monitoring program using a novel in-line deposition monitoring probe was implemented. The probe was placed in-line at the onshore processing facility to track changes in the production fluids prior to and during the acid stimulation program. The resulting data was correlated to several events that occurred within the process including a process shut-in, deposition of heavy oil residue that fouled the probe during a period of poor separation, and scale deposition upon reduced chemical treatment.
Real-time data obtained during flowback from two acid stimulation jobs is presented, demonstrating how it was possible to optimize the scale inhibitor treatment program such that no scale deposition occurred during these treatments. The value of the real-time monitoring data versus other methods of assessing the risk of scale formation within these fluids is highlighted and the ability to optimize inhibitor treatment rates in real-time demonstrated.
The development and implementation of on-line real-time monitoring for deposition control of an active and changing scaling environment shows the clear value that this technology brings to scale control within process facilities.
Study of BaSO4 Formation Kinetics and Inhibition Effect of Polyphosphino-Carboxylic Acid (PPCA) With Synchrotron X-Ray Diffraction (SXRD)
Authors: Mavredaki Eleftheria , Neville Anne , Sorbie Ken S. 
Published: May 2008

Abstract
Precipitation of barium sulphate from aqueous supersaturated solutions is one of the most well known problems in the oil industry. Precipitation of barite and other insoluble scale types (metal sulphates, calcium carbonate and silicates) propagate to undesirable formations, which adhere strongly in production tubing and in equipment parts. Formation of BaSO4 lead to a decrease in the performance of the petroleum facilities and to inevitable damage in the oil industry.
Barium sulphate is one of the most insoluble types of inorganic scale. It resists many chemical methods of removal. Inhibition of barium sulphate by chemicals is generally recognized as the most appropriate approach for flow assurance.
In this study Synchrotron X-Ray Diffraction was used to investigate the kinetics of barium sulphate formed on stainless steel surface at two different temperatures. For the first time SXRD measurements of BaSO4 formed in the presence of foreign ions (Sr2+, Ca2+ etc) are presented. The in-situ measurements allowed the assessment of the crystallographic nature of the formed scale and the probation into the precipitation mechanisms. Additionally this study focused on the effect of PPCA on the barium sulphate precipitation. PPCA was examined for its inhibition action in two concentrations at both temperatures. The formed barite crystal faces after the treatment with PPCA were recorded.
Control of Silicate Scales in Steam Flood Operations
Authors: Gallup Darrell L. , Hinrichsen Charles J. 
Published: May 2008

Abstract
Water circulating during steam flooding to recover additional oil from reservoirs often becomes enriched in dissolved silica. As the silica concentration increases in the water, silicate minerals become supersaturated. At supersaturation conditions, amorphous silica and metal silicates may deposit in heat exchangers. Scale deposits not only reduce heat exchange efficiency due to fouling, but they may plug tubes resulting in tube failure. Control of these deposits in boilers and co-generation equipment is necessary to reduce down-time for mechanical cleanout.
In the present study at a steam flooded field, steam boiler and co-generation tube deposits consisted of opal-A, pectolite, aegerine, clinamphibole, serpentine-like minerals, iron oxide corrosion products, and apatite. Iron in the silicate minerals appears to derive from transporting incompletely oxygen scavenged circulating water to the boilers and co-generation unit in carbon steel pipe. Increasing the concentration of oxygen scavenger and EDTA-based scale inhibitor in the feed water has significantly reduced scale deposition.
Other methods that may be used to control silica/silicate scaling in steam flood operations include: (a) dilution with fresh water, (b) reducing the pH of the water, (c) treating the water with reducing, complexing and sequestering agents, (d) removing silica from water by lime softening, (e) precipitation of silica in water with metals or cationic surfactants, and (f) treating the water with geothermal silica scale inhibitors/dispersants.
Kinetics of CaCO3 Scale Formation During Core Flooding
Authors: Larsen Tore , Randhol Preben , Lioliou Marianna , Jøsang Leif Olav , Østvold Terje 
Published: May 2008

Abstract
Many oil fields in operation today have major scale control problems, and new insight and know-how in this area are important in order to maximize production at minimal operational costs. The models on mineral precipitation available today are based mainly on thermodynamic data found in the literature. The impact of scale precipitation on well performance, however, is not being accurately modeled due to lack of data on precipitation kinetics. It is therefore important to gain a proper understanding of the kinetics of scale formation and its detrimental effects on porosity and permeability in the near well bore region. A series of core flooding experiments were conducted at 80°C to investigate CaCO3 scale formation. This paper focuses mainly on the CaCO3 precipitation kinetics data obtained at various flow rates, supersaturation ratios (SR) and substrates. However, permeability and porosity alteration due to precipitation during flow are also presented and discussed. Kinetic data were derived from both continuous pH measurements and determination of the remaining calcium concentration in the effluent. The precipitation rate was very dependent on the amount of CaCO3 already precipitated. The combination of residence time and duration of the experiment determined the effluent SR. After a steady state precipitation rate was reached in a Lochaline sandstone, the SR of the effluent changed from the initial 3.00 to ~1.55 and ~1.15 for core residence times of 1 and 4.5 minutes, respectively. With initial SR = 2.00 the corresponding SRs were ~1.25 and ~1.13 for residence times of 1 and 4 minutes, respectively. A permeability-porosity profile was determined showing that the permeability changed rapidly early in the experiment and was followed by a long period with relatively little change as a function of porosity decrease. Towards the end of the experiment a dramatic decrease in permeability, typical to tube blocking test behavior, was observed. Visualization experiments using two dimensional glass porous medium models showed that when crystals had been formed by nucleation, further precipitation occurred preferably on existing crystals.
Development of a Viscosified Scale Inhibitor for Improving Placement in Acid Fractured Limestone Reservoirs
Authors: Heath S. M. , Sim Michael , Archibald Marc , Stalker Robert 
Published: May 2008

Abstract
Scale is a major problem for the oil and gas industry and is often controlled by the use of downhole scale inhibitor squeeze treatments. The placement of scale inhibitor in acid fractured limestone reservoirs presents a particular challenge and effective placement of scale inhibitor cannot be guaranteed when performing conventional low rate (&lt;10bpm) bullhead squeeze treatments. In order to ensure the fluid package is placed over the whole of fractured interval it is necessary to perform high rate scale squeezes (40-60bpm) in conjunction with mechanical divertors. However, these treatments are expensive and limit the amount to treatments that can be performed per day in a scale squeeze campaign.
This paper describes the development of a range of viscosified polymeric scale inhibitors for squeeze application in acid fractured wells. A particular feature of these products is their viscous self diverting nature which means they can be used at low pump rates at rates of &lt;10bpm. This method also precludes the use of mechanical divertors and enables cross flow problems to be overcome and effective chemical placement over the whole of fractured interval. In addition, this offers the benefit of improved scale control and squeeze lifetimes coupled to considerable economic savings by being able to perform more treatments per day using conventional pumping equipment.
A detailed investigation into the rheological properties of selected products has been performed to design the optimal delivery system. Experimental data on the compatibility of a variety of viscosifying agents and chemical breakers different types of polymeric scale inhibitors will be presented. This will include viscosity profiles, shear thinning behavior and breaking times for these systems. Inhibitor performance and core flood studies to evaluate formation damage potential and retention and release characteristics will be also be presented. In addition, the paper will add the results of a computer modelling study to validate the experimental data and aid the placement strategy for optimum field application.
Mechanistic Study of Chemicals Providing Improved Halite Inhibition
Authors: Guan Hua , Keatch Richard , Benson Charles , Grainger Neil , Morris Liz 
Published: May 2008

Abstract
This paper investigates the application of halite inhibitors and the mechanisms associated with salt formation and inhibition. Several new chemistries (two inorganic compounds and one organic nitrogen-based product) have been identified which provide improved halite inhibition. Their inhibition performance was studied and compared with commercially available inhibitors.
Salt deposition in high salinity brines can cause blockages to production and process systems requiring remedial action, often on short notice. Current commercial halite inhibitors are only effective at high concentrations (250 – 5,000 ppm). Therefore, a more efficient salt inhibitor would need to reduce both treatment level and production downtime.
The inhibition performance of three new chemicals and two commercial products were evaluated under static conditions along with performance assessment after aging. Both sea salt and pharmaceutical-grade sodium chloride were used in the tests. All three new chemicals showed improved inhibition efficiency over the two commercially available products. The retention property for one of the three new chemicals was evaluated using two different core materials. The test results showed a satisfactory amount of adsorption under favourable pH conditions. Core floods using field core materials were conducted to evaluate the chemical squeeze packages. No formation damage was observed, both oil and brine permeabilities have recovered following the chemical treatments.
A lower dosage (10–50 ppm) was required for the new chemical as compared with conventional treatment levels. The lower treatment level provides the potential to reduce cost, treatment intervals and production downtime. Moreover, there is the opportunity for the new product to be batch squeezed into the reservoir, providing prolonged protection against salt deposition.
A New Chemical Treatment to Inhibit Iron Sulfide Deposition
Authors: Lehmann Marc , Firouzkouhi Fafa 
Published: May 2008

Abstract
This report documents laboratory studies that display the potential of the new iron sulfide treatment that, instead of preventing the formation of the scale, allows a dispersed iron sulfide to form that is both water wet and deactivated. Evidence has been provided that shows how the treatment keeps the particle size small so that is unlikely to associate and deposit in production systems. The mechanism of control is and the parameters that control the performance are discussed. The dispersant facilitates the transport of the scale with the produced water but prevents the FeS from forming pads at water-oil interfaces. Results from a limited field trial demonstrate the success of the treatment in the preventing the formation of pads in a primary separator, and solids deposition in a heater treater.
Two Year Results of a Breakthrough Physical Water Treating System for the Control of Scale in Oilfield Applications
Authors: Rzeznik Lawrence , Juenke Michael , Stefanini Daniel , Clark Martin , Lauretti Paolo 
Published: May 2008

Abstract
The presence of scale in a well is arguably one of the most difficult and expensive problems facing the production function of the oil industry today and despite many years of concentrated effort to effectively combat it, the problem still exists in a widespread manner. Much of the effort to mitigate the scale problem and render it less of a threat to production has been centered on methods of inhibiting its formation with chemicals or by mechanically removing it, but in many cases the action taken has not met the overall effectiveness sought by industry. A new approach to the problem is indicated but what form might it take? If a method were to exist that would prevent the deposition of scale rather than treating it when it appears, then this would represent a quantum leap forward in production operations.
This paper presents a unique and non-chemical method for the control of oilfield scales using a physical water treating device that was originally developed for industrial water treatment. This patented technology presents an alternative for oilfield scale treatment and control when it is installed at the surface of the well. It functions by inducing a randomly pulsed high frequency signal into the piping system which causes the scale crystals to form in the produced fluid rather than on the walls or surfaces of down hole and topside equipment. Prior to field testing this mechanism was evaluated under laboratory conditions using a dynamic tube-blocking test with concentrated brines that produced calcium carbonate, barium sulfate and combinations thereof. Subsequent field studies encompassed the treatment of oil and gas wells with various forms of lift in four different regions in North America with over ten different companies. The system was designed to overcome the wide range of variables that exists from well to well and specific results from several wells will be reviewed to illustrate the value that this approach is bringing to well management.
The conclusion to be drawn from this work is that physical water treating technology can be effective in controlling oilfield scale deposition and there are many benefits to be enjoyed by an operator including increased production, significant cost savings and a positive impact on the environment. It is these benefits that make continued work in this field of science a worthy endeavor to pursue for the oil industry.
Performance of Scale Inhibitors Under Carbonate and Sulfide Scaling Conditions
Authors: Smith J. Kevyn , Hammons Julie , Boyd Galyn , Fu Qiang 
Published: May 2008

Abstract
This paper compares the scale inhibition efficiencies of a phosphate ester, two phosphonate and two polymer chemistries in the presence of ferrous iron, calcium carbonate, barium sulfate, iron sulfide and iron carbonate scales, as well as combinations therein. The results show that as the scale speciation of the precipitating solids change so does the scale inhibition efficiency. These changes in efficiency were attributed to the cumulative effects of crystal matrix distortion by either exogenuous scale specie or effect of metal complexation to the scale inhibitor chemistry. The ultimate conclusion of this study is that because of the relationship between the scale inhibitor performance and ferrous iron concentration, it is important to consider this relationship when determining the minimum inhibitor concentration (M.I.C.) for the inhibition of scale growth in oilfield production systems.
Scale Challenges in Talisman's Varg Field
Authors: Sorhaug E. , Graham G. M. , Stalker R. , Littlehales I. J. , Kidd S. L. 
Published: May 2008

AbstractThe Varg field (PL038, Block 15/12) is located in the Norwegian Sea. The Varg reservoir is Oxfordian sandstone of Jurassic age, with an upper (1000-2000 mD) and lower (100-200 mD) sand separated by a mud rich sandstone. The field is highly compartmentalized and is located around a salt dome, and contains a number of different formation waters ranging from high salinity, higher barium (up to 280 mg/l) in the West and lower salinity and lower barium (30 mg/l) in other areas. All waters contain naturally occurring dissolved iron at concentrations up to 175 mg/l. Following scaling in several wells, a chemical re-selection and treatment optimisation programme was initiated. Extensive laboratory studies were undertaken to select optimum inhibitors, which was further complicated by environmental requirements. The presence of dissolved iron was shown to have an adverse effect on the incumbent scale inhibitor, leading to the selection of a number of alternative products. Given the highly compartmentalized nature of the reservoir and the large permeability contrast between zones, near wellbore modelling studies, examining chemical placement using both conventional (aqueous) based treatments and also viscosified treatments, were conducted. The potential for poor placement and subsequent poor lifetimes led to further detailed simulation work using up to date PLT logs to further refine the treatments in subsequent wells. Therefore, this paper describes the various challenges facing scale control in the Varg field. The paper presents results from a chemical re-selection exercise showing the controlling influence of dissolved iron, together with coreflood studies used to select the most effective non-damaging product for subsequent field trials. Extensive near wellbore modelling results are presented to illustrate the challenges faced with respect to effective chemical placement, which highlight the challenges faced. Several field trials have now been conducted with a new chemical and the results of these are also discussed.
Using Nature to Provide Solutions to Calcareous Scale Deposition
Authors: Cheong W. C. , Neville A. , Gaskell P. H. , Abbott S. 
Published: May 2008

Abstract
The field of biomimetics is expanding in engineering and refers to the mimicking of natural system functionality in technological systems. The most well known example of biomimetics is the development of Velcro which resulted from the inability of burrs from bushes to be removed from the fur of a dog. Biomimetics in surface engineering is also receiving attention as nature provides surfaces with a whole range of functionality. This is often achieved by nanostructuring at different length scales. This work is an initial study of some nanostructured polymer surfaces, derived from the anti-reflective moth-eye structure as surfaces to reduce mineral scale deposition. The study has shown that compared to stainless steel the polymer surfaces all reduce scale deposition and also within the polymers there is a range of behaviour. Some initial suggestions of the controlling factors in deposition on these systems are discussed.