bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Turbulence (or Hydrodynamic Effects) on Strontium Sulphate Scale Formation and Inhibitor Performance
Authors: Johnston Clare , Sutherland Louise 
Published: February 2021

Abstract
Inorganic scale (carbonate, sulphate and sulphides) formation can be predicted from thermodynamic models and over recent years better kinetic data has improved the prediction of such scales in field conditions. However these models have not been able to predict the observed deposition where flow disturbances occur, such as at chokes, tubing joints, gas lift valves and safety valves. This can lead to unexpected failures of critical equipment such as downhole safety valves (DHSV’s), and operational issues such as failure to access the well for coiled tubing operations due to tubing restrictions.
In recent years it has been recognised that the turbulence found at these locations increases the likelihood of scale formation and experiments have been able to demonstrate that increased turbulence also impacts the minimum scale inhibitor concentration required to prevent scale.
One of the industry standard test methods used to screen inhibitors for sulphate scale inhibition is the static bottle test. In this paper the ‘static’ bottle test method is modified to investigate the effects of increasing levels of turbulence on the formation of strontium sulphate scale at a fixed brine composition. Using this modified method it has been possible to demonstrate the impact of varying turbulence on the performance of two common generic types of scale inhibitor (phosphonate and vinyl sulphonate co-polymer). Data on the mass of scale formed, scale morphology using SEM imaging and inhibitor efficiency will be linked to degree of turbulence and scale inhibitor functionality (nucleation inhibition vs. crystal growth retardation). This study builds on the previously published10 findings for barium sulphate which showed phosphonates were less affected by turbulent conditions by carrying out similar tests on strontium sulphate. A clear mechanistic conclusion can now be drawn for sulphate scale formation and inhibition under increasingly turbulent conditions.
The findings from this study have a significant impact on the methods of screening scale inhibitors for field application that should be utilised and development of suitable inhibitors that perform better under higher shear conditions.
Carbon Nanotubes: A New Methodology for Enhanced Squeeze Lifetime CNTs
Authors: Ghorbani N. , Wilson M. C. , Kapur N. , Fleming N. , Neville A. 
Published: February 2021

Abstract
A new potential application of nanotechnology for mineral scale prevention in the oil and gas industry is presented. In current squeeze treatments, in which scale inhibitors are squeezed into wells to adsorb or precipitate onto rock surfaces for later release, a large proportion of the injected inhibitor does not adsorb and is therefore returned very quickly from the reservoir upon well re-start. Here it is demonstrated that nano-particles have the potential to enhance squeeze lifetime by greatly increasing the adsorption of inhibitors within the formation. An extensive literature review is presented, exploring the potential for using nano-scale materials in squeeze treatments. One of the observations from scale inhibitor squeezes into sandstone reservoirs is the apparent lack of suitable surfaces available for adsorption. The main constituent of sandstones, quartz, has a very low ability to adsorb inhibitor (1 mg/l). Given this, research using nanotechnology was targeted towards enhancing the available sites for scale inhibitor adsorption within the near wellbore. Specifically, research was undertaken to examine the potential benefits of using carbon nanotubes in a process called Nanotechnology Assisted Squeeze Treatment (NAST). The process involves carbon nanotubes adsorbing and permanently modifying the near wellbore with scale inhibitors subsequently adsorbing onto the nanotubes. This process was observed to be significantly higher than a non-modified near wellbore surface, with a maximum adsorption of more than 85 and 160mg/g onto the nanotubes in solution of distilled water (DW) and CaCl2 in DW; respectively, compared to 1 mg/g directly onto the rock. Coreflood tests comparing the NAST procedure with a simplified standard coreflood show the potential for improvement of the squeeze lifetime.
Influence of Calcium and Bicarbonate Ions on the Kinetics of CaCO3 Formation at High Temperature in the Absence and Presence of Scale Inhibitors
Authors: Xu Bo , Chen Tao , Chen Ping , Montgomerie Harry , Hagen Thomas , Guo Qi , Yang Xu 
Published: February 2021

Abstract
The calcium and bicarbonate ions, present in the produced waters in the oilfields, are two major scaling ions in CaCO3 formation. In the last decade, a lot of studies have been focused on the thermodynamic or kinetics of CaCO3 formation, including the effects of scaling ions, temperature, pH, pCO2, etc. Seldom studies are focused on the kinetics of calcium carbonate surface deposition with different levels of calcium and bicarbonate, especially in the presence of scale inhibitors.
In the work reported herein, dynamic loop tests were carried out to study the kinetics of CaCO3surface deposition in three typical produced waters (Water-1, high calcium and low bicarbonate; Water-2, medium calcium and medium bicarbonate; Water-3, low calcium and high bicarbonate) with same saturation index (SI) at 150°C. Typical scale inhibitor chemistries, including phosphonate, polycarboxylic, polymaleic, polysulphonate, polyacrylic, polyaspartate based scale inhibitors, have been tested in three tested waters.
The following conclusions are drawn based on the test results.
SI generated by applied prediction software is a parameter indicating the thermodynamic driving force. The kinetics of scale formation, more representative field conditions, should be studied as well to give a guideline of scale formation in the fields. Comparison of calcium, bicarbonate is the dominant kinetic factor for CaCO3 formation in the absence and presence of inhibitors. Higher bicarbonate water, higher minimum inhibitor concentration (MIC) is requested, even the three tested waters with a same SI. The ranking of the performance of scale inhibitor are dependent on the water chemistries and inhibitor chemistries. Some of the best ranking phosphonates in Water-1 and Water-2 with low and medium bicarbonate showed poor performance on Water-3 with high bicarbonate. Some polymers showed contrary ranking performance.
This paper gives a comprehensive study of the kinetics of CaCO3surface deposition considering the effects of calcium and bicarbonate, including prediction, laboratory evaluation, mechanisms and inhibitor selection. It will contribute to understand the kinetics of CaCO3 formation and recommend effective inhibitors for field application. Environmentally acceptable inhibitors have been developed for different CaCO3 water chemistries at elevated temperature and are suitable for applications through squeeze treatment or continuous injection.
Scale Removal with Ultrasonic Waves
Authors: Kunanz Hartwig , Wölfel Sylvia 
Published: February 2021

Abstract
Today, ultrasound is a widely used technology for a number of industrial applications, from processing liquids and slurries, cleaning of optical lenses and jewellery, purification of water, enhancement of mechanical and physical properties of metals, welding, dispersing, humidifiers, to material testing. In the oil and gas industry the ultrasonic technology is typically used for measurement applications. This paper describes first test and research results using ultrasonic waves to remove scaling in the borehole. So far most standard scaling treatments involve the use of chemicals. With ultrasonic treatment, it may be possible to reduce or even substitute the chemical applications. This transgression from a chemical to a physical cleaning process would most likely save costs and reduce the environmental impact. Scaling from calcium carbonate, gypsum/anhydrite or barium/strontium sulfate is considered a major issue with oil and gas production, causing the industry enormous efforts on prevention and removal. To assess the usability of ultrasound for scaling removal, a series of laboratory experiments were conducted, starting with gypsum due to its easy handling and continuing with the more critical calcium carbonate scaling. The cleaning effects could be proven and the main factors influencing the ultrasonic cleaning efficiency could be identified in the laboratory. This paper will present and discuss the findings so far and will give an outlook on future research issues with ultrasonic scale removal.
Prediction of Barite Scaling Risk and Inhibition for Oil and Gas Production at High Temperature
Authors: Zhang Fangfu , Bhandari Narayan , Kan Amy T. , Tomson Mason B. , Yan Chao 
Published: February 2021

Abstract
Barite (BaSO4) is one of the common scales in oil and gas production. Extensive work has been conducted to study barite nucleation and inhibition at temperatures below 100 °C. However, with the advance in deepwater exploration and production which can encounter high temperature conditions, a better understanding of barite scaling risk at high temperature (e.g., &gt;150 °C) becomes essential. In this paper, a systematic study was conducted to explore barite nucleation kinetics from 70-200 °C in synthetic brines containing phosphonate (0-10 ppm) or polymeric (5-10 ppm) scale inhibitors. A 2-hour protection time with or without any detectable barite nucleation was employed to define the scaling risk. To detect barite nucleation, two novel apparatus were developed, a modified dynamic flow loop and a batch reactor. The modified dynamic flow loop has a retention time of up to 4 hours and is ideal to carry out experiments at above 100 °C. Ba concentrations in the effluents were monitored to determine barite nucleation more precisely compared to traditional “tube blocking” technique. The new batch reactor employs our newly developed laser detection method, a transparent pressure tube, and an oil bath. The transparent pressure tube allows laser to pass through and can withstand 150 psi pressure at 150 °C, which therefore provides an efficient and convenient approach to study the precipitation kinetics of scales and evaluate inhibition efficiency of inhibitors at high temperature. Constant inhibitor concentration isoplethes of diethylenetriamine pentamethylene phosphonic acid (DTPMP) for barite inhibition were constructed based on our experimental data. The results of this study can facilitate the selection of an appropriate DTPMP concentration for scale treatment for high-temperature oil and gas production.
Attachment/Release of Phosphonate to/from a CaCO3 Surface in Supersaturated Brines
Authors: Zhang Nan , Kan Amy T. , Tomson Mason B. 
Published: February 2021

Abstract
One of the most intractable concerns when engineers try to reuse the produced water as frac fluid in the Bakken and some other shale plays is the scale formation caused by the incompatibility of produced water with additives in the frac fluids and with the formation. In order to obtain a more efficient scale treatment for a successful hydraulic fracing that handles the extraordinary amount of water with high supersaturation level, the better understanding of inhibitor retention and release in the production system is urgent.
To explore the mechanism of attachment/release of phosphonate to/from a mineral surface, calcite supersaturated feed solutions with different diethylenetriamine penta (DTPMP) concentrations were introduced into the steel tubing that was internally pre-coated with a thin layer of CaCO3. It is unveiled that DTPMP attachment was dominated by the precipitation of calcium phosphonate solid once the solution is supersaturated with Ca3H4DTPMP (pKsp=53.5), and the total amount of DTPMP attached on the calcite surface added up with the increasing supersaturation of Ca3H4DTPMP. The co-precipitation of CaCO3 and Ca3H4DTPMP has facilitated the attachment of the inhibitor with the increase of supersaturation of CaCO3. The retained phosphonate was released from the surface with a steady and low level inhibitor concentration over extended period of time. Combining with the kinetics of calcium carbonate precipitation in the presence of inhibitor, a 1500 gram of calcium phosphonate precipitation can protect the scaling for about 100 days (100 bbl/day) when the saturation index of calcium carbonate (SIcalcite) is as high as 1.3.
The results provide a better understanding of calcium-phosphonate-carbonate interaction, and show the phosphonate inhibitor can continuously accumulate on the carbonate and slowly dissolve. We anticipate this study can shed a light on how much inhibitor can be delivered to the unconventional reservoir as well as the theoretical limitation of inhibitor return in the flowback water.
Scale Inhibitor Residual Analysis: Twenty-first Century Approach
Authors: Zhang Y. , Daniels J.K. , Hardy-Fidoe J. , Durnell C. , Broussard M. E. , Hammond E. , Huang X. 
Published: February 2021

Abstract
Control of inorganic scale deposition within the near well bore area under both natural depletion and injection water support has been a challenge to the oil industry for a number of decades. The application of scale inhibitor squeeze treatments to production wells to control the onset of inorganic scale within the near-wellbore and production tubing has been a common practice within the onshore and offshore oil and gas industry for over 30 years.
The development of subsea fields require scale inhibitor squeeze treatments with extended squeeze lifetimes while limited number of flowlines to the host facility has increased the difficulty in obtaining and evaluating individual well water samples from which residual scale inhibitor concentrations are derived. Traditional analytical techniques, while robust and widely accepted, do not provide differentiation between scale inhibitors that belong to the same chemical family (i.e.: two or more phosphonates or two or more polymers).
The individual analysis of phosphonate scale inhibitors in co-mingled flow backs from subsea wells is a particularly challenging application for analytical techniques in the industry. Advances in separation and mass detection techniques, however, provide new options to accurately measure the concentration of scale inhibitors in these fluids to very low detection limits.
This paper will describe the analytical development of these new techniques and discuss its implication to the optimization of scale squeeze treatments in subsea, deepwater developments.
Laboratory Methods for Scale Inhibitor Selection for HP/HT Fields
Authors: Daniels J. K. , Littlehales I. , Lau L. , Linares-Samaniego S. 
Published: February 2021

Abstract
HPHT (high pressure, high temperature) conditions create challenges and push the limits of existing technology (i.e., scale prediction modeling, testing methodology and instrumentation) and commercial scale inhibitor chemistry. Scale prediction modeling often fails at HPHT conditions and laboratory testing under appropriate field conditions have to be compromised due to instrument limitations. This paper details work done under high temperature (204°C) and elevated pressure (3,000 psi) conditions in in order to obtain effective scale control.
More specifically, this paper will discuss selection methods for continuous and squeeze scale inhibitor application via dynamic performance testing and coreflood studies for scale control in this deep-water oil production field. The technical challenges encountered such as matching the scale type predicted in the prediction software to the scale observed during dynamic tube blocking will be outlined. Thermal ageing procedures/performance testing for continual injection chemicals and performance testing of coreflood effluent from HT coreflood studies will be outlined.
Do We Need Higher Dose Scale Inhibitors to Inhibit Scale under Turbulent Conditions? Insight into Mechanisms and New Test Methodology
Authors: Chen Tao , Chen Ping , Montgomerie Harry , Hagen Thomas , Benvie Ronald , Guo Qi , Anyanwu Uche , Xu Bo , Yang Xu 
Published: February 2021

Abstract
Turbulent flow, especially around chokes, downhole safety valves and inflow control devices, favors scale deposition potentially leading to severe loss of production. Recently, scale formation under turbulent conditions has been studied and progressed, focused on the bulk precipitation (SPE164070) and a small bore valve loop test (SPE 155428). However, bulk precipitation is not fully representative the surface deposition in the fields and the Reynolds number of modified loop is unknown. The relationship between a measured Reynolds number and surface deposition up until this study has not been addressed.
A newly developed test methodology with rotating cylinder has been applied to generate high shear rate and evaluate surface deposition with Reynolds numbers up to ~41000. The relationship between Reynolds number and surface deposition is addressed. Using this highly representable test method for BaSO4 scale deposition, several different generic types of inhibitor chemistries, including polymers and phosphonates, were assessed under different levels of turbulence to evaluate their performance on surface deposition.
The results showed it is not always true that higher turbulence results in higher dose of inhibitor being required to control scale. It is inhibitor chemistry and mechanisms dependent. The scale inhibitorscan be classified as three types when evaluating the trend of mass deposition versus Reynolds number and the morphology of the crystals deposited on the metal surface.
➢ Type 1: Crytal growth inhibitors. The mass of surface deposition increases with the increase of turbulence, along with smaller crystals. ➢ Type 2: Dispersion and crystal growth inhibitor. The higher the turbulence, the less mass deposition, along with smaller crystals. ➢ Type 3: Dispersion scale inhibitors. The higher the turbulence, the less mass deposition. The size of the crystals has no major change.
This paper gives a comprehensive study of the effect of flow condition on the scale surface deposition and inhibition mechanisms. In addition, it details how this methodology and new environmentally acceptable inhibitor chemistry can be coupled to develop a chemical technology toolbox that also includes techniques for advanced scale inhibitor analysis and improved scale inhibitor retention, to design optimum scale squeeze packages for the harsh scaling conditions associated with turbulent flow conditions.
Minimizing Scale Deposition Through Surface Enhancement in Downhole Tools
Authors: Graham G. M. , Goodwin N. , Albino E. , Guan H , Pinto H. L. , Bezzera M. C. 
Published: February 2021

Abstract
The intervention of sophisticated downhole tools, such as inflow control devices (ICDs) and inflow control valves (ICVs), has led to increased shear stresses being experienced in the wellbores near these devices. This results in an increased risk of scale formation and adherence even under mild levels of oversaturation - i.e. scale is likely to form as a result of the increased shear conditions. This can lead to situations where mildly oversaturated downhole carbonate scaling regimes result in scaling when they would otherwise remain “meta-stable” and not precipitate until further up the production system where they can be easily managed. Materials of construction and surface conditions can potentially have a critical impact on whether downhole scaling and productivity impairment is observed.
In this work, we have focussed on downhole carbonate scaling under new deepwater field conditions where the drawdown in the near wellbore area results in oversaturated brine systems. Downhole conditions have been modelled and closely simulated in the laboratory to ensure that test conditions match the mild level of oversaturation expected.
The work initially examines the relationship between increased shear and increased scaling examining bulk scaling (homogeneous precipitation) and the relationship between shear and surface scaling, showing that increased scaling can be expected at higher shear. More significantly the work progresses to examine several different materials commonly used in ICVs including different metallurgies, and surface finishes as well as selected coatings. Work at elevated shear conditions clearly shows the potential to minimise surface scaling by careful material selection and/or by the use of appropriately selected coatings.
In addition to tests designed to examine the affect of shear under conventional conditions (e.g. bulk tests and high shear rotating coupon tests), a pilot rig incorporating a mock-up valve has been designed and commissioned, allowing testing of the potential for scaling under realistic downhole flow conditions at representative temperatures and pressures and at test flow rates of up to 8 l/minute. Complementary results from these tests will also be presented in the paper to further illustrate the importance of surface conditioning in critical locations.
Qualification of Chemicals/Chemical Injection Systems for Downhole Continuous Chemical Injection
Authors: Stewart-Liddon Christine , Goodwin Neil J , Graham Gordon M , Tjomsland Tore , Hustad Britt Marie , Svela Odd Geir , Olsen John Helge , Østgaard Simon 
Published: February 2021

Abstract
Downhole Continuous Injection (DHCI) Systems are increasingly being installed in wells for the delivery of a range of chemicals, including application-specific formulations and multi-component chemicals. Although costly, these systems offer the advantage of controlling chemical doses, preventing interruptions to production by providing constant delivery of chemicals and can be used in place of squeeze treatments that can be costly or inappropriate if formation damage is a risk.
However, such systems are not without challenges for engineering design, operation and the effective qualification required for the chemicals before use. DHCI involves chemical injection through multi-kilometre capillary tubing, as well as injection through inline filters and one or more injection valves. Failures of continuous injection systems have been linked to a variety of causes such as corrosion, particulate formation or chemical gunking, resulting in line plugging or blockage of injection valves and filters. The work described in this paper was initiated to investigate known DHCI issues within Statoil fields and to develop laboratory tests to identify characteristics of chemical formulations that result in similar behaviour, and thus allow such formulations to be de-selected prior to use.
The paper describes a range of chemical qualification methods for DHCI systems, focusing on qualifying the chemical for use in a DHCI. Test methods have been developed which demonstrate the ways in which changes in physical properties can readily occur under downhole injection which can have a considerable detrimental impact on the integrity and effectiveness of the DHCI system. These methods have now been finalised into a set of chemical qualification protocols for Statoil.
This paper will present the basis of these test protocols and thereby intends to present best practice for chemical/system qualification for DHCI. Results from both extensive laboratory method development studies and field case histories will be included throughout the paper to illustrate the challenges faced and the qualification solutions developed.