Lu, Alex Yi-Tsung (Rice University) | Ruan, Gedeng (Rice University) | Harouaka, Khadouja (Rice University) | Sriyarathne, Dushanee (Rice University) | Li, Wei (Rice University) | Deng, Guannan (Rice University) | Zhao, Yue (Rice University) | Wang, Xing (Rice University) | Kan, Amy (Rice University) | Tomson, Mason (Rice University)
Deposition of inorganic scale has always been a common problem in oilfield pipes, especially in raising safety risk and producing cost. However, the fundamentals of deposition mechanism and the effect of various surface, temperature, flow rate and inhibitors on deposition rate has not been systematically studied. The objective of this research is to reveal the process of barium sulfate deposition on stainless steel surfaces.
In this work a novel continuous flow apparatus has been set up to enable further investigation of deposition rate, crystal size and morphology and the effect of scale inhibitor. In this apparatus supersaturate barium sulfate solution is mixed and passed through a 3 feet stainless steel tubing with ID = 0.04 inch or 0.21 inch at 70 to 120 degree C. The barium concentration is measured at the effluent to quantify the concentration drop. After 1 to 200 hours the tubing is cut into pieces to measure the barite deposition amount and observe the barite crystal morphology using SEM.
Under the experimental conditions, the deposition rate along the stainless steel tubing can be modelled by second order crystal growth kinetics, the SEM micrograph also shows that most of deposited barite is micrometer sized crystals. The highest deposition rate happens at the beginning of the tubing even before the expected induction time of bariums sulfate. The results indicated that the deposition happens even before the mixed solution is expected to form particles, which suggest that the heterogeneous nucleation might be the dominate mechanism in the initial stage, then crystal growth takes place and governs the deposition.
The mechanism of scale attachment to tubing surface has never been well-understood. The apparatus in this work provides a reliable and reproducible method to investigate barium sulfate deposition. The findings in this research will enhance our knowledge of mineral scale deposition process, and aid the use of inhibitors in mineral scale control.
This paper discusses research on performance of scale inhibitors in the presence of ferrous ion. Iron ion is the most abundant heavy metal ion in wastewater and oilfield produced water. Fe(II) is the dominant form of iron ion in oil and gas wells due to the downhole high anoxic conditions. Fe(II) can form FeS and FeCO3 which will cause severe problems in production. Further, it is important to thoroughly investigate the inhibitor compatibility with these cations in oilfield as the existence of iron in solution effects on inhibitor chemistry.
In this research, Fe(II) effect on various scale inhibitors on barite was tested using an improved anoxic testing apparatus along with laser light scattering nucleation detection method. In this newly designed apparatus strict maintenance of anoxic condition is guaranteed by constant argon flow and switch valve to transfer solution. Moreover, the high Fe(II) tolerance concentration for common inhibitors were tested by varying Fe(II) concentrations from 50-100 mg/L at 90°C and near neutral pH conditions. Most scale inhibitors show good Fe(II) tolerance at experimental conditions, while the inhibition performance of phosphonates were significantly impaired by Fe(II). It is proposed that the formation of insoluble precipitates between Fe(II) and phosphonate is very likely the reason behind the observed significant impairment. Further, two methods to reverse the detrimental effect of Fe(II) on barite scale inhibitor performance is investigated and discussed here. First, a most common organic chelating agents used in oilfield, EDTA, was tested for its ability to reverse the detrimental effect of Fe(II) on scale. Secondly, Fe(II)/Inhibitor concentration ratio was changed so that remaining inhibitor in the aqueous phase would conduct the scale inhibition.
Harouaka, Khadouja (Rice University) | Lu, Yi Tsung (Rice University) | Ruan, Gedeng (Rice University) | Sriyarathne, H. Dushanee (Rice University) | Li, Wei (Rice University) | Deng, Guannan (Rice University) | Zhao, Yue (Rice University) | Wang, Xin (Rice University) | Kan, Amy T (Rice University) | Tomson, Mason (Rice University)
Calcium carbonate deposition experiments were carried out by pumping a brine solution through PTFE plastic, carbon steel, and 316 stainless steel tubing at 150°C and at a maximum SICaCO3 of 1.36. The kinetics of deposition were inferred from the variation of HCO3- concentration in the effluent with changing flow rate. The inhibition kinetics were determined before, during, and after the addition of NTMP inhibitor into the system. On the metal surfaces, deposition occurred within 10 minutes of the start of the experiment and had similar behavior with changing flow rate, whereas deposition did not begin on the PTFE surface until 30 minutes had passed. No more than 1ppm of NTMP was sufficient to completely halt deposition in the PTFE and stainless steel experiments, whereas up to 2 ppm of NTMP was required in the carbon steel experiment. The deposition kinetics were indistinguishable between the metal surfaces, and were ultimately similar on the smoother hydrophobic PTFE surface once an initial coating of scale had developed. The inhibition efficiency of the NTMP was negatively affected by the corrosion products produced in the carbon steel experiments, assumed to be primarily dissolved Fe (II). Inhibitor retention was higher in the metal surfaces than in the PTFE, possibly due to the preferential adsorption of the NTMP to the surface of the Fe rich steel tubing. Our results suggest that it is the hydrodynamics of brine in the tubing, controlled by flow rate, and the SI that are the main factors controlling scale deposition. Calcium carbonate scale attachment occurs via heterogenous nucleation directly onto the surface of the tube when the brine solution approaches oversaturation from a state of equilibrium with respect to calcium carbonate. The mechanism of inhibition in our system is likely to proceed through the formation of Ca- and Fe-NTMP complexes that either poison the growth surfaces of the scale, or drop the SI of the calcium carbonate by reducing the acitivity of free Ca in the brine.
Li, Wei (Rice University) | Ruan, Gedeng (Rice University) | Bhandari, Narayan (Rice University) | Wang, Xin (Rice University) | Liu, Ya (Rice University) | Dushane, H. (Rice University) | Sriyarathne, M. (Rice University) | Harouaka, Khadouja (Rice University) | Lu, Yi-Tsung (Rice University) | Deng, Guannan (Rice University) | Zhao, Yue (Rice University) | Kan, Amy T. (Rice University) | Tomson, Mason (Rice University)
Increasing production activities in sour environments with equipment and piping made of low corrosion- resistant carbon steel result in significant iron sulfides (FeS) corrosion and scaling problems. FeS scale control is challenging as FeS formation is favored in production water chemistry (extremely low solubility and fast precipitation kinetics) with complex phase transformations. Efficient chemical control of FeS scales has not been found. A polymeric compound containing amide or its derivative functionalities showed a promising effect by controlling the FeS particle size on a nano-meter scale at threshold quantities. The FeS scales were successfully managed by forming a stable FeS particle suspension in the aqueous phase without partitioning into the oil-water interface. Current development focuses on understanding the interactions between the polymeric-compound based dispersants and environmental factors such as the presence of an oil phase, as well as silica. In addition, performance improvement of the identified dispersants by new chemical additives has been explored. Our results show that biocides such as Tetrakis (hydroxymethyl) phosphonium chloride (THPS) may not be as effective as needed for FeS scale inhibition benefit. At the tested conditions, EDTA shows satisfactory FeS scale inhibition and dissolution performance. In addition, silica significantly affects wettability of FeS particles with part of the previously oil-wet FeS partitioning into the aqueous phase. The FeS inhibition and dissolution effects of EDTA are kinetically "poisoned" by silica; while FeS-dispersing effect of polymeric compounds remains unaffected. However, the previously-shown ability that polymer dispersants keep already-formed large size FeS particles in the aqueous phase is also impaired.
Kan, Amy T. (Rice University) | Dai, Joey Zhaoyi (Rice University) | Deng, Guannan (Rice University) | Ruan, Gedeng (Rice University) | Li, Wei (Rice University) | Harouaka, Khadouja (Rice University) | Lu, Yi-Tsung (Rice University) | Wang, Xin (Rice University) | Zhao, Yue (Rice University) | Tomson, Mason B. (Rice University)
Numerous saturation indices and computer algorithms have been developed to determine if, when, and where scale will form, but scale prediction can still be challenging since the predictions from different models often differ significantly at extreme conditions. Furthermore, there is a great need to accurately interpret the partitioning of H2O, CO2, and H2S in different phases, and the speciations of CO2 and H2S. This presentation is to summarize current developments in the Equation of State and the Pitzer models to accurately model the partitioning of H2O, CO2, and H2S in hydrocarbon/aqueous phases and the aqueous ion activities at ultra high temperature, pressure and mixed electrolytes conditions. The equations derived from the Pitzer ion-interaction theory have been parametrized by regression of over 10,000 experimental data from publications in the last 170+ years using a genetic algorithm on the super computer, DAVinCI. With this new model, the 95% confidence intervals of the estimation errors for solution density are within 4*10'4 g/cm3. The relative errors of CO2 solubility prediction are within 0.75%. The estimation errors of the saturation index mean values for calcite, barite, gypsum, anhydrite, and celestite are within ± 0.1, and that for halite is within ± 0.01, most of which are within experimental uncertainties. This model accurately defines the pH of the production tubing at various temperature and pressure regimes and the risk of H2S exposure and corrosion. The developed model is able to predict the density of soluble chloride and sulfate salt solutions within ±0.1% relative error. The ability to accurately predict the density of a given solution at temperature and pressure allows one to deduce when freshwater breakthrough will occur. Lastly, accurate predictions can only be reliable with accurate data input. The need to improve accuracy of scale prediction with quality data will also be discussed.
In recent years, surface photovoltaic power generation has attracted more and more attention by the new energy industry. Compared with onshore photovoltaic power generation, the water surface photovoltaic power generation system has more advantages. It is more efficient, it can save land use. The water surface photovoltaic power generation system consists of two parts. One is the floating body which is the support basis of water surface photovoltaic power generation system; another is the photovoltaic panel that is installed on the floating body. The performance of the floating body is directly related to the structural strength and service efficiency of the whole photovoltaic power generation system. Therefore, it is significant to study the hydrodynamic performance and structural strength of water surface photovoltaic floating body.
In order to accurately evaluate the wave loads and structural responses of the water surface photovoltaic floating body, one kind of it that will be used in inland waters is selected as the research object in this paper. First, the hydrodynamic performance of the floating body is analyzed by software ANSyS/AQwA that is based on 3-D potential theory. Then the design wave parameters are determined and the wave loads of the water surface photovoltaic floating body under various working conditions are predicted by the design wave method. Finally, the finite element calculation of the surface photovoltaic floating body is carried out. The results show that the overall strength of the photovoltaic floating body meets the yield strength of the material and conforms with the requirements. The results obtained in this paper can be used as reference for the model test of floating bodies and the further design of water surface photovoltaic floating body in restricted waters.
With the continuous exploitation, fossil energy gradually dried up, the living environment is facing severe challenges. As a new development field, new energy is becoming more and more popular. Solar energy, as a renewable and clean energy with huge reserves, is an important part of clean energy. The water surface photovoltaic power generation system consists of several photovoltaic components that are set up on water surface, it makes the solar power generation technology relate to reservoirs, lakes and so on, and it is a new way of energy development. At the same time, the existing power equipment can be used by the water surface photovoltaic power generation system, which provides convenience for the construction of the power generation system and reduces the cost of the system. As early as 2011, the American Science Daily reported on the floating photovoltaic power stations. In Japan, floating photovoltaic power plants are widely used. Japanese Saitama okegawa floating photovoltaic power plant was completed in 2013. The capacity of the power plant is 1.18MW. The Japanese Hyogo photovoltaic power station was built in 2015. The Japanese Chiba water surface photovoltaic power plant is expected to be built in 2018. It will be the largest water surface photovoltaic power plant in the world. Britain, Norway, India, Korea, Singapore, Brazil, Australia and other countries are focusing on the water surface photovoltaic power generation in recent years.
Tian, Zhe (Ocean University of China) | Lai, Qinghao (Ocean University of China) | Li, Wei (Powerchina Huadong Engineering Corporation Limited) | Li, Zhixiong (Ocean University of China) | He, Wentao (Ocean University of China) | Liu, Guijie (Ocean University of China)
In recent years, with the increasing of the ship size, the ship propulsion should transfer more torque and thrust than before to guarantee the normal operation during the ship navigation which could cause severe vibration of the shaft. For the large vessels, the ship hull is always regarded as a thin walled cavity. Effected by the wave pressure, temperature, stormy waves, streams, the intrinsic materials properties, it easily causes dynamic response of the ship such as heaving, pitching, rolling, heeling. As a result, the hull could be deformed randomly and nonlinearly. Moreover, the deformation of large ship hull changes the position of the bearings which means that the bearings could endure unbalanced supporting forces and be worn dramatically. Meanwhile, due to these unbalanced forces, the propulsion shaft would have a great vibration which could reduce the stability and reliability of the ships propulsion system and threaten the safety of the ship navigation. Therefore, this paper focuses on the vibration characteristics of the ship propulsion shaft excited by the hull deformation. An experimental test of real ship for the shaft propulsion is taken. During the navigation of the large vessel from Yangshan port to Xin port and from Xin port to Fuqing Port, several sensors are used to collect the data from ship hull and shaft propulsion system. Based on the experimental study, several vibration characteristics of the shaft are concluded as well as some suggestions to improve the reliability and safety of the ship operating system.
The development of large vessels such as the VLCC, VLOC, containerships has a great effect on the world trade transportation. It improves the operational efficiency and economy benefits. At the same time, the breakthrough of manufacturing technologies to build the large vessels and its supporting equipment make a great progress in the advanced shipbuilding field. However, the high loss caused by mechanical failure during the operation for large vessels should be paid much more attention. Based on the statistics about 1,484 large vessels from the Swedish Club (Main engine damage study, 2012), the average cost per machinery claim had risen from USD 323,000 to USD 519,000 from 2005 to 2011. During these period, the main engine and propulsion damage contribute more than 55% of total hull and machinery claims cost. As a result, the investigation on the characteristics of the propulsion system of large vessels is quite meaningful to reduce the failure and improve the economy.
He, Jiayi (Marine Design & Research Institute of China, Shanghai Jiao Tong University) | Fan, Sheming (Marine Design & Research Institute of China) | Wang, Jinbao (Marine Design & Research Institute of China) | Noblesse, Francis (Marine Design & Research Institute of China, Shanghai Jiao Tong University) | Yang, Chen-Jun (Shanghai Jiao Tong University) | Li, Wei (Shanghai Jiao Tong University)
The important basic practical problem of filtering inconsequential short waves that have no significant influence upon the wave drag of a ship that travels at a constant speed in calm water of large depth is considered. This problem is an essential and nontrivial element of the prediction of ship waves within the Neumann-Michell theory, a practical theory useful for routine applications to ship design. A simple analytical relation that explicitly determines the wavenumber of insignificant short waves in terms of the Froude number and three main parameters that characterize the ship hull shape is given. This relation is obtained via a parametric numerical analysis, based on the classical Hogner potential flow model, for a wide range of Froude numbers and thirty hull forms associated with a broad range of nondimensional hull-shape parameters. The relation provides a reliable and particularly simple way of filtering inconsequential short waves that have no appreciable influence upon a ship drag.
The flow around a ship of length L that travels at a constant speed V along a straight path, in calm water of large depth and horizontal extent, is considered within the classical framework of linear potential flow theory, which is realistic and useful for most practical purposes as is well documented; e.g. Noblesse et al (2013a), Huang et al (2013), Yang et al (2013), Ma et al (2017), Ma et al (2018). The Froude number F is defined as
where g denotes the acceleration of gravity.
Within the framework of linear potential flow theory considered here, the flow created by the ship can be formally expressed as the sum of a non-oscillatory local flow component that vanishes rapidly away from the ship and a wave component, dominant in the far field as well as in the nearfield. The local flow component can be evaluated in a straightforward manner, as is shown in Noblesse et al (2011), Wu et al (2016), and is not considered here. The ship waves can be expressed as a linear Fourier superposition of elementary waves, and can also be evaluated very simply via the classical Fourier-Kochin approach; e.g. Noblesse et al (2013a), Huang et al (2013), Zhu et al (2017).
Li, Wei (University of Kentucky) | Landon, James (University of Kentucky) | Irvin, Bradley (University of Kentucky) | Thompson, Jesse (University of Kentucky) | Nikolic, Heather (University of Kentucky) | Liu, Kunlei (University of Kentucky)
Corrosion mitigation is an important topic for amine-based post-combustion carbon dioxide (CO2) capture operations due to the desire to use less expensive but corrosion-vulnerable materials such as low carbon steels in the construction of a capture system. In this study, the corrosion behavior of carbon steel in an in-house solvent was investigated in a pilot-scale post combustion CO2 capture process. Carbon steel specimens were placed inside process units where corrosion problems were previously found in the stripper column and the CO2-rich amine piping. An organic compound was studied as a corrosion inhibitor and degradation inhibitor in a range of 0 to 1000 ppm. It was found that the use of this corrosion inhibitor effectively retarded the corrosion rates of carbon steel in both unit locations.
Anthropogenic carbon dioxide generation from the combustion of fossil fuels such as coal and natural gas is one of the main acid gases projected to contribute heavily to global climate change. 1-2 One effective mitigation option is to adopt post-combustion CO2 capture and sequestration, which is a process consisting of the separation of CO2 from industrial and energy-related sources by typically using aqueous solutions of alkanolamines, and then transporting pressurized CO2 to a storage location for long-term isolation from the atmosphere. It is well known that monoethanolamine (MEA) is a benchmark solvent for the commercial application of post combustion carbon dioxide capture systems because of its cost-effectiveness, high capacity for CO2, fast reaction kinetics, and high removal efficiencies. 3 However, documented results have shown that MEA is highly corrosive to steels in the presence of oxygen, H2S, and CO2. 4-6 This can directly affect the whole system efficiency as well as the economics from solvent losses, unplanned downtime, reduced equipment lifetime, and even injury or death due to the damage by corrosion of main components of equipment made of steel.
Zhong, Xun (Department of Petroleum Engineering, University of North Dakota) | Wang, Yuhe (Department of Petroleum Engineering, Texas A&M University at Qatar) | Pu, Hui (Department of Petroleum Engineering, University of North Dakota) | Li, Wei (College of Petroleum Engineering, Northeast Petroleum University) | Yin, Shize (Missouri University of Science and Technology) | Ling, Kegang (Department of Petroleum Engineering, University of North Dakota)
Chemical enhanced oil recovery(EOR) such as polymer flooding and alkali/surfactant/polymer(ASP) flooding have been applied throughout the world for more than several decades. However, few large-scale successes of these technologies have been reported, except in China. The annual crude oil production rate by chemical EOR in Daqing Oilfield has been kept over 10.0 million tonnes (~73.5 million barrels) per year for 16 consecutive years. Considerable experience has gained and lessons have learned on large-scale chemical flooding, including major factors that influence the recovery factor and methods to increase the oil recovery; measures to obtain the highest economic efficiency; and how to minimize the costs.
To date, incremental oil recovered by polymer flooding is over 10.0% OOIP. Due to some disadvantages of polymer flooding, like the existence of inaccessible pore volume and lack of the EOR mechanism of ultralow interfacial tension, some substitute technologies are needed, and ASP flooding is a promising one, which was reported and proved to have an ability of recovering more than 20.0% extra oil over water flooding. However, negative scaling problems caused by alkali are severe and problematic, as a result, weak-alkali ASP (WASP) and even surfactant-polymer (SP) flooding were developed or are under development. To alleviate the bad effets of scale and further improve the performance of ASP flooding, some new technologies such as refracturing and application of new anti-scaling chemicals like compound scale removal agent were applied. SP flooding is a theoretically feasible EOR technology, but there are few field test data available, and more effective surfactants are required.
In this paper, the development of commonly used chemical flooding technologies, normal problems that may merge during commercial implementation, together with the updated solutions are included. All the valuable experience obtained from commercial-scale application of chemical flooding in Daqing Oilfield is not only of great significance for the expansion of Daqing Oilfield itself, but also worth learning by other countries.