Dan Dan Yuan

Effect of Specific Ions in Preparing Water on Viscosity of Polyacrylamide Solution

Served as polymer flooding for the enhanced oil recovery, partially hydrolyzed polyacrylamide (PAM) has widely been employed for the oil production. The PAM solution prepared by the ground clean water was characterized with a higher viscosity in the early years while one, made by the oilfield produced water in the existence of complicated constituents, features a worse viscosity in the recent operation. In the practical opinion, the viscosity is an important indicator of the polymer flooding. The high viscosity of aqueous PAM solution has being pursued for a goal of the successful operation. For the reason, this research objective could be set toward seeking the causes of the viscosity degradation. In this paper, specific ions in the preparing water on effects of the PAM viscosity were identified and evaluated by the analysis of produced water quality used by the operation of preparation in Daqing oilfield. Effects of the specific ions on PAM viscosity were investigated in the lab test for understanding and controlling the viscosity. The results show that the dominant specific ions were found out to consist of the divalent cation (Ca2+ and Mg2+), trivalent cation (Al3+), divalent ferrous ion (Fe2+) and divalent sulfide ion (S2-) by means of the data and related chemical theory. Much notable viscosity degradation of PAM solutions was observed in the degree-viscosity curves as the role of most of the specific ion factors. Totally, the retention rate of the viscosity was obviously lowered with the extension of the specific ion by degrees. By the results, the mechanism of the viscosity degradation was briefly proposed and discussed. These data can be provided and suitably specified for the benefit of polymer flooding production.

Effect of Physical Factors on Viscosity of Polyacrylamide Solution Prepared by Oilfield Produced Water

In the recent industrial practice, the produced water has been used for the preparation of polyacrylamide (PAM) for the enhancement of oil recovery in Chinese oilfields. With more affecting factors than the tap water, the produced water, originating from the existence of complicated constituents in the water, leads to the worth viscosity of the PAM solution. In this paper, the affecting factors were identified and evaluated by the analysis of the PAM operations of preparation, storage and production in Daqing oilfield. Effects of physical factors on PAM viscosity were studied in the lab test for understanding and controlling the viscosity. The results show that the dominant physical factors are composed of the heat, storage time, mechanical stress and photo/sonic radiation. Most notably viscosity degradation of PAM solution was exhibited by actions of most of the factors. By the results, the mechanism of the controlling viscosity was briefly proposed and discussed. These data can be provided and suitably specified for the benefit of polymer flooding production.

Corrosion of Steel Tank for Treatment of Oil-Water Transition Layer with ClO2-Oxidation Process

The separation of oil/water transition layer in settling tank becomes deterioration during the late oil production. For improving the dehydration of oil - water layer in settling tank, the oxidation technique by chlorine dioxide was adopted for the demulsification. Chlorine dioxide typically is strong oxidizing reagent. The touched materials would be corroded by the chemical. Therefore, it is necessary to evaluate the corrosion of chlorine dioxide for the steel in the settling tank. In this paper, the research was made to the determination of corrosion rate and corrosion morphology of steel equipped for oil/water transition layer treated with Chlorine dioxide oxidation. The experiments showed that, in the oil/water transition layer after treatment, water phase has the highest corrosion rate of up to 0.151 mm/a and lower than the company-formulated standard of 1.0 mm/a, which falls into the permission range (0.1-1.0 mm/a) of the corrosion standard Class 3. From steel-hanging corrosion morphology, it can be seen that the steel corrosion is weaker before the treatment while becoming stronger with the addition of ClO2 system and acidic solution. The reaction and mechanism were also explained on the corrosion chemistry of oil/water transition layer treated by oxidation process. With the experimental data, the oxidation and corrosion performance of chlorine dioxide can be controlled effectively to play an important role for stable production of oilfield.

Effect of Reaction Conditions on ClO2-Oxidation Demulsification for Oil-Water Transition Layer in Settling Tank

In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2-oxidation demulsification for oil-water transition layer in settling tank is introduced. In this paper, effects of reaction conditions on ClO2-oxidation demulsification were studied. The results show that the reaction temperature, reaction time and PH value have a heavy effect on the dehydration rate of the oil-water transition layer. With the increasing of the reaction time, the dehydration rate largely rises, and it can reach 84.18% and keep steady when the reaction is in 4 hours. With going the temperature up, the dehydration rate increases in a nonlinear way, and it can reach 85.23% at the temperature of 55°C. By decreasing the PH value, the dehydration rate significantly rises, and the maximum dehydration rate of 84.18% was achieved when adding 0.5 vol. % of the acid. The chemistry was discussed based on the principles and experiments. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

Analysis of Physical Structure and Chemical Composition of Oil-Water Transition Layer in Oil Gathering and Transportation System

he existence of oil-water transition layer brings a great trouble to the dehydration of oil gathering and transportation system. It leads to raising the electric current of dehydrator and becoming worse of the deoiling and dehydrating properties of the treatment equipment, resulting in the serious influences on oil recovery. For the efficient treatment of the transition layer, it is necessary clearly to understand the structure and composition of the layer. In this paper, the physical structure and chemical composition of the layer were systematically, layer by layer and phase by phase, analyzed by modern instrumental methods The results show that (1）the layer is an emulsion which is composed of oil, water and suspended solids. The water phase has characteristics of weak alkaline，high salinity and viscous polymer. The oil phase contains many natural emulsifiers such as colloid, asphaltene and so on. The solid phase mainly concludes FeS particle which plays a decisive role in suspended solids; (2) the typical transition layer is composed of water and oil which accounts for above 90%, the content of solid impurity, which controls the emulsion of the layer, is less than 10%. Compared with oil phase, the water content of typical transition layer is larger with the density of 0.9~1.0 g/L and high freezing point. The analytical data can be adopted for the treatment of oil-water transition layer and smoothly run operations for oil gathering and transportation.

Scaling Laws and Forecasting Techniques of Silicate in ASP Flooding

Served as alkaline-surfactant-polymer flooding for the enhanced oil recovery, alkaline-surfactant-polymer has widely been employed for Chinese oil production. In the practical opinion, the silicate scaling, which was formed by alkali, would harm layer gradually and affect oilfield production seriously. For the reason, in this paper, the phase diagrams of silicate scale were obtained in three different systems, including single silicon system, calcium/ magnesium/ silicon coexistence system, and calcium/ magnesium/ silicon/ aluminum coexistence system. The results showed that, other ions would affect the morphology and process of silicate scaling. In the experimental research range, silicate scaling is more easily to form with the lower temperature or pH value. The mixing scale was formed by absorption of silicate scale on the surface of carbonate scale. The aluminosilicate was formed by aluminum ions and silicon. The silicon scale forecasting model and equation of three different systems in ASP flooding with alkali was set up according to lab date. These data can provide theoretical basis for preventing scaling in oil production

Influence of La2O3 on NOx Emission in Iron Ore Sintering

NOx emission in coke combustion with and without La2O3 was investigated in a fixed bed quartz reactor. The effects of La2O3 loading and lanthanum oxide particle size on NOx emission were discussed. NOx emission was also studied by sintering pot tests with lanthanum oxide modified coke as sintering fuel. The results showed that lanthanum oxide was catalytically active in promoting not only coke combustion but also NOx reduction. In coke combustion experiments, NOx and CO emission decreased with increasing lanthanum oxide loading up to 2.0wt% and decreasing lanthanum oxide particle size (28~150μm).

Investigation on the Extraction of Aluminum and Iron from Fly Ash by Sodium Carbonate Fusion Method

In recent years, utilization of fly ash has gained much attention in public and industry, which will help reduce the environmental burden and enhance economic benefit. In the utilizations of fly ash, the most high value-added applications is extraction of metal elements from fly ash. In this paper, the aluminum and iron extraction was investigated by orthogonal experiments. The results show that the optimum extraction condition was reaction temperature 800 °C, reaction time 3 h, the mass ratio of fly ash to Na2CO3 was 1:1.5.

Comparative Study on Compositions of Oil-Water Transition Layer before and after ClO2-Treatment Process

In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2 treatment for oil-water transition layer in settling tank is introduced. The field test displayed that the technique was achieved by a good performance. For understanding the oxidation and mechanism, compositions of oil-water transition layer were comparatively studied for before/after ClO2-treatment in this paper.The experimental results show that the compositions before and after ClO2-treatment, including physical structure and chemical composition, were varied in the great extension. The physical structure, consisting of water, oil and solid phase, was reduced to less than 5% of water and 0.5% of solid particle and increased to 95% of oil in layer compared with before-treatment, easily leading to clearly separating water from oil. The chemical composition of iron sulfide and acid insoluble substance in solid phase was decreased to more than 90% while the carbonate was reduced more than 70% . After the treatment, the viscosity reduction of the water phase in the layer was reached to 50% after oxidation demulsification with ClO2. The chemistry was discussed based on the principles and experiments. Due to ClO2 destroying (oxidizing) the rigid interface membrane structure which is supported by natural surfactant, polymer and solid particles with interface-active materials, the action accelerates the separating of water and oil and sedimentation of insoluble residue of acid in the layer. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

Effects of Processing on Mechanical Properties of Polypropylene Composites

Based on the mechanism of processing and molding of multivariate polypropylene composite system, this paper studies the effect of the screw length-to-diameter ratio and the wedge angle of the helix angle of the twin-screw extruder on the properties of elongation at break of polypropylene composite. The relationship between injection temperature and injection pressure of injection molding machine is also analyzed. Experiments show that when length-to-diameter ratio is 30, and wedge angle is 16±5o, the elongation at break of test sample reaches its maximum value and tends to be stable. When melting pressure is 40 MPa and the injection temperature at 190 °C-220 °C, injection molding machine can improve the process flowing property of composite materials.