ASP Flooding Research Articles

Effects of Temperature on Silicate Scale Inhibition During ASP Flooding

Effects of Temperature on Silicate Scale Inhibition During ASP Flooding

Research on Alkaline Detergent and Descaling Mechanism in ASP Flooding

In view of the oil well scaling phenomenon and the disadvantages of existing pickling descaling, the alkaline detergent which can be used in oil well was prepared. The effect factors of the alkaline detergent were studied. The results show that the alkaline detergent in ASP Flooding has certain descaling effect on different composition of scale. The descaling effect of the carbonate is better than that of silicon aluminosilicate. The temperature and reaction time has a great influence on the descaling effect. Raising the temperature and prolonging the reaction time can obtain good effect.

The Characterization of the Rock Microscopic Pore Structure before and after Strong Base ASP Flooding

ASP flooding technology is an important means to further improve oil recovery of oil field later high water-cut stage. As is found in pilot test of ASP flooding, in the process of injecting ASP combinational flooding fluid, alkaline chemical react with the rocks minerals in reservoir and dissolve and elute the portion of the silicon in rocks minerals after injecting into formation. Due to the mixed flow occurred in near well bore zone and the changes in pressure and temperature, produced liquid produces mixed silicon scale near the well .The serious scaling phenomenon has affected the production efficiency and the further popularization of the ASP flooding technology.The serious scaling phenomenon has affected the production efficiency and the further popularization of the ASP flooding technology.It is very important to study and solve the problem of ASP flooding silicon scale.In this paper,we studied the interaction ternary displacement liquid and formation, analysised the physical and chemical processes of silicon scale, researched and analysised the differences on the microscopic pore structure between water flooding cores and ASP flooding cores as well as the situation of silicon scale after the ASP flooding by using SEM technology.

Impact of Acrylic Acid on ASP Flooding Performance: Interfacial Tension Behaviour

Impact of Acrylic Acid on ASP Flooding Performance: Interfacial Tension Behaviour

Simultaneous/sequential alkaline‐surfactant‐polymer flooding in fractured/non‐fractured carbonate reservoirs

Alkaline‐Surfactant‐Polymer flooding is one of the most novel chemical enhanced oil recovery methods in the petroleum industry. This method has attracted interest due to its remarkable advantages. In this work, a series of ASP floods are conducted on fractured/non‐fractured carbonate rocks. The performance of the tests was investigated by various ASP floods consisting of five types of polymers, two surfactants and one common alkaline. ASP was flooded simultaneously and sequentially in four defined scenarios after water flooding. The results showed that although using hydrolysed polymers increases the recovery factor in the fractured medium, sulfonated polymers increase oil recovery even more due to their capability to increase viscosity in saline solutions. Also, since polymers with a higher molecular weight have a larger hydraulic diameter, they increase oil recovery considerably. Moreover, using cationic surfactant improves the efficiency of ASP flooding due to the serious reduction of interfacial tension (IFT) in comparison to using the anionic one. In addition, according to the four scenarios' results, pushing ASP by polymer is much more effective than pushing it with brine. Also, the difference in final oil recovery between simultaneous and sequential ASP floods is more remarkable when ASP is pushed by brine. Thus, choosing a process completely depends on the slug type and the injected volume.

Study of the Formation and Influence Factors of Silica Scale in ASP Flooding

ASP Flooding has a better displacement efficiency, but there is still a serious problem of wells scaling. Researched on formation mechanism and influence factors of silica scale in ASP flooding with alkali, the formation of silica scale is mainly due to the alkali dissolution reaction of reservoir rock to produce the soluble silicon ions and form silica scale in formation conditions. Laboratory experiments simulated formation mineralization aqueous solution, analyzed the morphology of silica scale by scanning electron microscopy, and studied the role played by calcium, magnesium, aluminum ion, polyacrylamide, surfactant. The experimental results show that: calcium, magnesium, aluminum ions, polyacrylamide, and surfactant can promote the formation of silica scale, and the morphology characteristics of silica scale are different.

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

Optimizing Structure about Strong Base ASP Flooding Molecule Weight Adjusting Mechanism

Daqing oilfield ASP flooding drive target gradually changes from the first reservoir to the second and third reservoir,which leads to the unequal of the reservoirs producing extent, and seriously affects the developing for ASP flooding molecule weight. On the basis of that, we optimum the Molecule Weight Adjusting Mechanism of low permeability reservoir, and use the method of control variables to change the nozzle angle of diffuser section, cylinder length, diffuser angle, nozzle angle to establish 81 models. At the same time, we simulate flow field characteristics of these models with the help of Fluent. Ultimately, the models of low pressure drop and high stick loss rate could be found. Through analyzing and contrasting large of models, we found that shrinkage angle is 30 degree models under the same pressure drop condition the stick loss rate relativity high. Simultaneously, these models are suitable for the field requirements, and can provide theoretical basis for molecular weight adjusting and optimizing structure.

Study and Application of Numerical Simulation of Deep Profile Control with Weak Gel

With the development of numerical reservoir simulation technology, numerical simulation has been widely applied to studies on the mechanics of all chemical flooding and injection approaches. In this study, a mathematical model for three-dimensional two-phase sixcomponent deep profile control with weak gel is established based on the mechanics of deep profile control with weak gel. The established model takes diffusion, crosslinking reaction, adsorption, degradation and other physical or chemical phenomena into consideration. A numerical simulation software for deep profile control with gel was created with FOR99 programming language. Using this software, we performed optimization on the slug combination and slug size for the intra-flooding deep profile control with gel in ASP flooding for Xingbei development zone of Daqing oil field. The analysis on the mechanics of deep profile control with gel demonstrated that the addition of the profile control system could strengthen the profile adjustment effect. After the crosslinking system is injected into oil layer, less displacing fluid could enter the high-permeability layers, stimulating more displacing fluid to enter moderate or low-permeability layers, thereby the oil displacement effect is improved.

Effect of Reaction of NaOH and Daqing Crude Oil on Oil/Water Interfacial Properties and Emulsion Stability

The oil/water interfacial properties and the stability of the emulsion of ASP flooding in Daqing Oilfield were investigated with the measurement of interfacial tension, interfacial shear viscosity,Zeta potential and turbidity of the oil/water system. The results show that, after NaOH has reacted with Daqing crude oil for a long time, the interfacial tension between the aqueous phase and Daqing model oil decreases. The absolute value of the Zeta potential of the surface of oil droplets increases. The changes of the interfacial shear viscosity between the aqueous phase and the oil phase do not appear to be obvious. The stability of O/W emulsion formed by Daqing model oil and the aqueous phase is enhanced. After NaOH has reacted with crude oil for 1d, the interfacial tension between oil phase and simulated water, Zeta potential and the stability of the oil/water emulsion become higher than that of the emulsion without NaOH. However, after NaOH has reacted with crude oil for 10 d and 30 d, respectively, the interfacial tension between oil phase and simulated water, Zeta potential and the stability of the O/W emulsion are lower than that of the emulsion with the same reaction for 1d.

The Prediction of Scaling Time in Producing Wells of ASP Flooding in the Fourth Plant of Daqing Oilfield

After used technology of the ASP flooding in the fourth plant of Daqing oilfield, the problem of scaling becomes serious in oil wells. The scale samples do not dissolve to acid or alkali, and it difficult to be treated with regular method, so it has influenced the normal proceeding of well production. For solving this phenomenon, the displacement experiment was proceeded to simulate the site actual oil production conditions by using the high pressure physical simulation tests. By measurement of variation law of permeability in the process of ASP flooding and pH value in produced liquid along with time, the paper predicted the starting time and duration of scaling during oil well production. And rationality of the prediction results was verified by using the local test results. Finally the prediction formulas of scaling time which the oil wells with different spacing in ASP flooding were summarized.

Investigating the role of polymer type and dead end pores’ distribution on oil recovery efficiency during ASP flooding

Although alkaline-surfactant-polymer flooding is proved to be efficient for oil recovery from petroleum reservoirs, effects of existence of dead end pores on this process need more discussions. In this work, several ASP flooding tests constituted from 4 polymers, 1 surfactant and 1 alkaline were performed on micromodels designed in four various dead end pore distributions initially saturated with crude oil. The results showed that although using ASP solution constituted from hydrolyzed polymers at high molecular weights significantly increases oil recovery factor due to increasing apparent viscosity of the solution, using sulfonated polymers in ASP solution increases oil recovery much more because of their capability to increase viscosity even in saline solutions. In addition, it was concluded that the number of dead end pores as well as their distribution with respect to the flow direction are two main characteristics that identify the efficiency of brine and ASP floods in dead end porous media. Moreover, although in ASP flooding, since the viscosity is higher and the front is flatter, the role of the number of dead ends on the recovery efficiency is more identifiable than the role of dead ends’ distribution, in waterflooding, since the mobility ratio is not low enough, the role of dead end direction with respect to the flow direction plays a more significant role in recovery process. So, considering the efficient direction of injection is too important during waterflooding and chemical EOR especially in reservoirs that have a remarkable percentage of dead end pores in their geological structure.

The scaling conditions for ASP flooding oilfield in the fourth Plant of Daqing oilfield

The fourth Plant of Daqing oilfield which uses ASP flooding has a serious foul water problem. So, scaling conditions were analyzed to discuss the petroleum production and oil–gas–water treatment. In the flooding process in stratum, scaling in the ASP flooding is because of chemical condition changes. The silica and aluminum irons in the rocks are dissolved in the formation water. It breaks the original ion balance and results in reservoir scaling and damage. Several influencing factors were analyzed by investigating scaling conditions in ASP flooding.

Current development and application of chemical combination flooding technique

Abstract Great progress and success have been achieved in the fundamental study and field test of chemical combination flooding in recent years. In China, a low concentration ASP formula is employed to achieve ultra-low interfacial tension by the synergistic effect of alkali and surfactant. The viscosity of polymer solution prepared from produced water can meet the technological requirement when salt tolerance polymer is applied. ASP or SP flooding can increase both oil displacement efficiency and sweep volume. ASP pilot tests and industrial field tests in Daqing Oilfield have resulted in an oil recovery increase of 18.5%-26.5%. The chemical combination flooding has entered into the industrial promotion and application stage, with a series of supporting techniques formed in the field tests. The main challenges in this technique include short pump-checking period and difficulty in produced liquid handling and high cost. Micelle-polymer flooding as the major chemical combination flooding technique was applied abroad in the early stage of chemical flooding tests. However, the micelle-polymer flooding has not been applied widely due to its high cost. With the rise of oil price in recent years, low concentration chemical combination flooding has drawn more attention. Because of high temperature and high salinity in most reservoirs abroad where chemical combination flooding is used, high performance temperature and salt tolerance oil displacement agents are the bottleneck for future chemical flooding.

Optimal Design for ASP of Mixed Surfactants with Rhamnoilpid

Under the same injection conditions, the compounded system of alkylbenzene sulfonate (ABS) and rhamnoilpid mixed in the proportion of 1:1 has the same effect as ASP (ABS system) on enhanced oil recovery with lower production cost. So the field test of ASP flooding of mixed surfactants with rhamnoilpid was developed the in Nanliuqu 1# injection plant.

A New Strategy for Minimizing Precipitations during ASP Flooding in Carbonate Reservoirs

A New Strategy for Minimizing Precipitations during ASP Flooding in Carbonate Reservoirs

Demulsification Performance of Hyper-Branched Dendrimer in ASP Flooding

Owing to the double actions by ternary liquid of ASP flooding and natural emulsifier in oil, the recovery liquid emulsified seriously as well as oil content in water rose after oil-water separation. Demulsification on recovery water in ASP flooding has been discussed via the modified terminal groups of hyperbranched tree macromolecules dendrimers polyamidoamine (PAMAM). Laboratory tests showed that PAE01 demulsifier had good demulsification efficiency. When demulsifier dosage was 120mg/L, sedimentation time was 90min, temperature was 45°C, oil content in water dropped from initial 5000mg/L to 197mg/L after demulsification, the deoiling rate was 96.1%. When initial oil content was 1500mg/L, oil content in water dropped to 215mg/L, the deoiling rate was 85.7%.

Research on Microscopic Characteristics of Remaining Oil Distribution after Strong Alkali ASP Flooding by Laser Scanning Confocal Technology

Different types of micro-pore structure and variation characteristics after long-term washing have a greater impact on micro-remaining-oil migration direction, distribution and content. This article applied Confocal Laser Scanning Technology to study reservoir fluid property and remaining oil micro distribution after strong alkali ASP flooding. Comparing the Laser Confocal analysis pictures of natural core after water drive and ASP flooding, coming to the conclusions that strong alkali ASP flooding sweep out larger amounts of heavy oil than water drive. Counting the ratio of different types micro-remaining-oil, and analysing on the displacement effects and mechanism of different types remaining oil after strong alkali ASP flooding.

Mass Transfer Mechanisms of ASP Flooding in Porous Media

Experiments on chromatography separation are taken for ASP flooding. Mass transfer equation is estabilished and mutiple adsorption factor is obtained. Mutiple adsorption factor is used to analyze the experiment results. The Mass transfer property of alkali, surfactant and polymer during single fooding and ASP flooding and the effect on interfacial tension of oil/solution are discussed. The results show the diffrence of hesteris degree of alkali, surfactant and polymer deduce the chromatography separation, lowing the active of ASP flooding. Accoding to interfacial tension, the efficent length of ASP slug is discussed.

Visco-Elastic Property Studies on Polymer Flooding Systems with High Concentrations

Keywords: Visco-elastic property; polymer flooding; oil recovery Abstract. Polymer flooding and ASP flooding has improved oil recovery a lot in Daqing oil field. In ASP flooding, the existence of alkali decreases the visco-elastic characteristic of polymer, which decreases the oil recovery of polymer flooding. The aim of this paper was to study the visco-elastic characteristic, shear resistance in high concentration and high molecular weight polymer flooding, and analyzed the suitable parameter of it .They can provide the theory of polymer flooding development and application research.