Binary Flooding Research Articles

Construction and Properties Evaluation of the Binary Flooding System Based on Lipid Peptide.

To enhance crude oil recovery under complex reservoir conditions and reduce the environmental impact of the oil displacement system, a biosurfactant lipid peptide (TH) was combined with four chemical surfactants. From these combinations, those capable of achieving an ultralow interfacial tension region (<10-2 mN/m) were selected. The selected surfactant mixtures were then combined with polyacrylamide (HPAM) to construct a surfactant-polymer binary oil displacement system. The results showed that TH/OAB(2:1), TH/OAB(3:1), and TH/EAO(3:1) could reduce IFT to the ultralow interfacial tension region. Compound surfactants are easier to form mixed micelles than single surfactants, and the EACN of TH/OAB(2:1) and TH/EAO(3:1) is consistent with EACNOil, which can achieve higher surface activity at lower concentrations. The three compound surfactants have a wide range of ultralow interfacial tension concentrations and excellent antidilution performance. TH/OAB(2:1) and TH/EAO(3:1) have better antiformation adsorption performance than TH/OAB(3:1), and the oil washing rate of TH/OAB(2:1) is up to 80.30%. TH and OAB have spatial complementarity, which can increase the molecular packing density at the oil-water interface and reduce the IFT. In CaCl2 and NaCl solutions, the IFT of the two binary flooding systems constructed by TH/OAB(2:1) and TH/EAO(3:1) and HPAM remained in the ultralow interfacial tension region, with excellent salt resistance. When aged in the reservoir for 90 days, the IFT slightly increased but the viscosity decreased significantly. Adding a viscosity retaining agent (JW) was required to maintain the viscosity of the system. In the simulated oil displacement experiment, the recovery improvement of the two binary oil displacement systems was higher than those of surfactant and polymer alone. This study provides a new idea for the alkali-free surfactant-polymer binary oil flooding system and provides theoretical support for the practical application of TH in tertiary oil recovery.

Geomorphic flood hazard mapping: from floodplain delineation to flood hazard characterization

ABSTRACTRecent studies show how geomorphic descriptors, retrieved from digital elevation models (DEMs), can be used for flood hazard mapping. As they strictly depend on the accuracy of the input DEMs and reference flood hazard maps used for training, DEM-based flood hazard models may display severe inconsistencies. Our study shows the application of two advanced DEM-based models to a large study area, and presents two main innovative points. First, the delicate tasks of appropriately selecting the input DEM and flood hazard map are specifically addressed with newly defined methods. Second, the ability of DEM-based models to exploit their natural features to enhance flood hazard mapping over the study region is investigated. Our results show (a) the benefits of considering multiple geomorphic descriptors, (b) the potential of DEM-based models for completing the information of imperfect reference flood hazard maps, and (c) the advantages of continuous representation of hazard over binary flood maps.

The influence of permeability and heterogeneity on chemical flooding efficiency and remaining oil distribution—based on NMR displacement imaging

To investigate the impact of permeability and heterogeneity on oil displacement efficiency and remaining oil distribution of chemical flooding, three groups of high and ultrahigh permeability core samples from an ultrahigh water-cut oilfield in western China were selected as the research objects in this study. High-pressure mercury injection, scanning electron microscopy, wettability test, and other methods were used to characterize the reservoir properties of core samples. Six groups of experiments were performed using the nuclear magnetic resonance (NMR) displacement imaging technology to simulate the oilfield development process considering the economic benefits. The displacement stage with the best oil displacement effect in the process of waterflooding, chemical flooding and then waterflooding was defined, and the control effect of permeability and heterogeneity on the improvement of oil displacement efficiency by polymer-surfactant binary flooding was discussed. The distribution position of remaining oil in different displacement stages was quantitatively and visually displayed, and its control factors were revealed. The research shows that during the simulation process of first waterflooding followed by chemical flooding and then waterflooding in the oilfield, the T2 spectrum signal amplitude increases the most in the two stages, one is from saturated oil flooding to 50% water cut and the other one is from 95% water cut to the end of 1 PV polymer flooding. The oil displacement efficiency increases the most, and the oil is primarily discharged from pore throats larger than 90 ms (or with pore throat radius of 8.37 μm). Compared with heterogeneity, permeability plays a more obvious controlling role in improving the oil displacement efficiency of polymer-surfactant binary flooding. The influence of fingering phenomenon on the distribution of remaining oil is most obvious in the second waterflooding, and the distribution of remaining oil with polymer slug is more obviously affected by the fingering phenomenon than that with polymer-surfactant slug. The study results provide theoretical guidance for tapping the remaining oil potential of old oilfields with high to ultrahigh permeabilities.

Difference in Step-Wise Production Rules of SP Binary Flooding for Conglomerate Reservoirs with Different Lithologies.

The purpose of this study is to clarify the difference in oil production rules of conglomerate reservoirs with different pore structures during surfactant-polymer (SP) binary flooding and to ensure the efficient development of conglomerate reservoirs. In this paper, the full-diameter natural cores from the conglomerate reservoir of the Triassic Kexia Formation in the seventh middle block of the Karamay Oilfield (Xinjiang, China) are selected as the research objects. Two schemes of single constant viscosity (SCV) and echelon viscosity reducing (EVR) are designed to displace oil from three main oil-bearing lithologies, namely fine conglomerate, glutenite, and sandstone. Through comprehensive analysis of parameters, such as oil recovery rate, water content, and injection pressure difference, the influence of lithology on the enhanced oil recovery (EOR) of the EVR scheme is determined, which in turn reveals the differences in the step-wise oil production rules of the three lithologies. The experimental results show that for the three lithological reservoirs, the oil displacement effect of the EVR scheme is better than that of the SCV scheme, and the differences in recovery rates between the two schemes are 9.91% for the fine conglomerate, 6.77% for glutenite, and 6.69% for sandstone. By reducing the molecular weight and viscosity of the SP binary system, the SCV scheme achieves the reconstruction of the pressure field and the redistribution of seepage paths of chemical micelles with different sizes, thus, achieving the step-wise production of crude oil in different scale pore throats and enhancing the overall recovery of the reservoir. The sedimentary environment and diagenesis of the three types of lithologies differ greatly, resulting in diverse microscopic pore structures and differential seepage paths and displace rules of SP binary solutions, ultimately leading to large differences in the enhanced oil recoveries of different lithologies. The fine conglomerate reservoir has the strongest anisotropy, the worst pore throat connectivity, and the lowest water flooding recovery rate. Since the fine conglomerate reservoir has the strongest anisotropy, the worst pore throats connectivity, and the lowest water flooding recovery, the EVR scheme shows a good "water control and oil enhancement" development feature and the best step-wise oil production effect. The oil recovery rate of the two schemes for fine conglomerate shows a difference of 10.14%, followed by 6.36% for glutenite and 5.10% for sandstone. In addition, the EOR of fine conglomerate maintains a high upward trend throughout the chemical flooding, indicating that the swept volume of small pore throats gradually expands and the producing degree of the remaining oil in it gradually increases. Therefore, the fine conglomerate is the most suitable lithology for the SCV scheme among the three lithologies of the conglomerate reservoirs.

Study on the Oil Displacement Mechanism of Different SP Binary Flooding Schemes for a Conglomerate Reservoir Based on a Microfluidic Model

The objective of this study is to elucidate the oil displacement mechanism of different surfactant- polymer (SP) binary flooding systems in conglomerate reservoirs and to determine the optimal scheme. On the basis of water flooding, the microfluidic model is used to reveal the oil–water flow law of different SP binary flooding systems and then determine the oil displacement mechanism. The experimental results show that the SP binary flooding solution can enhance oil recovery by enhancing the sweep volume; the oil displacement efficiency of the echelon viscosity reducing (EVR) scheme is better than that of the echelon viscosity increasing (EVI) scheme and the single constant viscosity (SCV) scheme. For the EVR scheme, the oil displacement system with a high molecular weight and high concentration preferentially enters the large-scale pore-throat of the reservoir. After a period of time, a high resistance area can be formed in the large-scale pore-throat along the main flow direction of water flooding so as to reduce the mobility of the displacement solution in the dominant seepage channel and decrease the frequency of water channeling and then improve the oil displacement efficiency in the large-scale pore-throat to enhance the oil recovery. When the molecular weight and viscosity of the SP binary solution are both reduced, the oil displacement solution with a low molecular weight and low concentration mainly produces low-permeability layers by adjusting the displacement path to enhance the sweep volume in the small-scale pore-throat. Through the reconstruction of a pressure field and the redistribution of seepage paths of chemical micelles with different sizes, the displacement mechanism of crude oil in pores and throats shows a changing trend from large-scale pore-throats to small-scale pore-throats. After the viscosity reduction of the SP solution, the lower production limit of the pore-throat radius is reduced to 1 μm and the sweep volume of the small-scale pore-throat is enhanced. The stepwise production of crude oil in pores and throats with different radii is realized so as to enhance the oil recovery of the conglomerate reservoir. Finally, a new model of SP binary flooding suitable for “echelon injection and stepwise production” of a conglomerate reservoir is established innovatively.

Bayesian calibration of a flood simulator using binary flood extent observations

Abstract. Computational simulators of complex physical processes, such as inundations, require a robust characterization of the uncertainties involved to be useful for flood hazard and risk analysis. While flood extent data, as obtained from synthetic aperture radar (SAR) imagery, have become widely available, no methodologies have been implemented that can consistently assimilate this information source into fully probabilistic estimations of the model parameters, model structural deficiencies, and model predictions. This paper proposes a fully Bayesian framework to calibrate a 2D physics-based inundation model using a single observation of flood extent, explicitly including uncertainty in the floodplain and channel roughness parameters, simulator structural deficiencies, and observation errors. The proposed approach is compared to the current state-of-practice generalized likelihood uncertainty estimation (GLUE) framework for calibration and with a simpler Bayesian model. We found that discrepancies between the computational simulator output and the flood extent observation are spatially correlated, and calibration models that do not account for this, such as GLUE, may consistently mispredict flooding over large regions. The added structural deficiency term succeeds in capturing and correcting for this spatial behavior, improving the rate of correctly predicted pixels. We also found that binary data do not have information on the magnitude of the observed process (e.g., flood depths), raising issues in the identifiability of the roughness parameters, and the additive terms of structural deficiency and observation errors. The proposed methodology, while computationally challenging, is proven to perform better than existing techniques. It also has the potential to consistently combine observed flood extent data with other data such as sensor information and crowdsourced data, something which is not currently possible using GLUE calibration framework.

Optimization Study of Polymer-Surfactant Binary Flooding Parameters in Maling Jurassic Low Permeability Reservoir

The low-permeability Jurassic reservoir in Changqing Maling has been in the middle and high water cut stage after long-term development of water injection. In order to improve development efficiency and further explore a new way to enhance oil recovery of the reservoir, a significant development test and a polymer-surfactant flooding study were carried out in the Maling Beisan area in 2011. Compared with other polymer-surfactant flooding reservoir of PetroChina, Jurassic reservoir in Beisan area had relatively low permeability and high salinity of formation water and injected water, which puts forward higher requirements on the injectivity and salt resistance of the binary system. At the same time, the viscosity of the formation crude oil was low, and the viscosity of the polymer required to achieve the optimum fluidity ratio was relatively low, which is an important advantage of implementing the binary flooding in the reservoir. In this paper, hydrophobic associating polymer and betaine surfactant were selected through laboratory experiments. According to the experimental data, numerical simulation technology was used to analyze and optimize the influence factors, including injection speed, injection-production ratio, slug size, slug polymer, and surfactant concentration. Finally, the development index of binary flooding was predicted. The results show that the optimized polymer-surface system had good injectivity and high formation compatibility. Through on-site differential control measurement of injection and production, the recovery was enhanced significantly. This study had guiding significance for the production of polymer-surface flooding in the similar reservoirs.

Residual oil start-up mechanism of polymer/surface dual flooding after polymer flooding in medium-high permeability reservoir

The remaining oil distribution and displacement mechanism of poly/surface dual flooding stage in medium and high permeability reservoir are not clear. In this paper, the reservoir conditions in Gangxi Area 3 of Dagang Oilfield were taken as the research object. Based on nuclear magnetic resonance and large model physical simulation experiment, the characterization of micro and macro residual oil start-up mechanism and enhanced oil recovery experiment were carried out respectively after polymer flooding poly/surface binary flooding. The experimental results suggest that polymer-surfactant flooding could increase the oil displacement efficiency by 12-29% after polymer flooding, and the contribution of porous to recovery degree is in the order of medium pore, large pore, and small pore. When the surfactant concentration is higher than 0.25%, the increase of oil displacement efficiency tends to be stable, and further enhancing oil recovery requires the expansion of sweep volume. Physical model experiments results show that medium permeability layer has the highest contribution to the recovery degree in the chemical flooding stage, and the displacement mechanism is mainly based on the synergistic effect of expanding sweep volume and improving displacement efficiency. The contribution of low permeability layer to recovery degree is next, and the displacement mechanism is mainly to expand sweep volume. The high permeability layer has the lowest contribution to the recovery degree, and the oil displacement mechanism is mainly to improve the oil displacement efficiency.

Study on the influence of different key parameters on EOR in LB block

The high temperature reservoir is in the high water cut stage after long-term development, and the inefficiency or invalid circulation caused by injected water is aggravated. With a long development history, the well pattern has been adjusted many times, and the remaining oil distribution is highly dispersed. Based on the high-temperature reservoir conditions of the target block, the influence analysis of different key parameters on EOR effect of LB- block was carried out. The gas flooding and chemical flooding potential were evaluated by numerical simulation method, and the EOR effect of different oil flooding systems was defined. The gas flooding and binary flooding numerical models were established according to the well pattern, reservoir and fluid physical parameters. The development effect is predicted under different formation dip, reservoir permeability, oil viscosity, oil saturation, effective thickness and reservoir temperature. The simulation results show that the key factors of EOR in gas flooding and binary flooding are formation dip.

Injectability of Partially Hydrolyzed Polyacrylamide Solutions Improved by Anionic-Nonionic Surfactant in Medium and Low Permeability Reservoirs

Injectability of the polymer solution is a very important factor that determines the effectiveness of polymer flooding for enhanced oil recovery. Here, the medium and low permeability oil reservoir was taken as a research object, and effects of relative molecular weight, concentration and core permeability on the flow and injection performance of a partially hydrolyzed polyacrylamide (HPAM) solution with and without anionic-nonionic surfactant (ANS) were studied by indoor outcrop core physical model experiments. It was found that the influence of HPAM concentration on the flow performance was related to the core permeability. When the core permeability was lower than 59 mD, the resistance factor and residual resistance factor of HPAM increased with increasing the concentration. High molecular weight and low core permeability were not conducive to the injectability of HPAM solutions. The addition of ANS was beneficial in enhancing the injectability of HPAM solution by reducing the critical value of injectability of HPAM solution, which was elucidated by the Hall curve derivative method. In the presence of ANS, the flow pressure gradient and the residual resistance factor of the HPAM solution decreased. It is believed that the injectability of HPAM solution improved by ANS in the medium and low permeability reservoirs can be attributed to decrease in fluid viscosity and competitive adsorption on the surface of porous media. The study provides a new idea and theoretical basis for improving the injectability of an HPAM solution and the application of polymer flooding and a polymer/surfactant binary flooding system in medium and low permeability reservoirs.

Numerical Simulation of Injection Parameters of Polymer/Surfactant Binary Composite Flooding in High Watercut Reservoir

Numerical Simulation of Injection Parameters of Polymer/Surfactant Binary Composite Flooding in High Watercut Reservoir

Effect of Rhamnolipid Amidation on Biosurfactant Adsorption Loss and Oil-Washing Efficiency.

Surfactant adsorption loss seriously hinders the economy of surfactant binary flooding technology for enhancing oil recovery, especially for biosurfactants with higher manufacturing costs. Here, biosurfactant rhamnolipid (RL) is chemically modified to develop a more efficient surfactant, rhamnolipid monoethanol amide (RL-MEA), which is characterized by decreased adsorption loss and increased oil-washing efficiency for enhanced oil recovery at a laboratory scale. Synthesis and characterization of the rhamnolipid monoethanol amide are carried out using high-performance liquid chromatography (HPLC), HPLC/MS, 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. The aggregation behavior is disclosed by surface tension, dynamic light scattering, and fluorescence spectra with pyrene as the probe. The applied performances of RL-MEA in the simulated enhanced oil recovery are researched, including the efficiency of oil washing, wettability to crude oil, and adsorption isotherms on silicates. Compared with the critical micelle concentration (CMC) of rhamnolipid of 14.23 × 10-5 M in pure water and 9.02 × 10-5 M in 0.2 M NaCl solution, the modified RL-MEA shows a significantly lower CMC of 7.15 × 10-5 M in pure water and 5.34 × 10-5 M in 0.2 M NaCl solution. More importantly, the modified RL-MEA reduces adsorption loss by 20% and enhanced oil-washing efficiency at higher temperatures and salt concentrations compared with the parent RLs. These findings would provide valuable information for developing efficient surfactant flooding agents for harsh reservoir geological conditions.

Laboratory experimental study on the binary combination flooding system in low permeability conglomerate reservoir

In view of the poor injection-production effect of low permeability conglomerate complex fault block reservoir in Xinjiang Oilfield in the late development stage of high water cut, the indoor experimental study of binary compound flooding system was carried out. By compounding the petroleum sulfonate and polymer binary system, the viscosity and morphology parameters of the binary compound flooding system were measured. The microscopic pore structure of the core in this block was analyzed by GE Phoenix Nanotom S, and four groups of experimental schemes were designed to study the oil displacement efficiency of the whole diameter core binary compound flooding system. The experimental results showed that the binary system of surfactant and polymer showed additive synergistic effect. The performance of binary compound system is less affected by polymer molecular weight and solution concentration, which meets the viscosity requirement of low permeability conglomerate for binary compound flooding system. The porosity of samples is relatively small and the connectivity between pores is relatively poor. The experimental results of physical model oil displacement efficiency show that the oil recovery can be increased by more than 17% by injecting 0.3PV 1200mg/L polymer + 0.5% (w) surfactant binary compound system.

Classification methods of conglomerate reservoirs based on the adsorption and retention law of surfactant-polymer binary systems

Factors such as clay minerals and micropore structure can lead to the adsorption and retention of chemical agents when the components of surfactant-polymer systems enter porous media. This study aims to clarify the influence of adsorption and retention of surfactant-polymer components on reservoir permeability and oil displacement efficiency and then classify the reservoirs into types. The natural cores of conglomerate reservoirs from the Badaowan Formation in the 7th block are selected as research objects to reveal the adsorption law of surfactant-polymer components on different minerals and different micro pores through the dynamic oil displacement method based on physical model and the N element calibration method. Experimental results show that the adsorption capacity of clay minerals for surfactant-polymer components is significantly higher than that of carbonate and skeleton minerals, and different clay minerals differ in adsorption capacity for surfactant-polymer components depending on their cation exchange capacity and end surface adsorption activity. In addition, the adsorption and retention capacities of reservoirs for surfactant-polymer components are closely related to the type and content of clay minerals. The combination type of clay minerals controls the adsorption activity of surfactant-polymer components, and the values of polymer and the surfactant are quantitatively calculated to be 11.3 and 21.4 mg/g, respectively. The adsorption strength of surfactant-polymer components is controlled by the content of clay minerals. With increasing clay content, the adsorption strength of the polymer ranges from 0.5 to 2.5 mg/cm 3 , and that of the surfactant ranges from 1.0 to 4.5 mg/cm 3 . On this basis, the “N element calibration method” is used to determine the occurrence state and content of chemical agents in micropores for different permeability samples after surfactant-polymer binary flooding. Research results show that the polymer and surfactant components mainly have two types of occurrence form in micropores, including the complex pores accumulated by clay minerals and the intersections of small pores and throats. With decreasing reservoir permeability, the number and content of detected N element gradually increase, indicating an increase in the adsorption and retention of polymer and surfactant, and the influence on the reservoir seepage capacity also increases. Finally, the conglomerate reservoirs in the Badaowan Formation from the 7th block are divided into four types after considering the influence of clay minerals and micropore structure on the adsorption and retention of surfactant-polymer components, and the reasonable classification of reservoir types can effectively enhance the oil recovery of surfactant-polymer binary flooding. • The adsorption law of SP binary components on different minerals in conglomerate reservoir was clarified. • The adsorption capacity of polymer and surfactant can be accurately calculated according to the petrophysical volume model. • The N element calibration method was used to determine the occurrence state and content of chemical agent in micro pore after SP binary flooding. • A method of reservoir classification considering the influence of clay minerals and micro-pore structure on the adsorption of SP binary components is established to further EOR.

Production calculation of the second and tertiary recovery combination reservoirs under chemical flooding

Based on the analysis of the production composition of reservoirs developed by the second & tertiary recovery combination (STRC), the relationship between the overall output of the STRC project and the production level during the blank water flooding stage is proposed. According to the basic principle of reservoir engineering that the “recovery factor is equal to sweeping coefficient multiplied by oil displacement efficiency”, the formula for calculating the ultimate oil recovery factor of chemical combination flooding reservoir was established. By dividing the reservoir into a series of grids according to differential calculus thinking, the relationship between the ultimate recovery factor of a certain number of grids and the recovery degree of the reservoir was established, and then the variation law of oil production rate of the STRC reservoir was obtained. The concept of “oil rate enlargement factor of chemical combination flooding” was defined, and a production calculation method of reservoir developed by STRC was put forward based on practical oilfield development experience. The study shows that the oil production enhancing effect of STRC increases evenly with the increase of the ratio of STRC displacement efficiency to water displacement efficiency, and increases rapidly with the increase of the ratio of recovery degree at flooding mode conversion to the water displacement efficiency. STRC is more effective in increasing oil production of reservoir with high recovery degree. Through practical tests of the alkali free binary flooding (polymer/surfactant) projects, the relative error of the oil production calculation method of STRC reservoir is about ±10%, which meets the requirements of reservoir engineering.

Study on the adaptability of binary flooding in a certain oil field

Abstract To explore the synergistic mechanism of polymer and surfactant in the binary combination flooding of low-permeability reservoirs, the adaptability experiment of polymer salt-resistant partially hydrolyzed polyacrylamide and nonionic surfactant was carried out in the indoor system. Experiments at different ratios are also performed. The results show that the selected poly/surface binary flooding system increases with the concentration of polymer or surfactant, the viscosity of the poly/surface binary system also increases and, at the same time, has better temperature and salt resistance. The viscosity of the binary system will decrease when the salinity increases. When the surfactant concentration CS = 0.2% and the polymer concentration CP = 0.2%, the viscosity of the system is the highest. The viscosity of the poly/table binary system at different concentrations decreases when the temperature rises: pure polymer (CP = 0.2%), poly/table binary system displacement fluid CP = 0.1% + CS = 0.2% and CP = 0.2% + CS = 0.2%; and the injection pressure first rises and then drops. The final recovery rate is 51.8%, which meets the development of most oil reservoirs.

Visualization of Water Plugging Displacement with Foam/Gel Flooding in Internally Heterogeneous Reservoirs

During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs, it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages. In this study, two types of internally heterogeneous systems, i.e., vertical and horizontal wells are investigated experimentally through a microscopic approach. The results show that plugging agent types have a greater impact on oil recovery than well types, and foam injection can enhance oil recovery more effectively than gel injection. Additionally, the injection sequence of plugging agents significantly affects oil displacement efficiency. Injecting gel after foam is more beneficial. According to the present results, the main formation mechanisms of remaining oil in each displacement stage are influenced by: capillary force, viscous force, inertial force, shear force, microscopic fingering & channeling.

Optimization of the binary flooding systems prepared with sewage

Optimization of the binary flooding systems prepared with sewage

Laboratory studies on a novel salt-tolerant and alkali-free flooding system composed of a biopolymer and a bio-based surfactant for oil recovery

Alkali/surfactant/polymer (ASP) flooding is one of the most effective tertiary oil recovery technologies. However, the formation of an alkali scale potentially results in the reduction of the formation permeability and pipeline corrosion, which affect its industrial application. Recently, the surfactant/polymer (SP) flooding system in the absence of alkali has received increasing attention. Here, we screened a high-yielding strain, which is capable of producing salt-tolerant biopolymer. The results of rheological properties evaluation showed that this biopolymer possessed a stable viscosity at high salinities (up to 200 g/L NaCl, 100 g/L Ca2+, and 100 g/L Mg2+) and a wide range of pH (4–11), indicating its superior salt and pH resistance. Based on these properties, a novel salt-tolerant and alkali-free binary flooding system was constructed with this biopolymer and bio-based surfactant newly synthesized in our lab. The ultra-low interfacial tension (IFT) between crude oil and the binary system containing 0.5 wt % biopolymer and 1.00 g/L surfactant could be achieved in the presence of 100 g/L NaCl or 400 mg/L Ca2+. Moreover, it exhibited good resistance to oil sands adsorption, excellent anti-dilution, and ageing stability. These results indicate that the biopolymer produced by the Kosakonia oryzae strain possessed great potential in the construction of an alkali-free SP system for enhanced oil recovery (EOR) in high salinity and high temperature oil reservoirs.

3D Physical Simulation Experiment of Edge Water Reservoir by Polymer/Surfactant Binary Flooding

To investigate the enhanced oil recovery (EOR) technology by chemical flooding in an edge water reservoir, a 3D physical simulation experimental device for the edge water reservoir was developed, and polymer/surfactant binary flooding experiments were carried out under different edge water energies. In addition, the effect and mechanism of binary flooding on EOR under different edge water energies were comprehensively analyzed. Experimental results show that edge water intrusion considerably affects EOR by binary flooding. The stronger the edge water energy, the worse the effect of EOR by binary flooding. Edge water possibly diluted the concentration of the chemical agent medium that is injected into the reservoir, and the degree of dilution varied in different regions. The dilution region was mainly distributed between the injection wells and edge water. The stronger the edge water energy, the higher the dilution multiple of chemical agent and the greater the recovery loss rate by binary flooding.