Dispersed Particle Gel Research Articles

A high temperature-resistant, strong, and self-healing double-network hydrogel for profile control in oil recovery

Hydrogels are widely used in profile control to plug high-permeability zones in oil recovery. In this study, a novel double-network (DN) hydrogel is developed for profile control. The two networks of the prepared hydrogel are polyacrylamide (PAAm) crosslinked by N,N’-Methylenebisacrylamide (MBAA) and konjac glucomannan (KGM) crosslinked by borax (B), respectively. The two networks are interconnected by their interpenetrating structures and hydrogen bonds. Based on the results of a series of evaluation experiments, the AAm/KGM DN hydrogels developed in this study exhibit a strong mechanical strength with their fracture stresses exceeding 0.137 MPa. Meanwhile, the AAm/KGM DN hydrogels can remain thermally stable after being heated at 130 °C for 24 h, indicating the good high-temperature resistance of the new sample. Moreover, the prepared AAm/KGM DN hydrogels present excellent self-healing performance due to the abundant hydrogen bonds in their structures, which helps form stable and long-term plugging in porous media. In addition, the pure PAAm hydrogel and the AAm/KGM DN hydrogel are sheared into two dispersed particle gel (DPG) suspensions to investigate their plugging performances. The results demonstrate that the AAm/KGM DN DPG can effectively plug a high-permeability sandpack with a plugging efficiency of 93.2 %, while the pure AAm DPG can only provide a much lower plugging efficiency of 60.5 %. The AAm/KGM DN hydrogel developed in this study, with its high mechanical strength, high-temperature resistance, and self-healing capability, offers a promising new candidate for profile control in oil recovery.

Self-growing biomimetic functional hydrogel particles for conformance control in tight reservoir fracture network

Hydraulic fracturing is gradually becoming a common approach for enhancing the oil production from tight reservoirs. Blocking agents such as soft particle systems are necessary as a means of conformance control to mitigate the side effect of reservoir heterogeneity due to hydraulic fracturing. In this work, a novel technique based on the mussel biomimetic concept is proposed to generate self-growing biomimetic functional hydrogel particles (SG-BFHPs). The fracture conformance control capacity of the products is evaluated, and the results show that multi-scale (0.5–3.0 mm) SG-BFHPs can cohere and grow at the reservoir condition, and the median agglomerated particle size can increase by 20–25 times. High flow resistance (Frr = 10.7–11.8), facilitated by the higher adhesion between the biomimetic particles and the pore walls, can be established by SG-BFHPs while maintaining a good injectivity. In the single-fracture model, the increased oil recovery by SG-BFHPs is about 12.2 %, and in the matrix-fracture model can be increased from 9.2 %–13.5 % to 25.8 %–28.8 %. AFM experiments show that SG-BFHPs have stronger adhesion between particles or rock surface than conventional hydrogel particles. After conformance control of SG-BFHPs, the particles are distributed in an irregular structure in the fractures and adsorbed on the fracture wall under the effect of inter-particle cohesion and adhesion, which can realize fracture channel adjustment by the particle self-growing. The SG-BFHPs studied in this paper provide valuable insights for the development of dispersed particle gel, which is of great significance in improving oil recovery in tight reservoirs.

Synthesis and characterization of in-situ self-growth mineralization-responsive dispersed gel nanoparticles

This study employed a reverse emulsion method to prepare dispersed nanoparticle gels that respond to mineralization and exhibit excellent characteristics such as small particle size, high dispersion, and strong stability by introducing catechol-like structures and temperature/salt-resistant functional monomers. Experimental results showed that the particle size of the dry dispersed gel particles ranged from tens to 100 nm, as observed by scanning electron microscopy. Laser particle size analyzer testing demonstrated that the size of the dispersed gel particles progressively increased with the mineralization degree of the dispersed particle gel, indicating a certain level of mineralization responsiveness. Additionally, these particles could maintain stable dispersion for up to 40 days in a solution with a mineralization degree of 20,000 mg/L. The rheology testing results indicate that the dispersed particle gels exhibited the properties of the pseudo-plastic fluid. Even under extreme conditions such as high temperature and mineralization, the strength of the dispersed particle gels remained intact, measuring 95.76 kPa after 40 days of aging. Using Materials Studio molecular simulation software, the stability and self-growth mechanism of dispersed gel particles were explained from the quantum mechanics perspective. The geometry of the dispersed gel particles was optimized using the Compass II force field, and the total energy of the model was calculated to be −757.579 kcal/mol, with the dihedral torsion energy contributing the most to the total energy. The molecular bond lengths in the polymer chain were then calculated, with the O–H bond being the shortest and the O-Na bond in the carboxylate sodium group being the longest. This indicated that the –OH group was more stable and the carboxylate sodium group was prone to hydrolysis, forming a –COOH group and increasing the dispersion stability. The charge distribution and molecular orbitals in the polymer molecule were also calculated, with the LUMO value being −7.405 eV and the HOMO value being −4.487 eV. This study used a reverse emulsion method to in-situ generate mineralization-responsive, multi-haired dispersed gel nanoparticles, which fundamentally solved the injection problem of low-permeability oil reservoirs and provided new materials for long-term plugging of high-temperature and high-salinity oil reservoirs.

A Novel Profile Control Agent in High-Temperature and High-Salinity Reservoirs: Dispersed Particle Gel Prepared from Modified Nanographite-Strengthened Bulk Gel

A Novel Profile Control Agent in High-Temperature and High-Salinity Reservoirs: Dispersed Particle Gel Prepared from Modified Nanographite-Strengthened Bulk Gel

Towards in-depth profile control using dispersed particle gels (DPGs)

In-depth profile control is an important technique used to improve oil recovery from the water-flooded reservoirs. But how to achieve in-depth profile control is a challenging task. This work investigates the feasibility of achieving in-depth profile control by striking a good balance between the plugging efficiency of dispersed particle gel (DPG) and the migration depths of DPGs in a given porous media. First, a polyacrylamide (PAAm) hydrogel is prepared, and its rheological properties are measured. Then, we shear the PAAm hydrogel with different durations to generate DPG suspensions with different particle size distributions. Finally, three DPG slugs with varied particle size distributions are sequentially injected into the sandpacks. The injection sequences and the corresponding particle size distributions of different DPG slugs are optimized based on the plugging efficiency and the migration depths of DPGs in a sandpack. Among the injection schemes tested, the optimal scheme is the one that comprises three DPG slugs with matching coefficients of 0.72, 0.78, and 0.46, respectively. These optimal DPG slugs can migrate into the deeper parts of the sandpack as well as yield a high plugging efficiency by forming bridging-plugging in the porous media. This study provides a new approach of achieving in-depth profile control by optimizing the injection sequence and particle size distribution of DPGs.

Coalescence Behavior of a CO2-Resistant Dispersed Particle Gel (SCDPG) in Supercritical CO2

The reservoir heterogeneity and unfavorable oil/gas mobility ratio lead to gas channeling and low CO2 sweep efficiency during CO2 flooding in low-permeability reservoirs. A dispersed particle gel (DPG) could migrate deep into the reservoir and coalesce, which has the potential for CO2 gas channeling control. In this work, a CO2-resistant bulk gel was prepared by a cross-linking reaction of a copolymer with acid-resistant groups and catechol–hexamethylenetetramine, which exhibited excellent CO2 resistance. Subsequently, a CO2-resistant dispersed particle gel (SCDPG) used in supercritical CO2 was successfully prepared from the CO2-resistant bulk gel by a high-speed mechanical shearing method. Meanwhile, the coalescence behavior of the SCDPG particles in supercritical CO2 was systematically investigated from the microstructure, particle size, ζ potential, and mechanical strength. The results showed that the SCDPG particles were dispersed in the liquid phase as a single particle. SCDPG had good dispersion stability during storage and injection. In supercritical CO2, the dispersion stability of SCDPG decreased, and the particles coalesced with each other to form aggregates with a stereostructure instead of degradation. The SCDPG particles maintained high mechanical strength, showing the long-term effectiveness for gas channeling control during CO2 flooding. In addition, the interparticle force of SCDPG particles was measured by an AFM colloid probe based on the reservoir characteristics. The interparticle force of SCDPG particles changed from repulsion to adhesion with increasing salinity. At a salinity of 0.5 mol/L, the adhesion force increased with the increase of temperature and the decrease of the pH value. According to the type of intermolecular force, the adhesion force originated from the hydrogen bond, π–π stacking, and cation−π interaction. This work provides theoretical support for the field application of the dispersed particle gel and promotes the development of utilization of carbon dioxide in oilfields.

A novel fluorescent dispersed particle gel: Fluorescence monitoring method and breakthrough flow channel identification

The breakthrough flow channel generated by formation heterogeneity has severely restricted oil recovery improvement, and its identification and control methods have received extensive attention. In this study, we developed a novel fluorescent dispersed particle gel (FDPG) for identifying and regulating breakthrough flow channels based on the dispersed particle gel (DPG). A copolymer of acryloyl fluorescein and acrylamide (PAMAF) was synthesized by free-radical copolymerization for the preparation of the FDPG. The fluorescence properties and identification method of FDPG were systematically investigated. The results showed that the FDPG had stable fluorescence properties, and its concentration showed a linear relationship with fluorescence intensity. The excitation and emission wavelengths of FDPG fluorescence fall within the interval that can avoid the influence of crude oil on its detection. FDPG can accurately reflect the migration of particles in the formation and avoid the chromatographic separation effect. FDPG has excellent injection and migration properties and can effectively control the high permeability layer after ageing. By analysing the output of the FDPG, breakthrough flow channels that exist between formation layers and within well groups can be effectively identified. FDPG provides a promising approach for identifying breakthrough flow channels and monitoring particle profile control agents.

Breakup and coalescence mechanism of high-stability bubbles reinforced by dispersed particle gel particles in the pore-throat micromodel

Bubble breaks up and coalesces continuously during migration in reservoirs, which determines the size distribution of bubbles. As a key parameter of foam technology, the bubble size greatly affects foam stability and plugging performance in the reservoir. Aiming to solve the problem of poor stability of ordinary foam under reservoir conditions, in this study, a high-stability foam for profile control was prepared using dispersed particle gel particles as a foam stabilizer. The characteristics of foam were mainly investigated by the modified Ross-Miles method and microfluidic experiments. The obtained results showed that the foam reinforced by dispersed particle gel particles had a longer half-life under reservoir conditions. It is easier to break up from parent bubbles to daughter bubbles during the migration, which can form foam with higher stability in the porous media. The average size of the daughter bubbles decreased with increasing liquid-phase flow rate, pore-throat ratio and capillary number. The average size varied with the capillary number in a power-law form. Because of the viscoelastic interfacial film and liquid-phase viscous network, the shear effect on the parent bubble in reinforced foam was increased when passing through the pore-throat structure with variable diameter. The large parent bubbles were more likely to break up into more small and stable daughter bubbles. And the interfacial film with higher mechanical strength makes it difficult for the daughter bubbles in reinforced foam to coalesce again. The results indicated that the reinforced foam had stronger dynamic stability and better plugging performance in the reservoir. This work revealed the breakup and coalescence mechanism of bubbles reinforced by dispersed particle gel particles in porous media and provided theoretical guidance for the application of foam technology in high water-cut reservoirs.

Numerical simulation of in-depth profile control for dispersed particle gel in heterogeneous reservoirs

Introduction: As a new agent of enhancing oil recovery, the dispersed particle gel (DPG) has been gradually used for in-depth profile control in mature oilfields. Many researchers investigated the preparation, profile control mechanism and application of DPG based on a series of laboratory experiments. However, few numerical studies have been carried out on profile control mechanism of DPG.Methods: This paper proposes a novel mathematical model to proceed numerical simulation of profile control for DPG, considering DPG particles adsorption and weak shear thinning effects. The numerical codes are verified by the UTCHEM simulator.Results and discussion: The effects of the DPG viscosity, the DPG concentration, the water saturation of high permeable regions and the permeability ratio between high and low permeable regions on decreasing the water-cut of producing well are studied. Simultaneously, this paper also investigates the influence of different mobility ratios between high and low permeable regions on water shutoff of DPG. The numerical simulation results show that the effects of DPG profile control become better as the DPG solution viscosity, the suspension concentration and the permeability ratio increase. But the increased water saturation of high permeable regions is not helpful to improve oil recovery. Water plugging effect of DPG becomes worse with increasing mobility ratio between different regions. According to comparison results between DPG profile control and polymer flooding, it is found that DPG profile control is more suitable for heterogeneous reservoirs. These findings are of benefit to guide the efficient field application of DPG profile control in heterogeneous reservoirs.

A novel CO2-resistant dispersed particle gel for gas channeling control in low-permeability reservoirs

A novel CO2-resistant dispersed particle gel (CR-DPG) for gas channeling control was successfully prepared by shearing an organic–inorganic composite bulk gel. The basic properties, CO2-resistance characteristics, gas channeling control capacity and enhanced oil recovery potential were systemically investigated. The prepared CR-DPG particles were regular spheres, which could maintain a uniform dispersion during the injection process. The CO2 resistance test was carried out at 90 ℃ and CO2 pressure of 20 MPa. After the CO2 resistance test, the dispersion stability of CR-DPG decreased, and the particles coalesced to form large aggregates instead of degrading, exhibiting excellent CO2 resistance. Furthermore, the mechanical strength of the CR-DPG particles aged for different time was measured using atomic force microscope (AFM). Due to the silica gel particles, the CR-DPG particles retained high mechanical strength in the long-term experiment, which could maintain a high plugging effect for a long time during CO2 flooding. A fractured core flowing model was employed to investigate gas channeling control capacity and EOR potential of CR-DPG. The CR-DPG particles could migrate to fractures in-depth, in which particles coalesced to form large aggregates and adsorbed to mitigate gas channeling. In addition, CR-DPG had great potential for enhanced oil recovery by 10.4 %. This work provides an alternative material with a simple preparation process and low cost for gas channeling control in oilfields with CO2 flooding.

Development of re-crosslinkable dispersed particle gels for conformance improvement in extremely high-temperature reservoirs

Micro-scale and nano-scale dispersed gel particles (DPG) are capable of deep migration in oil reservoirs due to their deformability, viscoelasticity, and suitable particle size. Therefore, it has been widely studied and applied in reservoir conformance control in recent years. However, for highly permeable channels, their plugging performance is still limited. In addition, conventional in situ cross-linked polymer gels (ISCPGs) have fast gelation time under extremely high-temperature conditions, which often causes problems such as difficulty in pumping. Therefore, a re-crosslinkable dispersed particle gel (RDPG) system applied for conformance control in highly permeable channels of extremely high-temperature petroleum reservoirs was investigated. The particle size distribution, gelation time, gel strength, injection performance, and performance strength in porous media were investigated using a laser particle size meter, the Sydansk bottle test method, rheometer, and core displacement experiments, respectively. Results show that the RDPG suspension can be stable for more than 6 months at room temperature with storage modulus G ′ much lower than 10 Pa. It can pass through the pore throat by elastic deformation effect and does not cause strong blockage. Moreover, it can undergo re-crosslinking reaction at 150 °C to form a strong bulk gel. The gel strength G ′ of re-crosslinked RDPG can be as high as 69.3 Pa, which meets the strength requirement of conformance control. The RDPG suspension has the properties of easy injection, and it also has strong plugging, and high-temperature resistance after re-crosslinked in the core, which can be a very promising material for conformance improvement in extremely high-temperature reservoirs.

Potential application of dispersed particle gel strengthened alkali as a novel combination flooding system for enhanced oil recovery

A novel dispersed particle gel strengthened alkali (DPGSA) combination flooding system was proposed for enhanced oil recovery in high water cut mature oilfields. When crude oil and the alkali in the DPGSA combined flooding system interact, petroleum soap is produced, causing a lowering of the interfacial tension (IFT). It can reverse the oil-wetted rock surface to a water-wetted rock surface. The dispersed particle gel (DPG) has viscosity, and the particles are less affected by alkali, temperature, and aging time. Additionally, DPG can strengthen the mobility control ability through single particle expansion and micro coalescence of multiple particles at a specific temperature. Compared with the alkali and polymer/alkali (PA) flooding system, the DPGSA combination flooding system has better viscosity retention and mobility control ability. Based on the sand-pack flow experiment, the DPGSA combination flooding system has good injectability and profile improvement ability. The dispersed particle gels plug the macropore throats through adsorption and bridging. Through the synergistic effect of reducing IFT and increasing swept volume, the DPGSA combination flooding system also shows excellent performance in EOR. The DPGSA combination flooding system is better than the alkali and polymer/alkali (PA) combination flooding system. It can be used as a new alternative to enhance oil recovery in high water cut and highly heterogeneous mature oilfields.

Probing the effect of Young's modulus on the plugging performance of micro-nano-scale dispersed particle gels

The effect of mechanical strength of the dispersed particle gel (DPG) on its macro plugging performance is significant, however, little study has been reported. In this paper, DPG particles with different mechanical strengths were obtained by mechanical shearing of bulk gels prepared with different formula. Young's moduli of DPG particles on the micro and nano scales were measured by atomic force microscope for the first time. The mapping relationship among the formula of bulk gel, the Young's moduli of the DPG particles and the final plugging performance were established. The results showed that when the Young's moduli of the DPG particles increased from 82 to 328 Pa, the plugging rate increased significantly from 91.46% to 97.10% due to the distinctly enhanced stacking density and strength at this range. While when the Young's moduli of the DPG particles surpassed 328 Pa, the further increase of plugging rate with the Young's moduli of the DPG particles became insignificant. These results indicated that the improvement of plugging rate was more efficient by adjusting the Young's moduli of the DPG particles within certain ranges, providing guidance for improving the macroscopic application properties of DPG systems in reservoir heterogeneity regulation.

Conformance control by a microgel in a multi-layered heterogeneous reservoir during CO2 enhanced oil recovery process

Injecting CO2 into the underground for oil displacement and shortage is an important technique for carbon capture, utilization and storage (CCUS). One of the main problems during the CO2 injection is the channeling plugging. Finding an effective method for the gas channeling plugging is a critical issue in the CO2 EOR process. In this work, an acid-resistance microgel named dispersed particle gel (DPG) was characterized and its stability was tested in the CO2 environment. The microgel size selection strategies for the homogeneous and heterogeneous reservoirs were respectively investigated using the single core flooding and three parallel core flooding experiments. Moreover, the comparison of microgel alternate CO2 (MAC) injection and water alternate CO2 (WAC) injection in the dual core flooding experiments were presented for the investigation of the role of microgel on the conformance control in CO2 flooding process. The results have shown that the microgel featured with NH and CN groups can keep its morphology after aging 7 days in the CO2 environment. Where, the small microgel with unobstructed migration and large microgel with good plugging efficiency for the high permeability zone were respectively featured with the higher recovery factor in homogeneous and heterogeneous conditions, which indicate they are preferred used for the oil displacement and conformance control. Compared to WAC injection, MAC injection had a higher incremental recovery factor of 12.4%. It suggests the acid-resistance microgel would be a good candidate for the conformance control during CO2 flooding process.

Conformance control study by micrometer sized dispersed particle gel in three-dimensional tight oil fracture network

With the increasing demand for petroleum resources, the efficient development of unconventional resources is of great significance, such as tight oil. Hydraulic fracturing is necessary for the production of tight oil. However, it aggravates the reservoir heterogeneity with fracture network. With better fluid conformance control in the fractures, heterogeneity in tight oil reservoir will be improved. The high production period can be extended. In this study, the fracture equivalent width of the fracture network model was calculated with conversion coefficient R as 0.52ⅹ106, 4.04ⅹ106 and 4.54ⅹ106 for the two, four and six turning points fracture network models, respectively. A dispersed particle gel (DPG) was used to control fluid mobility in tight oil fracture network model. The median particle size of this fluid is 3.17 μm and viscosity is 2.85 mPa s. In this study, it shows a better conformance control effect at a flow rate of 0.5 mL/min, with matching coefficient between DPG diameter and fracture equivalent width is 0.6. It is found that when the matching coefficient is less than 0.6, DPG can form unstable multi-layer stacking, and stable double-layer bridge stacking in the fracture when matching coefficient is 0.6. It would be single layer retention when it is greater than 0.6. With matching coefficient of 0.6, the conformance control rate would be 72.6% at flow rate 0.5 mL/min. This study would contribute to recovery the tight oil reservoir through heterogeneity remedy with conformance control in fracture network.

Chromatography and oil displacement mechanism of a dispersed particle gel strengthened Alkali/Surfactant/Polymer combination flooding system for enhanced oil recovery

In recent years, a newly developed dispersed particle gel (DPG) has attracted significant attention because of its excellent properties and a good application prospect in an enhanced oil recovery process. The preparation method is convenient and easy to scale up for the field application. The dispersed particle gel with sizes ranging from submicron to micron can block the high permeability layers by accumulating in large pore spaces or directly plugging small pore throats. Furthermore, the dispersed particle gels can achieve in-depth profile control due to the elastic deformation and migration into the reservoir's porous media. These characteristics have demonstrated great potential for the dispersed particle gels to strengthen the alkali/surfactant/polymer combination flooding system. The polymers used are the principal sources of viscosity in the system; the surfactant and alkaline produce the synergistic effect by generating the ultralow oil-water interfacial tension. The added dispersed particle gel has a synergistic viscosity increase effect, temperature tolerance, and thermal stability. However, the combined flooding system suffers from the surfactant loss and chromatographic separation that affect the chemical components' synergistic effect for enhanced oil recovery. In this paper, the chromatography separation effects linked to a new method of oil displacement mechanism based on the dispersed particle gel strengthened Alkali/Surfactant/Polymer as a novel combination flooding system was investigated. The addition of dispersed particle gel in the Alkali/Surfactant/Polymer combination flooding system could interleave in the system's network structure and increase the viscosity stability by strengthening the flooding system to improve the oil recovery capacity. The novel dispersed particle gel strengthened alkali/surfactant/polymer flooding systems have a high displacement efficiency and a better-swept volume capacity considering the oilfield requirement for the enhanced oil recovery process. The effects of polymer, surfactant, alkaline, and dispersed particle gel concentration on the combination flooding system were evaluated, furthermore the impact of external factors on the system such as salinity; aging time was described. The results showed that the effects of external factors aging time and salinity slightly affected the system's interfacial reduction capacity. The increase in interface elasticity produced significantly favorable effects on system stability. For the displacement mechanism, when the dispersed particle gel strengthened alkali/surfactant/polymer combination flooding system moved in a porous medium, the dispersed particle gel passed through the pore throat directly or by deformation depending on the system's pressure variation.Furthermore, the phase separation was formed due to the combined component's effects, resulting in the differential migration between the systems, which led to different degrees of chromatographic separation phenomenon to affect the displacement mechanism. As we can see in the micro visualization simulation experiment, the residual oil interacted with Alkali molecules and form the in-situ surfactant, which makes the remaining oil emulsified, as well the surfactant adsorbed by DPG particles, make the crude oil emulsified and get enhanced. The chromatography and micro visualization experiments results of the dispersed particle gel strengthened alkali/surfactant/polymer combination flooding system indicated a favorable application of the system in an enhanced oil recovery process.

Interfacial characteristics and the stability mechanism of a dispersed particle gel (DPG) three-phase foam

Dispersed particle gel (DPG) was added to foams to obtain a more stable foam system: the DPG three-phase foam. Film drainage, interfacial rheology, and stability mechanism of the DPG three-phase foam were studied. The foam volume of the DPG three-phase foam was slightly higher than that of the traditional foam, and the half-decay time was five times that of the traditional foam. The results of film drainage show that DPG particles mainly improve the stability of thin films, i.e., the ability to bond with and capture water. Interfacial characteristics were investigated by the interfacial tension relaxation method. DPG particles slowed down the overall molecular relaxation process of the foam system, which enhanced the viscoelasticity and the mechanical strength of the interface. The stability mechanism can be explained as follows. The adsorption between DPG particles and Tetradecyl hydroxyl sulfobetaine (THSB) occurs owing to the hydrophobic attractive interaction. Therefore, DPG particles aggregate at the interface to form a shell structure, which increases the mechanical strength of the thin film by its low relaxation process; thus, a stable interface is formed, and the stability of the foam is enhanced.

A novel binary compound flooding system based on DPG particles for enhancing oil recovery

Aiming at deep profile control in water flooding reservoirs, a heterogeneous combination flooding system, composed of dispersed particle gel (DPG) and a zwitterionic surfactant (THSB), was developed. The mean particle diameter was adjusted and then the DPG morphology and diameter were characterized using a laser scanning, confocal microscope, and dynamic light scattering. The effects of DPG concentration, temperature, pH, and salinity on THSB interfacial tension (IFT) were investigated. A method for determining DPG concentration was proposed, and the dynamic retention and migration mechanisms of the particles were evaluated, using cores with different permeabilities. Finally, the oil displacement mechanism of the combination flooding system was explored through visual simulation experiments and scanning electron microscopy. The results showed that the particle diameter was 2.5 μm, that compared with a surfactant system, the IFT of the combination flooding system was relatively low, and that the temperature, pH, and NaCl content of solutions had little effect on THSB IFT. Since specific matching relationships between DPG particles and reservoir pore throats existed, the retention amount and injection pressure were improved with the increased core permeability. Visual simulation experiments revealed the oil recovery mechanism of the combination flooding system. This combination flooding system can be used in reservoirs under varied conditions, as the particle diameter can be adjusted on a case-by-case basis, and the THSB surfactant proved to be high-temperature resistant and high-salinity tolerant. The combination flooding system can be applied to deep profile control and oil displacement, in oil fields.

Novel Chemical Flooding System Based on Dispersed Particle Gel Coupling In-Depth Profile Control and High Efficient Oil Displacement

In order to achieve both in-depth profile control and high efficient oil displacement, a novel heterogeneous combination flooding system (HCFS) composed of dispersed particle gel (DPG) and dodecyl ...

Research on heterogeneous compound flooding system based on dispersed particle gel

Aiming at the problem that the heterogeneity of the reservoir became strong, the remaining oil distributed universally after polymer flooding and the existing chemical compound flooding systems had limited application, a heterogeneous compound flooding system based on gel dispersion particles (DPG) was proposed as a substitution technology for further enhanced recovery of reservoirs after polymer flooding. This paper has carried out the design and characterization of heterogeneous compound flooding system, influencing factors, and application performance. With the system viscosity and oil-water interfacial tension as evaluation indicators, the application performance of the optimized heterogeneous polymer flooding system based on DPG was examined. The results showed that the system viscosity was 12.1 to 17.3 mPa•s while the interfacial tension was maintained at 10 -3 mN/m magnitude. At 80 °C, with 60 days aging, the viscosity retention ratio of the system is over 83.5%, and the interfacial tension between oil and water was still maintained at 10 -3 mN/m. The core flow experiment shows that, the heterogeneous compound flooding system has good injection performance, moving characteristics of plugging, breakthrough migration and re-plugging. After high-temperature aging, subsequent water flooding still maintained at a high pressure with good resistance to erosion. Through the selective high and low permeability layers, the water absorption profile was improved, and finally enhanced oil recovery to 20.61% after polymer flooding. Cited as : Li, H., Wang, K., Han, X., Zheng, J. Research on heterogeneous compound flooding system based on dispersed particle gel. Advances in Geo-Energy Research, 2019, 3(2): 156-164, doi: 10.26804/ager.2019.02.05