Dispersed Particle Gel Research Articles

Interfacial rheology of a novel dispersed particle gel soft heterogeneous combination flooding system at the oil-water interface

The interfacial phenomena reflected by the thickness of oil films and the stability of oil-in-water emulsions were observed in the soft heterogeneous combination (SHC) flooding process, which were closely linked with the oil recovery. In this work, the effects of tetradecyl hydroxyl sulfo betaine (THSB) concentration and dispersed particle gel (DPG) concentration on the interfacial rheology were investigated; the adsorption performance at different temperatures, salinities and aging times were also systematically evaluated to determine the impact of external factors. The results show that three interactions appeared between the surfactant molecules and DPG particles. The adsorption process presents four stages. At a low THSB concentration and low DPG concentration, some DPG particles can adsorb on the interface together with the surfactant molecules, which markedly increase the adsorption film strength. When the THSB concentration increases, the surfactant molecules tend to interact with each other and aggregates of the surfactant molecules with DPG particles also appear, thereby damaging the compact film structure. As DPG particles are continuously added, the aggregates between particles enhance the strength of the adsorption film. Additionally, interfacial properties were maintained at high-temperatures, high-salinities and long aging times, which indicates the promising application of the SHC flooding system in reservoirs.

Characteristics and displacement mechanisms of the dispersed particle gel soft heterogeneous compound flooding system

Considering high temperature and high salinity in the reservoirs, a dispersed particle gel soft heterogeneous compound (SHC) flooding system was prepared to improve the micro-profile control and displacement efficiency. The characteristics and displacement mechanisms of the system were investigated via core flow tests and visual simulation experiments. The SHC flooding system composed of DPG particles and surfactants was suitable for the reservoirs with the temperature of 80−110 °C and the salinity of 1×104−10×104 mg/L. The system presented good characteristics: low viscosity, weak negatively charged, temperature and salinity resistance, particles aggregation capacity, wettability alteration on oil wet surface, wettability weaken on water wet surface, and interfacial tension (IFT) still less than 1×10−1 mN/m after aging at high temperature. The SHC flooding system achieved the micro-profile control by entering formations deeply and the better performance was found in the formation with the higher permeability difference existing between the layers, which suggested that the flooding system was superior to the surfactants, DPG particles, and polymer/surfactant compound flooding systems. The system could effectively enhance the micro-profile control in porous media through four behaviors, including direct plugging, bridging, adsorption, and retention. Moreover, the surfactant in the system magnified the deep migration capability and oil displacement capacity of the SHC flooding system, and the impact was strengthened through the mechanisms of improved displacement capacity, synergistic emulsification, enhanced wettability alteration ability and coalescence of oil belts. The synergistic effect of the two components of SHC flooding system improved oil displacement efficiency and subsequently enhanced oil recovery.

A Study of the Stability Mechanism of the Dispersed Particle Gel Three-Phase Foam Using the Interfacial Dilational Rheology Method.

The dispersed particle gel (DPG) three-phase foam is a novel profile control and flooding system. The stability mechanism of the DPG three-phase foam was studied using an interfacial dilational rheology method. The results show that the elastic modulus of the DPG three-phase foam is up to 14 mN/m, which is much higher than the traditional foam. The increase in interface elasticity produces significantly positive effects on foam stability. Emphasis is given to the influences of frequency, temperature, pressure, and concentration on the viscoelasticity and interfacial adsorption of DPG particles, which change the modules of the foam interface and have a significant effect on foam stability. In addition, the microstructure of the DPG three-phase foam was observed. A viscoelastic shell is formed by the aggregation of the DPG particles on the interface. The irreversible adsorption gives the interface high elasticity and mechanical strength. The electrostatic repulsion between particles increases the spacing between bubbles. The combined effects of these factors give the interface higher mechanical strength, slow down the film drainage, effectively prevent gas permeation, and significantly improve the foam stability.

Enhanced Oil Recovery Study of a New Mobility Control System on the Dynamic Imbibition in a Tight Oil Fracture Network Model

Aiming at increasing the recovery in tight oil reservoir with fractures, a new kind of mobility control system with function of imbibition (MCSI) was prepared with dispersed particle gel (DPG) and surfactant. The dynamic imbibition can effectively control the mobility ratio in a tight oil fracture network and increase oil recovery. Based on the characteristics of tight oil reservoir fractures, the preparation method of a multiple fracture network model was established. The prepared fracture network model has the characteristics of controllable fracture length, width, and height. The MCSI system can reduce the oil–water interfacial tension to 10–2 mN/m. It features low viscosity, strengthening water wet, thus promoting the imbibition effect. Dynamic imbibition tests of the multiple fracture network model show that the MCSI system has higher oil recovery than each single component. At the same time, the subsequent water flooding after soaking also has the function of enhancing oil recovery. The effects of f...

Preparation and application of a novel phenolic resin dispersed particle gel for in-depth profile control in low permeability reservoirs

Phenolic resin dispersed particle gel (PDPG) was successfully prepared from bulk gel by a mechanical shearing method. The effects of bulk gel strength, shearing time, shearing rate, and bulk gel-water ratio on the PDPG particles were systematically analyzed. The morphological results showed that the PDPG particles have a round shape with nano-size to micron-size distribution. The shearing rate is one of the most critical factors in the preparation, while the shearing time and bulk gel strength are secondary factors in preparing the PDPG particles. In addition, the bulk gel-water mixing ratio has a slight impact on the prepared PDPG particles. The PDPG particles had a good shearing resistance and expansion capacity which enhances their application performance in oilfields. Sand pack flowing experiments indicated that PDPG particles can easily enter the in-depth formations and effectively plug high permeability channels. The higher the formation permeability ratio of sand packs, the better the profile improvement rate. By retention or adsorption in large permeability zones, trapping and bridging across pore throats or large channels, the prepared PDPG particles can effectively improve the formation profile and divert the following water into low permeability zones, and then the oil is enhanced. The injection of PDPG particles was first successfully applied to Changqing Oilfield in China which provided a reference to control water production in other similar low permeability mature oilfields.

Adsorption and retention behaviors of heterogeneous combination flooding system composed of dispersed particle gel and surfactant

Heterogeneous combination flooding system composed of dispersed particle gel (DPG) and tetradecyl hydroxyl sulfo betaine (THSB) has been developed as a cost-effective EOR method due to highly beneficial synergistic behavior of improving both sweep efficiency and displacement efficiency. However, the combination flooding system suffered from surfactant loss and chromatographic separation which would raffect synergistic effect of chemical components for extra oil recovery. In this paper, static adsorption and dynamic adsorption of combination flooding system were systematically investigated. Additionally, effects of core permeability, DPG concentration and flow distance on chromatographic separation were also investigated by means of core flooding experiments. Static adsorption experiments indicated that after DPG particles and THSB surfactant were combined, adsorption of THSB surfactant on the quartz sand was lowered while the adsorption of DPG particles was improved, which was attributed to the interactions between DPG particles and THSB surfactant. Dynamic adsorption experiments showed that DPG particle could reduce the surfactant mobility and lead to increase of surfactant retention. Core flooding experiments confirmed that chromatographic separation phenomenon existed when combination flooding system flowed through porous media and the degree of separation phenomenon was lower than that of surfactant and polymer combination flooding system. Smaller surfactant losses, higher particle adsorption and lower chromatographic separation were all responsible for better synergistic behavior of heterogeneous combination flooding system.

Investigation on matching relationship between dispersed particle gel (DPG) and reservoir pore-throats for in-depth profile control

The current study aims at in-depth profile control to further improve oil recovery by studying the matching relationship between the size of dispersed particle gel (DPG) and geometry of reservoir pore-throat. The DPG products with different sizes were prepared, and their microscopic characteristics and particle size distributions were analyzed. The matching factor, which was defined as the ratio of average size of DPG particles to mean size of pore-throats, was introduced to represent the matching relationship. The injection properties and plugging capacities were systematically studied by a series of core flooding experiments to optimize the matching factor. The matching factor was optimized from 0.21 to 0.29 depending on both the injection pressure and the plugging rate. In addition, the results of multi-point pressure measurement experiment verified that the DPG particles exhibited good in-depth migration and plugging ability within the optimized matching factor values. Meanwhile, scanning electron microscope (SEM) was used to study the distribution of DPG particles in porous media. The results intuitively showed that the DPG particles can migrate to the deep of porous media and induce effective plugging to the pore-throats. Moreover, the enhanced oil recovery experiments for different matching factors were conducted, and the mechanisms for enhanced oil recovery by DPG with different matching factors were proposed. The enhanced oil recovery with an optimized matching factor was much higher than that with a smaller or larger matching factor. Owing to good in-depth migration and plugging ability of DPG particles with optimal matching factors, the subsequent injected water was diverted into low permeability zones with high oil saturation and, consequently, widely swept the remaining oil in low permeability zones.

Application of Dispersed Particle Gel to Inhibit Surfactant Adsorption on Sand

AbstractThis article highlights an efficient and cost‐effective additive‐dispersed particle gel (DPG) to reduce surfactant adsorption on sand. Indoor experiments were conducted to study the effect of DPG on static adsorption and dynamic adsorption of the surfactant. The static adsorption data were evaluated using different isotherm models and the Redlich–Peterson isotherm matched the best. Results showed a significant inhibition of surfactant adsorption in the presence of DPG. The dynamic adsorption of SDS on sand decreased to 0.78, 0.68 and 0.61 mg/g compared with original value of 1.17 mg/g by adding 0.1, 0.2 and 0.3 wt% DPG particles, respectively. This study suggests that DPG can inhibit the adsorption of surfactant on sand effectively.

A novel strengthened dispersed particle gel for enhanced oil recovery application

A novel strengthened dispersed particle gel (SDPG) was proposed and investigated to improve high-temperature and high-salinity stability of foam, which uses silica nanoparticles as reinforcing material to support the inner framework of particle gel. In this paper, SDPG was successfully prepared and applied to a new three-phase foam system (STPFS). Indoor experiments were conducted to evaluate the salt tolerance, thermal tolerance, plugging capacity and enhanced oil recovery capacity of the STPFS. It proved that silica nanoparticles could improve the high-temperature and high-salinity stability of the gel particles effectively. Consequently, the new three-phase foam system (STPFS) exhibited superior salt and temperature resistance, with a salinity of 80,000mg/L of Na+, 15,000mg/L of Ca2+ and Mg2+ and temperature tolerance of 110°C. In addition, core-flooding test indicated the STPFS possessed better plugging capacity with a resistance factor of 310 and better enhanced oil recovery capacity with the oil recovery increment of 26.79% under high temperature (110°C) and high salt environment (212,633.8mg/L).

Investigation on Preparation and Profile Control Mechanisms of the Dispersed Particle Gels (DPG) Formed from Phenol–Formaldehyde Cross-linked Polymer Gel

To achieve in-depth profile control and further improve oil recovery, a new profile control agent, termed a dispersed particle gel (DPG), has been developed and reported. In this paper, the DPG particles with sizes ranging from submicrometer to micrometer are prepared successfully from phenol–formaldehyde cross-linked polymer gel by the high speed shearing method. The preparation method is convenient and easy to scale up for the field application. The microscopic characteristics of the DPG have been investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Parallel sandpack tests and microscopic visualization tests have been conducted to gain insights into the profile control mechanism. Additionally, scanning electron microscope (SEM) has been used to study the distribution of DPG particles in porous media. The results show that the DPG particles can block the high permeability layers by accumulating in large pore spaces or by directly plugging small pore throats. Meanwhil...

Stability mechanism of a novel three-Phase foam by adding dispersed particle gel

A novel three-phase foam as a profile control agent in mature oilfields was successfully prepared by adding dispersed particle gel (DPG). The effects of surfactant concentration, DPG particle concentration, salinity, oil concentration, and the gas-liquid ratio on the foaming capacity of the three-phase foam were systematically investigated. Both the viscosity and surface tension of the surfactant solution were increased when DPG particles were added. Although adding DPG particles caused a slightly negative effect on the solution’s surface tension, the increase in solution viscosity brings significantly positive on foam stability. The DPG particles and surfactant bring a synergistic electrostatic repulsion between the three-phase foam interfaces, which prevented the coalescence of bubbles. By increasing solution viscosity, adsorption at the gas-liquid interface, non-adsorption behavior, and electrostatic repulsion in the solution, the DPG particles effectively stabilized the three-phase foam. An increase in surfactant concentration, DPG particle concentration, and the gas-liquid ratio increased foam volume and decay half-life of the novel three-phase foam, whereas an increase in salinity and oil concentration decreased foam volume and decay half-life. All the above factors affect the surface tension and viscosity of the foaming solution, and thus the abilities to reduce surface tension and increase solution viscosity are the decisive factors for the stability of the novel three-phase foam.

Investigation of the profile control mechanisms of dispersed particle gel.

Dispersed particle gel (DPG) particles of nano- to micron- to mm-size have been prepared successfully and will be used for profile control treatment in mature oilfields. The profile control and enhanced oil recovery mechanisms of DPG particles have been investigated using core flow tests and visual simulation experiments. Core flow test results show that DPG particles can easily be injected into deep formations and can effectively plug the high permeability zones. The high profile improvement rate improves reservoir heterogeneity and diverts fluid into the low permeability zone. Both water and oil permeability were reduced when DPG particles were injected, but the disproportionate permeability reduction effect was significant. Water permeability decreases more than the oil permeability to ensure that oil flows in its own pathways and can easily be driven out. Visual simulation experiments demonstrate that DPG particles can pass directly or by deformation through porous media and enter deep formations. By retention, adsorption, trapping and bridging, DPG particles can effectively reduce the permeability of porous media in high permeability zones and divert fluid into a low permeability zone, thus improving formation profiles and enhancing oil recovery.

A Study on the Morphology of a Dispersed Particle Gel Used as a Profile Control Agent for Improved Oil Recovery

To achieve in-depth profile control of injection water and improve oil recovery, a new profile control agent, termed as dispersed particle gel (DPG), has been developed and reported. In this paper, the morphology of DPG and the factors that influence its morphology are systematically investigated using atomic force microscopy (AFM). The AFM studies show that DPG is composed of small pseudospherical particles and that their sizes can be controlled by adjusting the shearing rate, the initial polymer mass concentration, and the salinity. Dynamic light scattering (DLS) is used to study the effects of the initial polymer mass concentration, the shearing rate, the salinity, and the high-temperature aging on the particle size of DPG. The aggregation ability of DPG is explained using the DLVO theory and space stability theory. This work provides a scientific basis and technical support for the formula design of DPG and its application in the oil and gas field.

Investigation of Preparation and Mechanisms of a Dispersed Particle Gel Formed from a Polymer Gel at Room Temperature

A dispersed particle gel (DPG) was successfully prepared from a polymer gel at room temperature. The polymer gel system, morphology, viscosity changes, size distribution, and zeta potential of DPG particles were investigated. The results showed that zirconium gel systems with different strengths can be cross-linked within 2.5 h at low temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) results showed that the particles were polygonal particles with nano-size distribution. According to the viscosity changes, the whole preparation process can be divided into two major stages: the bulk gel cross-linking reaction period and the DPG particle preparation period. A polymer gel with a 3-dimensional network was formed in the bulk gel cross-linking reaction period whereas shearing force and frictional force were the main driving forces for the preparation of DPG particles, and thus affected the morphology of DPG particles. High shearing force and frictional force reduced the particle size distribution, and then decreased the zeta potential (absolute value). The whole preparation process could be completed within 3 h at room temperature. It could be an efficient and energy-saving technology for preparation of DPG particles.

Study on Performance Evaluation of Dispersed Particle Gel for Improved Oil Recovery

This work investigates the performance of dispersed particle gel (DPG) by core flow tests including injectivity, selective plugging, thermal stability, and improved oil recovery (IOR). Results showed that the resistance factor is small when DPG was injected, but obviously became larger while turning into brine water flooding. Both the oil and water relative permeability were reduced and greater reduction appeared in water relative permeability. DPG could block water flow without affecting oil flow, and oil–water segregated flow mechanism was proposed to explain this selective plugging. The injection pressure increases, caused by strong plugging due to the DPG aggregation aging in high temperature, which was consistent with the observation of atomic force microscope (AFM) photos. The DPG could effectively block high permeability zone and produce oil from low permeability zone, which could provide a practical way to enhance hydrocarbon recovery while reducing water production for extremely heterogeneous reservoirs.

Study on formation of gels formed by polymer and zirconium acetate

The gel system used in the preparation of dispersed particle gel for water shutoff treatments, which is composed of polyacrylamides and zirconium acetate, was investigated. The gelation process, the effects of various parameters on the gelation properties, the thermal stability, and the microstructure were addressed. The cross-linking reaction process is divided into three successive steps: induction, rapid cross-linking, and stabilization. High polymer and crosslinker concentrations reduce gelation time and increase gel strength. In addition, adding salts to the brine or increasing the temperature also decrease gelation time and increase gel strength. The optimum pH for the gel system is 7.49. In field applications, this gel system is recommended to be used within 130 °C using differential scanning calorimetry. The gel formed in a three-dimensional network structure was confirmed through environmental scanning electron microscopy.

Preparation of Dispersed Particle Gel (DPG) through a Simple High Speed Shearing Method

Dispersed particle gel (DPG) has been first successfully prepared using cross-linked gel systems through a simple high speed shearing method with the aid of a colloid mill at room temperature. The gel microstructure and particle size were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and dynamic light scattering (DLS) measurements. The results clearly show that the prepared DPG particles have highly uniformly spherical structures with an average size of 2.5 μm. A possible mechanism for the formation of DPG has been put forward and discussed in details. The high speed shearing method is considered to be the simple and rapid method for the preparation of DPG.