Synergistic Effect of Alkali–Surfactant–Polymer and Preformed Particle Gel on Profile Control after Polymer Flooding in Heterogeneous Reservoirs

Abstract

Heterogeneity is a significant feature of many mature oilfields after polymer flooding, which presents great challenges for further enhanced oil recovery (EOR). The displacing fluid after polymer flooding should have the dual effects of improving the swept volume and increasing oil displacement efficiency. At present, alkali−surfactant−polymer (ASP) flooding is an important approach for further EOR after polymer flooding in the Daqing Oilfield. Preformed particle gel (PPG) is a new type of chemical agent with a powerful ability to deform and pass through the pore throat. Here, a series of experiments were carried out to investigate the profile control of PPG/ASP mixed solutions in heterogeneous reservoirs. The results show that, with respect to profile adjustment and EOR after polymer flooding, PPG/ASP mixed solutions are better than ASP-only solutions. Regarding PPG/ASP mixed solutions, PPG and hydrolyzed polyacrylamide (HPAM) could block the reservoir preferential fluid flow pathways via their properties of easy deformation and high viscosity in order to achieve the purpose of improving the swept volume; at the same time, Na 2 CO 3 and petroleum sulfonate could reduce oil−water interfacial tension so as to increase oil displacement efficiency. Besides, compared with ASP-only solutions, PPG/ASP mixed solutions have greater resistance and residual resistance coefficients, higher viscosity, and better flow control stability. Oil recovery enhanced by using PPG/ASP mixed solutions after polymer flooding boasts 3.4% more original oil in place (OOIP) when compared to ASP-only solutions, and the consumption of chemical agents is reduced by 15.8%. Furthermore, the proportion and characteristics of microscopic residual oil distribution after different flooding systems were investigated. The results are consistent with the core flooding experiment and confirm that when combined, PPG and ASP have a synergistic effect on profile control after polymer flooding in heterogeneous reservoirs.

High Blocking Capacity of Fuzzy-Ball Fluid to Further Enhance Oil Recovery after Polymer Flooding in Heterogeneous Sandstone Reservoirs

“…As shown in Figure 3 , the F MR of 200, 600, 1200, and 5000 mD is 76.25, 78.81, 115.16, and 239.96, respectively, and the F MRR is 13.95, 15.20, 21.57, and 49.91, respectively. The F MR and F MRR of fuzzy-ball fluid are significantly greater than those of polymers 30 and gels, 31 which are commonly used in profile control and enhanced oil recovery (EOR). It demonstrates that fuzzy-ball fluid has excellent sealing property and has a high potential for further EOR after polymer displacement.…”

Synergistic Effects of Weak Alkaline–Surfactant–Polymer and SiO2 Nanoparticles Flooding on Enhanced Heavy Oil Recovery

“…In China’s Daqing oilfield, an ASP compound solution was first injected in March 1997, which achieved very promising results in terms of productivity compared to water flooding . Compared to water injection, the additional oil recovery of ASP solution injection can be increased to about 20% of the original oil in place (OOIP) …”

“…20 Compared to water injection, the additional oil recovery of ASP solution injection can be increased to about 20% of the original oil in place (OOIP). 21 The use of nanoparticles (NPs) in EOR has attracted widespread interest. An EOR method was proposed by combining traditional chemical agents (surfactant/polymer) flooding and nanotechnology.…”

Impact of Sodium Dodecyl Benzene Sulfonate Concentration on the Stability of the Crude Oil–Mineral Water Interfacial Film: A Molecular Dynamics Simulation Study

“…Surfactants, as an industrial additive, are widely applied in petrochemical, mining, medical treatment, food processing, and other industrial fields due to their unique interfacial properties. − Due to their performance in reducing oil–water interfacial tension, alternating wettability, solubilizing crude oil, and changing the interfacial rheology, they can release the crude oil trapped and adhered in the porous medium of the rock, thus enhancing oil recovery (EOR). − Especially, in response to the emergence of the tertiary oil recovery process in recent years, a growing number of surfactants have been screened, designed, or improved to become efficient chemical flooding agents, such as those applied in alkaline/surfactant/polymer (ASP) flooding. − At present, anionic surfactants, such as sodium dodecyl benzene sulfonate (SDBS), are the most widely used surfactants in the tertiary oil recovery process, which have an amphiphilic molecular structure. When present in oil–water systems, they are bound to be adsorbed and arranged at the oil–water interface to form an interfacial film .…”