Synthesis of a custom-made suspension of preformed particle gel with improved strength properties and its application in the enhancement of oil recovery in a micromodel scale

Abstract

The objective of this work is to develop a new Preformed Particle Gel (PPG) suspension to enhance oil production and monitor water production in a porous medium on micromodel scale. To achieve the above goal, the following synthetic method was used. At the outset, the PPG samples were synthesized with polyethylene amine (PEI) as a crosslinker, 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (AAPH) as initiator and acrylamide (AM) and 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) monomers to improve the strength properties of PPGs by the radical polymerization method. Also, to characterize the micro and macro structural the samples, the scanning electron microscopy (SEM), environmental scanning electron microscope (ESEM), Fourier transforms IR spectra (FTIR), and particle size distribution (PDS) analytical techniques were used. The viscoelastic properties, structural strength, thermal stability and swelling capacity in two different conditions of room temperature (in distilled water) and at the temperature of 90 °C (in both distilled water and brine solution with 10 wt% NaCl) were analyzed for the samples prepared in this work. Based on the results of the frequency sweep test (FST), not only the formation of the 3D structure of hydrogels was confirmed but also the effects of material composition on the rigidity modulus G′(∞) in the structure of PPGs were investigated. The results of swelling and the FST tests led to introduce a novel and custom-made formulation for the suspension of (AM-AMPS)/PEI with an optimal composition of crosslinker and AM/AMPS. The flow curve of the customized sample with optimal PPG concentration also indicated that the Newtonian behavior of the new suspension at the lowest and highest shear rates and a shear-thinning behavior in the middle region, i.e., 0.01 to 1000 1/s. Additionally, to further examine the new PPG, the Thermalgravimetric Analysis (TGA), Derivative Thermogravimetry (DTG) and Temperature Sweep Test (TST) methods were used to evaluate the thermal stability of the 1 wt% PPG suspension. According to the TGA and DTG results, the synthesized sample could maintain its structure up to 260 °C and the destruction of the structure occurred at the temperature above 520 °C. Also, the results of the TST test confirmed the rubbery plateau state with increasing the system temperature. Finally, the micromodel technique was used to study the effect of injection of the PPG suspension on the amount of oil recovery. Therefore, the optimal PPG suspension was injected into an oil saturated micromodel and the amount of oil recovery was measured as 81%. Based on the results of the micromodel experiments, it was concluded that the oil recovery from the injection of the PPG suspension could increase 2.5 times more comparing to that of water injection with no PPG suspension.