Effect of Network Parameters of Preformed Particle Gel on Structural Strength for Water Management

Abstract

Summary Preformed particle gel (PPG) is an appropriate solution for conformance control and water management in low permeability reservoirs. In this paper, the network parameters of PPGs are evaluated through swelling tests and rheology and by determining their role in maintaining structural strength. Several PPG hydrogels were prepared by varying the concentrations of polyacrylamide and chromium triacetate [Cr(OAc)3] as copolymer and crosslinker, respectively, using a central composite design. The characterization of these hydrogels was performed using a scanning electron microscope (SEM), electron dispersion X-ray (EDX), and environmental scanning electron microscope (ESEM). The correlation between reaction conditions and the network parameters of polymer networks, such as the molecular weight of the polymer chain between two neighboring crosslinks (Mc¯), the crosslink density, and the size fraction, have been determined. In addition, swelling of the hydrogels took place through the Fickian diffusion mechanism. Structural states of Laponite dispersions strongly depend on concentration and ionic strength. Based on the rheological tests, the dynamic modulus of the PPG was strongly dependent on the initial concentration and resulting network parameters of the hydrogel. The results showed an effective interaction between Mc¯ and the elastic modulus of the gel network. Through the optimization of the network parameters, the appropriate composition was presented on the basis of the factors of strength (complex modulus of 4×104 Pa in the plateau region), the formation of a 3D network, and the preservation of the viscoelastic structure in the presence of Na+, Ca2+, and Mg2+, at a salt sensitivity of 0.5. In addition, the optimum sample structure was confirmed on the basis of microscopic images. Based on the coreflooding data, the optimal PPG showed a disproportionate permeability reduction (DPR) index of 17.01 and indicated the dual performance of these materials against water and oil. Also, the permeability diagrams of the core showed wettability of the oil-wet core could shift to more water-wet after PPG injection. To summarize this research, we present the determination and analyses of the network parameters as a novel technique for predicting the performance of hydrogels in porous media, and for investigating their strength under harsh reservoir conditions. In other words, determination of the network parameters can be used to ensure the success of the gel performance in porous media.

Investigating the effects of polymer plugging mechanism of liquid production decrease and improvement by the cross-linked gel performance

“…Gel injection is one of the most efficient techniques of EOR to increase oil recovery. Water management can be a better option than increasing oil production 70 , 71 . Especially in heterogeneous reservoirs, gel injection, could be selected instead of polymer injection 72 .…”

Review of Microgels for Enhanced Oil Recovery: Properties and Cases of Application

“…Extended oilfield exploitation leads to an increase in the water content in well production. We obtained a PPG adapted to the reservoir conditions of the Volga-Ural oil-and-gas province characterized by a low oil reservoir temperature (T < 30 • C) and a high mineralization of formation water (200-230 g/cm 3 ). The PPG was synthesized in a concentrated solution of polyacrylamide with the addition of acrylic acid.…”

“…Polymer gels are widely used in mature reservoirs due to their excellent profile control ability, easy preparation, and disproportionate permeability reduction property [ 2 ]. A new trend in gel preparation for EOR is the synthesis of preformed particle gels (PPG) having significant potential for conformance control [ 3 ]. PPGs do not have the disadvantages of other in-situ gels such as gelation time, insufficient strength in the presence of formation water [ 4 ], gel structure deformation due to shear degradation and changing of gelant composition induced by contact with reservoir minerals and fluids [ 5 ].…”

Synergistic mechanism of well pattern adjustment and heterogeneous phase combined flooding on enhancing oil recovery in mature fault-block reservoirs

“…In addition, PPG can swell in formation brine and have certain strength. The suspension of PPG shows a strong ability of profile control and significant EOR effect in mature reservoir (Goudarzi et al 2015;Salehi et al 2020;Wang et al 2022). In recent years, based on the development status of Shengli oilfield, a novel branch-preformed particle gel (B-PPG) has been developed on the basis of PPG (Sang et al 2014;Li et al 2021).…”