Investigation of Polyvinyl Alcohol–Phenolic Aldehyde–Polyacrylamide Gel for the Application in Saline Oil Reservoirs for Profile Modification

Abstract

Polymer gels are widely used in the oil and gas industry, and high-molecular-weight polymer gels have significant effects on reservoir water plugging operations. Based on nontoxic polyvinyl alcohol (PVA), its stability in solvents containing formation saltwater (Tahe oilfield, NW China) was studied, and the composite gel solution was prepared using saltwater. The polymerization mechanism of PVA with phenolic resin (PF) and polyacrylamide (PAM) was analyzed, using hexamethylenetetramine (HMTA) instead of formaldehyde for cross-linking, and the rheological properties of the prepared gel were tested; the results showed excellent elastic properties. The application value of the gel was evaluated by gelation performance, thermal stability, and indoor simulated core displacement. The gelation time of the PVA/PAM/PF gel at 130 °C was 4 h; after aging at 130 °C for 40 days, the gel strength of the polymer gel remained at the G level, and no dehydration occurred. The simulated core plugging results showed that the breakthrough pressure was 11.79 MPa and the plugging rate was 99.83%. Compared with the PAM/PF gel, the PVA/PAM/PF gel has a higher breakthrough pressure, which is beneficial to reduce the permeability of the porous medium.

Gelation and Plugging Performance of Low-Concentration Partially Hydrolyzed Polyacrylamide/Polyethyleneimine System at Moderate Temperature and in Fractured Low-Permeability Reservoir

“…Moreover, its effect on the gelation time and gel strength were analyzed (Figure 3). The gel strength codes (A-I) of the bottle test were converted into numerical values (1)(2)(3)(4)(5)(6)(7)(8)(9). The results showed that there was a noticeable upward trend in both the gelation rate and gel strength as the hydrodynamic radius of the HPAM increased.…”

“…An effective solution to mitigate or eliminate this problem is polymer gel treatment [ 4 , 5 , 6 , 7 ]. Polymer gels can be categorized into inorganic crosslinked gels and organic crosslinked gels based on the type of crosslinker employed [ 8 , 9 ].…”

Fine Modeling of Multiscale Fracture Cavity Fusion in Fault Solution Reservoirs Based on Multiscale Discrete Crack Modeling Method

“…Marinković et al conducted a composite hydrogeothermal investigation of the post-Neotethys Late Paleogene Neogene crustal core complex in the Kopaonik Mountains of the southwestern Serbian Plateau. The fractured carbonate reservoirs in Tahe Oilfield are different from conventional porous sandstone reservoirs and other karst carbonate reservoirs. − The main storage space of oil reservoirs is mainly composed of cracks and caves formed by structural deformation and collapse, as well as pores and caves formed by karst processes. − The large karst caves are the most important storage space, and cracks are the main connecting channels. − Due to the different types of karst caves and cracks of different scales, their morphology and scale are different, making it difficult to establish a unified geological model using a single method. − Therefore, different modeling methods are used to establish discrete models for different constituent elements. − Then, the discrete models were integrated into a wpore, establishing a three-dimensional distribution model of the fractured and vuggy reservoir. − …”

“… 34 − 38 Therefore, different modeling methods are used to establish discrete models for different constituent elements. 37 − 38 39 Then, the discrete models were integrated into a wpore, establishing a three-dimensional distribution model of the fractured and vuggy reservoir. 45 − 56 …”