Polyacrylamide and its derivatives for oil recovery

 
Timeline for the Development of Polyacrylamides for Enhanced Oil 
Recovery
 
Through proper crosslinking linear PAMs, plenty of three dimensional hydrogels 
could be prepared with various properties applicable to oil recovery. [41] Currently, two 
types of gels are commonly applied in controlling conformance of EOR: in-situ 
crosslinking gels[42] and preformed particle gels (PPGs). [43-45] For in-situ-crosslinking 
gels, a mixture of monomers and crosslinkers are injected into a target formation to 
polymerize at the reservoir temperature and form an in-situ gel, that is intended to fully or 
partially seal a formation region. PPGs are prepared before injection. PPGs are 
crosslinked dry powder particles forming hydrogels, that can absorb water and expand to 
several tens or hundreds times their original size when dispersed in water. [46, 47] In-situ 

---

6 
gels are generally weak gel whereas PPGs could be strong and also weak gel by adjusting 
the type and amount of crosslinkers. Hydrogels with different strength could be applied 
in different area. Weak gels generally have good deformation abilities sealing the porous 
medium in the deep reservoir.

---

7 
2.
 
OBJECTIVE OF THIS RESEARCH 
Polyacrylamides have intensive applications in oil recovery and other areas. 
Especially, hydrophobically modified polyacrylamide is one of the most promising type. 
Currently, the difficulties in preparing modified polyacrylamide arise from the 
insolubility of the hydrophobic monomers in water. Additionally, traditional 
polyacrylamides and hydrogel products synthesized in and swollen by water are difficult 
and energy intensive to isolate from the water phase into dry particles. The mentioned 
problem can be solved by supposedly developing a water-free polymerization method.
Polyacrylamide (PAM) hydrogel is one of the most common plugging/diverting 
agents applied in conformance controls and it is preferred become of its low cost, non-
toxic and biological inertness, long chain length, capability to preserve their mechanical, 
morphological and adjustable properties. However, under some strong stimuli of acid or 
salinity, PAM hydrogels display dramatic shrinkage in size due to ion shielding effect. 
And, highly swollen PAM hydrogels are generally brittle since they are lacking an 
efficient energy dissipation mechanism and irregular distribution of crosslinking points. 
These drawbacks had limited PAMs’ applications under some circumstances. Thus, 
improving the mechanical properties of this kind of hydrogel has become a research 
target to expand their range of application. 
The following studies were planned to pursue these objectives: 
1.
To develop water-free methods to synthesize PAMs to solve the problem of 
incompatibility between the acrylamide monomer and hydrophobic co-monomer. To 
optimize the reaction condition of the system, including the type and amount of 
surfactants, maximum amount of monomer feeding.

---

8 
2.
To choose or synthesize proper polymerizable surfactant (sufmer) to introduce 
hydrophobes into polymer chain and make hydrophobically modified PAMs.
3.
To study the composition and properties of the products prepared by the water-free 
polymerization with different characterization methods. 
4.
To synthesize hydrogels with secondary network to achieve desired properties and 
study their swelling kinetic, tolerance to salt and pH change. 
5.
Use proper model and theory to study the hydrogels’ swelling and plugging 
capabilities. 

---

9