Influence of salinity on the properties of the different HPAM/Al³⁺systems

Abstract

In order to achieve oil increment and water cut reduction in the heterogeneous oil reservoirs, a conformance control technology by using HPAM/Al 3+ systems has been widely used due to the low price and environmental friendliness. However, the complex structure and state of high-valent metal ions in brine water can directly affect the properties of the different HPAM/Al 3+ systems, which may lead to unreasonable applications. Therefore, in order to better utilize the HPAM/Al 3+ systems, the characteristics of gelation of HPAM and the three types of aluminum citrate under different salinities are systematically studied. Experimental results show that an important reason for the cross-linking reaction of HPAM/Al 3+ being affected by salinity is that the morphology and structure of the aluminum citrate complex is different under the different salinities. Although the change of characteristics of the reaction time and the cross-linking degree of the three HPAM/Al 3+ systems are different, the process of the cross-linking reactions of the three HPAM/Al 3+ systems are the same. Besides, the thermal stability of the HPAM/Al 3+ gels is weakened with the increasing of salinity regardless of the ratio of citrate ligands to Al 3+ . According to the matching relationship between salinity and HPAM/Al 3+ systems, the reaction time can be controlled to achieve the requirements of on-site construction operation for the conformance control of a given heterogeneous oil reservoir.

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

“…The logarithm data of GT in this study is extracted and fitted to the reciprocal of absolute temperature, and the plot of ln(GT) vs. 1/T is given in Figure 9. The data of GT are fitted well with Equation (8). The activation energies of two formulas were calculated to be 51.91 and 55.45 kJ/mol, respectively.…”

“…The hydrolyzed polyacrylamide contains many amide groups (-CONH 2 ) and carboxyl groups (-COO − ) in its molecular chain. It could crosslink with different types of crosslinkers, such as Cr 3+ [ 6 , 7 ], Al 3+ [ 8 ], Zr 4+ [ 9 ], phenolic resin [ 10 , 11 ], etc. However, multivalent metal ions and phenolic resin are toxic.…”

Development of pH-Controlled Aluminum-Based Polymeric Gel for Conformance Control in Sour Gas Reservoirs

“… 33 , 34 While pH and temperature have the most significant effect on the gelation time, other factors influence the equilibrium gel strength such as the salt type and content and the polymer to crosslinker ratio. 27 , 33 , 35 …”

“…Another factor that affects the stability of colloidal crosslinkers is the type of additives in the system where recent studies showed that silica nanoparticles can enhance both the thermal as well as physical stabilities of micro-sized particles in the polymeric solutions. , Apart from the stability of particles, crosslinking of the inorganic crosslinkers was found to be pH-triggered, having the gelation time decreased as the pH increases . The effect of pH is believed to result from the hydrolysis of PAM that is increased at high pH, leading to the conversion of more amide groups to carboxylate groups resulting in more crosslinkable sites. , Moreover, the crosslinking reaction follows Arrhenius’s equation where the increase in the temperature increases the crosslinking rate. , While pH and temperature have the most significant effect on the gelation time, other factors influence the equilibrium gel strength such as the salt type and content and the polymer to crosslinker ratio. ,, …”

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for Indepth Water Control in Mature Oilfields

“…The polyacrylamide contains a large number of amide groups (-CONH2) and carboxyl groups (-COO -) in its molecular chain after hydrolysis. It could crosslink with different types of crosslinkers, such as Cr 3+ [6,7], Al 3+ [8], Zr 4+ [9] or phenolic resin [10][11] et al. However, multivalent metal ions and phenolic resin are toxic.…”