Abstract
Polymers are one of the most widely used chemicals in the oil and gas industry. They are used for mobility control in enhanced oil recovery, in conformance control as a cross-linked plugging agent, as a fracking fluid for fracture propagation and proppant transportation, and in drilling fluids as an additive for drilling mud enhancement. This research characterizes the polymer injectivity in different pore sizes under different conditions and evaluates the polymer conditions after injection. Based on this, the ability to reinject the polymer in the porous media is discussed. The factors studied include the pore size, the polymer concentration, the polymer injection flowrate, and polymer injectivity. When the porous media size was reduced to 1.59 mm (1/16th of an inch), the injectivity value reduced significantly, reaching less than 0.2 mL/min/psi and the polymer degradation increased primarily due to shearing. Results also showed that the polymers underwent four main degradations during injection including dehydration, syneresis, shearing, and excessive hydrolysis. In continuous fractures, the degradation is a strong function of the fracture size, length, and the polymer structure. The experimental results showed that one or more of the polymer degradations resulted in the inability to reinject the polymer in most cases.