The Development of a Low-Shear Valve Suitable for Polymer Flooding

Abstract

Summary Hydrolyzed polyacrylamides (HPAMs) are used as mobility-control agents to improve the macroscopic sweep efficiency of oil reservoirs. To maximize their viscosifying power, very-high-molecular-weight (MW) polymers are preferred, which in turn make them very sensitive to shear degradation. Shear degradation originates from chain stretching and breaking when the solution is subjected to a sudden acceleration. Fundamental development work is presented, where polymer degradation is studied in flow through reducers and expanders of various geometrical shapes, as well as through straight pipes and pipe coils of various diameters and lengths. The work also demonstrates that the creation of pressure drop through viscous pipe friction is very ineffective with regular tubes, most likely because of the drag-reducing effect of polymer. In addition, the arrangement of very long, straight, or coiled pipes in parallel is impractical and bulky. This paper further presents the development of a novel valve technology that solves these challenges. First, through the unique use of spiraling flow channels with optimally designed reducer and expansion zones, machined on the surface of disks, shear forces and thereby polymer degradation is controlled. Second, by arranging numerous such disks to form a disk stack, any target capacity can be met efficiently. Third, the disk-stack concept enables an easy and reliable plug-based solution for flow regulation and control. The performance of the new valve technology is demonstrated through small- and large-scale prototype tests. At very-shear-sensitive test conditions, it is demonstrated that polymer degradation of the new valve is less than 10% at 40- to 45-bar pressure drop, compared with 60 to 80% for a standard valve.

Experimental evaluation of the mechanical degradation of HPAM polymeric solutions used in Enhanced Oil Recovery

“…Furthermore, this mechanical degradation reduces polymer viscosity affecting the oil recovery, which demands greater energy consumption to carry out a homogeneous oil sweep [11]- [15]. To determine the physicochemical factors involved in the mechanical degradation of polymer solutions, different alternatives have been proposed, such as the one authored by Husveg T. et al, [16], who developed a novel valve technology for its use in EOR with polymers. By designing spiral channels adding expansion and reduction zones, greater control of shear forces is evidenced, reducing the percentage of polymer degradation.…”

Influence of the Injection Scheme on the Enhanced Oil Recovery Ability of Heterogeneous Phase Combination Flooding in Mature Waterflooded Reservoirs

“…Among these chemical flooding technologies, polymer flooding has been widely applied in mature waterflooded reservoirs . The high viscosity of the polymer solution can reduce the oil–water mobility ratio and inhibit the fingering phenomenon during the displacement process. − Nevertheless, for serious heterogeneous mature reservoirs, the viscous polymer can have limited ability of expanding the swept volume.…”