Propagation of Swellable Microgels through Superpermeable Channels: Impact of Particle-Pore Matching Size Relationship

Excessive water production during fossil fuel extraction causes worldwide environmental and economic challenges. Micrometer-sized hydrogel particles were tested to solve the problem. Propagation behavior of the microgel particles in superpermeable channels (i.e., target locations of the particles) plays a key role in the effectiveness of the technology. The impact of the particle-pore matching size relationship was systematically studied. Microgel dispersions were injected into superpermeable channels (55-221 darcies, mimicked with sand packs). We observed that a critical (minimum) pressure gradient (del P-cr) was required to drive the gel particles to propagate through the channels. Below del P-cr, the gels could not transport in the porous channels. The existence of the VPcr was confirmed with gel injection experiments carried out in constant-injection-pressure mode. The particle-to-pore matching size ratio (MSR) had a significant impact on the del P-cr. The del P-cr increased exponentially with the MSR at relatively low MSRs (<2). The del P-cr was lower than 60 psi/ft. A correlation was proposed to describe the del Pcr-MSR relationship in the superpermeable channels. Diagrams were developed to estimate the maximum propagation distance of the gels in channels in conceptual field applications. At low MSRs, the gel particles could transport a significant distance away from the wellbore, which was favorable for in-depth conformance treatments. At high MSRs, the transport distance of the gel particles was limited, which was favorable for near-wellbore treatments. The transport-distance diagrams can help engineers select proper gel products to address water channeling problems in reservoirs. Also, this work provides an effective procedure to study the impact of other parameters (e.g., dispersion concentration and gel strength) on the propagation distance of gel materials.

Automated summary

This study investigated the propagation behavior of micrometer-sized hydrogel particles in superpermeable channels and found that the particle-pore matching size relationship played a key role in the effectiveness of the technology. Specific pressure gradients were required for gel particle propagation in the channels, and this pressure gradient was influenced by the particle-to-pore matching size ratio.