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

Abstract

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 (∇P cr) was required to drive the gel particles to propagate through the channels. Below ∇P cr, the gels could not transport in the porous channels. The existence of the ∇P cr 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 ∇P cr. The ∇P cr increased exponentially with the MSR at relatively low MSRs (<2). The ∇P cr was lower than 60 psi/ft. A correlation was proposed to describe the ∇P cr–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.

Laboratory Evaluation of Placement Behavior of Microgels for Conformance Control in Reservoirs Containing Superpermeable Channels

“…The distinctly different threshold pressures in reservoir matrices and super-K channels resulted in the selective entry of gel particles into the super-K channels. Moreover, a critical pressure gradient was required for gel particles to propagate into a porous medium …”

“…The different threshold pressures in channeling features and reservoir matrices were responsible for the selective penetration of gels in heterogeneous reservoirs. , A critical pressure gradient was required for gel particles to propagate in porous media . The critical pressure gradient was found to exponentially increase with the particle/pore matching size ratio . Gel dispersions exhibited apparent thinning behavior when flowing through porous media .…”

“…27,28 A critical pressure gradient was required for gel particles to propagate in porous media. 29 The critical pressure gradient was found to exponentially increase with the particle/pore matching size ratio. 29 Gel dispersions exhibited apparent thinning behavior when flowing through porous media.…”

“…29 The critical pressure gradient was found to exponentially increase with the particle/pore matching size ratio. 29 Gel dispersions exhibited apparent thinning behavior when flowing through porous media. 30 The thinning behavior benefits the indepth placement of the gel materials.…”

“…A threshold differential penetration pressure should be overcome in order for deformable particles to enter a porous media . The different threshold pressures in channeling features and reservoir matrices were responsible for the selective penetration of gels in heterogeneous reservoirs. , A critical pressure gradient was required for gel particles to propagate in porous media . The critical pressure gradient was found to exponentially increase with the particle/pore matching size ratio .…”