Flow Behavior and Viscous-Oil-Microdisplacement Characteristics of Hydrophobically Modified Partially Hydrolyzed Polyacrylamide in a Repeatable Quantitative Visualization Micromodel

Abstract

Summary To profoundly investigate the flow behavior and viscous-oil-microdisplacement characteristics of hydrophobically modified partially hydrolyzed polyacrylamides (HMHPAMs) as well as the effect of associating monomer content on those behaviors and characteristics, compared with partially hydrolyzed polyacrylamide (HPAM), the flow experiments through three serial mounted flat-sand-inclusion micromodels and the viscous-oil-microdisplacement experiments in both homogeneous and interstratified connected heterogeneous repeatable quantitative visualization micromodels were conducted by use of a series of polymers with varied associating monomer content (0–1.0 mol%) at similar viscosity within all shear rates concerned. The results obtained from flow experiments show that the resistance factors (RFs) and residual resistance factors (RRFs) generated by HMHPAMs were noticeably higher than those of HPAM, and the RFs and RRFs exhibited significant permeability dependence and increased with associating monomer content. The greater RFs and RRFs for associative polymer might not be mainly caused by polymer adsorption or retention but mostly caused by increasing aggregate sizes. At concerned permeabilities (1.1–6.1 µm2), all injections of HMHPAMs could tend to be stable, which indicates that all HMHPAMs could propagate deep into the porous media. The viscous-oil-microdisplacement experiments regarding the visualization micromodels with varied permeabilities (and permeability contrasts) provide new insights into the viscous-oil-microdisplacement characteristics of HMHPAMs, such as the piston-like displacement and profile modification. In homogeneous models, under different permeabilities (1.1–6.1 µm2), the variations of final viscous-oil recovery first increased and then decreased as a function of increasing hydrophobe content, and the hydrophobe content of the polymer to obtain maximum oil recovery enhanced with increasing permeability. This might qualitatively indicate that a constant permeability matches an optimal content of hydrophobic groups. At permeability contrast of approximately three, the HMHPAM with lower hydrophobe content (0.2 mol%) could obtain the maximum viscous-oil recovery. In contrast, the maximum viscous-oil recovery was achieved by the HMHPAM with higher hydrophobe content (1.0 mol%) at a contrast of approximately five. The HMHPAM with higher content of hydrophobic groups is suitable for the significant heterogeneity.

Experimental Study on Medium Viscosity Oil Displacement Using Viscoelastic Polymer

“…Comparing with HPAM, the resistance factors and residual resistance factors produced by HMHPAMs are higher than those of HPAM due to an increase of aggregate size of HMHPAMs. The microdisplacement experiments indicated that the HMHPAMs could move deep into the porous media of reservoirs [7]. Moreover, the existing literature also reported that HMHPAMs had more stable displacement front and easily formed a piston-like displacement.…”

“…However, with the rapid growth in energy demand and a depletion of conventional oil, the development of nonconventional energy sources, such as viscous oil, bitumen, and shale oil, is significant for the entire petroleum industry [4][5][6]. The viscous oil is mainly distributed in many basins, especially in the region of Middle East, North America, and South America [7,8]. Reports by the U.S. Department of Energy showed that 40% of the 900-1300 billion barrels of reserves in the world is viscous oil and ultraheavy oil [9,10].…”

“…Moreover, the existing literature also reported that HMHPAMs had more stable displacement front and easily formed a piston-like displacement. The keys depended on what polymer viscosity injected and when the polymer injection should be reduced or stopped; the extensive review of polymer flooding in many oil fields are presented elsewhere [7,11,16,41]. The polymer viscosity, concentration, and slug size employed in the viscous oil field application were also discussed and considered.…”

Experimental evaluation of ASP flooding to improve oil recovery in heterogeneous reservoirs by layered injection approach

“…However, most Chinese oil field reservoirs are continental deposits with serious heterogeneity and prominent interlayer contradictions. Under the traditional injection method, 7 ASP solution is injected into high‐permeability reservoirs in large amounts, 8‐10 while it is injected into low‐permeability reservoirs in small amounts, and the compatibility of low‐permeability reservoirs with ASP solution is poor, 11‐13 resulting in a poor production degree and low total oil recovery in low‐permeability reservoirs. Therefore, in order to improve the total oil recovery of heterogeneous oil layers, a layered injection method which is for the different levels of oil permeability is proposed for Daqing Oilfield, and the method is shown in Figure 1 14,15 .…”

Experimental Study on the Effect of ASP Flooding on Improving Oil Recovery in Low Permeability Reservoirs Based on a Partial Quality Tool

“…An ASP solution with a high molecular weight and high concentration can greatly improve oil recovery in high permeability oil layers [4]. However, for heterogeneous reservoirs, the injection effect of the displacement agent in high permeability reservoirs is better and the injection amount is greater [5,6], which results in less displacement agent flowing into low permeability reservoirs, and it is difficult for high molecular weight and high concentration displacement agents to enter low permeability reservoirs [7], resulting in a low overall crude oil recovery. For this reason, Daqing Oilfield has proposed a type of injection technology.…”