Characterization of Crosslinked Gel Kinetics and Gel Strength by Use of NMR

Romero‐Zerón, Laura; Hum, Florence M.; Kantzas, Apostolos

doi:10.2118/86548-pa

Cited by 45 publications

(16 citation statements)

References 39 publications

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“…In waterinjection wells, gels are used to improve reservoir sweep efficiency (Tweidt et al 1997;He at al. 2006;Norman et al 2006;Saez et al 2012;Altunina et al 2013;Crespo et al 2014) when oil is bypassed by water in high-permeability streaks. This is performed by diverting injected water into less-swept (less-permeable) zones.…”

Section: Introductionmentioning

confidence: 99%

Gelation of a Water-Shutoff Gel at High Pressure and High Temperature: Rheological Investigation

et al. 2015

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Polymeric gels are used to reduce or shut off excess water in petroleum reservoirs. The strength of polymeric gels needs to be high enough to withstand the water flow. This study investigates the strength of an organically crosslinked polyacrylamide (PAM) with polyethylenimine (PEI) as crosslinker. Dynamic testing measurements at high temperatures up to 130 C (266 F) and high pressure (500 psi) were used. During the gelation process, the rate of crosslinking increases with increased temperature. However, after the crosslinking reactions were completed, G 0 was lower at higher temperatures than at lower temperatures. Polymer concentration has a stronger impact on G 0 in comparison with the crosslinker. Salinity of mixing water has a negative impact on G 0 . High G 0 was observed in distilled water (1044 Pa) in comparison with field water (725 Pa) at 130 C (266 F). Moreover, samples prepared at alkaline and acidic conditions produced stronger gels compared with samples prepared at neutral conditions. However, the gelation time is longer at a pH of 7. Ammonium chloride is found to be a very effective retarder in comparison with NaCl. The yield stress of the gel was correlated to the pressure gradient for the gel extrusion through fractures. It was found that gels with 7:0.3 and 5:0.3 wt% PAM/PEI gave pressure gradients of 155.5 kPa/m (55.2 psi/m) and 3572 kPa/m (518 psi/m), respectively. The decrease or increase in gel strength was explained through the impact of the different parameters on PAM hydrolysis.

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Section: Introductionmentioning

confidence: 99%

Gelation of a Water-Shutoff Gel at High Pressure and High Temperature: Rheological Investigation

et al. 2015

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“…Cylindrical outcrop core plugs were drilled out from larger slabs of Bentheimer sandstone (permeability, K ¼ 1.2 D, and porosity, U ¼ 23%) (Schutjens et al 1995;Klein and Reuschle 2003) and Edwards limestone (K ¼ 3 to 28 mD, and U ¼ 16 to 26%) (Tie 2006;Johannesen 2008), and cut longitudinally with a band saw, which created smooth fractures. Core and fracture surfaces were washed with tap water, and the core plugs were dried for one week, first at room temperature and thereafter at an elevated temperature of 60 C. Fractured core plugs were assembled by placing a polyoxymethylene (POM) spacer between two core halves, creating a 1-mm fracture aperture with a calculated permeability of approximately 8.4 Â 10 4 D (Witherspoon et al 1980).…”

Section: Methodsmentioning

confidence: 99%

“…For crosslinked polymer solutions, numerous studies have shown that one can attribute volumetric changes in a gel after placement in a reservoir to syneresis (Vossoughi 2000;Romero-Zeron et al 2008), in which solvent is expulsed from the gel network, or dehydration, either from imposing an external pressure gradient on the gel network (Al-Sharji et al 1999;Krishnan et al 2000;Wilton and Asghari 2007) or caused by capillary spontaneous imbibition of solvent from the gel into an oil-saturated adjacent porous rock (Brattekås et al 2014). Recent works have also concentrated on the swelling and shrinking behavior of polymer gels caused by contrasts in salinity or pH between the gel solvent and formation fluids, which influence the osmotic pressure balance between a polymer gel network and its surroundings.…”

Section: Introductionmentioning

confidence: 99%

Low-Salinity Chase Waterfloods Improve Performance of Cr(III)-Acetate Hydrolyzed Polyacrylamide Gel in Fractured Cores

Brattekås

Graue

Seright

2015

SPE Reservoir Evaluation &Amp; Engineering

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Polymer gels are frequently applied for conformance improvement in fractured reservoirs, where fluid channeling through fractures limits the success of waterflooding. Placement of polymer gel in fractures reduces fracture conductivity, thus increasing pressure gradients across matrix blocks during chase floods. A gel-filled fracture is reopened to fluid flow if the injection pressure during chase floods exceeds the gel-rupture pressure; thus, channeling through the fractures resumes. The success of a polymergel treatment, therefore, depends on the rupture pressure.Salinity differences between the gel network and surrounding water phase are known causes of gel swelling (e.g., observed in recent work on preformed particle gels). Gel swelling and its effect on fluid flow have, however, been less studied in conjunction with conventional polymer gels. By use of corefloods, this work demonstrates that low-salinity water can swell conventional Cr(III)-acetate hydrolyzed polyacrylamide (HPAM) gels, thereby significantly improving gel-blocking performance after gel rupture.Formed polymer gel was placed in fractured core plugs, and chase waterfloods were performed using four different brine compositions, of which three were low-salinity brines. The fluid flow rates through the matrix and differential pressures across the matrix and fracture were measured and shown to increase with decreasing salinity in the injected water phase. In some cores, the fractures were reblocked during low-salinity waterfloods, and gelblocking capacity was increased above the initial level. Low-salinity water subsequently flooded the matrix during chase floods, which provided additional benefits to the waterflood. The improved blocking capacity of the gel was caused by a difference in salinity between the gel and injected water phase, which induced gel swelling. The results were reproducible through several experiments, and stable for long periods of time in both sandstone and carbonate outcrop core materials. Combining polymer gel placement in fractures with low-salinity chase floods is a promising approach in integrated enhanced oil recovery (IEOR).

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“…The gel strength of organic cross‐linked polymer was also considered in high‐temperature field application. The gel is placed into the target zone through techniques such as bullheading or coiled tubing . Mostly coiled tube intervention method was selected instead of workover rigs because of the versatility of its operations.…”

Section: Field Applicationsmentioning

confidence: 99%

In situ organically cross‐linked polymer gel for high‐temperature reservoir conformance control: A review

Amir

Said

Jan

2018

Polymers for Advanced Techs

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Polymer gel has been established as water‐blocking agents in oil recovery application. In this practice, a mixture known as gelant is injected into target area and set into a semisolid gel after a certain adequate time. Besides profile modification and water shutoff, the role of the polymer gel in conformance control is to block high permeability regions, before diverting injected water from high permeability to low permeability zones of the reservoir. It is to boost the oil displacement and sweep efficiency. This is the key to improve oil recovery in the heterogeneous oil reservoirs. However, very limited gels are applicable for harsh conditions, especially in high‐temperature reservoirs. Organically cross‐linked polymer is 1 of the materials for conformance control at high‐temperature reservoirs. Many experimental works and field applications have exhibited the potential of this technology. This paper presents a concise review on this polymer gel for conformance control at high‐temperature wells. Firstly, in situ organically cross‐linked polymer gel has been introduced, and the reason of the use over other types of polymer gels is summarized. The early studies of organically cross‐linked gel systems are also discussed, followed by the chemistry and the gelation mechanisms. An extensive review on factors that affect gelation kinetics and field applications is also discussed in some detail.

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Characterization of Crosslinked Gel Kinetics and Gel Strength by Use of NMR

Cited by 45 publications

References 39 publications

Gelation of a Water-Shutoff Gel at High Pressure and High Temperature: Rheological Investigation

Gelation of a Water-Shutoff Gel at High Pressure and High Temperature: Rheological Investigation

Low-Salinity Chase Waterfloods Improve Performance of Cr(III)-Acetate Hydrolyzed Polyacrylamide Gel in Fractured Cores

In situ organically cross‐linked polymer gel for high‐temperature reservoir conformance control: A review

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