Laboratory Development and Successful Field Application of a Conformance Polymer System for Low-, Medium-, and High-Temperature Applications

Abstract

This paper presents the laboratory development of an organically crosslinked polymer (OCP) system with a wide temperature range of execution (60 to 350°F). The OCP system is targeted to address conformance problems (water and gas shutoff) to ultimately improve hydrocarbon recovery. This paper presents an overview of case histories in which the OCP system was implemented in various regions of the world in onshore and offshore hydrocarbon-producing wells. The OCP system has been successfully applied to sandstone, carbonate, and shale formations needing a conformance treatment. The OCP system has proven to be resistant to acid and stable in CO2 and H2S environments. In addition, the activation time and gel strength of the system is not affected by lithology, formation fluids, or heavy metals. The OCP system is acceptable to be used in some areas of the North Sea (including UK and Netherlands). Recently, a base polymer (for low temperatures) and a retarder (for high temperatures) have been introduced to the system to allow a wider temperature range of applicability without compromising its effectiveness or thermal stability. With the new base polymer, reasonable gelation times (~4 to 6 hours) can be achieved at 60°F with low crosslinker loadings. In addition, the new retarder allows reasonable placement times up to 350°F, without the need of cooling down the formation to obtain enough pumping time. Neither the new base polymer nor the retarder are detrimental to the thermal stability or gel strength of the system. To date, more than 600 jobs have been performed with the OCP system around the world to address conformance problems, such as water coning/cresting, high-permeability streaks, gravel-pack isolation, fracture shutoff, and/or casing leak repair. Because of the capability of the OCP system to withstand pressure, workover operations have been successfully performed in previously treated wells, including acid stimulation, sand control, and frac-pack treatments, among others. Case histories are presented for onshore and offshore applications.

Polymer Systems for Water Shutoff and Profile Modification: A Review Over the Last Decade

“…The PAtBA/ PEI gel system was introduced before 2000 by several researchers (Morgan et al 1997;Hardy et al 1998;Urlwin-Smith 1998 as a sealant for water in petroleum reservoirs. This system was applied widely in various parts of the world (Uddin et al 2003;Polo et al 2004;Eoff et al 2006;Vasquez et al 2006;Junesompitsiri et al 2009;Vasquez and Eoff 2010). 5 and 9, respectively.…”

Laboratory Evaluation of Organically Crosslinked Polymer for Water Shutoff in High-Temperature Well Applications

“…Gelation time data using a carbonate retarder reported by Vasquez et al (2010) shows a gelation time of around 6 hr at 350°F with 8 wt% of carbonate retarder. This was using an OCP system comprised of 7% active PAtBA and 0.66% PEI in 2% KCl brine.…”

“…Though this system has been successfully evaluated up to 350°F (Vasquez et al 2010), there has been no data reported on the applicability of this system at temperatures as high as 400°F. Though this system has been successfully evaluated up to 350°F (Vasquez et al 2010), there has been no data reported on the applicability of this system at temperatures as high as 400°F.…”

Experimental research of syneresis mechanism of HPAM/Cr3+ gel

“…In order to decrease the syneresis, some novel polymers with comonomers meeting the criteria of resistance to hydrolysis and inactivity toward divalent cations have been investigated and used in the gel. Although a fairly wide number of new acrylamide polymers have been described in the literature [9][10][11][12][13][14][15]. only a relatively small number of them, including acrylamide copolymers of N-vinyl pyrrolidone (N-VP), 2-acrylamido-2-methyl-propanesulfonate (AMPS), and Nvinyl acetamide (N-VA), have been commercialized.…”