Thermally Active Polymer To Improve Sweep Efficiency of Waterfloods: Simulation and Pilot Design Approaches

Abstract

A common problem in many waterflooded oil reservoirs is early water breakthrough with high water cut through highly conductive thief zones. Thermally active polymer (TAP), which is an expandable submicron particulate of low viscosity, has been successfully used as an in-depth conformance to improve sweep efficiency of waterfloods.This paper describes the workflow to evaluate technical feasibility of this conformance technology for proper pilot-project designs supported with detailed simulation studies. Two simulation approaches have been developed to model properties of this polymer and its interaction with reservoir rock. Both methods include temperature-triggered viscosification and adsorption/retention effects. Temperature profile in the reservoir is modeled by energy balance to accurately place this polymer at the optimum location in the thief zone. The first method considers a single chemical component in the water phase. The second method is based on chemical reactions of multiple chemical components. Both simulation approaches are compared and discussed.Results show that temperature-triggered polymers can increase oil recovery by viscosification and chemical adsorption/retention, which reduces thief-zone permeability and diverts flow into unswept zones. Sensitivity analyses suggest that ultimate oil recovery and conformance control depend on the thief-zone temperature, vertical-to the horizontal-permeability ratio (K v /K h ), thief-zone vertical location, injection concentration and slug size, oil viscosity, and chemical adsorption and its reversibility, among other factors. For high-flow-capacity thief zones and mobility ratios higher than 10, oil recoveries can be improved by increasing chemical concentration or slug size of treatments, or both. Reservoirs with low K v /K h (< 0.1) and high permeability contrast generally shows faster incremental recoveries than reservoirs with high K v /K h and strong water segregation.The presented workflow is currently used to perform in-depth conformance treatment designs in onshore and offshore fields and can be used as a reference tool to evaluate benefits of the TAP in waterflooded oil reservoirs.Gholamreza Garmeh is a Reservoir Engineer at TIORCO. He is responsible for modeling and design of chemical-flooding and conformance-improvement projects. His research interests are chemical and miscible gas EOR techniques and numerical reservoir simulation. He holds a BS degree from the Petroleum University of Technology in Iran and MS and PhD degrees from the University of Texas at Austin, all in petroleum engineering. He serves as peer-reviewer for SPEREE and SPE Journal.Mehdi Izadi is a Senior Reservoir Engineer at TIORCO. He has more than 9 years of experience in reservoir simulation and EOR techniques. He is responsible for modeling and design of chemical-flooding projects and support of post-treatment

Application of nanofluid to control fines migration to improve the performance of low salinity water flooding and alkaline flooding

“…Furthermore, the alkali utilized in alkaline/polymer (AP) injection and alkaline/surfactant/polymer (ASP) flood can enhance the efficiency of polymer flooding projects. In this process, polymer is added to the water as a viscosifying agent to improve sweep efficiency and prevent fingering during water injection into the reservoir (Garmeh et al, 2012;Hild and Wackowski, 1999;Kazempour et al, 2012;Lei et al, 2011;Perez et al, 2012;Seright et al, 2009;Urbissinova et al, 2010); however, the early adsorption/loss of polymer on the rock surface can deteriorate the cost-efficiency of the process. This challenge seems to be handled by the effect of alkali utilized in AP injection and ASP flood, which results to mitigate the adsorption/loss of the expensive polymer and/or surfactant which in turn makes the process more cost-effective (Flaaten et al, 2010;French and Burchfield, 1990;Kazempour et al, 2012;Liu et al, 2008;Liu et al, 2010;Stoll et al, 2011).…”

Design Considerations of Waterflood Conformance Control With Temperature-Triggered, Low-Viscosity Submicron Polymer

“…Other field trials were reported by Ghaddab et al (2010); Husband et al (2010), Mustoni et al (2010), and Roussennac and Toschi (2010). Garmeh et al (2011) reported that almost 60 treatments have been performed so far.…”

“…This is consistent with Akanni's numerical experiments. More recently, Garmeh et al (2011) introduced singlecomponent and multicomponent chemical reaction approaches to study the problem. The authors reported a simple sensitivity study on several reservoir and design parameters.…”

“…The authors reported a simple sensitivity study on several reservoir and design parameters. In the current study, we followed the single-component model approach introduced by Garmeh et al (2011). It may be that one of the biggest technology gaps about in-depth profile modification methods is the absence of a robust and feasible slug-sizing method.…”

“…Garmeh et al (2011) proposed two different approaches to simulate such a treatment process. The first one is a chemical reaction approach in which the propping agent is the product of a reaction between polymer and crosslinker.…”