DGMK 746

Experimental and numerical analysis of the polymer flooding process using micromodels

Duration

January 1, 2018 – June 30, 2020

Management

Description

Polymer flooding is a method for mobility-controlled oil recovery from reservoirs. Due to its recovery mechanism, minimal equipment requirements, and relatively low costs, it is considered one of the low-risk and often economically attractive Enhanced Oil Recovery (EOR) methods. Understanding the nonlinear physical and chemical processes that govern polymer flooding plays a crucial role in the efficient design of polymer flooding projects. The goal of this project is to conduct a fundamental analysis of these processes using micromodels.

When examining the polymer flooding process, it is essential to understand the properties of the crude oil and the polymer solution, as well as the interactions between the fluids and between the fluids and the rock. The approach of using micro-models to study the polymer flooding process offers the opportunity to visualize and investigate in greater detail the wide variety of effects that play a role in polymer EOR.

Compared to flooding tests on cores, micro-models provide a detailed visual insight into the flooding process. This allows the local distribution of static and dynamic flow parameters to be observed on the model, which is intended to enable a fundamental investigation of the flooding process.

Current Phase 3

The final phase of the project aims to evaluate the application of the microfluidics developed in the first two phases to other areas, such as production optimization. Key research questions in this context include the stability of foams in porous media, the deposition of asphaltenes and their removal, and the filtration of drilling muds. In addition, the design and production of models will be further refined during the development of new chips with a permeability in the range of a few hundred millidarcy. In this process, the pore structure of a natural rock sample is mimicked, and its properties are transferred to a two-dimensional model. The results from the microfluidics experiments are validated using core flooding in the rock used for the design. Furthermore, methods are being developed to modify the internal surface, which initially exhibits water-wetting properties, through the adsorption of a self-assembled monolayer (SAM).

Previous project phases

Phase 1

Completed in 2014. This first phase of the project by the German Scientific Society for Petroleum, Natural Gas, and Coal (Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V.) was supported by ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, RWE Dea AG, and Wintershall Holding GmbH.

In the first phase of the project, proprietary micro-models were developed that offer several improvements over commercially available models. The models developed at ITE consist of a “sandwich” of two glass layers enclosing a porous layer of silicon. As a result, the models exhibit water-wetting surface properties similar to those of the sandstones found in many reservoirs. Furthermore, the models are resistant to most chemical influences and can withstand high temperatures and pressures. Artificial structures, as well as a realistic structure based on a thin section of a rock sample, served as porous structures. The flow across the square micromodel, which was designed based on a "quarter-to-five-spot" borehole pattern, enables the analysis of the efficiency of vertical displacement.
To conduct the experiments, an experimental setup including a model holder is designed to continuously record images of the porous structure and the flowing media, as well as the pressures before and after the model. The measured values and image data are automatically evaluated using algorithms that calculate the proportion of different fluids. A simulation toolbox also enables the numerical analysis of the experiments.
For the analysis of polymers, the rheology was determined for a selection of different products relevant to Enhanced Oil Recovery (EOR) at various concentrations, temperatures, and with different mixing waters of varying salinity and composition. The results were collected and organized in a database.
Following several single-phase experiments with Newtonian and non-Newtonian fluids, EOR experiments with polymers were conducted in secondary mode (polymer flooding in the oil-saturated model) or tertiary mode (polymer flooding following a water flooding experiment). The data obtained were used for the numerical analysis and simulation of flooding experiments in the micro-model.

New linear chip derived from a micro-CT scan of Bentheimer sandstone.

Phase 2

Completed in 2017. This second phase of the project by the German Scientific Society for Petroleum, Natural Gas, and Coal (Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V.) was supported by ExxonMobil Production Deutschland GmbH, Neptune Energy Deutschland GmbH, DEA Deutsche Erdoel AG, and Wintershall Holding GmbH.

In the second phase of the project, the experimental setups were expanded to enable testing at high temperatures. A core flooding facility was constructed to compare the experimental results from the microfluidic tests. Flooding tests were conducted on Bentheim sandstone in this facility. To enable a comparison with the microfluidics, new chips were developed whose porous structure was derived from a µCT scan of Bentheim sandstone and whose porosity and permeability are comparable to those of real rock samples. Instead of the “quarter-to-a-five-spot” configuration, a linear geometry was chosen for the models to allow for a direct comparison with core flooding tests. In various single-phase and multiphase tests using micro-models, cores, and sand fillings, measurement data were collected and the results were replicated in the simulator. In addition, extended rheological investigations were conducted for biopolymer and HPAM solutions, including, in addition to standard rheology, oscillatory measurements and the determination of extensional viscosity.

Publications

In books and magazines

Födisch H. 2019. Investigation of Chemical Enhanced Oil Recovery Core Flooding Processes with Special Focus on Rock-Fluid Interactions. Papierflieger Verlag, Clausthal-Zellerfeld. ISBN: 978-3-86948-697-0.
Wegner J, Ganzer L. 2017. How Microfluidic Solutions Using a Rock-on-a-Chip Approach Look Set to Revolutionize IOR/EOR Process Visualization. Oilfield Technology Journal 7: pp. 15–18.
Duffy J, Hincapie R. 2016. Using Rheology to Optimize the Performance of EOR Fluids. Oil and Gas Innovation Magazine 10: 42–43.
Rock A, Hincapie R, Wegner J, Födisch H, Ganzer L. 2016. Pore-scale Visualization of Polymer Viscoelasticity Using Particle Tracing in Glass-Silicon-Glass Micromodels. EAGE First Break 34: DOI 10.3997/2214-4609.201600917.
Födisch H, Hincapie R, Wegner J, Ganzer L. 2015. Visualization of connate water replacement during flooding experiments using Glass-Silicon-Glass micromodels. EAGE First Break 33: DOI: 10.3997/2214-4609.201412500.
Hincapie R. 2016. Pore-Scale Investigation of the Viscoelastic Phenomenon during Enhanced Oil Recovery (EOR) Polymer Flooding through Porous Media. Papierflieger Verlag, Clausthal-Zellerfeld. ISBN: 978-3-86948-531-7.
Wegner J. 2015. Investigation of Polymer Enhanced Oil Recovery (EOR) in Microfluidic Devices that Resemble Porous Media – An Experimental and Numerical Approach. Shaker Verlag, Aachen. ISBN: 978-3-8440-3520-9.
Ganzer L, Wegner J, Buchebner M, 2014. Benefits and Opportunities of a “Rock-on-a-Chip” Approach to Access New Oil. OIL GAS-EUROPEAN MAGAZINE 39: pp. 43–47.
Wegner J, Ganzer L. 2013. Numerical Analysis of Polymer Micro-Model Flooding Experiments. In Proceedings of the 3rd Sino-German Conference “Underground Storage of CO2 and Energy,” Goslar, May 21–23, 2013, (eds. Hou MZ, Xie H, Were P), pp. 131–142. Springer-Verlag, Berlin Heidelberg.