Enhanced Oil Recovery through co2 utilisation

Project funded by: The Danish Advanced Technology Foundation (Højteknologifoden)

Coworkers:

Erling H. Stenby, Ida L. Fabricius, Wei Yan, Alexander Shapiro, Ben Niu, Mohammad Monzurul Alam - DTU-CERE

Helle Christensen - GEO

Dan Olsen - GEUS

Enhanced Oil Recovery through CO₂ utilisation

Today’s largest global challenges are climate changes and security of energy supply. At the European level substantial research funds are allocated to develop processes and methods for CO₂ utilisation and increased reliability of supply. With its efficient power plants located near the coast and the North Sea Denmark has a unique position to enable the development of methods to combine the utilisation of CO₂ with enhanced oil recovery (EOR). The purpose of the project is to ensure the build-up of knowledge within EOR in Denmark, to establish the necessary research platform to attract European research funds, to train candidates within the area and thus assist in supporting the establishment of new knowledge jobs and business ensuring that Denmark solves a CO­₂ problem and at the same time increases the recovery of oil and gas in the North Sea, which has a large social value

The project is in close collaboration with DONG Energy, who carries out a CO₂ capture feasibility study and development and planning of a CO­₂ injection pilot project. In parallel to DONG Energy’s work, a scientific programme is carried out by three participants CERE, GEO and GEUS. The scientific programme relies heavily on a strong interaction between very specialized knowledge in different disciplines. It has been formulated as three research projects and six work packages:

Project 1: Fluid-Rock Interactions

WP 1.1. Monitoring changes in Pore-structure and Fluid Properties as a Result of CO₂ Injection into Hydrocarbon Reservoirs

WP 1.2. Measurement of Rock Mechanics Effects of CO₂ Flooding

Project 2: Phase Equilibria of Fluids

WP 2.1 Phase Equilibrium Measurements in Mixtures of Brine, Oil and CO₂

WP 2.2 Modeling and Simulating the Compositional Effects during CO₂ injection into a

Waterflooded Oil Reservoir

Project 3: Multi Phase Flow

WP 3.1 CO₂ Flooding Experiments under Reservoir Conditions

WP 3.2 Studies of CO₂ Flooding by Use of X-ray CT-scanning

The project started in January 2007 and ended in December 2010. All the work packages have been carried out in an active and productive manner. Some highlights of the research activities are given below:

• Changes in porosity, pore-geometry, stiffness and wettability due to CO₂ flooding have been studied (WP 1.2). The relevant properties were measured before and after CO₂ flooding experiments.
• Quantification of the mechanical effects of CO₂ flooding was made through rock mechanics measurements (WP 1.2).
• A comprehensive experimental study on PVT and CO₂ injection behavior of the South Arne reservoir fluid has been made (WP 2.1). In addition to the routine PVT data, the study also provides the influence of CO₂ concentration and temperature on saturation pressure and viscosity.
• Measurement and modeling of CO₂ solubility in brine and CO₂ saturated brine density at high pressures was made (WP 2.1 & 2.2). The measurement provides valuable data which are needed for modeling. A model for CO₂ solubility in brine is improved for application in reservoir simulation.
• PVT modeling using non-cubic equations of state was investigated (WP 2.2). The tested advanced EoS models are aimed at providing accurate density description over a wide temperature and pressure range.
• The influence of CO₂ solubility in brine on CO₂ reservoir simulations was investigated (WP 2.3). It shows the solubility influence is generally non-negligible and must be taken into consideration in reservoir simulations.
• CO₂ flooding experiments for two different formations were performed at reservoir conditions at GEUS (WP 3.2). Although two different formations show very different responses to water flooding, CO₂ flooding after water flooding has efficiently recovered most of the remaining oils for both of them.
• CO₂ flooding experiments with CT scanning were performed at DTU-KT (WP 3.3). The flooding experiments similar to the GEUS flooding experiments were performed and the results are in general agreement with the GEUS’ observations. In addition, the saturation change during the flooding process was revealed.