Investigating residual trapping in CO₂ storage in saline aquifers – application of a 2D glass model, and image analysis

Abstract

Two-dimensional glass model experiments are used to investigate the residual trapping mechanism of CO 2 stored in saline aquifers. For this purpose, two proxy fluids are chosen to simulate the CO 2 -brine behavior under reservoir conditions. The first set of experiments is carried out by flooding n-heptane in a mixture of glycerol and water inside a glass bead porous media. Fluids and porous materials are designed so that the dimensionless groups are in the range of real storage sites. Another set of proxy fluid consists of dodecane and a different mixture of glycerol and water, representing the second wettability condition for the system. The size of the glass beads chosen was fine (70-110 lm) in order to investigate residual trapping phenomena. For each set, after complete drainage process, an imbibition process is performed and in each time step, images are taken from the phenomena. The images are processed using a red, green, blue (RGB) color concept using a Matlab code that was developed for this study. By using this process, it is possible to measure the residual trapping of CO 2 proxy fluid for each test and to determine the saturation profile in the model. Tests are carried out at various imbibition and drainage rates to study the effect of the rate on the results. Fine-scale numerical simulation models are constructed for comparison with experimental results. Good agreement is obtained between the simulation results and the image processing estimations, as well as the readings from the material balances during the experiments. This study could provide a framework for modeling different reservoir conditions for residual trapping mechanism and the impact of different parameters in future studies.

Wettability impact on supercritical CO2 capillary trapping: Pore‐scale visualization and quantification

“…Their work also indicated that even though the two‐pore network model (pore doublet model) [ Chatzis and Dullien , ] can well describe snap‐off mechanism, it fails in describing the bypass trapping when considering the fluid distribution. Later, the effects of Ca [ Chatzis et al ., ; Soroush et al ., ; Kimbrel et al ., ] and pore structure [ Tanino and Blunt , ; Chaudhary et al ., ; Geistlinger et al ., ] on immiscible flow and capillary trapping were extensively investigated using advanced visualization technology, including X‐ray computed tomography core‐flooding experiments [ Krevor et al ., ; Pentland et al ., ; El‐Maghraby and Blunt , ; Iglauer et al ., ; Andrew et al ., ; Geistlinger et al ., ; Xu et al ., ; Zuo and Benson , ; Li et al ., ; Niu et al ., ; Khishvand et al ., ; Rahman et al ., ; Herring et al ., , ], and micromodel experiments [ Zhang et al ., , ; Wang et al ., ; Kazemifar et al ., ; Cao et al ., ; Chang et al ., , ; Zhao et al ., ]. These studies indicated that (1) at Ca on the order of 10 −7 or even smaller, the snap‐off trapping mechanism by the precursor‐thin film dominates, and it is enhanced by the roughness of pore surface and the throat‐body aspect ratio of pores; (2) at Ca > 10 −7 , the main trapping mechanism involves propagation of invading fluid fingers that lead to islands of defending fluid being bypassed.…”

Dynamic capillarity during displacement process in fractured tight reservoirs with multiple fluid viscosities

“…[1][2][3][4] During the fluid flow process, fluid viscosity varies caused by the mixing of different kinds of fluids, which can have strong influence on the dynamic capillarity and fluid flow. [1][2][3][4] During the fluid flow process, fluid viscosity varies caused by the mixing of different kinds of fluids, which can have strong influence on the dynamic capillarity and fluid flow.…”

“…Capillary pressure is an important property that can affect multiphase flow during various physical and chemical process such as petroleum recovery and CO 2 storage. [1][2][3][4] During the fluid flow process, fluid viscosity varies caused by the mixing of different kinds of fluids, which can have strong influence on the dynamic capillarity and fluid flow. 5,6 The dynamic capillarity means a dynamic effect on the capillary pressure; that is, P c -S w relationship not only depends on the fluid saturation, but also the time derivative of saturation S w ∕ t. The fluid flow behavior is correspondingly affected by the dynamic capillarity.…”

Connecting Pressure‐Saturation and Relative Permeability Models to Fracture Properties: The Case of Capillary‐Dominated Flow of Supercritical CO2 and Brine

“…Unlike immiscible two‐phase flow equations for porous media (Keller et al, ), the local flow area (i.e., b ) for a fracture varies from point to point (Nicholl et al, ); thus, the governing flow equation considering varying b is where i represents phase ( n is for the nonwetting phase and interchangeably for CO 2 , and w is for wetting phase and interchangeably for brine), b is local aperture, S li is local saturation of phase i , k is local intrinsic permeability, k lri is local relative permeability of phase i , μ i is dynamic viscosity of phase i ( μ w = 1.2 × 10 −3 Pa·s and μ n = 5.8 × 10 −5 Pa·s for a cold shallow reservoir at temperature = 35 °C and pressure = 10 MPa (Soroush et al, )), P li is local pressure of i , ρ i is fluid density for phase i ( ρ w = 1,121 kg/m 3 and ρ n = 714 kg/m 3 at temperature = 35 °C and pressure = 10 MPa (Soroush et al, )), Q i is a local sink and source term for phase i (=0 in this study), g is gravitational acceleration (9.8 m/s 2 ), and z is the relative elevation.…”