TY - THES

T1 - Sensitivity of capillarity on spatial wettability variation

T2 - Application of a modified morphological approach

AU - Dragovits, Mario

N1 - no embargo

PY - 2021

Y1 - 2021

N2 - The field of Digital Rock Physics (DRP) aims to compute fluid displacement processes in rock directly on the imaged rock’s pore space, resulting in capillary pressure and relative permeability saturation functions. Therefore, DRP has the potential to replace time consuming and labor-intensive laboratory SCAL (Special Core Analysis) experiments. Thereby, one of the major targets is to compute those saturation functions in a time and cost-competitive way. In order to achieve a macroscopically representative description, the respective pore-scale fluid distributions must be realistic. A common and computationally attractive method of obtaining these distributions is the morphological approach. However, as the applicability of the morphological methods has reached limits with respect to the imbibition saturation range and a realistic description of wettability alteration. Therefore, new innovative solutions are required.Recently and in collaboration with the software developer, qualitatively new features have been implemented in the commercial simulation toolbox GeoDict. The new features allow to extent the simulation capability from spontaneous to forced imbibition, to introduce multiple contact angles, and contact angle distributions with different spatial correlations. Those features now allow to simulate the total saturation range and to determine uncertainties. The present MSc thesis investigates whether or not those features reflect a physically meaningful behavior. For this purpose, a digital twin of a sandstone sample was exposed to different conditions with regard to the number of contact angles and their associated spatial distribution in each simulation case covered. The results show that this new approach enables the computation of forced imbibition processes, and hence extending the achievable saturation range. On the other hand, the results point out the exerted influence of varying contact angle distribution and spatial variation. The corresponding modifications always introduce an alteration of the prevailing wetting conditions, which in turn is captured correctly within the simulation processes and resulting in computed capillary pressure curves depicting the corresponding trends according to the altered wetting conditions. Ultimately, the results provide information on the most influential parameters of these implementations and show the general trend to the right physical behavior.

AB - The field of Digital Rock Physics (DRP) aims to compute fluid displacement processes in rock directly on the imaged rock’s pore space, resulting in capillary pressure and relative permeability saturation functions. Therefore, DRP has the potential to replace time consuming and labor-intensive laboratory SCAL (Special Core Analysis) experiments. Thereby, one of the major targets is to compute those saturation functions in a time and cost-competitive way. In order to achieve a macroscopically representative description, the respective pore-scale fluid distributions must be realistic. A common and computationally attractive method of obtaining these distributions is the morphological approach. However, as the applicability of the morphological methods has reached limits with respect to the imbibition saturation range and a realistic description of wettability alteration. Therefore, new innovative solutions are required.Recently and in collaboration with the software developer, qualitatively new features have been implemented in the commercial simulation toolbox GeoDict. The new features allow to extent the simulation capability from spontaneous to forced imbibition, to introduce multiple contact angles, and contact angle distributions with different spatial correlations. Those features now allow to simulate the total saturation range and to determine uncertainties. The present MSc thesis investigates whether or not those features reflect a physically meaningful behavior. For this purpose, a digital twin of a sandstone sample was exposed to different conditions with regard to the number of contact angles and their associated spatial distribution in each simulation case covered. The results show that this new approach enables the computation of forced imbibition processes, and hence extending the achievable saturation range. On the other hand, the results point out the exerted influence of varying contact angle distribution and spatial variation. The corresponding modifications always introduce an alteration of the prevailing wetting conditions, which in turn is captured correctly within the simulation processes and resulting in computed capillary pressure curves depicting the corresponding trends according to the altered wetting conditions. Ultimately, the results provide information on the most influential parameters of these implementations and show the general trend to the right physical behavior.

KW - DRP

KW - Forced Imbibition

KW - Morphological Approach

KW - Capillary pressure functions

KW - DRP

KW - Morphologischer Ansatz

KW - Kapillardruckfunktionen

KW - Forcierte Imbibition

M3 - Master's Thesis

ER -