Investigation of Initial Water Mobility and its Effects on SAGD Performance in Oil Sands
Abstract
Steam-assisted gravity drainage (SAGD) has become a primary commercial in-situ thermal recovery method for oil sands in Alberta. Evidence of initial water mobility during the SAGD process has been observed by many previous field studies. However, no its effective determination method and little research about its effects on SAGD performance have been reported.
In this thesis, a novel method is proposed to effectively determine the mobility of initial water existing as the continuous wetting phase in oil sands. More specifically, wax is used for the first time to simulate the immobile oil phase. Laboratory experiments are conducted to determine the initial water mobility with a stationary oil phase. To obtain a general correlation of initial water saturation and its mobility, a triangular tube bundle model is constructed to simulate the measured experimental data. A correlation of the initial water mobility is developed by matching the experimental results with the constructed triangular tube bundle model.
To conduct a lab-scale study of initial water mobility, a new two-dimensional physical model with a water flowing boundary is proposed for the first time. The greatest novelty of the 2D model is that the capillary pressure generated from the very fine sands with very strong water wettability, can prevent the oil from flowing into the fine sands zone, but can allow the water flow into the fine sands zone. It is proved by the experiments for the first time that the mobile initial water can promote the vertical and lateral growth of the steam chamber.
To investigate effects of initial water mobility on SAGD performance at the field-scale, an elaborated numerical simulation study, with the properties of a typical Athabasca oil sands, is conducted. Initial water mobility is firstly classified into two categories (low and high) based on their steam chamber shapes. The simulation results show that, for a single well pair, low initial water mobility can benefit the steam chamber growth, but high initial water mobility has a negative impact. For the adjacent steam chambers in the same pad, low initial water mobility case with the same injection pressure has the highest NPV.
Description
Keywords
Energy, Engineering--Petroleum
Citation
Zhou, W. (2016). Investigation of Initial Water Mobility and its Effects on SAGD Performance in Oil Sands (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26656