Heat Extraction and Interlayer Interference in Heterogeneous Multi-Layer Commingled Production Oil Reservoir

Abstract

ABSTRACT: Geothermal development of oil reservoirs using abandoned or high water-cut wells has received a lot of attention. The heterogeneity is a common feature of oil reservoir, and it cases the production characteristics are distinct. We have established a coupling model of oil-water two-phase heat flow in the heterogeneous multi-layer commingled production reservoir. The model considers local thermal non-equilibrium (LTNE) and is a dual porosity model, which can be used to describe the fluid flow in the fractured reservoir. Using the model, the effects of different reservoir characteristics and injection parameters on production characteristics are analyzed. Reservoir characteristics include dip angle, cubic matrix block side length, and injection parameters include injection temperature and mass flow. Under the conditions studied in this paper, after 5 years, the maximum differences of production temperature and deviation values can reach 27.5 °C and 65.34% at different injection mass flow, respectively. The maximum deviation value difference can reach 45.90% at different cubic matrix block side length, while the impact on production temperature is small. The injection temperature and dip angle have a relatively small impact on the above production characteristics. This study has certain significance for the application of geothermal energy in oilfields. 1. INTRODUCTION Geothermal energy is one of the important renewable energy sources, with advantages such as features weather independence, stable, operationally reliable, and environmentally friendly nature (Wang et al. 2018). Compared with the utilization of shallow geothermal energy, the high drilling cost has led to the slow development of mid-deep geothermal resources. Many oil reservoirs have produced liquids with water content of more than 95% and have become "hydrothermal geothermal fields". Some oil wells in high water-cut oil fields have reached their economic limits and have even been abandoned. The oilfield area usually has a high geothermal gradient, and many abandoned wells have abundant geothermal resources, such as Texas, Oklahoma, Louisiana and North Dakota in the United States, and Songliao Basin, Bohai Bay Basin, and Ordos Basin in China (Augustine and Falkenstern 2014; Jiang et al. 2019). Using abandoned oil wells to develop geothermal energy can alleviate the pressure of energy supply and demand, save drilling and sealing well costs, and control the pollution of abandoned wells (Cheng et al. 2016; Lin et al. 2021).