Heat Extraction Evaluation and Well Pattern Comparison of Abandoned Oil Wells Converted into Geothermal Wells

Geothermal energy has many advantages in utilization, but well construction account for half of the total costs, and its promotion and utilization are restricted. Some abandoned wells have abundant geothermal resources, using them to develop geothermal can significantly reduce costs. More, the high water-cut oil reservoirs that are on the verge of economic limits can also be used to extract heat and realize the co-production of heat and oil. Currently, most of the well pattern system studies are fixed well patterns or/and do not consider oil-water phases. However, the oil-water flow and heat transfer characteristics in the oil-bearing reservoir under different well patterns are of great significance for the design and adjustment of oilfield geothermal development schemes. Therefore, a new heat-flow coupling model considering oil-water two-phase flow is established. And the production characteristics of the diverse well patterns are discussed, such as production temperature, pressure difference, liquid production, and oil production. Research shows that the maximum difference of the production temperature and pressure difference of diverse well patterns can reach 22.56 K and 1.03 MPa, respectively. The injection wells and production wells are cross-symmetrically distributed, it has the highest production temperature, oil production, and lower production pressure difference. The evolution of temperature and pressure fields during heat extraction from different well patterns are revealed, providing a basis for designing and adjusting the well patterns, and it provides some guidance for the evaluation of oilfield heat-oil co-production.