The Chinese petroleum business has experienced a decline in oil quality from traditional production wells, accompanied by a gradual loss in capacity. Therefore, the corporation must not only use innovative technologies for the discovery and development of oil and gas fields but also make high-quality, scientifically informed investment decisions. This work utilises the Xinjiang oil field as a case study to construct a rapid economic and technical assessment of unexplored reservoirs and to compare the input-output outcomes in reservoirs with varying permeability. This study employed the Arps exponential method and the Ordinary Least Squares method to analyse historical data concerning first-year capacity, EUR, and drilling and production investments for vertical water-flooding wells in low and mid-permeability conglomeratic sandstone reservoirs from 2017 to 2024. The results demonstrated strong correlations, with goodness-of-fit values for first-year capacity, EUR, drilling investment, and production investment in low permeability. The DCF model results indicate that the input-output ratio of the middle permeability conglomeratic well group (8.74 × 10–4 Kt/KRMB) exceeds that of the low permeability conglomeratic well group (5.15 × 10–4 Kt/KRMB). Furthermore, the economic thickness range for the low permeability conglomeratic reservoir at oil prices of 40–90 $/bbl (10 m to 21.5 m) surpasses that of the mid permeability conglomeratic reservoir (4.5 m to 14.5 m). Despite the elevated expenditure in vertical water-flooding wells of mid-permeability conglomeratic sandstone reservoirs, their capacity and estimated ultimate recovery (EUR) are significantly enhanced due to superior permeability and porosity. The findings prove that the study's methodology can facilitate a rapid assessment of prospective untapped oil exploration and development, as well as identify the actual disparity between the input-output results and the minimum economic thickness threshold of two distinct types of oil reservoirs. This study offers a coherent and comprehensive evaluation procedure and outcomes for future exploration and development, ensuring the ranking of project pool blocks and improving decision-making efficiency in actual projects.