Abstract:
To achieve large-scale and efficient production of deep shale gas in the Permian Wujiaping Formation in the eastern Sichuan Basin, and in response to the complex geological conditions including thin high-quality reservoirs, great burial depth, and vertically developed calcareous interlayers, a systematic study was conducted on reservoir characterization, geological model establishment, and high-yield well cultivation technology, based on the drilling and fracturing practices from pilot test platform wells in the DY-1 well block, using a combination of geological modeling, numerical simulation, and field tests. It was identified that siliceous shale and mixed shale in the Wujiaping-3 Member are the most favorable lithofacies, revealing the reservoir endowment characterized as “one thinness and four highs”. Based on the distribution of calcareous interlayers and vertical fracture containment capacity, three geological models (continuous, interlayered, and interbedded types) were innovatively established, and a geology-engineering integration technology system for cultivating high-yield deep shale gas wells was developed, centered on “refined deployment, dual-optimum target placement, high-intensity stimulation, and scientific pressure-controlled production”. Field application demonstrated remarkable success: the 11 pilot test wells were completed 74.4 days ahead of schedule, with an average estimated ultimate recovery (EUR) of 1.34×10
8 m
3 per well and a cost reduction of 5.3 million CNY per well, successfully achieving a commercial breakthrough in ultra-deep shale gas at
5500 m. The research outcomes can effectively support the large-scale efficient development of deep shale gas in the Wujiaping Formation, and provide a replicable and extendable technical paradigm for the economic production of similar deep, thin marine shales.