深部煤层工厂化开发工程技术探讨及展望OA

[Background]Given China's energy and mineral resource endowment,the efficient and green development and utilization of deep coal resources are expected to become a significant strategic option for facilitating the country's green energy transition and achieving its goals of peak carbon dioxide emissions and carbon neutrality.This significant demand may be satisfied through development using a structurally complex well factory mode.[Method]This study in-troduces the basic concept of a three-dimensional,multi-functional,and precisely controllable underground structurally complex well factory,designed for the efficient and green development of unconventional energy and mineral resources.It then discusses the well factory engineering mode and the mechanisms behind in situ conversion through electric heat-ing for deep coal seam development.Finally,the current state and development trends of basic research on the applica-tion of drilling and production engineering technologies are analyzed.[Progress]To achieve the clean development and utilization of deep coal resources,an electric heating technique for dense well patterns in a structurally complex well factory has been developed.This technique,combined with hydraulic fracturing,electric heating additives,and radio-fre-quency parameter optimization,can improve the efficiency of both gas desorption in coal seams and in situ coal conver-sion,thereby providing theoretical and technical guidance for the green and efficient integration of coalbed methane(CBM)recovery and underground coal gasification.Multiple approaches,including the improved sparrow search al-gorithm(ISSA),a collaborative multi-well trajectory optimization strategy,and an error calculation model for definitive dynamics survey(DDS),have been developed.These approaches address the challenges associated with platform plan-ning and multi-well trajectory optimization in a structurally complex well factory,thereby enabling precise control of complex and three-dimensional well trajectories.To address issues such as wellbore instability,wellbore leakage,and differences in the structural and physical characteristics of coal in deep complex strata,various techniques and methods have been developed,including dual-string differential rotary drilling for horizontal wells,adaptive composite well com-pletion for coal reservoirs,and dense segmented radial jetting through screen pipes.These techniques and methods facil-itate diversified well completion and production growth for deep complex coal seams.[Prospects]In response to the challenges associated with engineering technologies for deep coal seam development using the well factory mode,key drilling and production technologies and equipment from the hydrocarbon field can be referenced to progressively ad-dress the following four issues through interdisciplinary research and practice.First,for the three-dimensional develop-ment of multilayer gas resources through structurally complex wells,reservoir clustering and multi-stage development should be implemented based on an assessment of interlayer interference.The single-well factory mode for multi-reser-voir development should be explored by combining underground three-dimensional structurally complex well factory and production under layered pressure control.Second,large-scale underground supercritical water fluidized beds and in situ conversion fields should be constructed by integrating multiple techniques,including electric heating of deep coal seams,in situ conversion of tar-rich coal,extended-reach wells,and reservoir stimulation.This approach will facilitate the efficient integration of in situ coal conversion and CBM production.Third,a coal gasification process with segmen-ted control based on the underground well factory mode should be developed to enhance the controllability of coal gasi-fication and wellbore stability.Specifically,this process can be achieved by connecting horizontal wells in coal seams and the coal seam roof through sidetracking and then implementing segmented control of the coal gasification process in production wells using an adjustment well located in the roof.Fourth,three-dimensional diversified well completion methods for a structurally complex well factory should be further optimized,thereby facilitating multi-mode CO2 stor-age in CBM wells through physical adsorption or chemical sequestration.