A process for controlled in-situ coal gasification is disclosed. The process includes surveying one or more selected coal bearing sites for designing a plurality of panels; designing a plurality of sub-panels of a plurality of corresponding panels with a plurality of bi-directional boreholes and a plurality of vertical service boreholes; channelizing the plurality of bi-directional boreholes and vertical service boreholes to one or more layers of coal seams; constructing one or more coal slice areas of predefined dimensions within the one or more layers of the coal seams; combusting coal inside the one or more coal slice areas; extracting combusted coal from the one or more coal slice areas through the plurality of vertical service boreholes; monitoring physical condition of at least one cavity created by extraction of the combusted coal; controlling remote filling of a filling material simultaneously at the at least one cavity using the filling device.

Embodiments of the present disclosure relate to methods of natural gas production and carbon sequestration. In one embodiment, a method of generating biogas is disclosed, comprising delivering a feedstock downhole to a coal reservoir, generating biogas within the coal reservoir, and harvesting the biogas. In another embodiment, a method for tracing the migration of biogas in a coal reservoir is disclosed. The method comprises delivering a feedstock downhole to a coal reservoir via an injection well, generating biogas within the coal reservoir through microbial action, creating a biogas that is isotopically differentiable from a background gas that is native to the coal reservoir, harvesting the biogas at the injection well and one or more offset wells of the coal reservoir, analyzing the biogas and coal bed methane from the coal reservoir at the injection well and at one or more offset wells within the same coal reservoir, detecting the biogas at the offset wells using isotopic differentiation, and mapping the migration of the biogas from the injection well to the offset wells using the biogas as an isotopic tracer.

Embodiments of the present disclosure relate to methods of natural gas production and carbon sequestration. In one embodiment, a method of generating biogas is disclosed, comprising delivering a feedstock downhole to a coal reservoir, generating biogas within the coal reservoir, and harvesting the biogas. In another embodiment, a method for tracing the migration of biogas in a coal reservoir is disclosed. The method comprises delivering a feedstock downhole to a coal reservoir via an injection well, generating biogas within the coal reservoir through microbial action, creating a biogas that is isotopically differentiable from a background gas that is native to the coal reservoir, harvesting the biogas at the injection well and one or more offset wells of the coal reservoir, analyzing the biogas and coal bed methane from the coal reservoir at the injection well and at one or more offset wells within the same coal reservoir, detecting the biogas at the offset wells using isotopic differentiation, and mapping the migration of the biogas from the injection well to the offset wells using the biogas as an isotopic tracer.

Methods and systems for gasifying coal are disclosed herein. In some embodiments, a representative coal gasification system can comprise (i) an injection well extending from a ground surface to an underground coal gasification (UCG) reaction region of a coal seam; (ii) a production well spaced apart from the injection well and extending from the ground surface to the UCG reaction region, and (iii) conduits each extending from the ground surface to areas of the coal seam. End portions of the conduits within the coal can be laterally peripheral to the UCG reaction region. The conduits are configured to deliver a primary fluid from the ground surface to the primary region, the injection well is configured to deliver an oxidant gas to the UCG reaction region, and the production well is configured to deliver the product gas from the UCG reaction region to the ground surface.

Methods and systems for gasifying coal are disclosed herein. In some embodiments, a representative coal gasification system can comprise (i) an injection well extending from a ground surface to an underground coal gasification (UCG) reaction region of a coal seam; (ii) a production well spaced apart from the injection well and extending from the ground surface to the UCG reaction region, and (iii) conduits each extending from the ground surface to areas of the coal seam. End portions of the conduits within the coal can be laterally peripheral to the UCG reaction region. The conduits are configured to deliver a primary fluid from the ground surface to the primary region, the injection well is configured to deliver an oxidant gas to the UCG reaction region, and the production well is configured to deliver the product gas from the UCG reaction region to the ground surface.

A spallation drilling apparatus is also disclosed that uses jets of hot fluid for drilling. This is compatible with drilling wells in high temperature zones, such as a lava dome. A simplified pyrolysis reactor for use in a lava dome is also disclosed, in which the dome functions to contain the reaction, and the apparatus to facilitate pyrolysis is far more compact.

A spallation drilling apparatus is also disclosed that uses jets of hot fluid for drilling. This is compatible with drilling wells in high temperature zones, such as a lava dome. A simplified pyrolysis reactor for use in a lava dome is also disclosed, in which the dome functions to contain the reaction, and the apparatus to facilitate pyrolysis is far more compact.

An injection device, which comprises a nozzle and which is used for an underground coal gasification process; the nozzle and the injection device are used for continuously injecting a high-concentration oxidant into an underground coal layer during the underground coal gasification process, in which case the high-concentration oxidant may be used safely and steadily to obtain a high-quality and stable product gas, while a retraction cycle and/or a retraction distance of a retraction method in the existing technology may be greatly shortened, thus achieving the continuous and steady operation of the underground coal gasification process. Also disclosed is a method for operating the injection device.

An injection device, which comprises a nozzle and which is used for an underground coal gasification process; the nozzle and the injection device are used for continuously injecting a high-concentration oxidant into an underground coal layer during the underground coal gasification process, in which case the high-concentration oxidant may be used safely and steadily to obtain a high-quality and stable product gas, while a retraction cycle and/or a retraction distance of a retraction method in the existing technology may be greatly shortened, thus achieving the continuous and steady operation of the underground coal gasification process. Also disclosed is a method for operating the injection device.

A hydrocarbon reservoir is treated with heat to induce gasification, water-gas shift, and/or aquathermolysis reactions to generate gases including hydrogen. The hydrogen alone is produced to the surface by using hydrogen-only membranes in the production wells.