Disclosed is a suitability evaluation method for developing underground coal gasification (UCG) engineering by utilizing a deep coal seam, including: acquiring basic geological conditions, engineering geological problems, hydrogeological conditions, contained coal quality, deep coal seam conditions, and heat and syngas components of unit coal gasification in a deep coal seam region to obtain scores of corresponding influencing factors; determining impact indexes of the geological condition and influencing factors; and determining the suitability of developing UCG engineering by utilizing the deep coal seam according to a comprehensive impact index. The suitability of developing UCG engineering by utilizing the deep coal seam is evaluated by a comprehensive analysis method.

A production well apparatus for underground coal gasification and an underground coal gasification method using same. The production well apparatus comprises a well head apparatus, a sleeve (8), a product pipe (1), a coolant pipe (3), and a monitoring meter system (7). Coolant is injected, during underground coal gasification, to be in contact and mixed with product gas, and the product gas is discharged after cooled, such that the operation is safer and more controllable. Moreover, most of the components of the production well apparatus can be completely or partially recycled and reused after the gasification is completed.

A production well apparatus for underground coal gasification and an underground coal gasification method using same. The production well apparatus comprises a well head apparatus, a sleeve (8), a product pipe (1), a coolant pipe (3), and a monitoring meter system (7). Coolant is injected, during underground coal gasification, to be in contact and mixed with product gas, and the product gas is discharged after cooled, such that the operation is safer and more controllable. Moreover, most of the components of the production well apparatus can be completely or partially recycled and reused after the gasification is completed.

An ignition device for an underground coal gasification process, and an underground coal gasification method for carrying out ignition by using the same. The ignition device comprises a conveying device, a cut-off device (7), an ignition detonator (6) and one or more fuel packs (5), all of which are sequentially connected. The multiple fuel packs are serially connected with each other. The conveying device is a coiled tubing/conjugation tube (12), or an integrated signal cable (21). The ignition detonator runs through one or more fuel packs and ignites the one or more fuel packs starting from the top of the device in a delayed manner. The cut-off device breaks off after the ignition detonator is started, so that ignition device components comprising the conveying device are at least withdrawn to a safe position. Each fuel pack comprises thermit and is used for igniting an underground coal seam (1) after the fuel pack is ignited.

An ignition device for an underground coal gasification process, and an underground coal gasification method for carrying out ignition by using the same. The ignition device comprises a conveying device, a cut-off device (7), an ignition detonator (6) and one or more fuel packs (5), all of which are sequentially connected. The multiple fuel packs are serially connected with each other. The conveying device is a coiled tubing/conjugation tube (12), or an integrated signal cable (21). The ignition detonator runs through one or more fuel packs and ignites the one or more fuel packs starting from the top of the device in a delayed manner. The cut-off device breaks off after the ignition detonator is started, so that ignition device components comprising the conveying device are at least withdrawn to a safe position. Each fuel pack comprises thermit and is used for igniting an underground coal seam (1) after the fuel pack is ignited.

This invention provides an oxidant injection device for an underground coal gasification process. The oxidant injection device includes an oxidant pathway which includes a swivel joint, coiled tubing, and a mechanical shear-off device which are in gas tight connection with each other in that sequence. Attached to the mechanical shear-off device is an oxidant nozzle, wherein the shear-off device is adapted to shear the oxidant nozzle to allow retraction of the coiled tubing when necessary, and wherein the swivel joint causes the surface oxidant source to be in gas tight connection with the coiled tubing reel centre shaft, thereby allowing continuous oxidant injection during the process of moving the oxidant nozzle via the movement of the coiled tubing when rotating the coiled tubing reel. In addition, the invention also provides the application of the oxidant injection device in the underground coal gasification process, whereby the oxidant injection device can specifically be used for the ignition and normal operation process.

This invention provides an oxidant injection device for an underground coal gasification process. The oxidant injection device includes an oxidant pathway which includes a swivel joint, coiled tubing, and a mechanical shear-off device which are in gas tight connection with each other in that sequence. Attached to the mechanical shear-off device is an oxidant nozzle, wherein the shear-off device is adapted to shear the oxidant nozzle to allow retraction of the coiled tubing when necessary, and wherein the swivel joint causes the surface oxidant source to be in gas tight connection with the coiled tubing reel centre shaft, thereby allowing continuous oxidant injection during the process of moving the oxidant nozzle via the movement of the coiled tubing when rotating the coiled tubing reel. In addition, the invention also provides the application of the oxidant injection device in the underground coal gasification process, whereby the oxidant injection device can specifically be used for the ignition and normal operation process.

A system and a method for underground gasification comprising a downhole ignition device. The downhole ignition device may comprise a connection housing at a first end of the downhole ignition device. The connection housing may comprise an igniter and a first fire mix. The downhole ignition device may further comprise a body coupled to the connection housing. The body may comprise pyrotechnic modules arranged in series and additional first fire mix. A cap may be disposed at a second end of the connection housing. Additionally, the downhole ignition device may comprise a supply line and a recovery system. A method for igniting an underground energy source may comprise positioning a downhole ignition device adjacent an underground energy source in a wellbore, igniting a first fire mix in the downhole ignition device, and igniting a series of pyrotechnic modules arranged in the downhole ignition device.

A system and a method for underground gasification comprising a downhole ignition device. The downhole ignition device may comprise a connection housing at a first end of the downhole ignition device. The connection housing may comprise an igniter and a first fire mix. The downhole ignition device may further comprise a body coupled to the connection housing. The body may comprise pyrotechnic modules arranged in series and additional first fire mix. A cap may be disposed at a second end of the connection housing. Additionally, the downhole ignition device may comprise a supply line and a recovery system. A method for igniting an underground energy source may comprise positioning a downhole ignition device adjacent an underground energy source in a wellbore, igniting a first fire mix in the downhole ignition device, and igniting a series of pyrotechnic modules arranged in the downhole ignition device.

This invention generally relates to natural gas and methylotrophic energy generation, bio-generated fuels and microbiology. In alternative embodiments, the invention provides nutrient amendments and microbial compositions that are both specifically optimized to stimulate methanogenesis, or methylotrophic conversion. Additionally, the invention provides methods to develop nutrient amendments and microbial compositions that are both specifically optimized to stimulate methanogenesis in a given reservoir. The invention also provides methods for the evaluation of potentially damaging biomass formation and scale precipitation resulting from the addition of nutrient amendments. In another embodiment, the invention provides methods for simulating biogas in sub-surface conditions using a computational model.