Methods are provided for sequestering a pollutant gas of carbon dioxide (CO.sub.2) gas and/or hydrogen sulfide (H.sub.2S) gas in a subterranean reservoir. In one method, a carrier gas containing pollutant-sorbent particles (e.g., nanoparticles) is pumped into the subterranean reservoir, the pollutant-sorbent particles attach to the subterranean reservoir, the pollutant gas is pumped into the subterranean reservoir, and the pollutant-sorbent particles attached to the subterranean reservoir adsorb the pollutant gas. In another method, pollutant gas is introduced into a carrier liquid containing pollutant-sorbent particles to produce a pollutant-rich carrier liquid, the pollutant-rich carrier liquid is pumped into the subterranean reservoir, and the pollutant-rich carrier liquid is allowed to remain in the subterranean reservoir. A modifier gas or modifier liquid may be injected into the subterranean reservoir to modify a condition in the subterranean reservoir and thereby cause the pollutant-sorbent particles to release the sequestered pollutant gas.

Methods of Enhanced Oil Recovery (EOR) from an oil reservoir by CO.sub.2 flooding are disclosed. One method comprises producing a well stream from the reservoir; separating the well stream into a liquid phase and a gas phase with a first gas/liquid separator, wherein the gas phase comprises both CO.sub.2 gas and hydrocarbon gas; cooling the gas phase with a first cooler; compressing the gas phase using a first compressor into a compressed stream; mixing the compressed stream with an external source of CO.sub.2 to form an injection stream; and injecting the injection stream into the reservoir. Systems for EOR from an oil reservoir by CO.sub.2 flooding are also disclosed.

A tight oil reservoir CO.sub.2 flooding multi-scale channeling control system and a preparation method, including nanoscale CO.sub.2 responsive worm-like micellar systems and micron-scale CO.sub.2 responsive dispersion gel, are provided. The nanoscale CO.sub.2 responsive worm-like micelle system is prepared by CO.sub.2 reactive monomers and organic anti-ion monomers stirred in water. The micron-scale CO.sub.2 responsive dispersion gel is made of acrylamide, a responsive monomer, a silane coupling agent modified hydroxylated multi-walled carbon nanotubes as raw materials, cross-linked in water. The tight oil reservoir CO.sub.2 multi-scale channel control system, has strong flow control ability during CO.sub.2 displacement, and high-strength carbon nanotubes are introduced into the micro-scale CO.sub.2 responsive dispersion gel, which effectively improves the strength and long-term stability of the dispersion gel, significantly enhances the sealing effect on cracks, and after displacement of the CO.sub.2 of the system, the worm-like micelles revert to spherical micelles with good responsive reversibility.

The present invention relates to a reagent for exploiting natural gas hydrates, which includes a regent A and a regent B. The reagent A is PEG400-polyurethane prepolymer; the reagent B includes PEG400 and an initiator; and a volume ratio of the PEG400-polyurethane prepolymer, the PEG400 and the initiator is (1-3000):(1-1000):(1-2000). The reagent of the present invention has excellent performance and high stability, and can effectively “replace” the “water” of the natural gas hydrate; and moreover, the reaction is exothermic reaction to effectively increase the reaction rate, which reduces the energy loss on the one hand, and reduces the blockage of a gas passage caused by the secondary generation of the natural gas hydrates in a low-temperature high-pressure pipeline during transferring on the other hand.

Injecting CO2 that is diluted within water, into a coal seam, which allows for the sequestering and control of downhole CO2 within connected fractures without damaging the subterranean formation.

Methods and systems for reducing greenhouse gas emissions, including producing a waste gas stream comprising form greater than 0 vol % to less than 20 vol %, inclusive, carbon dioxide, pre-concentrating the waste gas stream to increase a concentration of carbon dioxide, producing a concentrated byproduct stream comprising more than 40 vol %, dissolving carbon dioxide contained in the concentrated byproduct stream in water, producing a dissolved byproduct stream and an undissolved byproduct stream, injecting the dissolved byproduct stream or a portion thereof into a reservoir containing mafic rock, and allowing components of the dissolved byproduct stream to react in situ with components of the mafic rock to precipitate and store components of the byproduct stream in the reservoir.

Methods and systems for reducing greenhouse gas emissions, including producing a waste gas stream comprising form greater than 0 vol % to less than 20 vol %, inclusive, carbon dioxide, pre-concentrating the waste gas stream to increase a concentration of carbon dioxide, producing a concentrated byproduct stream comprising more than 40 vol %, dissolving carbon dioxide contained in the concentrated byproduct stream in water, producing a dissolved byproduct stream and an undissolved byproduct stream, injecting the dissolved byproduct stream or a portion thereof into a reservoir containing mafic rock, and allowing components of the dissolved byproduct stream to react in situ with components of the mafic rock to precipitate and store components of the byproduct stream in the reservoir.

CO.sub.2 in the liquid or super-critical state is delivered by at least one carrier vessel from at least one CO.sub.2 storage site, which may be an onshore site, to an integrated offshore facility. The integrated offshore facility is provided with at least one on-site storage tank or vessel adapted to store CO.sub.2 in the liquid or super-critical state and with equipment for marine transfer of CO.sub.2 in the liquid or super-critical state. CO.sub.2 is utilised as required from said at least one on-site storage tank or vessel for EOR at said offshore site or for EGR at said offshore site by injection into a sub-sea oil or natural gas bearing reservoir and recovery of oil and/or natural gas from a resulting production stream.

The invention relates to a method for extracting hydrocarbons from a subterranean formation, comprising: —providing a fluid, —injecting said fluid into the subterranean formation during a first period of time but not during a second period of time, and—collecting displaced hydrocarbons from the subterranean formation, wherein: at least part of the provision and/or injection of the fluid is carried out using solar energy.

A method for carbon dioxide recycle stream processing with ethylene glycol dehydrating in an enhanced oil recovery process includes receiving a first carbon dioxide recycle stream from a hydrocarbon formation, adding ethylene glycol to the first carbon dioxide recycle stream to produce an ethylene glycol and carbon dioxide recycle stream, condensing the ethylene glycol and carbon dioxide stream to produce a multiphase stream, separating the multiphase stream into a water and ethylene glycol stream and a second carbon dioxide recycle stream, separating the water and ethylene glycol stream into a water stream and an ethylene glycol stream, and separating the second carbon dioxide recycle steam into a carbon dioxide reinjection stream and a natural gas liquids stream.