During the formation of stalactite and stalagmite in karst caves carbonate minerals often trap gas and aqueous fluids, forming immiscible fluid inclusion population when they are crystallizing.

喀斯特溶洞中石钟乳和石笋在形成过程中，碳酸盐矿物结晶时，常常捕获周围水溶液和气体，形成不混溶流体包裹体组合。

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Methane hydrates are frozen water molecules that trap methane gas molecules in a crystalline, lattice-like structure known as a hydrate.

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Moffett has often called attention to the fact that the Mississippi River has been flowing down the center of our country for 60 million years and dumping sediment into the Gulf all the while, ultimately creating mounds and valleys that could trap debris that was eventually turned into oil and gas.

FORBES: Magazine Article

Coal beds often double as aquifers, and to remove the gas thousands of gallons of water (which trap it in the coal) must be got out first.

ECONOMIST: Energy supplies