As mentioned, these vast natural gas resources are trapped in shale rock formations. Two techniques are combined to release the gas from the shale and pump it to the surface. The natural gas producer first installs a well at the surface, which includes a steel pump or surface casing that is cemented into place. The producer then uses the well to pump in a combination of water and sand under high pressure. The water and sand hit the shale formations that contain the natural gas and create cracks in it. These cracks, or fissures, initiate the release of the natural gas, which then travels through the well to the surface, where it is collected. In most cases, the materials used to create the cracks consist primarily of water and sand. However, some chemical additives are also part of the mix, and they are added to improve the flow of the gas to the surface.