Final answer:
The production of more dry gas in the Eagle Ford shale as it dips closer to the coast can be attributed to higher underground temperatures and pressures that turn oil into gas. Geological activity, such as that indicated by reverse faults, also contributes to these conditions, leading to gas that is richer in methane, which is classified as dry gas.
Step-by-step explanation:
The Eagle Ford shale in Texas is known for producing more dry gas as it extends deeper toward the coast. This occurrence can be largely attributed to geological factors and the processes involved in the transformation of organic material into fossil fuels. As these remains are subjected to higher temperatures and pressures deeper underground, oil is more likely to be "cracked" into gas, leading to a higher ratio of methane, which qualifies the fuel as dry gas. The presence of a reverse fault, such as in the Eagle Ford outcrop west of Del Rio, Texas, indicates intense geological activity in the past that would have contributed to these changes. Such geological structures could have subjected the rock formations which contain oil and gas deposits to heat and pressures higher than normal, promoting the formation of natural gas.
Additionally, natural gas deposits can vary in composition depending on the conditions they were formed under. Gas that is rich in methane is labeled as dry, whereas gas containing higher hydrocarbons is known as wet gas. As we continue to extract fossil fuels, and particularly as we reach deeper, more challenging deposits, the characteristics of the extracted fuels change. The exploration and extraction process involves drilling down through layers of sand, silt, and rock to access these resources, and as the drilling reaches deeper layers closer to the coast, the higher temperatures and pressures result in the formation of more natural gas relative to oil, with an increased likelihood of encountering dry gas.