Final answer:
The question explores the stratigraphic elements of the petroleum system and their geological importance. It describes how crude oil varies by source and the environmental impact of extraction. Stratigraphy and the study of sedimentary rocks contribute to understanding Earth's history and identifying fossil fuel deposits.
Step-by-step explanation:
The question deals with the geological aspects of the petroleum system and focuses on the rock units or essential elements that form part of this system within a certain geographic extent at a critical moment. Petroleum, in a geologic sense, is found within stratigraphic layers of the Earth. When we extract crude oil from the ground, we encounter a complex mixture of organic compounds that vary depending on their geological source. Characteristics like being 'sweet' or 'sour' denote the sulfur content in the petroleum; for instance, Texas crude is known for being sweet, with less sulfur, compared to the sour crude of Saudi Arabia. Furthermore, extraction techniques such as drilling or strip mining to retrieve resources like bitumen or oil shale present environmental challenges and risks such as those seen in the Deepwater Horizon incident.
Stratigraphy helps us to understand these layers through the identification of sedimentary rocks, reconstructing past environments and ecosystems. Essential to the process are source rocks, which are sedimentary rocks rich in organic material that, under the right conditions of heat and pressure, can generate oil or gas. The composition of sedimentary rocks tells a story of the Earth's history, including the formation of valuable fossil fuels like petroleum. As such, understanding these geological events and the stratigraphy of an area is critical in the oil and gas industry.