Kerogen's a mixture of organic chemical compounds that make up a portion of the organic matter in sedimentary rocks. It's insoluble in normal organic solvents because of the huge molecular weight (upwards of 1,000 Daltons) of its component compounds. The soluble portion's known as bitumen. When heated to the right temperatures in the Earth's crust, (oil window ca. 60°-120°C, gas window ca.120°-150°C) some types of kerogen release crude oil or natural gas, collectively known a… (More on Kerogen)