Chevron is a ultrs large cap "Major" having refineries and retail gas stations. It's competitors are the likes of XOM, COP and Shell.
BRY is a mid cap oil and gas exploration company. It is one of just a few E&P's whose production and reserves are weighted to the oil side (a very good thing). In that group I would put in DNR, Wll, and NXY.
The company most like BRY for production rates and unbooked resource potential is WLL. Their reserves are about the same as BRY, debt level about the same size, production rate is somewhat higher (about 80% more), and market cap is 300% higher.