Chevron Corp, Occidental Petroleum Corp and Exxon Mobil Corp dipped between 0.9% and 1.2% in premarket trading as oil prices retreated on demand fears.
The company said a sheen was observed at around 3 p.m. (2300 GMT) on the water near the wharf at the Richmond refinery, which can process 245,271 barrels per day of crude oil.
Chevron, the second-largest US oil producer, in October closed a $4.1 billion all-stock purchase of oil and gas producer Noble Energy, gaining a majority stake in the pipeline business.
On Friday, the company said it has offered to buy the rest of Noble Midstream at $12.47 per common unit, the same price Noble's shares ended on Thursday.
Yet they also felt the pain. Demand for oil evaporated in early 2020 as governments imposed travel restrictions and stay-at-home orders to slow the COVID-19 pandemic's spread.
Oil companies are expected to benefit from a bounce-back in oil and gas prices after a one-two punch of falling demand and prices put the industry in a tailspin last year.
While we're optimistic about vaccines and getting on a pathway to recovery, we're not there right now,
Morgan Stanley on Monday upgraded Exxon's rating to overweight from equal-weight, saying it preferred the company to Chevron Corp for 2021.
We think that improved transparency, cost-reduction actions and increased investor pressure could all serve to push XOM to put up more consistent results