Petroleum industry in Nigeria to transport the crude oil. Also because of the lack of highly productive fields, money from the jointly operated (with the federal government) companies is constantly directed towards petroleum exploration and production. Nigeria's petroleum is classified mostly as "light" and "sweet", as the oil is largely free of sulphur. Nigeria is the largest producer of sweet oil in OPEC. This sweet oil is similar in composition to petroleum extracted from the North Sea. This crude oil is known as "Bonny light". Names of other Nigerian crudes, all of which are named according to export terminal, are Qua Ibo, Escravos blend,
Brass River at Yenagoa and flows south to discharge into the Gulf of Guinea. The tidal flats of the river have a reticulate drainage pattern, with higher elevation at the edges of the flats than at the center. Discharge varies depending on the season and state of the tide: An 1893 navigation guide says of the river, The mouth of the river is protected by a sand bar, which in 1893 could not be crossed by vessels with more than draft. Akassa creek, inland from the mouth of the river, provided a route from the Brass river to the Nun river for