The dataset includes heavy oil and non-heavy oil offshore production. In China's crude oil production, heavy oil accounts for 17%, while non-heavy oil accounts for 83%, representing an average production mix for China.
Heavy oil reservoirs refer to reservoirs where the crude oil viscosity under reservoir conditions exceeds 50 mPa·s. Crude oil from heavy oil reservoirs has high viscosity, poor fluidity, and is difficult to extract. Low-permeability oilfields are oilfields characterized by low reservoir permeability, low abundance, and low single-well productivity.
The net calorific value of crude oil is 43.4 MJ/kg, and the average calorific value of natural gas is 36 MJ/Sm³.