The dataset includes heavy oil and non-heavy oil onshore production. The proportion of crude oil production in China is 17% heavy oil and 83% non-heavy oil, representing an average production mix in 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 those with low reservoir permeability, low resource 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.