Abstract
The NMR of the Trinity reservoir indicate that changes in crude oil compositions result in differences in NMR characteristics. On this basis, the chemical properties of crude oil are analyzed, and two criteria affecting the NMR characteristics of crude oil with different physical properties are presented. The research shows that the chromatographic characteristics of crude oils with different maturity and biodegradability correspond well with NMR characteristics. Lateral relaxation time of heavy oil at low maturity stage and experiencing strong biodegradability is shortened. Two parameters, maturity index and biodegradation level, can be reliably applied to the evaluation and production of heavy oil reservoir.