Targeting at Ordovician carbonate reservoirs and their hydrocarbon enrichment characteristics in Tabei Uplift, this study focuses on the methodology and critical parameter distribution models for petroleum resources assessment in marine carbonate rocks. Petroleum resource of calibrated area in Ordovician carbonate reservoir was calculated, and it is shown that the Ordovician carbonate reservoir in Tabei Uplift can be divided into two types:the buried hill karst and the internal karst. Thin layers of oil and gas overlap vertically, and tend to connect laterally in the horizontal plane to form large areas of distribution. Therefore, the carbonate reservoirs are characterized by wholly oil-bearing and locally enriched oil, and the oil and gas enrichment is mainly controlled by carbonate reservoirs. By statistically analyzing petroleum geology data, critical distribution model parameters in petroleum resources assessment in marine carbonate calibrated areas were obtained. These parameters distribution models include effective thickness coefficients, effective area coefficients, effective volume resource abundance and effective area resource abundance model. Petroleum resource in the buried hill karst calibrated area was calculated based on Monte Carlo simulation using effective volume resource abundance and effective area resource abundance. The results show about 1.47343billion tons of oil and about 276.6billion cubic meters gas deposits, suggesting great exploration potential in marine carbonate rocks in Tarim Basin.