| Correlated with statistics and analysis of the characteristic parameters from eight Ordovician carbonate reservoirs in eight oil and gas fields in north American, the features and the main controlling factors of the Lower Paleozoic and Sinian carbonate reservoirs from some oil and gas fields in China are studied. In North American, the Ordovician sedimentary environments mostly were circular tide flats to shallow shelves and the carbonate reservoirs can be briefly divide into four types of lithofacies, including mudstone,wackestone, packstone and grainstone, in which intercrystal pores, pores related with breccia and dissolved pores are common while in China, the evolution of Lower Paleozoic and Sinian carbonate reservoirs are more complicated and primary pores are mostly damaged out. The both results of reservoir analysis to North American and China have shown that both of kast reservoirs and dolostone reservoirs are all effective ones. When burial depth are more than 3000m, dolostone is the dominant type of reservoir rock. As increasing depth, dolostone can keep good reservoir capability, which is a elementary trend. The Lower Paleozoic and Sinian carbonate rock are commonly greatly deep-buried in many basins in China so that the dolostone reservoirs are a domain worthy to pay an attention especially. |
