Abstract:

Cambrian and Ordovician are most important marine carbonate reservoirs in the Tarim Basin. On the basis of the analysis of plate tectonic environment, deep tectonic background, sedimentary, tectonic evolution and volcano activities, we reconstructed the CambrianOrdovician prototypic basin and lithofacies paleogeography of the Tarim Basin and analyzed their relationship with oil and gas accumulation. According to main tectonic stress, Cambrian and Ordovician can be divided into two stages, which are Cambrian and Early Ordovician extensional tectonic background stage and the Middle to Late Ordovician convergent tectonic background stage, we separately researched the basin prototype and paleogeography in these two stages, and mainly focused on the formation and evolution of paleouplift and carbonate platform and the distribution of open platform and restricted platform facies, which have important impacts on the oil and gas accumulation in carbonate reservoir. We have summarized the main source rock and reservoir development models of Cambrian and Ordovician. Three types of high quality source rocks were developed in the Tarim Craton, depending on the basin type and location where the source rocks were deposited, while the reservoir can generally be separated into sedimentary reef and bank reservoir and karst reservoir. The sedimentary and karst reservoir can both be divided into four kinds. Considered the basin evolution, source rock and reservoir distribution, we proposed favorable exploration areas for marine carbonate reservoirs in the Tarim Basin.

Key words: Tarim craton, CambrianOrdovician, prototype, palaeogeography, oil and gas fields