Abstract: The Ordovician fractured-vuggy Carbonate reservoirs in Tahe Oilfield are typically complicated ones with various
types of reservoir spaces and very strong heterogeneity. Studies reveal that the distribution of the reservoir spaces have strong
relation to the sedimentary condition but is determined by the tectonic karstification. Therefore the convention model method，
such as two point statistical methods，cannot provide accurate three-dimensional geology models. In this paper，one new concept
of karst phase is defined according to the characters of the the fractured-vuggy units. After the karst phases of the single wells
as wells as the training image model are studied，the 3D karst phase modes are established by using multi-point geostatistical
methods to simulate the karst phase distribution. Finally，taking the distribution as a constraining data，we create a reasonable
three-dimensional geology models with sequential algorithm.

Key words: Tahe Oilfield, fracture-cave reservoir, structure-karst facies, multi-point geostatistics, stochastic simulation