Identification of well connectivity in fractured-vuggy carbonate reservoirs:A case study of Tuofutai area in the Tahe Oil Field

The Ordovician reservoirs in the Tahe Oil Field consist of large-scale seams and holes and the effective reservoir space is mainly interconnected seam and hole units. Reservoir development practices show that under the control of the distribution difference of seam and hole units, multiple independent seam and hole complexes exist within the same reservoir. Connectivity between seam and hole complex is one of the decisive factors of reservoir development effect. In order to define the connectivity between different seam and hole complexes, the author puts forward several methods based on dynamic and static data:(1) The same seam and hole complex shows high and continuous rate of seismic amplitude change. On the contrary, different seam and hole complexes show lower and discontinuous rate of seismic amplitude change; (2) Fluid within the same seam and hole complex may be similar; (3) Wells in the same seam and hole complex often show similar pressure and fluid producing change tendency; (4) A well can correspond to the drilling and maintenance measures of other wells in the same complex. Based on abundant dynamic and static data, it has been clearly analyzed whether wells in the W1 well block are connected, and a division standard for well connectivity in fractured-vuggy carbonate reservoirs has been established.