Abstract:

Faulted-karst carbonate reservoirs have been a focus of study in the Tahe oilfield in recent years.The heterogeneity of the reservoirs is a key issue that restricts their development.The TH10421 unit in the block 10 of the Tahe oilfield is taken as an example to classify the reservoirs based on logging data and high-frequency seismic attribute analysis.There are four types of reservoir as a result, namely the cavity type, dissolved pore or cavity type, fracture-cavity type, and fracture type, among which the first two are the most common reservoir types, and the last two, still at early stages of evolving into large-scale cavities, serve mainly as connection between reservoirs.The results show that the evolution of reservoirs from fractures to pores and then to cavities indicates a gradual increasing dissolution from outside to inside, and that multi-stage fractures caused by strike-slip faults facilitated the dissolution.Each reservoir type in the faulted-karst carbonates corresponds to specific log and seismic responses.Seismic texture attributes can be used to clearly predict the distribution of different types of reservoirs within, which will in turn further confirm the proposed development model of the reservoirs.The study helps to promote the understanding of the forming process of faulted-karst reservoirs and to provide a geological basis for their future development.

Key words: identification and prediction, development model, faulted-karst reservoir, Tahe oilfield, Tarim Basin