A New Methodology on Reservoir Modeling in the Fracture-Cavity Carbonate Rock of Tahe Oilfield

Liu, Xueli¹, Xiaoxian Zhai² (1) Sinopec Northwest Company, Urumqi, China (2) The Northwest Oil Company, SINOPEC, Urumqi, Xinjiang, China

Tahe region, one of the large scale oilfields which are discovered in western China recent years, whose main storage is Ordovician carbonate, characterized with deeply embedding, various storage type and mainly are cavities and fractures. It is difficult to describe as its stronger heterogeneity and there is rare technical reference regarding the reservoir modeling methodology. Commonly the geology modeling is based on well logging and seismic data, and the stochastic method is reasonable applied. However, Tahe oilfield only has the very limited seismic data and the inaccurate well logging data interpretation, especially for the fracture-cavern section. Furthermore, as it is controlled by paleukarst, the stochastic geological method, which is widely used in the ordinary sedimentary, is unacceptable to Tahe. Also, the concept of porosity and saturation is less meaningful in this kind of reserves. As a result, there is no applicable modeling method to describe the geological characters of the Tahe carbonate reservoir. A new methodology which is characterized by the fracture-cavity volume is presented in this paper. Accordingly, a new reservoir modeling and a new reserve calculation is set up. Mainly from geology, jointed with static and dynamic data, a quantified 3D reservoir model of Ordovician reservoir is built, and this modeling methodology is proved practically by the results of history match from the streamline numerical simulation. The result will technically support the exploitation of Tahe oilfield.