Abstract:

The W low permeability oilfield with well 21 block in the Ordos Basin is characterized by ultra-low permeability oil reservoir with strong heterogeneity, and the effect of water flooding is not promising. In order to characterize the reservoir heterogeneity and its through-going characteristics, this paper establishes the structural model, lithofacies model, the sedimentary microfacies model, and the microfacies-controlled property model step by step using facies-controlled modeling technologies with multiple stochastic modeling methods based on the geology investigations, petrographic observations, log analysis, and production performances. The comparison between facies-controlled modeling and non-facies-controlled modeling reveals that facies-controlled property modeling resulted in a more reliable and realistic descriptions of the targeted reservoir heterogeneities. An seamless integration of 3D model established by Petrel and Eclipse simulations gets good application in later research on CO₂-EOR numerical simulation. The successful application of the facies-controlled property modeling technologies in the Ordos Basin shows that such approach can characterize the properties of the low permeability reservoir with multi sedimentary mirco-facies and strong heterogeneity, and can describe connectivity and distribution feature of sand, providing a reliable petrophysical property model for optimizing the development strategy of ultra-low permeability reservoirs.

Key words: Ordos Basin, low permeability oilfield, facies-controlled modeling, variogram function