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3-D Fractured Reservoir Modeling of Cao Fei Dian 18-1 Field, Bohai Bay, China

Wang, Hui 1; Hu, Guangyi 1
1 CNOOC, research center, Beijing, China.

The challenge at Cao Fei Dian 18-1 field was to predict the production performance of the granite fractured reservoir. This prediction was further challenged by 3-D distribution of fractured reservoir property, fracture porosity and fracture permeability. To assist with reservoir simulation and optimization of field development plan, a 3-D fractured reservoir model was conducted by integrating data from core description of fracture, DST data, structure strain simulation, fault distribution and well data for more accurate fractured reservoir characterization.

Three steps would be taken to conduct 3-D fracture property model in turn.

Firstly, the fracture geometry including fracture length, aperture, orientation, fracture density and the relationship between different sets of fractures, was described by using core and outcrop analogue.

Secondly and the most importantly, a set of Discrete Fracture Network (DFN) models was generated based on the genesis system of fracture. Taking all the secondary factors including structure strain, weathering and erosion into account to predict fracture distribution trend model. A boundary element / elastic dislocation approach was used to forward model strain which was then as the trend to conduct the first fracture distribution trend model. Based on the distance to the faults that reflected function of the weathering and erosion to fracture, the second fracture distribution trend model was set up. The final trend model was conducted by combining these two trend models. Constrained by fracture distribution trend model, a set of DFN models was generated by integrating fracture geometry, well data and vertical fracture distribution trend. By correlating with dynamic data from wells, the best DFN model was chose.

Finally, fracture permeability and fracture porosity was calculated based on DFN and fracture aperture. The final model provided fracture permeability and porosity for each model cell, which varied as a function observed well data, predicted strains, predicted fracture distribution trend, predicted fracture orientations and zones.

3-D fractured granite reservoir model was used for reservoir engineers to run several reservoir simulation cases and assisted them to make the oil field development plan.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009