Natural Fracture Intensity in Complex Carbonate Reservoirs, Improving Drilling
Location Selection in
Frass, Manfred1, Efrain Mendez2, Rodolfo Rocha3 (1) Veritas VHR, Villahermosa, Mexico (2) Pemex E&P, Villahermosa, (3) Pemex E&P, Villahermosa, Mexico
Fracture intensity curves, obtained from borehole micro-resistivity and/or ultrasonic image logs are guided by 3D seismic inversion data (post stack and pre stack), curvature attributes and other seismic attributes, to generate a fracture intensity 3D volume, in complex carbonate reservoir. Three different types of features are interpreted from the borehole image logs: Conductive fractures (open fractures), Resistive fractures (closed or partially open fractures) and Bed Boundaries. The aperture of the conductive fractures, the spacing and the resulting fracture intensity, is calculated for each fracture. Seismic attributes include P-wave velocity (Vp), Shear wave velocity (Vs), density, and mu-rho models from stochastic simulations, a number of other geometric attributes calculated from the Rp seismic volume and Curvature attributes generated from post stack seismic volume. All these attributes are loaded into a neural network system. At least three wells need to be used to generate models using stepwise multi-linear regression. During the stepwise multiple regression, the system attempts to use the data from two wells to predict the third. The production behavior is integrated into the model looking for correlations of the fracture intensity and the production log data, of the same well. A fracture intensity 3D model, is generated using the selected geometric and stochastic inversion attributes. This 3D model is then used to guide well trajectories for new infield and exploration drilling, optimizing cost and reducing risk of the new wells.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California