Prediction of
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