Abstract: Potential for Infill Drilling in a Naturally Fractured Tight Gas Sandstone Reservoir
HARSTAD, HUGO, and LAWRENCE W. TEUFEL, New Mexico Tech; JOHN C. LORENZ, Sandia National Laboratories; and WILLIAM H. BABCOCK, Burlington Resources.
Modeling of the Mesaverde Formation in the San Juan Basin,
northwestern New Mexico, shows the importance of using realistic
drainage patterns in a naturally fractured reservoir. Fractures not
only enhance the overall porosity and permeability of these
reservoirs, but fractures also create significant permeability
anisotropy
. Permeability
anisotropy
causes the drainage area around
the wells to be elliptical. Directional permeability is best found
with multiple well interference tests. Predicted potential for
infill drilling depends on the modeling approach, because
elliptical drainage creates more overlap and undrained sections
than a more radial drainage in an isotropic permeability case.
Modeling with permeability
anisotropy
increases the potential for
infill drilling and identifies optimum locations for new infill
wells.
This approach has been applied in the Mesaverde Formation to
determine economic optimization of infill drilling in these
reservoirs and demonstrates that field development based on
elliptical drainage areas can lead to a reduction in drainage
overlap of adjacent wells and prevent leaving undrained areas. From
multiple well interference testing a strong permeability anisotropy
was found. Reservoir simulations were performed in two pilot areas
of different fracture intensity to quantify the potential for
infill drilling, reducing the well spacing from 320 to 160 acre.
Simulation results indicate areas of effective drainage, the
optimum locations for infill wells, and the additional recovery
from infill wells.
AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah