Print this pageA New Technology for 3-D Seismic Exploration and Development
of 
Fractured
Tight Gas Reservoirs
A 3D seismic exploration method for fractured tight gas
reservoirs is developed in a study conducted for the U. S. Department of
Energy. The interpretation methodology is based on three principal reservoir
attributes, fracture density, clay volume, and gas content.
Seismic lineament analysis is used to map lineaments through the reservoir
zone using horizon slices and time slices. We interpret that in a probabilistic
sense where lineaments swarm and cluster together is where reservoir fractures
are most likely to be found. Leads identified using lineament density are
further screened using rock typing to identify reservoir that is more likely to
fracture. A collocated cokriged clay volume map using
near trace seismic amplitude (an AVO attribute) is used to identify reservoir
having low clay that is interpreted to be more brittle and more prone to
fracturing. Fractured reservoir and good reservoir rock do not necessarily make
a drillable prospect, as reservoir
fractures may provide a plumbing system to
both water and gas. For prospect development a gas sensitive phase gradient AVO
attribute is used to further screen the leads to insure that gas is present.
In a gas field previously plagued with poor drilling results in the San Juan Basin of New Mexico, four new wells were spotted using the methodology and recently drilled. The wells have estimated best of 12-months production indicators of 2106, 1652, 941, and 227 MCFGPD.