Seismic Monitoring

Fracture optimization can lead to a huge turn around in the production of oil and gas.  This is especially true in these unconventional reserves which are beginning to be produced today.  There are many tight gas sand and shales which depend upon fracturing to flip them from being uneconomical to economical.  One large step in the optimization of fracture placement and well spacing is the use of microseismic evaluation.  There are a few ways to obtain microsiesmic data.  The most effective method is to place receivers downhole in a monitor well but the equipment is restricted to about 330 degrees Fahrenheit.  Another method is to obtain data with surface receivers but surface noise such as bypassing trucks can make data worthless.  Typical fractures create hypocenters which is where the origin of the acoustic waves is located.  The problem with this evaluation, is that the location of the hypocenter determined from wave velocity is that the origin of the acoustic data isn't necessarily the location where fracturing is occurring.  A typical fracture will be monitored between -1 and -4 on the Richter scale.  A felt earthquake can be around 3 or so on this logarithmic scale.  As you can tell, the monitors are very sensitive to acoustic activity.  Research today is being directed toward evaluating this obtained data in hopes of optimizing well spacing and fracture placement.  As I said before, this discovery would enhance the economic potential of unconventional reservoirs for the future.  Also, this could mean better management of limited resources and reservoirs and lead to a longer life of the effective energy that oil and natural gas provides to the world.