Hydro Frac Monitoring - Which Method?

Since the early 2000s several new methods for detecting hydraulic fracturing events and ultimately obtaining the half-length and establish a best practice for field development was largely limited to borehole microseismic.

Suface seismic techniques offered a different method for observing microseismic activity, and while it added more certainty to the planar location of events, the depth distribution and costs (about an order of magnitude) made the technique limited to the mid-majors who already drilled multiple wells.

Distributed Acoustic Sensors (DAS) came offered a permanently deployed system which could monitor for the life of the well/equipment, however the single component aspect of the system limits the results or requires a second system to be deployed in a neighboring well, and costs were about an order of magnitude above that of the surface deployment.

Recently researches out of Stanford University have worked with a private entity on using K-waves to establish the half-length of each stage but appears to be limited in practice on the direction/orientation of the connected frac. This method appears to have promise in establishing a more accurate SRV when combined with a borehole or surface technique.

DAS $1million unlimited number of sensors in theory, practice is more limited. 1D solution (No Z data) Permanent. Symmetry unknown without an additional array.

Surface $300k XY plane coverage great, z depth limited. Symmetry well defined.

Downhole $80k See the smallest events, highest number of events, decreasing resolution with offset (XY plane) limited to offset monitoring well, possible to determine symmetric or asymmetric

K-wave $30K Little equipment, no depth or directional component symmetry unknown