Stanford University

Ge Jin, Colorado School of Mines, DAS Applications in Unconventionals

Thursday, Feb 27, 2020 12:00 PM
Mitchell, 350/372
Geophysics Department


Ge Jin

 Department of Geophysics, Colorado School of Mines

DAS Applications in Unconventionals

Date: Thursday, February 27, 2020

Location:  Mitchell 350/372

Time:  12:00 pm - 1:15 pm

Host:  Biondo Biondi

Many algorithms that have been developed in recent years use Distributed Acoustic Sensing (DAS) to monitor unconventional wells. A DAS system measures the distributed strain or strain rate along a sensing fiber. Unlike a geophone, it has a very broad frequency response. In the high-frequency band (>1 kHz), DAS serves as a noise logging tool, which monitors the acoustic energy generated at perforations during injection or production. The acoustic intensity can be semi-quantitatively associated with the injection or production allocation of the perforation clusters. In the mid-frequency band (10-1000 Hz), DAS enables seismic applications like VSP and microseismic monitoring. Interstage time-lapse VSP measures the effect of velocity perturbation induced by hydraulic fractures to estimate fracture height, impedance, and closure rate. DAS-based microseismic location and moment tensor inversion approximate fracture extent and orientation. In the extra low-frequency band (<0.1 Hz), DAS measures the stress perturbations induced by hydraulic fractures in the formation. This measurement provides critical information about fracture width, length, and density. During production, the low-frequency DAS signal can track very small thermal sluggings caused by fluid movement inside wellbore, which leads to production logging solutions. Using the same fiber, DAS can provide various types of diagnostic information for unconventional reservoirs.

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