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Crosswell monitoring

ArrayXwell™, the fibre optic distributed sensing-based crosswell monitoring service, accurately locates microseismic and strain events in real-time. This  allows operators to improve stimulation and completion designs to maximise recovery.

iDAS offers a cost effective alternative to conventional borehole microseismic monitoring.

Distributed acoustic sensing based microseismic and crosswell monitoring delivers greater insight into the subsurface hydraulic fracturing dynamics than conventional methods, offering detailed information on reservoir stability and fluid flow paths.

Benefits

Large aperture & higher data quality

Conventional microseismic surveys, acquired using geophones in observation wells, typically will have 12–40 receivers. Either the receiver spacing, array length, or both, will be less than optimal. Distributed acoustic sensing (iDAS™) captures acoustic energy every metre along a sensing cable installed either in an observation well or the stimulation well itself.

The fibre may be permanently in the cement or temporarily inside the casing. Silixa’s advanced sensing architecture provides noise reduction superior to other DAS systems, which is critical for microseismic event detection thresholds and hypocentre location accuracy.

The result for the client is vital information on the hydraulic fracture zone, enabling improvements to stimulation operations, wellbore spacing, and wellbore azimuth.


Greater insight, maximised recovery

A permanently installed fibre optic cable can deliver vital and actionable information on the hydraulic fracture zone, enabling improvements to stimulation operations, wellbore spacing, and wellbore azimuth.  Data can be acquired both in the observation or treatment well. This enables operators to maximise recovery.


No shut-in requirement

Significant cost-savings are delivered by the fact that data can be acquired even in the treatment well.

A serious deterrent to using geophones is the possible long-term damage to the monitor well during shut in. This limitation is removed for DAS, since no shut in is required.

In addition, the unavailability of a nearby monitor well is not a factor if the treatment well is also the monitor. Geophone tools in the treatment well would be destroyed by the proppant, but the DAS fibre is outside the casing.


One fibre – multiple applications ‑substantial cost savings

Vertical Seismic Profiles (VSP), strain and perf allocation surveys can be done with the either ArraySeis or/and  Carina Seismic same array, so no additional installation costs are required. Once the array is installed, all five of our downhole surveys are possible:

  • Hydraulic fracture microseismic monitoring
  • Hydraulic fracture strain monitoring
  • Production strain monitoring
  • Flow allocation monitoring
  • VSPs

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Microseismic events

Top: Plot of depth of microseismic events against time, the size of circle indicative of event energy. Red and blue traces indicate pressure waves through the formation

Bottom: Pumping activity against time, the black dots representing individual microseismic events

Top: An individual microseismic event

Bottom: IDAS measurements using fibre in offset well (blue) whilst frac operations took place in adjacent well (red)

Downloads

Hydraulic fracture monitoring brochure

Carina XwellXpress spec sheet

First Break publication April 2019

Hydraulic fracture monitoring brochure 2020

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