Baker Hughes and VSFusion, a borehole seismic processing joint venture between Baker Hughes and CGGVeritas, recently completed one of the largest microseismic hydraulic fracture monitoring surveys ever undertaken. The survey for Apache Canada Ltd in the Horn River Basin of northwest Canada deployed Baker Hughes’ geophone strings simultaneously in two observation wells for over 30 days. Microseismic events were recorded for hydraulic stimulations in 13 wellbores adjacent to the observation wells. In all, over 75 separate hydraulic stimulations were recorded.
The project used a variety of deployment geometries in both the horizontal and near vertical sections of the observation wells to optimise hydraulic fracture imaging in the reservoir. Operations were conducted 24/7 and VSFusion provided real time display of recorded microseismic events, both on the wellsite and in Apache’s offices in Calgary and Houston. Monitoring and analysis of microseismic information during operations provides the ability to optimise the hydraulic stimulation process by modifying the fracture stage design while pumping into the formation.
Using the real time data
Apache used the real time data to experiment with how different perforation patterns impacted fracture propagation and to then make real time changes in the fracture programme as a result. At one point, the data showed an absence of growing microseismic activity, alerting Apache to switch from pumping proppant to flushing the well with water to avoid a potentially costly sanding off of the fractures.
Recording microseismic events to monitor rock fracturing in 3D space and time during the stimulation process allows confirmation of the rock volume and formation geometry being stimulated. From this information, future well placement and completion designs can be optimised for cost effective drainage of unconventional reservoirs.