Over the last couple of years, there has been much confusion over the regulator's prescribed MWHIP's in BC and Alberta.
As a general rule of thumb, both regulators convert wellhead injection pressures from a step rate injectivity test to sandface conditions and then plot the data to determine the fracture pressure at sandface. However, there are some interpretation differences between the two jurisdictions.
In BC, the MWHIP is determined by multiplying the sandface fracture pressure by 90%, subtracting PHYD (10.5 kPa/m) and then adding a 200 kPa frictional component,
regardless of the actual injection rate used to fracture the reservoir .
In Alberta, the AER converts 90% of the sandface fracture pressure to wellhead conditions using the rate in which fracturing of the reservoir actually occurred. In other words, unlike the OGC method, the frictional component of the calculation is typically not static, though we have had situations where the AER has prescribed an MWHIP using static injection conditions (ie. no frictional loss).
This is a very distinct difference and one that may reduce your anticipated MWHIP significantly.
Remember, in Alberta, this method for determining MWHIP is used for disposal wells only, not injection wells.
If you have any questions with respect to these methods, please do not hesitate to contact us. We'd be happy to help.
