Toe Valve Calculations
Choose the right rupture disk and understand the max circulation pressure for your toe valve operation
(100 to 450)
| Hydrostatic Pressure | 0 | psi |
|---|---|---|
| Hydrostatic + Applied Opening Pressure | 0 | psi |
| Cement Volume | 0 | bbl |
| Cement Length | 0 | ft |
| Max Cementation Hydrostatic | 0 | psi |
| Max Circulating Pressure | 0 | psi |
| Volume to Toe Valve | 0 | bbls |
| Rupture Disk Selection | |||
|---|---|---|---|
| Nominal | 0 | 0 | 0 |
| Temp Adjusted | 0 | 0 | 0 |
Opening Pressures (psi) |
|||
Hydraulic Toe Valves
Most multi-stage frac wells utilize a hydraulically actuated toe valve to start their operation. Many of these tools include a rupture disk that protects a piston and atmospheric chamber. The rupture disk is designed to burst at a specific pressure, which exposes the piston to wellbore pressures opening the valve. Several variables must be considered with selecting the rupture disk for your toe valve.
Hydrostatic Pressure
The pressures acting against the rupture disk is the hydrostatic pressure plus the applied pressure at the surface. The hydrostatic pressure is dependent on the vertical depth of the valve and the weight of the fluid in the well.
Desired Pressure Test
The operator must pressure test their well to determine the integrity of the well construction. In the State of Texas, operators are required to pressure test the well to 80% of the rupture disk value. This pressure must be taken into account along with the accuracy of the rupture disk. The low end of the rupture disk tolerance must not be below the desired pressure test, due to the risk of the valve opening during the test.
Maximum Surface Pressure
The equipment and iron on surface will have a maximum rated pressure that cannot be exceeded. When selecting the rupture disk you must ensure that the high end of the disk tolerance doesn’t exceed the max pressure, for risk that the valve could be left unopened.
Desired Opening Pressure
This is the surface pressure the operator would like to apply to open the valve. This must the added to the hydrostatic pressure to find the desired rupture disk size. Once calculated, the rupture disk can be selected taking into account the downhole temperature.
Toe Valve Accuracy
Rupture disks will have a built in tolerance for instance +/- 3%. This means that a disk rated for 10,000 psi will rupture between 9,700 and 10,300 psi. These upper and lower ranges come into affect when determining if the valve could open early during the pressure test or not open at all due to exceeding the max surface pressure.
Cementation Operation
During the cementation operation heavy cement is pumped through the wellbore and out into the well annulus. The heavier cement increases the hydrostatic in the well. During the pumping operation the rupture disk value cannot be exceeded. The calculator above shows the max cementation pressure allowed during the operation.