Electronic time delay apparatus and method
A time delay apparatus for use with a downhole tool in a wellbore casing. In an exemplary embodiment, the apparatus includes an electronic circuit comprising a timer, a fusible link, a split spool device that includes a center pin held in place in a restrained position with a spool and a spring element surrounding the spool. A pressure applied to a trigger device, such as a rupture disk, activates a pressure switch and starts a timer, configured with a preset countdown time, in the electronic circuit. On expiration of the timer, the timer block of the electronic circuit generates a signal to cause breaking of the fusible link and releasing of the spring element such that the center pin of the split spool travels to a functional position and activates the downhole tool.
1. A time delay apparatus for use with a downhole tool in a wellbore casing, the apparatus comprising:
an electronic circuit having a timer configured to be programmed with a time interval;
a trigger configured to activate the timer to commence a countdown of a programmed time interval;
a downhole tool activator; and
a fusible link configured to connect between the downhole tool activator and the electronic circuit, the fusible link degrading during a predetermined time period,
wherein the electronic circuit, the trigger, the downhole tool activator, and the fusible link are located on the downhole tool, and
wherein, upon activation of the timer in the electronic circuit, and expiration of the time interval of the timer, the fusible link commences degrading such that after the predetermined time period, the downhole tool activator is automatically triggered.
2. The time delay apparatus of claim 1 , wherein the trigger comprises an environmentally activated trigger.
3. The time delay apparatus of claim 1 , wherein the trigger comprises an electrically activated trigger.
4. The time delay apparatus of claim 1 , wherein the fusible link comprises a link of an electrically conductive material that degrades as current passes through it.
5. The time delay apparatus of claim 1 , wherein the downhole tool activator comprises a split spool valve having a center pin held in place in a restrained position with a spool, a spring element surrounding the spool.
6. The time delay apparatus of claim 1 , further comprising a timer block, the timer block activated upon expiration of the programmed timer interval, the timer block generating a signal to degrade the fusible link.
7. The time delay apparatus of claim 1 wherein the downhole tool is a sliding sleeve valve, and the downhole tool activator allows, after being automatically triggered, a fluid from a bore of the sliding sleeve valve to move an inner sleeve to open a port formed in an outer sleeve.
8. The time delay apparatus of claim 1 , wherein the trigger includes a pressure sensor responsive to pressure pulses.
9. The time delay apparatus of claim 8 , wherein the electronic circuit is configured to be reset by pressure pulses transmitted to the pressure sensor.
10. The time delay apparatus of claim 1 , wherein the downhole tool activator comprises a rupture disk that is configured to rupture to allow a fluid from a bore of the downhole tool to move through the downhole tool activator.
11. The time delay apparatus of claim 1 wherein the downhole tool activator is configured to release a firing pin to activate a perforating gun.
12. The time delay apparatus of claim 1 wherein the downhole tool activator is configured to open a port in a spool valve of the downhole tool.
13. The time delay apparatus of claim 1 , wherein the apparatus is configured to receive batteries as a power source.
14. The time delay apparatus of claim 1 , wherein the trigger is pressure-activated, and the timer is configured to start or reset when pressure pulses are received by the trigger.
15. A time delay apparatus for use with a downhole tool in a wellbore casing, the apparatus comprising:
an electronic circuit having a timer configured to be programmed with a time interval;
a trigger configured to activate the timer to commence a countdown of a programmed time interval; and
a downhole tool activator in communication with the electronic circuit, the downhole tool activator activated by the electronic circuit after expiration of a programmed time interval of the timer,
wherein the downhole tool activator is configured to operatively manipulate the downhole tool from a first condition, in which no fluid from a bore of the downhole tool passes the downhole tool activator, to a second condition, in which the fluid from the bore of the downhole tool passes through the downhole tool activator, and
wherein the electronic circuit, the trigger, and the downhole tool activator are located on the downhole tool.
16. The time delay apparatus of claim 15 , wherein the trigger comprises an environmentally activated trigger.
17. The time delay apparatus of claim 15 , wherein the trigger comprises an electrically activated trigger.
18. The time delay apparatus of claim 15 , wherein the downhole tool activator comprises a split spool valve having a center pin held in place in a restrained position with a spool, a spring element surrounding the spool.
19. The time delay apparatus of claim 15 , further comprising a timer block, the timer block configured to generate a signal to the downhole tool activator.
20. The time delay apparatus of claim 15 , wherein the downhole tool activator comprises a rupture disk.
21. The time delay apparatus of claim 15 , wherein the downhole tool activator is configured to activate a perforating gun.
22. The time delay apparatus of claim 15 , wherein the apparatus is configured to receive batteries as a power source.
23. The time delay apparatus of claim 15 , wherein the downhole tool is a sliding sleeve valve, and the downhole tool activator allows, after being automatically triggered, a fluid from a bore of the sliding sleeve valve to move an inner sleeve to open a port formed in an outer sleeve.
24. The time delay apparatus of claim 15 , wherein the trigger is configured to respond to pressure pulses to start or reset the timer.
25. The time delay apparatus of claim 15 , wherein the downhole tool activator is configured to open a port in the downhole tool.