MISFIRE PROCEDURES

In the event of any total misfire or no-fire of the perforating guns, it is imperative that the perforating contractor is contacted immediately. The perforating contractor should, after assessing the sequence of events, prepare a detailed procedure for recovery of the guns. 5.7.1. Mechanical Firing Head

1) Due to the nature of the mechanical system, the guns can be fired during any subsequent fishing operations and this should be taken into account.

2) Adequate time should be allowed for the detonating bar to reach the firing head before a misfire is suspected. Allow twice the estimated time. If the guns do not fire, it is probably due to the detonating bar hanging up on debris on top of the firing head, or in a restriction further up the tubing.

3) Once a misfire has been established fishing operations will commence in an attempt to fire the guns. Record the following data:

• OD of fishing neck

• ID of the smallest restriction in the string

• Depth of the firing head.

• Length of the detonating bar

• Distance from the top of the firing head to the communication ports in the tubing. 4) Ensure that the following slickline tools are available and on site:

• Overshot designed to catch the fishing neck

• 1_1/4 ins OD bailer

• 11/4 ins lead impression block

• Chisel point bailer bottom for the 11/4 ins bailer.

5) Make sure that the length of the lubricator is adequate to accommodate the toolstring and the length of the detonating bar if recovered.

6) Confirm the distance from the firing head to the ports in the tubing string. This should be sufficient to allow both the toolstring and detonating bar to remain below the ports.

7) Rig up slickline and prepare the toolstring with an overshot to catch the detonating bar.

8) When running in hole confirm the fluid level in the well. Record this depth.

9) Shot detection equipment will be used and it should be monitored during all fishing operations and attempts to fire the guns.

10) When the detonating bar is located, spud down as hard as possible. Do not pick up straight away. If the bar moves, chase it to the firing head as quickly as possible. This will ensure that the slickline tool will not be above the entry ports (should the guns fire) and be blown up the well. Repeat this process three times.

11) If the guns do not fire fish the detonating bar and pull out of the hole.

12) Rig up with 1_1/4 ins bailer and ‘Chisel Point’ bailer bottom. The bailer should be dressed to a sharp point.

1) Run in the hole and jar down as hard as possible on the firing pin. Again ensure that the toolstring does not get pulled above the entry ports. Pull out of the hole and inspect the leading edge of the chisel point. Damage will indicate whether or not something hard (firing pin or foreign object) is being struck.

2) Carefully observe for any material recovered in the bailer, it may indicate what is preventing the detonating bar from reaching the firing pin. Fine black powdery deposits are an indication that the guns have fired and will be associated with a smell of burnt cordite. Hydrocarbons may also be present.

3) Repeat bailing operations until it is certain that the bailer is striking the firing pin. 4) If it becomes obvious that the bailer is striking something other than the firing pin, run

a lead impression block.

5) Check the fluid level in the well during every wireline run. Monitor carefully for losses/gains.

6) When it has been determined that the firing pin has been struck, and the guns have not fired, pull out of the hole with the drop bar.

7) In the event that a retrievable head has been used, this should be retrieved at this point and inspected.

• If it has not fired, run another firing head on slickline and repeat the procedure.

• If the head has fired, rig down wireline.

8) Top up the well with fluid, and if not already done so, rig up circulating lines from the cement unit to the production string. Attempt to pump into the formation to confirm that the guns have not fired. The leak-off pressure should be taken into consideration. 9) Unseat the packer and circulate the well contents to kill fluid. Circulate and condition

the brine. Prepare to pull the completion and retrieve the guns.

10) Once the firing head has been retrieved the guns are safe, and can be pulled from the well.

11) If it proves impossible to retrieve the detonating bar, the string and guns will have to be pulled. This is potentially very hazardous. Refer to base and seek the advice of the TCP gun manufacturer and senior Company personnel. No further action should be taken without written instructions endorsed by all parties concerned.

5.7.2. Hydraulic Firing Head

The hydraulic firing head (tubing pressure) is normally run with a time delay to allow underbalance conditions to be re-established after the tubing pressure is increased. 1) If no indication of the guns firing is observed, twice the duration of the time delay

should be allowed before repeating.

2) If the guns will not fire at the design pressure, increase the pressure (in increments of 500 or 1,000psi) and re-apply, allowing twice the time delay before repeating.

3) Monitor any fluid gains or losses.

4) Monitor the shot detection equipment. In the event that it is established that the guns will not fire, the TCP representative on location will evaluate the situation in conjunction with the Well Operations Supervisor. Both Eni-Agip and the TCP company onshore will be consulted. A detailed procedure will be prepared based on the current status of the operation, prior to any further action.

5.7.3. Fixed Hydraulic Firing Head

With this type of firing head, a misfire is potentially the most hazardous situation and both Eni-Agip and the TCP contractor operations management staff must endorse any further instructions or procedures for recovery of the guns.

5.7.4. Retrievable Hydraulic Firing Head

The firing head must be recovered using slickline, thus disarming the guns prior to their recovery. The TCP contractor will at this point must provide a procedure based on the current status of the operation. Once the firing head has been recovered, the guns are entirely safe and can be retrieved from the well.