Opening new flow path in expandable sand screens - 36 holes created in one run

In 2016, an oil producer well in the North Sea was completed using three 6-5/8” expandable sand screens covering the upper and lower formations. The two uppermost screens each contained inflow control devices to balance the flow across the two intervals.

After initial high gas rates, the well experienced a quick decline. Water broke in and required gas lift to produce. The operator believed that the screens were likely clogged near the production ports.

The client needed to open new access points to the production flow channels by mechanically punching the base pipe at the channels. The client requested an engineered solution that would enable the well to regain a more normal production level. To avoid accidental sand production, the screens themselves could not be milled or damaged. Additionally, the client requested that the new pathways be distributed axially to cover as much sand face as possible.

A previous third-party attempt had failed due to a complicated dual telemetry system that would lose orientation when activating drilling on the high side.

Welltec® proposed a solution and created an orientation system that was sponsored by the client.

The toolstring included:

- Well Tractor® – conveyance
- Well Stroker® – actuation
- Casing Collar Locator (CCL) – correlation
- Rotation sub – orientation
- Welltec Hardware Scanner® – to monitor and confirm
orientation
- Welltec® Puncher – non-explosive method to create
perforations/holes
- Welltec Release Device® – contingency for ‘stuck’
scenario

The system anchors the tool throughout the orientation process.

The number of perforations was determined by the required flow rate and 12 mm bit size, and the depth of the bit was limited to avoid damage to the screen outside.

The rotation sub was produced and tested to provide orientation of the bit in 30° steps.

Welltec mobilized and performed the operation using the new system, and during a single run the Welltec Puncher correlated and created 36 perforations of 12 mm diameter.

- 12 holes at 10,438 ft in the third screen.
- 12 holes at 10,400 ft in the second screen.
- 12 holes at 10,358 ft in the first screen.

Welltec met the client’s needs when other providers failed. The innovative solution, developed in conjunction with the client, performed superbly.

Running with the new Rotation Sub, the Welltec Puncher provided a non-explosive means of creating 36 perforations in a single run.

The 12 mm diameter holes provided approximately 50% larger flow area than alternative solutions and alternating “high” and “low” positions of the holes minimized reduction in mechanical properties. After the operation, the bit was in good condition.

The well exhibited a boost in production levels with less than half the stroke setting after implementing Welltec’s new system.