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

Challenge
Water shut-off
JNO19169 Opening New Flow Path In Expandable Sand Screens
  • Well type Oil producer
  • Pressure 1,740 psi
  • Deviation 78.4°
  • Max. depth 10,433 ft MD
  • Temperature 194°F

Background

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 allow 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 holes be distributed axially to cover as much sand face as possible.

The client first tried other service providers but was not satisfied with the results. The drilled holes were not oriented as expected because of a complicated dual telemetry system that would lose orientation when activating the drilling on the high side.

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

Operation

Welltec developed a mechanical Rotation Sub that is activated by the Well Stroker®. The toolstring includes wellhead release devices for stuck contingencies, casing collar locators for correlation, Well Tractor® for conveyance, Well Stroker for activation, Rotation Sub for orientation, Hardware Scanner to monitor and confirm orientation, and Well Puncher® to drill the holes. The system anchors the tool throughout the orientation process.

The required flow rate and the 12 mm bit size determined the number of holes needed for the operation. The depth of the drill bit was limited to avoid accidental damage to the screen outside. The Rotation Sub was produced and tested to provide orientation of the bit in 30° steps.

After the other service providers’ solutions failed, Welltec mobilized and performed the operation using the new system.

During a single run, the Welltec Puncher correlated and drilled 36 holes of 12 mm each in 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.

Achievements

Welltec met the client’s needs when other providers failed. The innovative solution, developed in conjunction with the client, performed well. The Welltec Puncher, running with the new Rotation Sub, drilled 36 holes 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 drill bit was in good condition.

The production experienced an initial boost to the previous production levels with less than half the stroke setting after implementing Welltec’s new system.