Regaining Production from a Sand-Plugged Reservoir in Deepwater Indonesia

Published: 01/01/2009

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High-producing deepwater well

For a high-producing deepwater well in the West Seno field, Indonesia, Chevron needed to regain access to a perforation zone plugged by sand fill. CT cleanout operations were attempted to remove the sand, but they had a low success rate because of

  • large casing—greater than 4.5-in ID
  • high deviation angles—greater than 60°
  • low BHP gradients—less than 0.3 psi/ft.

The company attempted direct circulation using gas lift, reverse cleanout using fluid, and direct foam circulation. Respectively, these techniques resulted in batched production, a stuck pipe incident, and high cost due to offshore logistical limitations.

Used with an engineered cleanout solution, the ACTive CT service provided real-time BHP and depth informa-tion that enabled effective cleanout.
Used with an engineered cleanout solution, the ACTive CT service provided real-time BHP and depth informa-tion that enabled effective cleanout.

New cleanout method

Schlumberger supplied a new cleanout method using an engineered cleanout solution, combined with ACTive in-well live performance. The gel is a diesel-base solution with a lower density than water-based gel fluids, resulting in a lower hydrostatic fluid column suitable for low-BHP cleanout applications. Core flow tests on the West Seno field showed the gel to be compatible with the water-sensitive formation. They also showed an increase in retained permeability using the gel. Furthermore, because it works in a single phase, the gel proved less complex than foamed fluids, and its high viscosity limited invasion.

The ACTive CT service provided real-time BHP data that worked with the existing gas lift system to perform the cleanout. This ability meant that transient effects on the gas lift mandrel could be measured and operations could be adjusted. With the real-time information, the fill-loaded column of fluids was managed, allowing circulation to be maintained at all times. Furthermore, the ACTive service’s casing collar locator (CCL) depth measurement enabled the cleanout to progress to the desired depth without surface measuring devices or critical depth offsets in error ranges.

Real-time decision making

The combination of the engineered cleanout solution and ACTive services supplied real-time downhole measurements, which eliminated all assumptions surrounding this cleanout job. Chevron personnel were able to make immediate decisions based on accurate real-time data. The cleanout operation proved successful, and the company regained access to its sand-plugged reservoir.

Indonesia, Asia, Offshore

Challenge: Use coiled-tubing (CT) cleanout to restore access to and regain production of a water-sensitive, sand-plugged perforation zone for a deepwater well with low bottomhole (BHP) gradients.

Solution Combine engineered cleanout solution with ACTive in-well live performance for real-time BHP and fluid flow data during the cleanout process.

Results: Achieved successful cleanout and regained access to high-producing reservoir.

Products Used