BiSN Collaborates with Sasol for Permanent Abandonment in Mozambique

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Sasol BiSN Tool Being DeployedSasol BiSN Tool Being Deployed

P&A with wel-lok™ Technology

BiSN collaborated with Sasol in Mozambique to prove the effectiveness of wel-lok™ technology.

June 7, 2023

BiSN collaborated with the major operator Sasol in Mozambique to successfully qualify the wel-lok™ CRT tool to begin the partnership ahead of a campaign in the country. As part of the first run BiSN and Sasol logged the resulting plug via a cement logging tool to prove the effectiveness of a wel-lok™ seal with great success.

  • Video
  • Challenge
  • Solution
  • Results
  • Business Value

Qualifying wel-lok™ Technology for Use in Mozambique

Sasol had run a baseline log showing that previous cement work was patchy and needed to find a rock-to-rock sealing solution. Thin cap rock in the region increased the difficulty of this task.

The decision was made to deploy wel-lok™ technology via perforations in 9-5/8” casing with the objective of isolating formation activity from a gas bearing silt layer from shallower formations. BiSN was challenged to place a wel-lok™ plug within a 10m thick shale layer identified as a suitable regional seal.

Sasol Data After BiSN DeploymentSasol Data After BiSN Deployment

wel-lok™ Cement Repair Tool

BiSN field engineers worked alongside a service partner and Sasol as a team effort to solve the downhole issue. First, the 9-5/8” casing was scraped, followed by a perforating gun run to provide access to the annulus. Next, a wel-lok™ CRT tool was deployed and activated by a timer and hydrostatic switch.

“Sasol believes that BiSN alloy is a material which is far less prone to contamination vs traditional cement and can effect a far higher sealing capability within a shorter column height due to its expansion characteristics upon cooling. Upon setting, it far exceeded our expectations and we will continue to use BiSN technology in Sasol campaigns.”Sandy Ferrari, Well Engineering Consultant, Sasol

Sasol BiSN CollaborationSasol BiSN Collaboration

Cost Efficient Solution for Sasol to Use in Future Campaigns

A wel-lok™ plug was set downhole effectively and efficiently. Inside the wellbore the bismuth plug was milled out to run logging to determine the effectiveness of the operation. The following results were observed:

  1. Large perforation guns were employed allowing more space for bismuth alloy to flow into the annulus. The alloy expanded to form a circumferential plug.
  2. No hydraulic lock was observed, meaning the bismuth alloy flowed with the viscosity of water and was forced into all available channels during the setting process.
  3. The plug was evaluated by an independent petrophysics resource to establish that the bismuth alloy had filled all available void space and micro annuli.
Business Value

Reduced Rig Time and Section Milling

The following was observed by Sasol personnel:

  1. Improved long term abandonment integrity alongside a reduced carbon footprint in operations.
  2. Reduced overall cost for the operator.
  3. Eliminated the need for extensive section milling saving rig time and removing a significant health hazard for rig personnel.

“A key to success was the excellent collaboration between BiSN and Sasol from ordering the tools to the successful bismuth alloy installation. The openness in communication and transparency on both sides was vital to the deployment’s success.”Klisthenis Dimitriadis, Well Engineering Manager, Sasol

Efficiencies of BiSN wel-lok™ TechnologyEfficiencies of BiSN wel-lok™ Technology

About the application

The wel-lok™ CRT (Cement Repair Tool) was developed to eliminate sustained casing pressure, or casing vent flow, in cemented annuli. Unlike traditional methods of perf and squeeze or perf and wash, this tool does not require any surface pumping pressure to squeeze or circulate the sealing material into place. The tool is also run rigless on electric line, sealing through casing perforations, so section milling is not required. The bismuth-based alloy has no porosity and solidifies to create a seal in minutes as opposed to hours with traditional cement and resins, eliminating the possibility of a micro-annulus being formed to allow future gas migration. If full bore access is required, it can be milled out and still maintain a gas tight seal in the annulus.

Cement Repair Tool - BiSN
Cement Repair Tool - BiSN
Cement Repair Tool - BiSN
Cement Repair Tool - BiSN

How it works…

The wel-lok™ CRT (Cement Repair Tool) was developed to eliminate sustained casing pressure, or casing vent flow, in cemented annuli.

How it works…

More wel-lok™ Case Studies

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