BiSN collaborates with Aker BP on successful 30 well P&A campaign

Following up with Aker BP after 2 years of monitoring and testing

Largest to date bismuth plug with Aker BPLargest to date bismuth plug with Aker BP

Catching up with
Aker BP

Aker BP, a major global operator, needed to safely plug and abandon 30 wells in the Valhall field in the North Sea. BiSN partnered with Aker BP to deploy Wel-lok™ technology to create safe and cost-efficient Wel-lok™ plugs. This not only allowed for a permanent plug and abandonment solution, but also allowed for new wells to be drilled and operated safely for the next 30 years.

After two years BiSN caught up with representatives from Aker BP to discuss the success of the campaign.

Representatives from Aker BP had the opportunity to reflect on the 2020, 30 well P&A campaign.

The Scenario

Multiple wells in the Valhall field were experiencing annulus pressure which increased the possibility of gas migration to the surface in the future.

Valhalla field heat map

Location of Valhall Field

The Valhall field is located in the southern sector of the Norwegian North Sea.

Testing and Qualification

For two years prior to the beginning of the campaign in 2020, Aker BP and BiSN carried out a joint testing program to ensure Wel-lok™ technology was the safest and cost-effective option at BiSN’s Houston location.

In order for the test to be successful, the following requirements were needed:

  • One material casing to casing barrier (i.e. heater removal)
  • Test above plug with water to 200 & 500 psi 
  • Test below with N2 – 200 & 500 psi – for 12 hrs (no bubbles)
  • Repeat same test after 14 days
  • Wel-lok™ plug tested to 5x the anticipated max differential pressure and temperature
  • Lifetime corrosion resistance

Watch the documentary of BiSN in Houston carrying out the qualification testing with Aker BP.

Results of Testing and Qualification

As a result of the rigorous testing done at BiSN’s Houston facility on behalf of Aker BP, BiSN Wel-lok™ technology received acknowledgement of consent for use including DNV-GL verification and PSA (NORSOK) evaluation of bismuth.

Trial Deployment with 24 Month Monitoring

24 months prior to the main campaign one well was chosen for a long term field test. A known gas generating zone was perforated below where the BiSN plug was set. After setting the well was continuously monitored for 24 months. At the beginning of the main campaign the plug was milled out and a large gas show was seen providing the final confirmation a gas tight seal had been created for the 24 month test duration.

The actual bismuth plug from the trial

The actual bismuth plug from the test well.

The Campaign

BiSN provided the customer with a reliable solution for permanent abandonment.

This eliminated the risk of an ineffective cement squeeze while providing the long-term reliability of Wel-lok™ alloy. As bismuth-based alloy can form an effective seal with a shorter plug length, the need to section mill a long window for a replacement cement plug represented significant cost savings for the operator. BiSN was able to help the operator reduce HSE risks, operation time, and cost.

  • Damaged cement replaced by Wel-lok™ alloy
  • Permanent plugs set in wells for abandonment
  • Eliminate need for unreliable cement squeezes
  • Significant cost savings for the operator
Read the full Aker BP article
The Valhall field in the North Sea.

The Valhall field in the Norwegian North Sea.

The Largest Bismuth Plug in the World

As part of the campaign, BiSN delivered the largest bismuth plug to ever be deployed to date. The tool was produced in BiSN’s UK facility.

Total weight: 33,191 lbs
Alloy weight: 20,366 lbs
Thermite: 2,778 lbs

Read Original Article
Largest to date bismuth plug with Aker BP

The largest bismuth plug in the world at the time of deployment.

Results

The following digram demonstrates the fluctuation in annulus pressure during the well history since 2014. The final column demonstrates the effectiveness in BiSN’s Wel-lok™ technology after the bismuth plug had been placed in each well.

Legend

DA Pmax 0 bar
DA Pmax < 0.5 bar
DA Pmax > 0.5 bar
DA Pmax > 5 bar

Before Campaign

Well 2014 2016 2017 2018 2019 2020
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30

After

Well 2014 2016 2017 2018 2019 2020 2021 – BiSN Plug
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30
BiSN Plug 2021
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30

Results - A Single Well Example

For well A-22, the difference in annulus pressure before and after setting a Wel-lok™ technology plug is evident. Since 2014, the well had experienced annulus pressure of DA Pmax of greater than 0.5 BAR. After the BiSN Wel-lok™ technology plug was set, that pressure dropped to 0 BAR immediately and was sustained over the next 24 month testing period.

Well A22 Before BiSN Plug

Before BiSN campaign with Aker BP.

After deployment of BiSN Wel-lok™ technology.

Business Value

Wel-lok™ Plug vs Cement – cost analysis in terms of rig hours between the two barrier materials

This table demonstrates the cost effectiveness of using Wel-lok™ plugs in terms of rig time for one individual well. For Wel-lok™ technology, the total time is only 1.7 days compared to cement’s 4.6 days.

When spread out over the course of a 30 well campaign, the total savings add up to 3 months of rig time, or approximately $2mm/well.

Rig Time (hrs)
Bismuth Cement
Dress of cement plug 6.1 6.1
Starter cut / Initiate window 6.7 6.7
Section mill window 10.1 75.75
Scrub window 4.7 10
Cleaning BOP / cleanout run 1.9 4
Install and verify foundation 4.6 5
Place Wel-lok™ plug 6.8
Place cement plug 4
Wait on bismuth and verify offline
Wait on cement and verify offline
Total (hrs) 40.9 111.55
We're very proud. The operation has gone beyond expectations. We planned and hoped for 72 hours per installation. We're down to 33 hours per installation just now.Kjetil Vadset - Senior Drilling Engineer
Kjetil Vadset - Senior Drilling Engineer - Aker BP
BiSN Well Plug and Abandonment

Learn More About Wel-lok™ STC (Seal Through Casing) Technology

BiSN Chevron BackgroundSTC - P&A Application Wel-lok™ Technology

About the application

The Wel-lok™ STC (Seal Through Casing) has been developed to achieve a gas tight V0 seal well annuli that cannot be achieved by traditional cement balance plugs. Run on electric line, this tool does not need surface pumping equipment to circulate the alloy in place. Due to its viscosity and density, once melted the liquid alloy will flow with gravity into the annulus. When it cools below its melting point it solidifies, expands and creates a gas tight seal across the entire wellbore. The entire process, from melting to solidification, takes place in minutes and the seal is ready to test within an hour.

Seal Through Casing - BiSN
Seal Through Casing - BiSN
Seal Through Casing - BiSN
Seal Through Casing - BiSN

How it works…

The Wel-lok™ STC (Seal Through Casing) has been developed to achieve a gas tight V0 seal well annuli that cannot be achieved by traditional cement balance plugs.

Get in touch to find a permanent solution for your well

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