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To retain or not to retain, that is the question

By Nuria Sanchez | 30 November 2022

As areas mature and fields are decommissioned the ongoing cost of sample storage is sometimes questioned and often drives a review of the retention requirement. However, new techniques and energy transition activities can spark renewed interest in subsurface samples. Additionally, at least in the UK, the regulator must be notified of any intent to dispose of samples.

So, what are the arguments for and against sample retention? Many of us, particularly those with a geoscientific background, would always lean towards retaining the samples; arguing that they are unique and offer an invaluable view into the past. However, as Data and Records Manager, we must make informed, logical retention decisions based upon regulation, business need and value.

We examine the arguments for and against retention and share our opinion on best practices for both the retention and disposal of subsurface samples.

The case for retention
The arguments for retention include the uniqueness of the data and the geological understanding it offers, the cost of acquisition versus the cost of retention, the legal requirements and the probability of new technologies and use cases emerging.

The case against retention
The arguments against relate to the ongoing cost and the ability to preserve the samples and related meta-data to a standard where they can still offer value. There are also Health & Safety aspects to consider.

At OASIS Group we offer, what we consider to be, best practice for core and cuttings retention and disposal based on decades of experience providing these services to our clients:

Best Practice: Retention
If you decide to retain your samples, it is essential that they are preserved in a state where they remain useful and that any Health and Safety risks are mitigated. It is important to consider the following:

  1. The physical state of the core/samples. This really comes down to the suitability of the storage environment and, as the samples are at most risk when being moved, the working practices of the responsible staff doing the move. Think about watching baggage handlers from the plane window! The staff and the service vendor should understand what they are handling, have working processes and procedures that preserve the samples and a quality management system to ensure compliance with these procedures.
  2. The samples become virtually useless if you don’t know where they are from. Samples commonly arrive with the contextual meta-data written on the box – sometimes in pen, sometimes on labels, sometimes both. The same (and additional information) can also arrive digitally and is associated with the physical box via a barcode. However, barcodes don’t stick well to wood and pen markings fade. Best practice is to first ensure that a complete set of meta-data is captured digitally and that the barcode remains attached. Ideally, barcodes should be stapled to boxes or attached to labels and a duplicate should be placed inside the box.
  3. The third aspect is the container itself. Many container types that were perfectly robust at the time of first use are now corroding or wearing. If a box collapses the samples easily get lost – and it presents a danger. Always consider re-boxing.

Best Practice: Disposal
But if you plan on disposal, best practice is:
1) Check that you are still the licensee for the relevant wellbore. Many physical subsurface samples get overlooked during asset transfers.
2) Before it’s too late:
• Check that core photos and other analytical results are available
• Consider if these are a sufficient record. With new digital capabilities emerging (some relatively cost effective) do you want to capture a ‘digital twin’ before disposing?
3) Follow the rules – check the regulations in the country the data is from. Check internal governance and take action accordingly.
4) Finally, plan the disposal.
• Consider the HSE. Check what you are disposing of. Is it hazardous and needs to be treated as hazardous waste?
• Ensure compliance through the waste management chain and gain the certificate of destruction.
5) Better than destruction, can you donate the samples to another party?

So, should we retain or dispose?
Only you and your organisation can answer that. However, organisations should proactively make the decision and best practice is to periodically review the retain/dispose decision. It’s also a good time to consider if further analysis may be warranted (with the advent of new techniques) and to check that the core/cuttings are being managed to ensure preservation.

If you want to find out more about responsibly dispose of obsolete subsurface core and cuttings samples in full compliance with the relevant regulations, contact OASIS Group today.

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