Unlocking the treasure chest of geophysical secrets

How legacy seismic data can offer value to major projects.

Question: Should you reprocess legacy data and save money, or invest in a new acquisition?

Answer: “It depends”, which is the most common answer you will receive from any geophysicist.

Legacy data from the UK offshore industry contains many hidden secrets. On first glance data acquired in the 1980s or early 1990s may be overlooked in favour of modern and vastly more expensive alternatives.


However, there is value to be gained by utilising these datasets in the right way. Whether you should or not, depends on the information you’re hoping to extract and the stage of your project. Here are four examples to illustrate how major projects have benefitted from using legacy data.

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Legacy Data: Use Case 1

Nuclear Waste Services

RockWave is working with Nuclear Waste Services (NWS) and their specialist geophysical consultant RPS to extract information from legacy data. This work is aimed at providing greater confidence in the location of key geological units and structures within the upper 1000-1500m, as part of the process to determine the suitability of sites for the development of a Geological Disposal Facility (GDF). Read more about these here.

 

Seismic data carries with it a fundamental measurement of the geology in the subsurface, that being the time taken for a soundwave to reflect back from a rock layer in the earth to a receiver array. Using high quality 2D data licensed from leading international vendors, the project aimed to apply modern evaluation algorithms to re-evaluate historical seismic datasets. These cutting-edge techniques, which were not available at the time of first processing reveal new and previously unseen details that were once hidden in the data.

Read more about it HERE

RockWave PSDM reprocessing of Dutch North Sea legacy seismic data

Legacy Data: Use Case 2

ONE-Dyas

ONE-Dyas contracted RockWave to reprocess legacy public domain data in order to refine their models and well locations prior to a winter campaign appraisal drilling on F06-IJssel. 


The two legacy 3D datasets from the late 1980s and early 1990s have proved highly valuable to the operator. With the additional RockWave reprocessing, the legacy data has been instrumental for a successful appraisal.

Read more detail on how improvements were made to the legacy data here.

Legacy Data: Use Case 3

ScotWind Applications

When SSE Renewables, Marubeni Europower and Copenhagen Infrastructure Partners (CIP) were building their ScotWind application for a highly competitive site, they needed to think outside the box. RockWave demonstrated that a lot of information about the top 100m below seabed, the zone of interest for wind developers, could be obtained from legacy O&G seismic data in the public domain, but only if reprocessed from raw field data.


RockWave reprocessed, or more to the point... Repurposed the UK government-funded MNSH 2015 2D dataset, for Atkins to then utilise for accurately mapping Quaternary sediment thickness across the site and identify possible geohazards such as depressions, tunnel valleys, faults and gas pockets that will require further investigation. The data provided early insights to the expected foundation design and costs, and can additionally be utilised for making more informed decisions about future Ultra-High Resolution geophysical and geotechnical surveys.

The project has been shortlisted for the Ground Engineering 2022 Technical Excellence Award. Take part in the conversation about it here.

Crown Estate Scotland - ScotWind applications and projects

Legacy Data: Use Case 4

Carbon Storage

There are a range of barriers and risks that are limiting private sector investment in carbon storage, as highlighted by the Global CCS Institute. Interested companies would therefore need to maximise data they already have available rather than making large upfront investments. They will typically have abundant seismic datasets and models at reservoir level, however accuracy of information about the overburden may be lacking due to the non-optimised data for shallower imaging.


Reprocessing from field data, before any resampling or frequency filters have been applied, and optimising the workflows to enhance resolution throughout the overburden, allows the company to more accurately assess risk of carbon dioxide leakage from any particular storage location.

Image by Johannes Plenio

Final thoughts...

Secrets contained within legacy data can be unlocked by paying attention to the details in a seismic processing sequence and designing parameters in close collaboration with the client, with open discussions about merits of each processing stage that will benefit their overall objectives. RockWave are experienced in dealing with the wide range of challenges associated with reprocessing legacy seismic data and achieving significant uplift in data quality.


“But how long will it take to locate and reprocess these geophysical treasure-troves?”, we hear you ask.


Answer: It depends. Obviously.

Have you considered utilising legacy data for your own purposes? If so, then contact the people who can unlock the treasure within... 

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