Finding Petroleum - RESQML – ready for September 2011 release

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RESQML – ready for September 2011 release

Friday, May 06, 2011 in Feature Articles

The industry ready version of Energistics’ RESQML, the exchange standard for subsurface data (reservoirs and earth models), will be released by September 1

If you regularly spend time trying to get subsurface data from one software application to another, or regularly encounter problems after transferring data (such as wells moving to the other side of the reservoir), you’ll be looking forward to the release of RESQML 1.1, an industry-ready data exchange standard for subsurface data, with development managed by Energistics. It will be released by September 1 this year.

“This RESQML initiative makes my life a lot easier for doing data interchange demanded by our customers,” said Dr Tony Fitzpatrick, simulation gridding architect with Schlumberger, speaking at the Finding Petroleum London conference on April 20, “business opportunities with subsurface data”.

Many people have experienced data corruption when transferring data from one system to another, such as well trajectories losing datums, 3D grids getting changed from time to depth, horizon data being damaged in the data transfer.

“When you find that your wells are on the other side of the reservoir it is particularly annoying,” Dr Fitzpatrick said. “It is entirely due to lossy exchange of information.”

Version 1.1 of RESQML will be released in September 2011, and vendors are expected to start supporting it around then (although the vendors are not following any specific time schedule).

Version 1.0 of RESQML has already been published (in January 2011), but was intended to be used for development purposes, not general industrial use, to provide an opportunity to remove any bugs in version 1.1.

RESQML can be used for all stages of subsurface work, from structural modelling to simulation and well planning.

RESQML is being integrated with other Energistics standards (WITSML, for drilling data, and PRODML, for production data), so (for example) you can add WITSML drilling data to update your RESQML reservoir model.

There are additional benefits to being able to move data easily from one software package to another.

It gives users more freedom to pick the software package which work best for them, rather than being restricted to using software supplied by one company.

“We recognise there are multiple applications, and you want to cherrypick,” Dr Fitzpatrick said. “Best in class applications are supplied all the time by vendors.”

Also, if users are less restricted to using subsurface software from a single manufacturer, there is more incentive for smaller software companies to develop software applications.

From the oil company’s point of view, if data can be moved from one package to another more easily and consistently, it is able to manage quality and consistency of the workflows and record exactly what was done, with metadata showing how the data came to be in its current format.

Testing

In April 2011, Energistics held a week long “ILAB” meeting, validating the exchange of reservoir models written using RESQML between different software applications owned by vendors and oil companies.

The RESQML development team have committed to running 2-3 “ILABS” every year, to move data files from one software application to another, testing everything. The team also uses this time to work through more complex development issues and plan future releases.

Oil companies are being encouraged to submit subsurface data files to the RESQML developers so they can use them for testing.

What RESQML includes

Data in RESQML format can include a gridded volume, data about horizons, static information, time data (for a simulation), units being used.

The system can record data about connections, not just the geometry of the reservoir model. For example, it can describe which cells specific wells intersect, and where the faults are.

If a gridded volume is imported into another piece of reservoir simulation software which doesn’t know that a fault exists, the software will create a simulation on the basis that fluid can flow freely from one cell to an adjacent one, without knowing that it would be blocked by a fault.

RESQML can handle faults modelled in both pillars and stair steps. It can include data about flows and temperatures.

RESQML can also manage data about multiple reservoirs which are connected by the same well.

“8 corners of the cell are insufficient to describe the geology,” Dr Fitzpatrick said. “We have to handle much more complex geometry and we’ve stepped up to that in a much more complex way.”

It can track where multiple grids have been developed for the same part of the subsurface. “You need to know which set was used in which particular simulation,” he said.

There have been attempts at building a standard format for reservoir data before, called “RESCUE”, but work on this stopped in 2009. This initiative which oil and service companies alike supported, supplied a C++ library to store and retrieve the data. “Like all software it rusted over time, and the underlying technology became obsolete” he said. RESQML provides the data interchange schema in XML format leaving companies free to create readers and writers inside their own applications.

To change data from RESCUE to RESQML, you load the RESCUE data into your normal software and export it in RESQML format.

RESQML also records which units are being used, something which RESCUE was not so rigorous in insisting upon. This could lead to mistakes when numbers were associated with the wrong unit.

“RESCUE wasn’t terribly good at handling units, it was just a string that was passed around,” Dr Fitzpatrick said. “Now it’s much tighter and there’s a schema for describing the units. For engineers you know how important it is to get units correct.”

Exchange vs storage

It is important to note the difference between data exchange and data storage, because data might not be in the same format for both.

The data is originally developed and stored in a software application, and is stored in whichever system that software application uses.

It is converted to RESQML when it needs to be exchanged (moved) to other software packages. There it will be converted into whatever data storage system that software uses.

In practise there is likely to be convergence over time between the ways that different software packages store the data, and with RESQML, particularly as many of the people building RESQML are also involved in building subsurface data packages. “Over time there will be considerable overlap between internal and external exchange model. The boundaries will be ironed out,” he said.

RESQML has been designed to honour the fidelity of these internal models as far as possible, to ensure that every detail developed in one software package can be carried across to another one within the RESQML data.

This won’t work if the first software package has functionality which the second one doesn’t, such as hierarchical zonation. This will mean that functions of the data created and viewable in one package can’t be accessed in another one.

Big data files

Because the reservoir data files are so large, users are recommended to compress the RESQML data before exchanging it, into Hierarchical Data Format (HDF5), a set of file formats for large amounts of numerical data, developed by a non profit organisation, HDF Group, and used in a variety of industries.

You can compress data by factors of ten, but do not lose any of the detail.

With data stored in HDF, it is easy to look at the reservoir model in specific regions – eg slabs or smaller zones, generated from the bulk data.

“It’s an efficient way to store multidimensional data across platforms,” Dr Fitzpatrick said. “It’s being adopted by some oil reservoir simulation people to store their output results. We encourage people to store bulk data in this format.”

“1.5m cells isn’t big in today’s world; we’ve been playing with 100m cells,” he said. “This is why we need to step up to this HDF 5 technology.”