5.1 Features, Interpretations, Representations , and Properties

Topic Version2Published04/19/2018
For StandardRESQML v2.0.1

The table below (repeated from Chapter 3 Organization and Key Concepts: Overview for convenience) defines these terms; each of these is a type of RESQML data object. Sections below describe additional details about each and the role of each (how it is used) in the knowledge hierarchy.

For a high-level list of RESQML data objects and their organization, see 3.4 High-Level Organization .

For each of these levels, each instance of the corresponding data objects is uniquely identified with a UUID and metadata (a citation data object). The ability to uniquely identify each instance allows a user to start a business process (for example, define horizons and faults or build an earth model) by creating an instance of one feature. This begins the modeling process.

As work progresses in the business process, the user can create interpretations of the feature, and representations of the interpretations. Properties can also be added to representations and geometry defined. This process can continue (according to the requirements of the specific business process), with as many interpretations and representations as the business process requires.




Something that has physical existence at some point during the exploration, development, production, or abandonment of a reservoir. For example: It can be a boundary, a rock volume, a basin area, but also extends to a drilled well, a drilling rig, an injected or produced fluid, or a 2D, 3D, or 4D seismic survey.

Features are divided into these categories: geological or technical.

Geological Feature

Objects that exist a priori, in the natural world, for example: the rock formations and how they are positioned with regard to each other; the fluids that are present before production; or the position of the geological intervals with respect to each other. Some of these objects are static—such as geologic intervals—while others are dynamic—such as fluids; their properties, geometries, and quantities may change over time during the course of field production.

Technical Feature

Objects that exist by the action of humans. Examples include: wells and all they may contain, seismic data (surface, permanent water bottom), or injected fluid volumes. Because the decision to deploy such equipment is the result of studies or decisions by humans, technical features are usually not subject to the same kind of large changes in interpretation as geologic features. However, because technical features are subject to measurement error and other sources of uncertainty, they can be considered as subject to “interpretation”. In the RESQML knowledge hierarchy, technical features do not require an interpretation.


RESQML uses the definition of David Gawith, which explains an interpretation as a single consistent description of a feature. An interpretation is subjective and very strongly tied to the intellectual activity of the project team members. The initial curiosity and reasoning of the people on the project team initiates the early pre-screening campaign (remote sensing, surveys). They make hypotheses that consist of as many interpretations as necessary to describe the features. (Gawith and Gutteridge 2007; for citation, see 5.5 References .

A typical example of interpretation is based on the opinion of the geometry of a feature. Other specific interpretation information may include the description of the throw of a fault, the horizon classification in a sequence stratigraphic approach, or the contacts in a structural model.

NOTE: The RESQML formal name is actually "feature-interpretation" and some of the class names use this full term. For conciseness of documentation, we use simply "Interpretation" where this usage is not confusing.

Version 2 uses the term “interpretation” instead of alternative terms that were used in v1.1, such as “version” or “opinion".

Most of the information contained as attributes or enumerations in individual feature interpretations or organization interpretations will help users understand how the representations of the geologic objects should be built or have been built, if the representation is already associated to the given interpretation.


A digital description of a feature or an interpretation. For example, currently in RESQML, a horizon interpretation may be represented by a point set, a set of triangulated surfaces, or a set of orthogonal grids.

A representation contains the topology and geometry of a structural feature.

Representations may not always be associated with interpretations, although this pattern is recommended for subsurface representations for which interpretations exist.

A representation contains the topology and the geometry of the data objects. These terms are defined in Section 5.2 Topology and Geometry .

NOTE: Like "feature interpretation" in the previous table row, this term is formally "feature interpretation representation", but we use "representation" for conciseness.


A property can be attached to any indexable element of any representation.

Properties refer to semantic variables (for example, porosity, permeability, etc.) and the corresponding data values, which are recorded in arrays, which may be stored in HDF5 datasets.

For more information about properties, see 8 Properties .