Three-D visualization and integrated interpretation technologies are driving changes in how exploration and production (E&P) companies explore and manage hydrocarbon assets. Today, 3-D visualization technology is clearly the catalyst for advancing integrated interpretation workflows now being leveraged across the industry to reduce uncertainty and risk, lower finding and development (F&D) costs, and maximize asset values.

During the last 20 years, the ability to view and interpret seismic or seismically derived attribute data in a 3-D view has significantly improved interpretation accuracy in complex geologic settings and is often cited as a key technology for lowering F&D costs. Advances in animation, opacity rendering and color control techniques have further improved interpretation accuracy. Visualization technology has evolved far beyond simply supporting domain-specific interpretation tasks. The push to visually integrate all spatially distributed data types has accelerated.

Today's 3-D visualization environments bridge the gap between data types and technical domains, ushering in a new era of innovative integrated interpretation workflows. These integrated workflows offer simultaneous access, viewing, interpretation and manipulation of geologic, geophysical, petrophysical and drill-path data (Figure 1). The result is a shared understanding of complex reservoirs and a step-change in project cycle-time efficiency.

However, during the past decade the software industry has underserved the geological interpreters. The majority of products developed have been focused on enhancing seismic-to-simulation workflows. This focus has resulted in the development of improved reservoir modeling tools which integrate with seismic data. But the traditional geological interpretation tools have received far less attention and significance.
With evolving software tools, however, interpreters no longer have to pick horizons and faults and build structural and stratigraphic frameworks in standard interpretation software before switching to more specialized 3-D visualization technology. Next-generation 3-D software tools fill the two-dimensional gap between 3-D seismic interpretation and 3-D modeling.

Well log interpretation

Well log correlation, which traditionally has been performed in time-honored 2-D views, can be more efficiently and accurately interpreted in a 3-D environment. As noted in a previous article (Chambers, H. and Williams, D., 2002; "Integrated visualization environments will be the key to better E&P workflow efficiency," First Break. May 2002), "Integrating data and multi-discipline geological and geophysical (G&G) tasks using 3-D volume visualization has created unquestionable excitement in and value to the upstream oil and gas industry. For years, software developers assumed that E&P professionals would naturally migrate toward integration within common 3-D visual environments. The earth, after all, is three-dimensional. Yet the fact remains that much seismic, well and reservoir data are still analyzed in 2-D views." While computer-based 2-D visualization and interpretation tools provide opportunities for greater creativity and a productivity step-change from the traditional paper-based process, the computer-based workflows were typically constructed with an objective to replicate the paper-based process.

In an interpretative 3-D environment, geologists have the ability to rapidly interpret large numbers of wells in a 3-D context for a more accurate understanding of complex structural and stratigraphic reservoirs. The traditional 2-D correlation approach provides tremendous value for side-by-side comparison of well logs but lacks the spatial context of the true well locations, which can be critical for detailed stratigraphic interpretation. Three-D interpretation applications allow for the direct comparison of well logs in their true spatial location and accurately present the wellbore position over the entire depth range of the well. This is essential for correlating events along highly deviated wells, especially where multiple occurrences of a stratigraphic interval have been penetrated.

One of the biggest challenges in the industry today is accurately interpreting along highly deviated and horizontal wells. In this example, 3-D well log correlation has dramatically improved the interpreter's ability to accurately and efficiently define structural and stratigraphic relationships by visualizing the subsurface data displayed in their true spatial context (Figure 2). Providing fully integrated 2-D map and cross-section displays with 3-D tools ensures geoscientists can perform both conventional interpretation and sophisticated 3-D interpretation in a single environment. Additionally, these familiar 2-D displays are also the traditional views used to communicate to peers and management. As interpretation tasks are performed, immediate feedback is provided to the geoscientist as all of the views are linked and synchronized to show the latest version of an interpretation.

Automated earth model building

Geological interpretation is a highly creative, non-linear process. However, traditional 2-D interpretation tools have been designed to present the user with linear workflows. Users are forced to spend considerable amounts of time repeating these workflows in their attempts to reach an optimal interpretation. This lack of interactivity limits the user's creativity, thus lowering the interpretation's quality and accuracy. These artificial limitations were imposed due to the nature of traditional software design and the lack of customer-driven design processes. Traditionally, workflow repetition has been addressed using batch and script-based systems, giving the user the ability to record and repeat a particular linear workflow. By varying script parameters, users can create multiple scenarios in an attempt to analyze uncertainty. This approach is incompatible with the creative geological interpretation process and actually generates a reluctance to alter interpretations, thus leading to lowered productivity.

New technological innovations in 3-D geological interpretation have been introduced to speed up traditional earth model-building workflows. In these modern software applications, linear, script-based workflows have been replaced with a more interactive, dynamic interpretation system capable of performing automatic updates while the user is interpreting. This helps the interpreter to focus on refining the interpretation instead of being forced to "drive the software." Utilizing the speed of modern desktop workstations, these fully automated workflows increase productivity of an interpreter by a factor of 10.

Earth model interpretations require geoscientists to combine a number of separate applications involving seismic interpretation, well log interpretation, surface modeling and 3-D visualization. Modern earth model interpretation software combines these tools into a single, integrated 3-D interpretation environment. A typical example requires the user to correlate well logs and tie the seismic horizon interpretations to the well data for a large number of horizons. In an automated earth model interpretation environment, the user is able to define a stratigraphic hierarchy, with each of the horizons mapped conformably to their corresponding seismic horizons and to their neighboring surfaces. These stratigraphic and structural relationships are automatically maintained and updated while the user is continuously refining the interpretation or adding new data (Figure 3). This unique methodology results in significant productivity increases, leading to more accurate interpretations.

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