Subsurface Geological Modeling: Subsurface Geology and Well Planning

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Geocellular modeling, on the left in the above image, and structural modeling, on the right, are essential at every stage of the reservoir life cycle. Integrating these models with existing infrastructure and proposed well plans with EarthVision promotes better understanding and clear decision-making.

Detailed subsurface geological modeling informs and supports asset teams at nearly every stage of the reservoir lifecycle. Geologists strive to create as accurate as possible geological models to allow petroleum engineers and other team members to better assess reservoir viability for further hydrocarbon exploitation.

Subsurface geological modeling has many challenges and can be a time-consuming process without the proper software tools. Consider, just the data management aspects of the process:

  • variety and quality of data involved in the modeling process
  • selection and application of appropriate formulas or algorithms that transform data points into meaningful 2D and 3D representations of subsurface environments
  • incorporation of other meaningful subsurface data that can improve the accuracy of the geological model

A comprehensive synthesis of these data requires an efficient method for data integration, organization, and analysis, as well as sophisticated visualization tools that facilitate collaborative interpretation by the various disciplines involved in reservoir development.

Subsurface Geological Modeling: Integrate, Collaborate, Interpret

Subsurface geological modeling can be conducted more efficiently and achieves greater accuracy with software that facilitates data integration, organization, and analysis, and provides sophisticated visualization tools that enable collaborative interpretation by the various disciplines involved in reservoir development.

Developing a three-dimensional geologic model is a highly-iterative, interpretive process. The spatial relationships of the geologic elements in a model are determined by quantitatively synthesizing subsurface data. The digital synthesis process requires the geologist to establish and apply a set of rules that define the relationships between geologic elements. These rules can determine the sense of slip on faults, or whether contacts between strata are conformable or unconformable.

The subsurface geological modeling process consists of a workflow of five distinct operations:

  1. Compile interpreted seismic and well data that characterize discrete subsurface locations for all geologic elements such as strata and faults.
  2. Interpolate these data to a three-dimensional regular grid that represents a surface, with a horizontal range that spans the rectangular model area.
  3. Assign the surfaces that represent faults an order of precedence to determine which surface to truncate when two surfaces intersect.
  4. Assign rules to surfaces that represent the tops of geologic units or unconformities to determine whether the surface adds material to the top of surfaces below or whether the surface subtracts material from the top of surfaces below.
  5. Assemble all the geologic elements into the model volume according to the defined rules.

A completed 3D geologic model of the Wilmington Field in Long Beach, CA, depicting intersections between faults and horizons.

At the completion of this sequence of operations, the model can be inspected quantitatively and visually by the reservoir team, and iteratively refined to test alternative scenarios (by modifying the geologic rules). Teams can further refine subsurface geological models by incorporating additional data such as well logs.

Refine Subsurface Geological Models With Additional Data

Well log data can be used to improve the accuracy of the initial subsurface geological model. By searching a well log for data that indicates a rapid change in values, a geologist can identify horizon locations and establish wellpicks to indicate where a horizon intersects with a well trajectory.

well data analysis

Gamma ray and resistivity logs for two wells, including tops and lithology annotations.

With the wellpicks visualized in the context of the geological model, a geologist can then see how accurately wellpicks matched the modeled horizons, and if necessary make adjustments to improve the accuracy of the geological model.

Subsurface Geological Models: Explore, Analyze, Plan

Subsurface geological modeling that combines and visualizes seismic data with other relevant subsurface data gives reservoir development teams greater confidence in assessing the potential of hydrocarbon resources and assessing economic risk for well placement optimization.

Accurate 3D models generate accurate contour and isochore maps and cross-sections that allow reservoir teams to better understand horizons, strata, faults, and complex formations as well as send those maps to regulatory agencies without any additional work. This insight provides a solid foundation for volumetric and hydrocarbon entrapment analysis, as well as planning well locations and trajectories that minimize drilling risks while maximizing wellbore exposure within a reservoir.

Detailed subsurface geological modeling provides the foundation for well planning that minimizes drilling risk and maximizes wellbore exposure within a reservoir. Data used with permission by the owner.

EarthVision Excels in Subsurface Geological Modeling

Petroleum producers worldwide use EarthVision, from Dynamic Graphics, Inc, for detailed subsurface geological modeling. EarthVision easily integrates and visualizes a wide range of subsurface data and renders it in an interactive, three-dimensional environment for collaborative analysis by reservoir teams. EarthVision provides a wide range of statistical analysis, volumetric calculations, and algorithms to efficiently process input and output data and models. Powerful 3D visualization facilitates direct comparison and validation of fault and horizon interpretations, as well as cross-sections along wellpaths, through geological models, seismic volumes, and cellular grids.

Petroleum producers worldwide use EarthVision, from Dynamic Graphics, Inc, for detailed subsurface geological modeling.

EarthVision from Dynamic Graphics, Inc., is an integrated software package for the analysis, synthesis, modeling, and visualization of any spatially referenced data. Powerful analytic and visualization capabilities facilitate detailed subsurface geological modeling, enabling reservoir teams to explore and analyze the characteristics that influence reservoir development. With a detailed understanding of subsurface geology, reservoir teams can make development decisions that minimize risk and maximize recovery. To learn more about EarthVision, contact our team.

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