Well placement optimization is an exercise in maximizing the economic return from hydrocarbon reserves while minimizing cost and risk. It’s a complex practice and is often conducted with a considerable degree of geological uncertainty. However, continually improving technologies for gathering geological data and methods for analyzing and interpreting that data have led to greater success in well placement optimization.
In this blog, we explore tools and techniques that provide well planners with a detailed understanding of complex geologic formations and properties. By combining relevant subsurface data—lithology, faults, rock properties, logs, reservoir grids—and visualizing it in 3D, the asset team can collaboratively evaluate a range of wellpath alternatives and get answers to questions such as:
- At what angles are the wellpath/fault intersections?
- How long is a wellpath within a stratigraphic zone?
- How will varying geophysical parameters along the planned wellbore affect drilling costs?
- Where is the best sidetrack kick-off point to avoid issues such as salt, salt exit, or rubble zones where desired build rates could not be achieved?
- Which sidetrack plan has the best chance of maximizing recovery?
- How exposed is a planned well path to a problem horizon?
- Are there any geological characteristics that prevent the wellpath from staying within the sweet spot?
Well placement decisions made in context of accurate geologic models visualized in a collaborative 3D environment can significantly reduce drilling risk and costs while maximizing the recovery.
Visualization Facilitates Geologic Understanding
Optimized well placement begins with the creation of accurate geologic models. Combining seismic, geologic, and wellbore datasets and displaying the data in 2D and 3D details subsurface structures that lie between the rig and intended target(s). When reservoir lithology, faults, horizons, offset wellpaths, as well as the petrophysical property distributions, are rendered as contour maps, isochore maps, fence displays, and cross-sections, and combined with 3D visualization, well planners have a clearer picture of the subsurface environment they must navigate.
By interactively planning wellpaths in the context of accurate geologic models, well planners and reservoir engineers can:
- Construct wellpaths by specifying a series of design points and automatically interpolating between points using a minimum curvature method within the context of the geologic information
- Define targets as a point, circle, ellipse, square, rectangle, or polygon and specify the dipping plane, thickness, and projection to mimic the geologic models
- Slice 3D models along a wellpath, providing a cross-sectional view of the stratigraphic or property model along the planned trajectory
- Visually remove portions of a model to enhance spatial understanding of geology.
- Create a “traveling cylinder” view that indicates the proximity of offset wellpaths near or intersecting a proposed wellpath.
- Back-interpolate a wellpath with a cellular grid, sampling the cell grid along the wellpath to provide detailed property attributes and averages intersected by the wellpath.
- Include annotations (to indicate additional information, such as core, plug, casing, casing shoe, slotted liner, perforation, side-wall core, open hole test, open hole completion, etc.) at selected points along the wellpath to guide drilling operations.
A particular target may offer many different trajectory options. Similarly, the geologic analysis may reveal challenging constraints in reaching the target. Determining the optimum well placement is easier when an initial plan can be retained while alternative plans are created, revised, and evaluated. The ability to visualize and evaluate options in context of geologic formations that influence well placement facilitates faster, better-informed planning and operational decisions.
The ability to visualize and evaluate options in context of geologic formations that influence well placement facilitates faster, better-informed planning and operational decisions.
Integrated Well Designer for Well Placement Optimization
CoViz 4D, a software solution developed by Dynamic Graphics, Inc. works in conjunction with an optional module—Integrated Well Designer—that helps anyone planning a well to understand the constraints on a wellpath imposed by the geologic context. CoViz 4D provides all of the capabilities mentioned above, and many more sophisticated algorithms and visualization techniques to facilitate faster identification and better management of problem areas. The combination of powerful well planning software and rich 3D visualization capabilities enables reservoir teams to accurately define drilling targets, avoid faults, and develop optimized well placement plans.