Extended reach drilling (ERD), characterized by paths with long horizontal distances, is an approach to cost-effectively recover reserves. With a single wellbore, long-reach wells maximize reservoir exposure to boost productivity and enhance drainage capability. ERD also brings the advantage of reduced environmental impact, reaching remote targets or covering a larger area from a single drilling pad.
Careful planning is critical to the success of extended-reach drilling projects. A detailed understanding of the geologic structures facilitated by 3D visualization and well-planning software can help identify and mitigate extended reach drilling challenges that might otherwise jeopardize the project. Below we explain how integrating relevant sources of subsurface data to create a 3D geologic model and then using this model to plan an extended reach well helps minimize risk and maximize recovery.
Design Well Trajectory to Minimize Risk
Well trajectory design is a critical process in minimizing the inherent risks posed by high-angle wellbores and long horizontal displacements of extended reach wells. Decisions made during the well design phase influence drill string and bottom hole assembly (BHA) designs, guide casing strategy, affect torque and drag, and determine directional drilling strategies.
An extended reach well trajectory is not a simple geometric curve extending from pad to target. Complex geologic structures and petrophysical conditions can present significant extended reach drilling challenges anywhere along a proposed wellpath. However, with as accurate as possible understanding of subsurface conditions, planners can design well trajectories that minimize risks associated with torque and drag, stuck pipe, and wellbore instability.
A Better Understanding of Geologic Structures
EarthVision is a comprehensive software package for 3D model building, analysis, and visualization of subsurface environments and conditions. Well planners and drilling engineers who face extended reach drilling challenges will find that EarthVision provides the tools to understand complex geologic structures in detail and plan extended reach well trajectories in context of the geology.
EarthVision tackles these challenges by allowing users to:
- create precise geologic models;
- plan wells in the context of geological structures and formations;
- optimize extended reach well trajectory along the entire wellpath; and
- improve drilling accuracy with near-real-time data.
Create Precise Geologic Models
EarthVision integrates relevant geophysical and geological data (2D grids, scattered data, property data, seismic sections, volumetrics) to create detailed models of complex geologic structures—compressional faults, major fault gaps, fault-wedge contours, salt diapirs, and overthrusts. The ability to visualize detailed geologic models in 3D enables well planners to more accurately identify the extended reach drilling challenges presented by the lithology, faults, and rock properties as they plan extended reach wells.
EarthVision offers a range of modeling capabilities that help to realize the maximum value from the integrated data used in creating the geologic model. Capabilities that provide an enhanced understanding of geologic conditions include:
- highly complex compressional and extensional geologic models consistent in three dimensions
- 3D fault block intersections and truncations
- intermediate surfaces based on a reference surface and intermediate horizon picks using limited horizon data
- 3D models of property distributions on a model-wide, fault block, or layer-specific basis
EarthVision enables reservoir teams to view and evaluate these 3D models at the field level, as well as a detailed understanding of the interactions of geologic and geophysical properties anywhere along a proposed extended reach well trajectory.
Plan Wells in the Context of Geological Structures and Formations
The 3D geologic model created by EarthVision provides the foundation for planning the extended reach well. To facilitate well planning, EarthVision also offers industry-standard well-design capabilities that work with the 3D geologic model. The ability to apply these tools in context of the 3D geologic model promotes efficient well trajectory planning, helping designers to:
- evaluate the pros and cons of various kickoff points;
- identify and avoid salt domes and problematic faults; and
- calculate desired trajectories at key points along the proposed well path to minimize drilling risk and cost.
Capabilities that also aid in designing wellpaths include the calculation of positional uncertainty, as well as base map and cross-section plotting. An added benefit of the integration between 3D geologic models and well planning tools is the ability to easily (and interactively) transfer coordinates from the 3D model into the design for the extended reach well.
Optimize Extended Reach Well Trajectory Along the Entire Wellpath
The well plan is created in a spreadsheet that contains targets and design points whose coordinates can be obtained directly from the 3D model. To design the desired trajectories, the software provides functions to help determine which curve or sets of curves should be used. Some of the functions relevant to planning extended reach wells include:
- calculating a wellpath, building inclination to the horizontal on the approach to the target
- creating a path to a target location with a specified final inclination and azimuth
- given multiple target locations, creating a path to the first target location so that it aligns with the second target
- given multiple target locations, determining an appropriate depth from which to kick-off
- given multiple target locations, creating a path “in reverse” (from depth back up to surface) to determine an appropriate surface location
Working in the context of the detailed 3D geologic model removes much of the guesswork of planning high-angle and extended reach wells. Well planners can more easily identify geologic challenges that would impact drilling efficiency and readily evaluate multiple alternatives to circumvent them.
Improve Drilling Accuracy With Near-Real-Time Data
Not only does EarthVision facilitate better planning of extended reach wells, during the drilling phase it can depict the actual wellpath in context of the 3D geologic model. By displaying and examining near-real-time data such as mud logs or gamma ray logs obtained from thebottom hole assembly, drilling engineers can more accurately monitor drilling progress.
By displaying and examining near-real-time data such as mud logs or gamma ray logs obtained from thebottom hole assembly, drilling engineers can more accurately monitor drilling progress.
Drilling data can also be used to update the geological model to improve the accuracy of the model and the drilling process. For example, if a top comes in higher than expected, the model can quickly (and automatically) be updated to reflect the correct horizon, thereby giving drilling engineers a more accurate location of the drill bit relative to the local geology.
Depicting the actual wellpath in 3D, comparing it against the original plan and in context of the geological model, gives drilling engineers greater ability to identify and mitigate any unforeseen extended reach drilling challenges.
EarthVision: A Solution for Extended Reach Drilling Challenges
EarthVision’s data integration, 3D modeling, visualization, and well-planning capabilities provide geoscientists, well planners, and drilling engineers exceptional ability to more efficiently and accurately plan and drill extended reach wells.
When well planners and drilling engineers have access to 3D geologic models that accurately depict subsurface environments and conditions, they can readily identify extended reach drilling challenges and explore a range of options to minimize those risks.