Advanced 3D Well Planning for Improved Wellbore Collision Avoidance

Planning a trajectory can be challenging in an open field, but when a drilling facility has dozens of existing wells, clearing high-pressured offsets can add extra complexity. For this North Sea operator with access to Dynamic Graphics’ WellArchitect software, the ability to visualize oil and gas collision avoidance results, created using tool-specific positional uncertainty models and their anti-collision rule (ACR), while planning in 3D, enabled the team was able to turn a typically challenging situation into a simple task. In this case, the offshore drilling facility had 58 existing wellbores and, although the presence of wellpaths can provide increased understanding of the reservoir (e.g., drilling hazards, fault locations), the busy drilling facility created a drilling environment with very tight tolerances (Figure 1).
Offshore drilling platform with 58 existing wellbores

Figure 1. Offshore drilling platform with 58 existing wellbores (a subset shown in brown) and location of new well being planned (blue).

Visualizing Oil and Gas Wellpath Collision Avoidance

Using WellArchitect, the drilling engineer was able to calculate and display the Minimum Allowable Separation Distance (MASD) in the 3D Viewer (Figure 2). WellArchitect quickly produced the clearance calculation results, utilizing the operator’s ACR with appropriate tool positional uncertainty models for the offset wells, and their specific survey program for the planned reference well. Visualizing the results within a short timeframe in a 3D environment enabled the well planners to easily see the available space where their wellpath could be better positioned through the tight-tolerance areas.
MASD, ACR, and queryable available-space symbols displayed in WellArchitect

Figure 2. Several types of information are automatically calculated, displayed, and easily evaluated when clearance calculation results are displayed in 3D: (1) The minimum allowable separation distance (MASD) is displayed as tubes around each offset well; (2) the pass/fail of the ACR is shown by coloring of the tubes (green = pass; red (not shown) = fail); (3) queryable available-space symbols (“dumbbells”) are automatically displayed in regions with less than 200’/60m between the reference and the MASD tubes; and (4) the symbols’ color and shape (green at 100’/30m; yellow at 50’/15m; dark red at 0’/m; and spheres for diverging; hourglass for converging; diamonds at failures) allow for quick assessment of possible “problem” areas while also highlighting areas for alternatives plans.

During the planning stages with most other software packages, well planners often rely on 2D traveling cylinder plots to clear the well passage (leaving the more onerous and often time-consuming ACR calculations until the end); yet interpreting these diagrams requires a skillset that is only refined with experience. Typically, in those workflows, 3D visualization is more for final review, rather than an integral part of the well planning process. This workflow often results in many iterations of the plan/calculate cycle, taking a significant amount of time.
Planning a wellpath in 3D with WellArchitect, however, allows the well planners to easily design a trajectory by integrating functionality during the planning process, reducing that cycle. In addition, by interactively calculating and incorporating the visualization of the ACR clearance results all without leaving the planning module, the well planner could explicitly see pass/fail areas while planning in 3D; immediately evaluate how changes in the well plan related to the MASD; and better understand “near misses”, which are harder to spot in reports and easier to avoid in 3D (versus a 2D traveling cylinder plot). A simple review of a ladder plot, automatically displayed at the same time as the 3D clearance calculation results, also ensured collision avoidance by visually confirming that the final trajectory was free of any collision risks (Figure 3).
Ladder plot of Reference MD versus Separation Ratio

Figure 3. Ladder plot of Reference MD versus Separation Ratio for the reference wellpath and a selection of offset wells.

With the assistance of WellArchitect’s powerful 3D planning and visualization environment, the drilling team made a successful well design in minimal time. These advanced visual representations prevented any misinterpretation of numeric data and provided an excellent check against human error.

Contact DGI to learn more about how WellArchitect can make well planning easier and more efficient.

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Data used with permission of owner.

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