Well-Collision Avoidance: Mitigating Risk in Mature Field Development

A geologic model “sliced” along a planned wellpath to evaluate the path within the target zone(s).

A major concern in planning a new well is to stay in-zone as long as possible while minimizing collision risks. WellArchitect and CoViz 4D provide the integrated tools and context to help accomplish these goals. In the image above, a geologic model is “sliced” along a planned wellpath to evaluate the path within the target zone(s). The green tubes indicate the minimum allowable separation distance (MASD) from the planned well to existing offset wells (representing essentially a “no-go” area), while the queryable, color-coded, spherical (diverging) and hourglass (converging) symbols indicate the available space the planner (or driller) has before entering a potential collision situation.

When developing well-collision avoidance strategies, petroleum professionals can rely on advanced data integration and 3D visualization to aid traditional tools used in well planning. Enhanced 3D visualization gives engineers the ability to see more of the subsurface and provides them with additional opportunities to prevent drilling into hazardous zones or colliding with existing wells. Dynamic Graphics’ CoViz 4D and WellArchitect are two software tools employed by asset teams to help them reduce mistakes and ensure comprehensive subsurface analysis.

This article will explain why data integration and visualization software integrally linked with a well-planning software package can improve well-placement endeavors and mitigate risk in mature field development.

Reducing Time to an Appropriate Plan

Incorporating 3D visualization of the geologic, petrophysical, and geophysical data along with the proposed path allows asset teams to plan well trajectories faster during the pre-drilling process, and monitor the planned course more effectively during the drilling campaign. WellArchitect, an advanced well planning and survey management system for integrated planning and drilling of directional wellpaths, can aid in such tasks as directional planning and drilling of multilateral wellpaths, sidetracks, and re-entry drilling, by integrating the asset team’s datasets into the process.

Typical workflows have the G&G (geology and geophysics) team picking target locations, which are often sent to the well planning team as points or corridors, without further context. What results is often a drawn-out back and forth to obtain a planned path that is expected to be both drillable and safe from hazards. In extremely complex mature fields, this process can take weeks to months to obtain a wellpath that is appropriate to drill: a path that minimizes tortuosity (which can influence completions), reaches all desired targets, and avoids any known collision situations. By planning in the context of the 3D data, that timing can be reduced to hours to days (rather than weeks or months), even in the most complex fields. Overall, advanced well-planning campaigns utilizing WellArchitect can save time and resources in the following ways:

  • visualizing the path in full context (e.g., geology, targets, and offset wells)
  • on-demand or automatic information on fault and/or horizon intersections while drilling and planning (e.g., the angle at which a drilled path will hit a fault)
  • integrated collision-risk analysis while planning and drilling, including traveling cylinder diagrams that update with each path change; 3D visualization of MASD zones (as tubes)—in addition to traditional 2D plots and reports; and automated clearance calculations ahead-of-the-drillbit

Mitigating Relative Positional Uncertainty

Each planned well trajectory is designed to provide a drillable solution to hit a target while safely avoiding existing wells. During the drilling process, however, the actual wellpath commonly diverges from the original plan. Once off plan, the collision avoidance program may no longer be appropriate, even as the directional drillers heads back to the plan or targets. WellArchitect has numerous tools to help drillers mitigate the risk during the process. In these cases, having a full understanding of where you are in a very short amount of time can mitigate the risks of being off plan: for example, drillers can easily check how far off plan they are, and are automatically alerted if they are an unacceptable (user-settable) distance off plan.

Obtaining near-real-time drilling information from a WITSML server is another way to mitigate risk. This information can be used to automatically update the current position of the well using WellArchitect, and any log information can also be automatically fetched and displayed next to the well, with the integration of CoViz 4D. The driller, or company drilling department, can see the well progress in near-real-time and minimize human factors associated with hand-entering data. 

In addition, when integrated with CoViz 4D, the drilling team can “slice” the geological model along the wellpath, revealing potential geological issues that must be resolved: Has the wellpath gone out of zone, or is it approaching a fault at an inappropriate angle. These tools aid the drilling and the G&G teams to understand the relative uncertainty and new potential hazards while drilling.

Adding in WellArchitect’s advanced tools to assess the risks (based on an operator’s chosen anti-collision rule) ahead of the actual wellpath allows the driller to actively avoid potential well collisions while drilling. As drilling progresses, WellArchitect automatically (and silently) performs a clearance calculation ahead-of-the-bit as each station is entered, alerting the driller immediately if any potential collision situations are found based on their expected course (and their anti-collision rules). Visualizing collision avoidance results combined with 3D earth models, and other geologic data help define safer and efficient well placement.

Well Collision Avoidance with WellArchitect and CoViz 4D

WellArchitect, on its own and more so when used in conjunction with CoViz 4D, can help reduce cost and mitigate risk. In offshore drilling operations, these advanced tools aid drillers as they contend with complex tangles of existing wellpaths, where there are higher chances of well collisions and other drilling complications. For unconventional reservoirs, when drilling multiple wells from a single pad or long-reach horizontals amid a field of existing vertical wells, both systems can help users easily evaluate collision risk as well as help them ensure that their well stays within the targeted zone and maintains appropriate spacing in the reservoir.

WellArchitect and CoViz 4D aids users to keep wellpaths away from problematic areas, keep the wells within ideal zones, and assess vital attributes along the length of the well. When it comes to collision avoidance, both tools increase the likelihood of better decisions before and during the drilling process, reducing the chance of human error and avoiding roadblocks that could stall operations.

CoViz 4D and WellArchitect, software created  by Dynamic Graphics Inc., give users the power to visualize subsurface conditions within a reservoir to avoid well collision. Contact our team today to learn how you can mitigate your risk profile and achieve cohesive data that paints a fuller picture of a mature field.


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