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A Relief Well Planning Case Study

In the Gulf of Mexico, a drilling trajectory needed adjusting due to a recent update to the reservoir model. Although the change to the trajectory was minor, the shift of the placement of the 14-inch and 11 7/8-inch casing shoes invalidated the previously designed relief well plans. With a fast-approaching deadline for drilling operations, the well planning team had little time to make a new relief well plan that could (1) achieve the objectives of the updated target plan, (2) meet industry-standard relief-well design constraints, and (3) be ready to send for permitting.

Dynamic Graphics’ WellArchitect software was selected to design a relief well plan quickly and efficiently; the plan needed to meet all the necessary relief well objectives to intercept the new target well design appropriately. WellArchitect’s ability to plan in reverse from target intercept to the locate, to a self-calculating surface-hole location, makes it ideal for designing an appropriate relief well plan in limited time.

Once the well planning team identified the new 14-in shoe depth, a 150 foot locate radius was established 1000 feet MD above the contingency intercept (Figure 1). The team kept the relief well trajectory within the locate circle, utilizing a low dogleg and an orientation close to parallel of the target. This created a “fly-by” scenario whereupon active ranging tools would be able to locate the existing 14-inch casing. The team was able to successfully complete the most difficult part of relief well planning in minutes.

Figure 1. 3D view of 150 foot locate radius used to create a “fly-by” scenario.

Being able to plan in reverse is one of the strengths of WellArchitect. With the locate phase of the relief plan established, alternate top-hole locations could easily be evaluated by entering different sail angles (usually limited by ranging tool) and alternate desired approach directions to complete the design process (Figure 2). The result was a surface hole location calculated by the software. The ability to plan in reverse enabled the team to easily construct and evaluate multiple options for an appropriate relief well plan.

Figure 2. WellArchitect spreadsheet showing relief well plan details.

Once a desired relief well plan was established, additional checks could then be carried out. Clearance reports, traveling cylinders, ladder plots (Figure 3), and 3D visualization allowed for a quick evaluation of drilling hazards. Anti-collision came back with only the target wellpath failing the clearance scan.

Figure 3. Ladder plot of the downhole measured depth of the relief well versus the clearance distance from the relief well to the original trajectory.

The result for the operator was a newly designed relief well that met objectives of the target wellpath as well as the constraints set by common relief well practice. Most importantly, the relief well plan was created in less than an hour while still providing a high-quality design with minimal effort. The design was ready to be included in the necessary pre-drilling permits.

As this example shows, WellArchitect, an industry leading well planning software package, simplified and streamlined relief well planning for a time-sensitive situation in a deep-water field. The flexibility of WellArchitect to plan in reverse provided critical functionality for the drilling team to create a quality well plan and meet their permitting deadline.

See the WellArchitect page for more information.


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