Product category:
Simulation, modelling and validation software
News Release from: Rebis | Subject: CAD design (Plant)
Edited by the Engineeringtalk Editorial
Team on 12 March 2001
3D modelling cuts CAD time for offshore
drilling
3D Modelling Decreases CAD Time for North Sea Drilling System by half
By creating a 3D model of the Snorre B RamRig, Aker Maritime's Norwegian subsidiary, Maritime Hydraulics, completed the CAD design in 50 percent less time than if they had used 2D CAD And when the rig was assembled, there were practically no clashes - an unlikely occurrence when a large project such as this is done in 2D
This article was originally published on Engineeringtalk on 27 Apr 2001 at 8.00am (UK)
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Instead of designing the various components of the rig separately and documenting them on a series of 2D drawings, engineers created a 3D model of the entire system, including piping, structural, architectural, electrical, HVAC, and mechanical components.
When they needed to make changes to the design, they did so on the 3D model instead of modifying individual drawings.
After the design was finalized, fabrication drawings were generated automatically from the 3D model.
The time that was saved on this project was the result of several factors, such as the ease of making changes on the 3D model versus revising drawings by hand, and the speed of generating isometrics automatically.
The lack of clashes was the result of the superior visualization that 3D modelling provides as well as the ability to include components from all design disciplines into one model.
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Aker Maritime manufactures a wide range of both conventional and state-of-the art offshore equipment and modules.
The Norwegian subsidiary, Maritime Hydraulics AS based in Kristiansand, has a worldwide network of branch offices with capacity for manufacturing and service support for both offshore and onshore drilling systems.
This company's product range includes both conventional drilling machinery, coiled tubing, and the advanced, automated RamRig drilling system.
The RamRig is a highly flexible concept for drilling and workover packages that can be used for both fixed and floating installations.
It is available as single, double or triple stand rigs with capacities ranging from 150 to 1000 tons.
Hoisting and lowering with the RamRig is done by two cylinders instead of the conventional drawworks and derrick.
The hoist lines are of fixed length, parallel lines with one end anchored at the drill floor, and the other end at the top drive.
The lines are run over the yoke sheaves, thereby transforming the push from the rams to upward lifting force to the top drive.
Subsequently, the travelling distance and speed of the top drive is double the stroking of the rams.
The main benefits of the concept are lower weight and cost, greater efficiency, and improved safety over conventional drilling packages.
The Snorre B project involves the installation of a RamRig drilling system on an offshore platform in the North Sea.
This project is a joint venture between Aker Maritime and Kv?rner Oil and Gas.
It involves the design and construction of a semi-submersible drilling and production platform for Norsk Hydro ASA.
In addition to a custom-designed RamRig supplied by Maritime Hydraulics, the platform features combined cycle power generation units (gas turbines and steam) and an undersea power cable linked to Snorre A for import and export of excess power.
Snorre B will export oil to Statfjord B and gas to Snorre A.
The total RamRig weight of Snorre B is 1.400 metric tons with dimensions of 20 meters by 20 meters.
"This was a very small area into which we had to fit a great deal of equipment, including manifolds, cabins and tensioning system, as well as all the mud and hydraulic piping," says Lars Butveit, a piping lead engineer at Maritime Hydraulics.
A RamRig uses high-pressure hydraulics to lift the drilling string.
There is very high flow on those lines, many of which are eight inches in diameter.
All piping for the drilling system had to fit within 20-meter by 20-meter dimensions of the rig.
Height was limited by the low drill floor and the height of the BOP (Blow Out Preventer), leaving less than 5 meters of effective height.
The Snorre B was Maritime Hydraulics' first use of advanced 3D modelling.
In previous projects, engineers had used 2D AutoCAD to place equipment, pipes, structural steel, and so on.
Routing pipe this way was particularly difficult in 2D because it required piping engineers to imagine elevations and indicate with elbow symbols whether a pipe went up or down.
They had to maintain consistency with other drawings as they worked, visualizing the z component of those other views as well.
Each 2D drawing was actually an exercise in piping design.
Another drawback to working in 2D was the difficulty of detecting interferences when only two dimensions were visible.
This was true within a single discipline, such as piping.
Designers used plan, section, and elevation views to try to spot clashes, but if the pipe heights on two drawings didn't match perfectly, it was possible for an interference to go unnoticed.
It was also difficult to detect interferences between disciplines because the different disciplines typically did not share a common base, like a 3D model.
A third drawback to the previous 2D method was that once a design was done, it was necessary to produce from scratch all of the isometrics and other drawings needed for fabrication.
A typical project required hundreds of isometrics and this could be one of the most time-consuming aspects of a project.
Finally, when changes to the design were needed, it was necessary to make modifications on the drawings.
This was time-consuming since one change could affect many drawings.
It also compromised accuracy because it was possible to overlook a drawing that should have been changed.
These drawbacks, combined with the tight space limitations of the Snorre B project, led Maritime Hydraulics to consider upgrading to 3D plant design software.
The search was limited to 3D programs that ran on top of AutoCAD since this program was so widely used, both within the company and in the oil and gas industry.
Maritime Hydraulics chose AutoPLANT from Rebis, Walnut Creek, California, because in addition to being an AutoCAD add-on program and providing full 3D modelling capabilities, it included modules for specific design disciplines.
This would make it possible to exchange 3D models between disciplines and automate more of the design process.
For example, rather than sketching crude representations of mechanical equipment, a structural engineer could place existing models of the equipment into his design.
Maritime Hydraulics purchased five seats of AutoPLANT Piping, one seat of AutoPLANT Equipment, two seats of the intelligent piping and instrumentation diagram (AutoPLANT P and ID) application, five seats of the AutoPLANT Structural steel design module, and four seats of AutoPLANT Isometrics, which produces isometric drawings automatically from the 3D model.
The company also purchased the necessary import/export utilities from Rebis for transferring AutoPLANT data to AutoPIPE and ISOGEN.
The software was purchased from Mandal Engineering Company, which also provided implementation support.
Fifty engineers worked on the Snorre B project, with approximately twenty of them working concurrently in AutoPLANT.
Some had previous experience working in 3D but the company also provided two and three-day training sessions to familiarize everyone with the new software.
On this project, the mechanical, piping, and structural engineers worked in AutoPLANT while those in the electrical, architectural, and HVAC disciplines used plain 3D AutoCAD.
Mechanical engineers used the AutoPLANT Equipment module to model and place pumps, tanks, and other vessels in the model.
This module automated much of their work by providing a library of parametrically defined components.
With the library, an engineer simply entered a few values representing the specifications of the equipment, and the software drew the model.
Piping engineers used the Piping module to route the pipe.
To do this, they drew lines indicating where pipes should be placed, as they would in 2D.
But rather than simply having geometric representations of the pipes, the digital model of each pipe was actually an object containing additional information from the database such as performance and material specifications.
And because the engineers were working in 3D, they were able to include the z dimension in the model, routing a pipe 10 meters horizontally, for example, then up 5 meters, and then horizontally another 10 meters.
Having the z dimension visible on the screen was easier than trying to imagine elevations on a 2D drawing.
Another benefit of building a 3D model of the piping was that entire lines were visible, compared to drawings that showed only the pipes in a certain section of the rig.
When an engineer finished routing a line, he could see the impact of his work immediately, rather than flipping through 2D drawings and trying to follow it.
All these features helped speed the process of routing pipes, but what made this approach significantly faster than 2D was that with the 3D model, piping was designed only once instead of over and over again on each individual drawing.
Structural engineers originally used plain AutoCAD to design the structural framework of the drilling rig for the Snorre B project.
Then they realized how easy it would be to convert their work to 3D using AutoPLANT's Structural module.
This application provides the functionality needed to place 3D structural steel, including drawing setup and creation, 3D grid placement, steel placement and database management, steel editing and display options, steel annotation, and access way (stairs, ladders, platforms, and handrails) placement.
Similar to the Equipment module, Structural Modeler has a library of standard shapes.
When an engineer wants to run a beam from one location to another, he simply chooses the beam shape he wants and indicates the desired location.
The software draws the 3D model of the beam automatically.
On this project, engineers simply selected lines from the AutoCAD drawings, indicated in a dialog box the type of members they were, and the software drew the 3D shape automatically.
Although the electrical, architectural, and HVAC engineers used plain AutoCAD, everyone's work contributed to the creation of the 3D model of the drilling system since geometry created in AutoCAD could be referenced into the 3D model by means of the AutoCAD "x-ref" feature.
This made it possible for the engineers to reference each other's models and be aware of changes in other designs that affected their work.
This was one way that the company was able to eliminate clashes on this project.
But Maritime Hydraulics also used AutoPLANT's Explorer module after the entire design was complete to perform a thorough evaluation of the 3D model for clashes.
The software recognized all one, two, and three-dimensional AutoCAD entities for viewing and interference detection; including lines, polylines, 2D surfaces, meshes, 3D faces, ACIS solids, and blocks, as well as any custom 3D objects created with AutoPLANT.
Some interferences were found during this operation.
The changes necessary to fix those problems, as well as other changes such as those requested by the customer, went much faster on this project compared those done in 2D.
This time, changes were made by modifying the 3D model.
It was not necessary to alter any individual drawings because drawings are associative to the model and are updated automatically when the model changes.
"This was much faster than going back and modifying many drawings to reflect a change," says Butveit.
"It was also more accurate.
When we worked strictly with drawings, it was possible to miss some that were affected by a change.
That doesn't happen now because drawings are spun off from the model." Isometrics were the only form of piping drawing used on this project.
As Butveit indicated, they were not produced by hand but generated automatically from the 3D model.
Engineers simply selected the views they wanted and commanded AutoPLANT's Isometrics module to create the drawings.
"We spent only a few minutes on each drawing, doing minor touchup work such as adding a special number required by the customer.
All the other information was automatically extracted from the 3D model," Butveit says.
"The drawings had elevations and dimensions tagged and located, for example, and materials for purchasing were automatically derived from the model database.
Drawings produced in this manner required minimal checking because the software ensured that they were consistent with the 3D model." The RamRig was installed on the Snorre B platform in May 2000.
Although it was clear to Maritime Hydraulics that working in 3D significantly reduced design and documentation time on the Snorre B project, the company was even more pleased with the new approach when the RamRig was assembled and there were no clashes.
"When we began this project we wondered if working in 3D would be a success," says Butveit.
"We can now answer that question with a definite 'Yes'.".
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