Where are the main applications of the Stockton Gyro?
The survey tool has a range of applications for mapping pipelines and at the moment we are finding some of the more important applications are:
- Gas pipelines – to ensure that these high-risk assets are installed to specification and accurately recorded on as-built drawings.
- Electrical cables – mapping the profile and three-dimensional configuration of ducts to determine accurate pull loads. This helps prevent damage to the cable and reduces the potential for the cable to become stuck during hauling.
- Locating existing services – to determine accurate as-built locations where existing data is not available or inaccurate, especially in the coal seam gas (CSG) industry where a large amount of pipe has been installed in recent years.
The Stockton Gyro is a quick and cost-effective way to verify a pipe’s location or profile before the expensive long lead pipes or cables are installed into the bore or conduit.
The Stockton Gyro can check and verify a bore’s exact position both during the drilling process and also after pipe installation. Why is it important to have this information readily available during the drilling process?
This will indicate if any unplanned bends or doglegs have occurred.
These bends can overstress the pipe, increase frictional loads and potentially stop the pipe or cable from being installed.
The inertia gyro is a quick and inexpensive way to check the profile of the bore, and any associated tie-ins and pipework before the pipe is installed.
It is especially important for large diameter holes, bores drilled to grade or holes that are drilled close to or at the minimum bend radius of the product pipe.
What are the risks associated with relying on pilot hole data?
Reaming and hole-opening operations can exaggerate undulations created whilst drilling the pilot hole.
The pilot hole record will only record a survey point at the end of each drill pipe (9.5 m spacings) and may not indicate where doglegs are present whereas the inertia gyro will provide accurate positional data every 10 mm, if required.
In addition, with successive reaming of large diameter holes in soft formation, the drill pipe will meander from the original alignment.
For example, the offset for a 1,066.8 mm pipe reamed to 1,524 mm will be greater than 1 m.
The Stockton Gyro incorporates 3D bend radius analysis. Why is it important to know details about the bend radius of a pipeline?
If the bend radius is too small and the operating pressure too high, the pipe could yield and fail.
The smaller the radius, the greater the stress exerted on the pipeline.
A minimum bend radius is calculated for steel pipelines in accordance with AS 2885 and takes into account the wall thickness and operating pressure.
Pipelines are rarely surveyed post-installation in Australia to confirm the minimum bend of the installed pipe complies with design criteria.
It is also critical to know the bend radius of the installed duct for electrical cable installations.
Having precise survey data for the entire run, including any joints and tie-ins, allows for the cable installer to accurately determine the pulls loads required to install the cable into the duct.
This then provides security against potential damage due to over-pulling of the cable sections by ensuring the design load is accurately determined before cable hauling commences.
The Stockton Gyro can also be used to locate any existing pipeline, regardless of its depth or location. Please explain why it is important to have this data on file.
If pipelines are buried without accurate positional survey information they will be plotted incorrectly on as-built drawings.
There is then a potential for the service to be damaged at a later date by subsequent construction works.
This is becoming an increasing problem in the CSG industry with the large amount of gathering lines being installed.
Explain how the Stockton Gyro completes surveying without requiring above-ground access.
The Stockton Gyro has more than 30 sensors, which passively log XYZ directional changes against distance travelled.
These are then plotted between the known survey points at each end of the survey run.
The Stockton Gyro can be used for both steel and high-density polyethylene pipelines, but access is required to both ends of the survey run to allow for tool calibration.
This could still be achieved offshore with divers, if necessary.
How quickly does the Stockton Gyro produce results and in what format can the results be viewed?
The data is downloaded and verified onsite.
Graphs and Excel files of the data can be viewed immediately after processing.
For more information visit www.stocktondrillingservices.com.