Horizontal directional drilling (HDD) activities have received a great thrust due to several government policies conducive to infrastructure growth. One of the major driving sectors of this growth is the oil and gas industry in which substantial investments in cross country transmission and distribution lines are currently being made. Resulting projects, fuelled by the booming energy demands, are getting bigger by day compared to earlier project sizes. This growth of demand ultimately is leading to requirements of larger equipment capacities and the higher skill sets to undertake such projects. Following project story discusses about one of such projects executed for Gujarat State Petronet Ltd. (GSPL), where a creek was crossed by a natural gas pipeline in Gujarat, India.
Gujarat State Petronet Ltd (GSPL) constructs and manages a statewide gas transmission network in the State of Gujarat, India. In October 2008 it awarded an order to construct the 130-km Morbi-Mundra natural gas pipeline project to Ahmedabad-based Jaihind Projects Ltd. The complete order was valued at US $42 million. The 130-km, 18-in. diameter underground pipeline is an important component of the gas grid being constructed by GSPL. The scope of the order included detailed engineering, procurement, supply, laying, testing and commissioning of the underground cross-country natural gas pipeline along with associated facilities.
The 130-km pipeline originates from near the Mundra port, located in the Northern Gulf of Kutch en-route major maritime routes and has very good connectivity through rail, road, air and pipeline and is one of the country’s most convenient gateways for cargo, bound westward. The line shall be supplying gas to glass and ceramic units located in the Morbi industrial belt in Rajkot district of Gujarat. Morbi-Mundra Pipeline Project is an important milestone to develop pipeline infrastructure in the State of Gujarat. The project is expected to be completed by the end of May 2010.
Under the EPC contract, two crossings under a creek had to be constructed. These crossings were to be done under Hadakiya Creek, near Smkhyali in Gujarat and were of the sizes 650 m x 18 in. x 10.3 thk API 5l X-65 and 650 m x 6 in. conduit x 6.4 thk. As already indicated, the project owner was Gujarat State Petronet Ltd., Project Management Consultant was J.P. Kenny Wood Group Engineering India Pvt. Ltd., and Third Party Investigation consultants were Velosi.
Being the first job under the creek, the regular rig and support equipment available with the contractor were found to be inadequate and a larger and more powerful rig system was required. Site location and pipe configuration required multiple pipe placements. In addition, the site offered enough geological challenges in shape of highly plastic clay, sand and gravel. Combinations of these in the formation make the reaming operations extremely difficult.
Equipment Chosen & Deployed
To meet the above challenges, contractors decided to purchase and deploy the Vermeer D330x500 and the Paratrack-2 surveying system.
The selection was made on the basis of reports about Vermeer D330x500 that it comes with 50,000 ft-lbs of rotational torque for drilling in difficult ground formations and turning large back reamers, and 330,000 pounds of thrust/pullback force, the D330x500 packs an impressive amount of muscle for those long and large-diameter drilling projects.
On the similar lines for wireless tracking the contractors chose ParaTrack-2. It is a magnetic tracking system employing state of the art electronics with advanced magnetic tracking capabilities. ParaTrack-2 uses selectable magnetic sources to fit the requirements of the most exacting HDD project.
After taking the necessary clearances from the client and the PMC, and with appropriate technology on its side, contractor, Jaihind Projects Ltd., took up the challenge to carry out the 18-in. + 6-inch gas pipeline beneath the Hadakiya Creek. This involved preliminary planning, feasibility, geotechnical report analysis, preparation of as built design drawings and installation of pipeline under the creek by HDD method.
- Being the first job with the Vermeer D330x500, organizing the man-power and the support equipment like the mud pump and mud mixing unit etc. was the biggest challenge.
- Two parallel holes were drilled, using the ParaTrack-2; Both were punched out right on target.
- Soil Strata: The formation was comparatively difficult to drill comprising of highly plastic clay, sand and gravel.
- Due to highly plastic clay in the formation, reaming operation proved to be extremely difficult but ultimately we crossed all the hurdles.
- Pipe pulling went very smooth with max. pull force getting upto 30-40T. An As-Built pipeline profile is detailed in the following figure.
Prof. Niranjan Swarup is the executive director of the Indian Society for Trenchless Technology (INDSTT). Swarup can be reached at email@example.com.