When technology went underground

The fuel that drives the millions of vehicles on Indian roads, be it petrol or diesel or gas, needs to be transported across the country from refineries. Large vehicles are deployed by oil companies, posing multiple risks — air pollution and danger of leaks being the big two. One way of reducing these twin dangers is to resort to laying underground pipeline networks to transport the fuels. Most oil companies, like Indian Oil Corporation, HPCL and BPCL, have been doing their bit. But one challenge is overcoming surface obstacles, including roadways, railroads, wetlands and waterbodies of varying sizes/depths.

The technology that is coming handy in finding the right solution here is horizontal deep drilling (HDD). Indian Oil Corporation (IOC) has successfully demonstrated it in a ‘mini engineering feat’ over a 3-km stretch under the river Godavari, near Rajahmundry in Andhra Pradesh. It was critical to implement the 1,212-km long Paradip-Hyderabad pipeline that traverses through the three States of Odisha, Andhra Pradesh and Telangana State.

More steel than Eiffel Tower’s

The Paradip-Hyderabad Pipeline Project (PHPL) is expected to consume approximately 80,000 tonnes of steel. To put it in perspective, think of the 324-metre tall Eiffel Tower in Paris. The marvellous structure built in 1889, a global landmark, was built with about 8,000 tonnes of steel and metal. Therefore, the IOC pipeline will consume 9 to 10 times the Eiffel Tower’s equivalent of steel when completed in mid-2020. In addition, a record 3 lakh cubic metres of soil will be excavated and filled up to conceal the long pipeline network, which will be safe and secure compared to the overground one, explains K Narender Babu, General Manager, PHPL. The ₹3,800-crore project will facilitate moving of petroleum products in an eco-friendly manner. It will help shape economic activity in the three States.

In cross-country pipelines, the issue of bypassing waterbodies, especially long rivers, has been challenging. Here, HDD comes in handy. IOC has implemented it successfully across the Godavari over a 3-km stretch, about 35 km from Rajahmundry.

The location was determined scientifically after elaborate planning. Extensive soil investigation was carried out for identification of soil strata, which is the major factor for design and success. Thereafter, 83 boreholes of 45-m depth were drilled along the river crossing within the right of way obtained.

Thereafter, two HDD closings of 2,100 m length to cover the major course of the river and another of 750 m with a hook-up of both sections at a minimum depth of 5 m were executed. The new pipeline system will be a contrast to another project that is functional now. The HPCL has executed the Visakhapatnam refinery to Hyderabad. GAIL has also used the overbridge structure to run its gas pipeline. A variety of drill bits, drill rigs, large diameter bores are deployed in cutting through the underground landmass with precision, made possible by the use of gadgets. Directional boring/HDD can be utilised with various pipe materials such as PVC, polyethylene, polypropylene, ductile iron, and steel, under acceptable stress limits.

HDD is usually carried out in three phases. First, a small diameter pilot hole is drilled along a directional path from one surface point to another. Next, the bore is enlarged to a diameter that will facilitate installation of the desired pipeline. Lastly, the pipeline is pulled into the enlarged hole, creating a continuous segment of pipe underground and exposed only at the two initial end points.

According to AK Tewari, ED (Operations), the pipeline will transport 4.5 MMTPA of petrol, diesel, and aviation fuel in an economic, reliable and environment-friendly manner, with almost zero pollution, compared to other modes of transportation. The complex operational aspects will be handled by the latest SCADA systems backed by state-of-the-art leak detection, pipeline inspection gauges (PIGs) and surveillance system on a 24/7 basis. Traditionally, petroleum products are moved from the refinery to oil depots and consumer points through hundreds of transport vehicles. This poses environmental issues, risks of accidents and is expensive. Instances of oil spills due to overturning of the long tankers carrying petroleum products on highway roads, posing a risk and leading to huge traffic jams can be avoided too.

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