In 1976, in the Republic of Tatarstan, Russia, several scenic islands were formed in the Menzelinsk region by artificially elevating the water level of the Kama River. In order to extract oil from one of the islands and bring it to the mainland, a lengthy process was required, which involved pumping the raw materials into a truck, transporting the truck by barge to the mainland, and then driving the truck to a collection station.
The client, Oil Drilling Company, wanted to streamline this process; however, it wasn’t until oil prices on the world market increased to $US100 per barrel that the company decided to install a pipeline from the island to the shore of the Kama River in what became known as the Treasure Island Project.
Combating the Russian winter
Because of the long Russian winter, the water between the island and mainland was frozen for much of the year. It was decided the only solution to the weather constraints would be to utilise horizontal direction drilling (HDD) technology to install the urgently needed pipeline, and EcoTEK Company was contracted to perform the work.
In addition to the constraints imposed by the climate, the strict contract stated that oil must be flowing through the pipeline after the New Year holidays, and it was already the end of September.
By this time EcoTEK had purchased a new machine from Universal HDD. The UNI-220×240 rig has 220,000 pounds of thrust and pullback force, 7,315 m per pound of rotation torque, and a UNIMUD 325 off-board mud system delivering 325 gallons per minute, all of which were supplied by UNIRUS Group.
The project required EcoTEK to install nearly a mile of 6.25 inch diameter steel pipe. After considering the conditions and requirements of the project, EcoTEK concluded that the risks were too high; the weight of the pipeline was around 54,431 kg and the weight of drill stems was 37,013 kg, which meant the combined weight exceeded the push and pull capacity of the rig. EkoTEK believed a different technical solution needed to be found. However, the customer believed the project was still feasible.
An EcoTEK spokesperson said “The customer had his own argument, which soon outweighed ours. Immediately, job site surveys began on the shore of the Kama River.”
Preparations for the project occurred while final decision on design and construction of the pipeline were being made. There was little time, with significant pressure being placed from the client.
The rig was delivered to the left shore site of Kama River. Site preparations began and a heated enclosure was constructed to encompass the rig, mud delivery system, and storage for mud supplies, including field laboratory, mud mixing ditch, and other small support equipment. The water was supplied to the site by a 2.5 inch pipe.
Working through failures
Engineering and project analysis was conducted by Geomaster using a geo-radar to access the geological conditions of the bore path. The analysis found the average depth of the bore hole was 14 m (10 m under the bottom of the river), and consisted of fatty, low-water clay. These parameters were acceptable, given the rig’s maximum capacity of 220,000 pounds.
The drilling fluid was tailored specifically for the project by engineers from UNIRUS Group, and contained the following MI-Swaco components: bentonite maxgel, additives poly plus, polypac, rod ease and duovis.
The drill head entered the ground on 18 October and EcoTEK began the pilot hole. A Cable DigiTrak Eclipse was chosen as the locating system. The first section of the pilot hole was drilled without complications; however, further progress was hampered by a deviation to the right of the planned trajectory, along with a lower rate of penetration.
Several attempts to adjust the direction of the pilot hole failed and the drill head had to be removed for visual inspection. Based on wear to the tooling, and the presence of gravel on the drill head, it was evident the bore path was not in clay, and ground conditions varied as the pilot hole drilled deeper.
It was evident that a layer of sand and gravel mixture was causing steering problems, and several attempts to circumvent this layer failed because the drill head kept deviating to the right. It was decided work had to be stopped until the situation could be resolved.
Time was passing and delivery dates for the job were quickly approaching. It was decided to perform a second and more thorough study of geological the condition of the crossing. The second study confirmed the worst; the initial study of the crossing was interpreted incorrectly and the bore path was in a fairly condensed layer of gravelly soil.
A new approach
Despite the significant loss of time and team morale, there were several options left on how to proceed:
- Continue drilling in gravelly soil – an option which has already proved difficult;
- Go under the layer of gravelly soil, which could result in failure of the last stages of pilot hole boring; or,
- Pass in a small corridor between the bottom of the river and the top portion of the layer of gravelly soil without allowing the pipeline to float up.
The decision was made to go with the last option, despite the fact it required very high precision, and there was still the possibility there could be gravel on the individual sections of the path. Drilling fluids had to be adjusted according to the new conditions of the crossing. The new formula specified doubling the duo-vis additive in the final section of the bore. Additionally, the depth of pilot hole allowed for using a wireless transmitter with the Eclipse locating system.
An icy situation
When all problems seemed to be resolved and the second attempt was ready to commence, winter arrived and the first ice appeared. The thin ice prevented use of a walk-over locating system, and it was unclear how long it would be until it was safe for crews to move across the ice. This problem was solved by the local ice fishermen, who were also eager to start fishing on first ice. As soon as they could safely to traverse the ice, it was time to start the job again.
In December work resumed. This was followed by eight days of continuous work and, after two twelve-hour shifts, the drill head exited at the indented break-through location on the island. The 1,594 m of 6.25 inch diameter pipeline was already waiting on the island.
The first ice on the Kama River was gaining strength very slowly. By the time the pilot bore was ready for the initial reaming, there was no way to transport drill rods from the rig to the exit point on the island. A reverse reaming process was utilised to complete the remaining parts of the job. The reaming was completed by pushing the reamer and chain on drill rods away from the rig. Complete expansion of the bore to 11.85 inches was completed successfully before the New Year.
A well-oiled machine
Pullback of the pipeline went without a hitch. On average, pullback of one 6 m rod took approximately three minutes – one minute for a pullback and two minutes for break-out and unloading of a rod). The job was completed after 28 hours.
For final completion, the pipeline underwent three different customer approval and acceptance tests. The first test was designed to find any deformation in the pipeline by pulling a
metal sphere through. The second assessment was done under 80 atmospheric pressure (atm). The final and third test was completed under 80 atm after connecting to a small section of pipeline on the island, which had been installed by EcoTEK earlier that year using a Universal HDD UNI-60×70.
All tests were completed successfully and one week later, oil was flowing from the island though the pipeline to the collection station across the Kama River, giving this tale of adventure a happy ending.
This article first appeared in the April edition of Trenchless International. To read about more exciting international trenchless projects, visit www.trenchlessinternational.com
