Fresh water from the sea
- Type of project
- Discovery of hidden water supply benefits Chinese Island community
- Location
- Near Shanghai (China)
- Continent
- Asia
- Company
- Fugro Ingenieursbureau
- Client
- Government of China
- Period
- 2007 – 2008
- Contract value
- Objective
Because of the shortage of fresh water, drilling investigation was needed
Project information
Shengsi is a scenically attractive, hilly island lying about 60 kilometres to the East of Shanghai. Part of Zhejiang Province, the island extends over 80 square kilometres and supports a population of about 100,000. Fishing is a major activity, but recently tourism has begun to flourish, benefiting the economy but aggravating the acute shortage of fresh water that has bedevilled the residents of Shengsi for many years.
A geological study conducted by local experts suggested that buried to the north of the island lie ancient channels formed during the Pleistocene Epoch. These are part of the Yangtze River system, extending eastwards from Jiangsu Province and the port of Shanghai, where the river meets the sea today. The geologists predicted that the aquifers in these ancient channels could contain a significant amount of fresh water, recharged by the Yangtze River. The channels were expected to lie buried at a depth of 170- 240 metres below seabed under layers of sand and clay. If these assessments could be verified, a new source of fresh water could exist on the doorstep of the island community.
Description of project
Fugro’s Hong Kong office was engaged by the local government to carry out exploration drilling at a target location 20 kilometres to the north-northwest of the island in an area with water depths of around 11 metres. Fieldwork, estimated to take fifty days, was scheduled between April and June, which was deemed the most suitable time of year for the proposed operations.After a careful study of site and environmental conditions, Fugro elected to mobilise the jack-up drilling platform Fugro 2 to the work site, complete with a drilling rig capable of operating to depths of 400 metres. Fugro 2 was supported by a crane barge moored adjacent to the platform by an array of six 7T anchors. All auxiliary equipment, drilling consumables and accommodation for the drilling crew were located on the 62.5 metre long,
20 metre wide cranebarge, which was bridgelinked to the drilling platform.
Fieldwork actually started in early May and was completed in 46 days, despite winds which, at times, reached almost 40 knots. The drilling was terminated at 210 metres below the seabed after penetrating 5 metres into bedrock. Several aquifers were identified during drilling and two pumping tests were carried out. Fresh water was discovered during one of the tests and the geologists have linked the strata producing fresh water to wells drilled along the coast near Shanghai. The Zhejiang and Shengsi governments are planning to drill additional boreholes next year to define the total potential for developing these aquifers as a water source for the nearby islands.
The islanders’ response to the discovery of fresh water on their doorstep has been overwhelmingly positive. The living conditions and future economic prosperity of the island community appear to be much more secure as a result of the
exploratory work.
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