HELP River Basins in Asia and the Pacific

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Tarim, China

Tarim, China

The Tarim Basin is an endorheic basin in northwest China occupying an area of about 906,500 km2 (350,000 sq mi). Located in China’s Xinjiang region, it is sometimes used metonymously for the southern half of the province, or Nanjiang. Its northern boundary is the Tian Shan mountain range and its southern boundary is the Kunlun Mountains on the edge of the Qinghai-Tibet Plateau. The Taklamakan Desert dominates much of the basin. The historical Uyghur name for the Tarim Basin is Altishahr (六域), which means “six cities” in Uyghur.

The Tarim Basin is the result of an amalgamation between an ancient microcontinent and the growing Eurasian continent during the Carboniferous to Permian periods. At present, deformation around the margins of the basin is resulting in the microcontinental crust being pushed under Tian Shan to the north, and Kunlun Shan to the south.

A thick succession of Paleozoic, Mesozoic and Cenozoic sedimentary rocks occupy the central parts of the basin, locally exceeding thicknesses of 15 km (9 mi). The source rocks of oil and gas tend to be Permian mudstones. Below this level is a complex Precambrian basement believed to be made up of the remnants of the original Tarim microplate, which accrued to the growing Eurasian continent in Carboniferous time. The snow on K2, the second highest mountain in the world, flows into glaciers which move down the valleys to melt. The melted water forms rivers which flow down the mountains and into the Tarim Basin, never reaching the sea. Surrounded by desert, some rivers feed the oases where the water is used for irrigation while others flow to salt lakes and marshes.

Lop Nur is a marshy, saline depression at the east end of the Tarim Basin. The Tarim River ends in Lop Nur.

The Tarim Basin is believed to contain large potential reserves of petroleum and natural gas. Methane comprises over 70 percent of the natural gas reserve, with variable contents of ethane (<1% ~18%) and propane (<0.5% ~9%). China National Petroleum Corporation’s comprehensive exploration of the Tarim basin between 1989 and 1995 led to the identification of 26 oil- and gas-bearing structures. These occur at deeper depths and in scattered deposits. Beijing aims to develop Xinjiang into China’s new energy base for the long run, supplying one-fifth of the country’s total oil supply by 2010, with an annual output of 35 million tonnes. On June 10, 2010 Baker Hughes announced an agreement to work with PetroChina Tarim Oilfield Co. to supply oilfield services, including both directional and vertical drilling systems, formation evaluation services, completion systems and artificial lift technology for wells drilled into foothills formations greater than 7,500 meters (24,600 feet) deep with pressures greater than 20,000 psi (1379 bar) and bottomhole temperatures of approximately 160 °C (320 °F). Electrical submersible pumping (ESP) systems will be employed to dewater gas and condensate wells.

 

Source: Wikipedia