Abstract

There will be a big marketing for drilling in deepwater in the world. But there are few drilling vessels or platforms to suit to drilling in deepwater or super deepwater in international. COSL (China oilfield Services Ltd.) has some semi-submersible platforms and they are only suit to operate lessen to 500 meters of water depth. It become a difficulty for the company how to enter deepwater drilling market in time according to its condition of equipment? COSL noticed a new concept of deepwater drilling from a Norway's company, and it means that some device might be fabricated, which may be matched with semi-submersible platform to drill in deepwater, operating depth about 500 m to 1500m. The concept name is Artificial Buoyancy Seabed (ABS). Its main principle is to set a tank of buoyancy under 300 m under sea level, which is located the center of bottom of the platform. The device utilizes the buoyancy force of the tank of column to support weight of BOP, so BOP will set in short distance from the face of sea. The result of using the device is that operation in deepwater will be the same as sallow water. It will improve the capability of the semi-submersible if ABS device would be used when drilling, which could increase the depth of water of operation, from 457 m to almost 1500 m in the offshore. It is very difference between shallow and deep sea that devices testing before operating in formal. In shallow sea, the device could be used directly after designed in primary. In contrary, the device of the deepwater will be used through a lot of testing and simulations because it is very expense that cost of operation in a day. The researchers and engineers would guarantee the device should be good properties and performances before it was used in the practice of the offshore. Since June 2004, COSL has carried out a series of item of the researches, experiments, and tests for the device, including to 9 experiments in some institutes in China and Norway, to proven its properties. The work correlative the device had been finished by cooperation both Chinese and Norwegian experts. This paper describes the procedure of work proven. The test in preliminary had been proven that the design of the device is reasonable, and COSL will do the first trial well in South China Sea at the end of 2006 or the beginning of 2007.

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