Collapsible Flexible Pipe Applied In Deep-sea Oil Extraction: Feasibility And Advantages

Recent years oil and gas exploitation shows the tendency to developing in deep-sea besides shallow sea generally. With the exploitation depth increasing, however, the marine environment increasingly harsh, design and construction of the traditional rigid pipeline increasingly complex, leading to geometrical increasing in laying cost. In view of this situation, a new type pipeline system with using collapsible flexible pipe for crude oil transportation in deep-sea oil extraction are proposed in this paper. And the corresponding pipeline laying construction technology is put forward, The laying process will be completed in offshore pipe laying ship, and the stability of submarine pipeline on the seabed can be ensured, which, has similarity with the traditional pipe laying process. With simple structure and perfect flexibility, the collapsible flexible pipe can be compressed to be hose reel, then very easy to construct and almost has no flexural buckling. Because the stress of tube wall in pipe laying and oil transportation can stay independent of water depth, the new type flexible pipe break the restriction of water depth on offshore pipeline. Besides, the collapsible flexible pipe has many technical and economic advantages such as:no welding defects, no vibration fatigue, no metal corrosion; can not be affected by the earthquake, recyclable, and so on.Meanwhile, the technics of crude oil transportation by sewage mixed application in the submarine collapsible flexible pipeline is proposed in this paper, which avoids the problem of heating and insulation, and reduces the apparent viscosity of flow. Then the pipeline pressure drop can be reduced and the flowability can be ensured.To prove the feasibility of heavy oil transportation by water mixed in low temperature, an indoor experiment is completed. The result shows that in the case of high moisture content, the fluid appears stable ideally water suspension flow. The apparent viscosity almost has nothing to do with oil viscosity and flow temperature. The pipe transportation flowability of crude oil with high wax content, high pour point and high viscosity can be highly improved. Energy consumption comparison between the collapsible flexible pipe with the traditional rigid one also has been made in this paper. The result shows that heating and insulation can take more than90%energy consumption in traditional rigid pipe while the collapsible flexible pipe consumes only about10%energy of rigid one, transporting identical crude oil of equal weight.At last of this paper, Qualitative discussion of the submarine collapsible flexible pipeline in safety, applicability, durability and economy has been taken, from the view of pipe stress, flowability of crude oil transportation by water mixed, pipe price, and so on. The safety, applicability and durability can be ensured by design, the economy is obviously superior to the traditional rigid pipe. A conclusion can be made that the submarine collapsible flexible pipeline will embrace a bright future in application.