冻土区天然气水合物钻井泥浆冷却系统设计及关键参数计算

Design of Cooling System for Gas Hydrate Drilling Mud in Frozen Soil Region and the Calculation of Important Factors

摘要:

泥浆冷却技术是天然气水合物钻探的关键技术之一，低温泥浆可以抑制天然气水合物在钻进和提钻过程中分解，有利于钻获水合物实物样品。新型天然气水合物钻井泥浆冷却系统主要包括载冷剂制冷器、翅片管式换热器、温度监测与记录和防冻装置4部分。制冷机组采用变频启动，减小了野外施工中配套发电机的功率，大幅度降低油料消耗；翅片管式换热器中泥浆与载冷剂对流换热，换热面积大，换热效率高；温度监测与记录装置对4个关键节点的温度进行监测和记录，同时防冻装置可防止泥浆在换热器中结冰堵塞，影响正常使用。运用传热学和流体力学理论对泥浆与载冷剂对流换热过程进行计算，在满足制冷要求的前提下，换热器换热面积是10.58 m2，管路压力损失为0.34 MPa。

Abstract:

Mud cooling technology is one of the key technologies in gas hydrate drilling, the low-temperature mud will restrain the decomposition of gas hydrate in the process of drilling and drill lifting, which is favorable for discovering hydrate samples. The new gas hydrate mud cooling system consists of the ethylene glycol cooler, finned tube heat exchanger, temperature monitoring & recording and anti-frost device. Frequency conversion starting mode is used for the cooler, which can reduce the generator power and the cost of fuel consumption is significantly cut down. Convection heat transfer mode is applied for mud and ethylene glycol in the finned heat exchanger with large heat-exchange area and high efficiency. The temperature of these 4 key parts can be monitored and recorded by the temperature monitoring and recording device and the mud freezing and icing clogging in the heat exchanger can be prevented by the antifreeze device. By using the heat transfer theory and fluid mechanics, the theoretical calculation for heat convection process of mud and coolant is made, the results show that with heat-exchange area of 10.58m2 and pipe pressure loss of 0.34MPa, the cooling requirements can be satisfied.