海域水平井钻井连续循环短节结构设计与分析

Design and analysis of continuous circulation valve for horizontal drilling in marine areas

摘要:

连续循环短节可在停钻时保持钻井液连续循环，实现连续循环钻井，有效解决井底沉渣、井底压力波动等问题，尤其适合海域油气水平井钻井工程。本文设计了一种连续循环短节，介绍了短节结构及工作原理，并对极限工况下的短节本体强度进行了受力分析和结构优化设计，优选了本体安全系数大于1.2的旁通阀侧开孔；对旁通阀进行了有限元受力分析，从应力分布和密封比压两方面综合分析，得到了密封副半锥角和阀芯板厚度变化对旁通阀受力和密封效果的影响规律，优选出了密封副半锥角α=30°和阀芯板厚度δ=8 mm，并对优选结构参数的连续循环短节进行了旁通阀密封测试和本体强度测试，证明短节强度和密封性能均满足极限内压力35 MPa和极限拉力3503 kN的实际使用需求。

关键词:连续循环钻井;连续循环短节;旁通阀;密封;受力分析;水平井钻井

Abstract:

The continuous circulation valve can maintain the circulation of drilling fluid when drilling is stopped， which can effectively solve the sediment at the bottom of the hole and the fluctuation of pressure at the bottom of the hole， especially for offshore oil and gas horizontal drilling. In this paper， a continuous circulation valve is designed， the structure and working principle of the continuous circulation valve are introduced， the force analysis and structural optimization design are conducted on the strength of the body under extreme working conditions， and the side opening of the bypass valve with a safety factor greater than 1.2 times was selected； A finite element stress analysis is conducted on the bypass valve， which comprehensively analyzes the stress distribution and sealing pressure. The influence of changes in the half cone angle of the sealing pair and the thickness of the valve on the stress and sealing effect of the bypass valve is obtained. The half cone angle of the sealing pair， α=30°， and the thickness of the valve core plate， δ=8mm， are optimized. and the bypass valve sealing test and body strength test are conducted， proving that the strength and sealing performance of the continuous circulation valve meet the actual usage requirements under the ultimate internal pressure of 35MPa and ultimate tensile force of 3503kN.

Key words:continuous circulation drilling;continuous circulation valve;bypass valves;seal;force analysis;horizontal drilling