全过程欠平衡作业用井下控制阀研制

作为传统的欠平衡钻井技术（UBD）的延伸，全过程欠平衡作业技术以其更好地保护油气藏、降低成本和提高采收率的优点得到了广泛的应用。国外技术和应用情况表明，传统的强行起下钻装置已不能很好地满足全过程欠平衡作业的要求，现场需要适应性更强的井下隔离技术和配套的套管阀工具。根据全过程欠平衡作业工艺，提出井下隔离工具的技术要求。通过有限元分析和优化设计等手段，开发出具有自主知识产权的全过程欠平衡作业专用井下控制阀（DCV），主要指标已经达到国外同类技术水平。

Development of Downhole Control Valve for Entire Underbanlanced Operation

With the evolution of traditional UBD, the operation with the underbalanced condition from drilling into oil reservoir to completion has been widely used so far with the advantages ofprotecting oil reservoir from damage, saving cost and enhancing oil recovery. The practical application proved that snubbing unit could not meet the demands of operators in the field. The advanced downhole isolation technology （DIT） and tools need to be researched and developed to meet the challenge e.g. well-control casing valve. The design criterion and specifications of DIT in detail according to the process of underbalanced operation was put forward. Using FEA and optimization, the patented downhole control valve （DCV） has been developed. It has been verified by workshop test that the great performance was achieved in terms of some parameters compared with the similar tools.