耐高温井下动力钻具测试技术方案研究

Research on technology scheme for high-temperature downhole-motor test

摘要:

深井、超深井及高温地热井等复杂工况对井下动力钻具的高温适应性、输出稳定性与服役可靠性提出了苛刻要求，地面模拟环境测试成为钻具入井前的关键环节，当前针对300 ℃高温和高压条件下井下动力钻具动态测试的条件缺失，成为深地钻探工程必须解决的关键问题。本文首先调研对比分析了国内外相关动力钻具测试系统技术特点和存在的主要技术问题；针对万米特深井科学钻探工程需求，提出了耐高温井下动力钻具测试初步技术方案：采用耐高温螺杆泵串联驱动、整体保温、集中冷却分布式动密封等建立高温高压钻井液闭式循环，通过驱动-负载能量回馈和状态监测降低功率消耗实现长周期测试，集成模拟负载和实钻碎岩等方式实现对井下动力钻具工作特性、钻进工艺、取心工艺的测试，为后续开展耐高温井下动力钻具试验平台研制提供方案支撑。

Abstract:

The complex operating conditions encountered in deep， ultra-deep， and high-temperature geothermal wells impose stringent requirements on the high-temperature adaptability， output stability， and service reliability of downhole motors. The test in the ground simulation environment becomes the key link before the drilling tool enters the well. However， facilities capable of dynamically testing downhole-motor at temperatures of up to 300 ℃ under high-pressure conditions remain unavailable， constituting a key technical challenge， which must be addressed in deep-earth drilling projects. In this study， surveys and comparative analysis are firstly made including the technical characteristics and major limitations of representative downhole-motor testing systems developed in China and abroad. To meet the requirements of scientific drilling in 10000 m-class ultra-deep wells， a preliminary testing scheme for high-temperature downhole-motor is then proposed. A closed-loop circulation system for high-temperature， high-pressure drilling fluid is established using multiple high-temperature screw pumps connected in series， whole-system thermal insulation， and centrally cooled distributed rotary seals. Drive-load regenerative energy feedback and condition monitoring are incorporated to reduce power consumption and support extended-duration testing. Simulated loading and actual rock-drilling modules are integrated to evaluate the operating characteristics of downhole-motor as well as their adaptability to drilling and coring processes. The proposed scheme provides a technical basis for the subsequent development of a high-temperature downhole-motor test platform.