Challenges and prospects of wireline coring technology for ultra-deep continental scientific drilling

Abstract:

Continental scientific drilling in ultra-deep wells is a crucial approach to revealing the deep Earth''s material composition， tectonic evolution， and resource potential， and cores serve as the first-hand physical evidence for interpreting stratigraphic information. As the core technology for highly efficient core acquisition， wireline coring directly determines coring quality and drilling efficiency. However， drilling beyond 10，000 meters， subjected to the combined effects of ultra-high temperature， ultra-high pressure， high stress， and complex formations， is prone to causing shortened bit life， seal failures， core jamming， and an increased risk of core loss. Meanwhile， numerous challenges persist， such as the poor strength-to-weight ratio of drill pipes， high wellbore friction， insufficient output torque of downhole motors， and low feed delivery accuracy. This paper systematically reviews the challenges， advances， and trends of wireline coring technology. It analyzes the technical bottlenecks of coring tools， drill strings， downhole motors， vertical drilling systems， logging-while-drilling （LWD） systems， and dynamic testing platforms under deep extreme working conditions， and summarizes the latest global advances in these fields. The results indicate that although significant breakthroughs have been made in various key technologies， urgent issues still remain to be resolved， including the adaptability of materials to extreme environments， downhole sealing and transmission reliability， and intelligent measurement and control synergy. Future development should rely on multidisciplinary cross-integration and innovation， focusing on developing drilling tool materials capable of withstanding 300 ℃ and 175 MPa， promoting the intelligent integration of smart coring bits， high-temperature-resistant mechanical vertical drilling systems， and coring processes， and constructing a multi-field coupled dynamic testing and evaluation standard system. This will achieve a strategic upgrade from traditional coring technology to intelligent wireline coring technology， providing a solid technical guarantee for 10，000-meter-level scientific drilling projects.