Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (6): 120-129.DOI: 10.13745/j.esf.sf.2024.7.13

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New technologies, methodology and application in directional high-temperature hard rock drilling—a critical review

WENG Wei1(), WU Shuo1, HE Yunchao1, LIN Wenjing2,3, FENG Meigui1, GAN Haonan2,3, LI Xiaodong1   

  1. 1. Beijing Institute of Exploration Engineering, Beijing 100083, China
    2. Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
    3. Technological Innovation Center of Geothermal & Hot Dry Rock Exploration and Development, Ministry of Natural Resources, Shijiazhuang 050061, China
  • Received:2024-02-12 Revised:2024-04-30 Online:2024-11-25 Published:2024-11-25

Abstract:

The depth of well drilling has been continuously rising in recent years with the increasing demands for energy resources development and earth systems research. Problems encountered in deep drilling include high formation temperature, high rock hardness, low drilling efficiency, high cost and frequent accidents. Key drilling technologies such as downhole motors, efficient drill bits, measurement-while-drilling tools and mud cooling systems have been researched abroad to address the above problems; the research results have been applied in the fields of oil and gas drilling, high-temperature geothermal exploration, etc. Relevant researches have also been conducted in China, but gap exists compared to the level of research abroad. This paper analyzes the technical difficulties in drilling high-temperature hard rock well in China and summarizes the technical requirements. A new drilling method, along with its technical characteristics and application results, are also introduced. The new method, in principle, seeks to utilize the existing equipments to achieve directional drilling of deep wells. It uses a bottom hole assembly (BHA) consisting of high-speed, strong diameter-retaining tri-con drill bits, high-temperature resistance positive displacement motor (PDM) and measurement-while-drilling (MWD) technique, and combines with high-temperature resistance drilling fluid, mud cooling system and segmented circulating cooling technology. However, future researches are needed in the areas of durable drill bits (e.g., polycrystalline diamond compact (PDC) and impregnated diamond drill bits), all metal downhole motors, impact drilling tools and high-temperature resistance MWD.

Key words: high temperature, hard rock, directional drilling, mud cooling system

CLC Number: