Plugging Technology for HTHP Wells in the Yingqiong Basin of the South China Sea

HAN Cheng1 HUANG Kaiwen1 LUO Ming1 LIU Xianyu1 DEND Wenbiao1

(1.CNOOC China Limited, Shenzhen Branch, Zhanjiang, Guangdong, China 524057)

【Abstract】The Yingqiong Basin in the western South China Sea is characterized by complex geological conditions, high bottomhole temperatures and pressures, and lost circulation which occurs frequently during drilling into the target layer. In order to solve the problem of frequent lost circulation in the target layer, the main causes of lost circulation were analyzed; the idea of combining the high temperature resistant rigid plugging materials with high temperature resistant elastic plugging materials was followed; and a plugging slurry was prepared by adding DXD (high-temperature resistant rigid plugging material) and TXD (high-temperature resistant elastic graphite plugging material) into drilling fluid. The performance evaluation showed that the density of plugging slurry could reach 2.40 kg/L and the temperature resistance could reach 200 °C. The DXD could form bridges in the induced fractures, while the TXD could enter the residual pores of induced fractures under pressure difference, preventing the induced fractures from further opening and expanding, blocking the induced fractures and improving the pressure-bearing capacity of formation. This plugging slurry was applied in several high temperature and high pressure (HTHP) wells in the Yingqiong Basin with the success rate of plugging increasing from 30% to 80%, indicating that the plugging slurry could block the induced fractures in the target layer of the Yingqiong Basin, improve the pressure-bearing capacity of formation and the success rate of plugging, and solve the problem of frequent lost circulation in the target layer.

【Keywords】 HTHP well; lost circulation; induced fractures; plugging agent; Yingqiong Basin; the South China Sea;


【Funds】 National Science and Technology Major Project of “HTHP Gas Enrichment Principle and Key Exploration and Development Technologies in the Yingqiong Basin (Phase III)” (2016ZX05024-005) CNOOC’s Major Scientific Research Project of “Study and Application of HTHP Drilling and Completion Fluids and Cementing Technology in the Yingqiong Basin” (CNOOC-KJ 135ZDXM 24 LTD ZJ 02)

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This Article



Vol 47, No. 06, Pages 15-20

November 2019


Article Outline


  • 1 Analysis of causes of lost circulation
  • 2 Plugging practice and performance evaluation
  • 3 Field applications
  • 4 Conclusions and suggestions
  • References