新疆石油地质

新疆石油地质 ›› 2023, Vol. 44 ›› Issue (zk(English)): 129-135.

• APPLICATION OF TECHNOLOGY • 上一篇    下一篇

Leakage Pressure Model of Natural Fractures in Igneous Rocks in Kelameili Gas Field

YANG Hu1, XUE Xiaojun2, CHEN Xianghui2, LI Xiubin2, XIE Junyu2, ZHANG Wei3   

  1. 1. College of Petroleum, Karamay Campus, China University of Petroleum (Beijing), Karamay, Xinjiang 834000, China;
    2. Research Institute of Geology, Xibu Drilling Engineering Company Limited, CNPC, Karamay, Xinjiang 834000, China;
    3. Research Institute of Engineering Technology, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China
  • 出版日期:2024-01-01 发布日期:2024-10-16

Leakage Pressure Model of Natural Fractures in Igneous Rocks in Kelameili Gas Field

YANG Hu1, XUE Xiaojun2, CHEN Xianghui2, LI Xiubin2, XIE Junyu2, ZHANG Wei3   

  1. 1. College of Petroleum, Karamay Campus, China University of Petroleum (Beijing), Karamay, Xinjiang 834000, China;
    2. Research Institute of Geology, Xibu Drilling Engineering Company Limited, CNPC, Karamay, Xinjiang 834000, China;
    3. Research Institute of Engineering Technology, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China
  • Online:2024-01-01 Published:2024-10-16
  • About author:YANG Hu, E-mail: 411195188@qq.com

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摘要： Fractures are developed in the igneous strata of the Kelameili gas field. The composite structure consisting of natural fractures and pores or cavities in such fractured formations may result in a large difference between the leakage pressure and the formation fracture pressure during drilling. The leakage mechanism was investigated according to the fracture-pore occurrence and the fracture opening/closing, connection and filling of the igneous rocks in different well sections, the leakage pressure models under different fracture states were constructed, and the layered leakage pressure profile was plotted depending upon pore pressure, in-situ stress and other parameters, so as to determine the leakage law of natural fractures in the igneous rocks in the Kelameili gas field. The results show that the leakage pressure of closed fractures in the igneous rocks is controlled by in-situ stress, and the leakage pressure of open fractures is affected by formation pore pressure and filling state. Furthermore, combining with the drilling parameters from typical wells, the variation law of fracture leakage pressure under different well trajectories was analyzed, and the safe density window of drilling fluid was determined to ensure drilling safety.

关键词: Kelameili gas field, igneous rock, fracture structure, leakage pressure model, drilling fluid, density window

Abstract: Fractures are developed in the igneous strata of the Kelameili gas field. The composite structure consisting of natural fractures and pores or cavities in such fractured formations may result in a large difference between the leakage pressure and the formation fracture pressure during drilling. The leakage mechanism was investigated according to the fracture-pore occurrence and the fracture opening/closing, connection and filling of the igneous rocks in different well sections, the leakage pressure models under different fracture states were constructed, and the layered leakage pressure profile was plotted depending upon pore pressure, in-situ stress and other parameters, so as to determine the leakage law of natural fractures in the igneous rocks in the Kelameili gas field. The results show that the leakage pressure of closed fractures in the igneous rocks is controlled by in-situ stress, and the leakage pressure of open fractures is affected by formation pore pressure and filling state. Furthermore, combining with the drilling parameters from typical wells, the variation law of fracture leakage pressure under different well trajectories was analyzed, and the safe density window of drilling fluid was determined to ensure drilling safety.

Key words: Kelameili gas field, igneous rock, fracture structure, leakage pressure model, drilling fluid, density window