Outline

  • Abstract
  • Keywords
  • 1. Introduction
  • 2. Drilling Environment
  • 2.1. Mylonite Zones
  • 2.2. Fractured Coal
  • 2.3. Very High Stress Areas in Coal
  • 2.4. Fault Zones
  • 2.5. Dyke Cinder
  • 2.6. Soft Clay Dykes, Sills and Bands
  • 2.7. Flaking Mudstone
  • 2.8. High Gas Content and Pressure
  • 3. Drilling Practices
  • 3.1. Drilling Additives
  • 4. Over-Coring Recovery
  • 5. Case Histories
  • 5.1. Central Colliery-Qld
  • 5.2. West Cliff Colliery
  • 5.3. Tahmoor 900 Panel
  • 5.4. Baijigou Mine, China
  • 5.5. Gujarat Wongawilli Seam
  • 5.6. Wuhai-Ping Gou Mine, China
  • 6. Conclusions
  • References

رئوس مطالب

  • چکیده
  • کلیدواژه ها
  • 1. مقدمه
  • 2. محیط حفاری
  • 2.1 مناطق میلونیت
  • 2.2 زغال سنگ شکست خورده
  • 2.3 مناطق دارای تنش زیاد در زغال سنگ
  • 2.4 مناطق شکست
  • 2.5 زغال آب بند
  • 2.6 آب بند های رسی نرم، سد و نوار ها
  • 2.7 ماسه سنگ پوسته پوسته
  • 2.8 محتوا و فشار گاز بالا
  • 3. شیوه های حفاری
  • 3.1 افزودنی های حفاری
  • 4. بازیابی مغز گیری دوباره
  • 5. تاریخچه های موردی
  • 5.1 تجارت زغال سنگ مرکزی- QLD
  • 5.2 تجارت زغال سنگ وست کلیف
  • 5.3 پانل 900 تاهمور
  • 5.4 معدن بایجیگو، چین
  • 5.5 شکاف گوجارات ونگاویلی
  • 5.6 معدن ووهای-پینگ گو، چین
  • نتیجه گیری
  • منابع

Abstract

Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.

Keywords: - - -

Conclusions

<p>(1) When faced with a new environment, past experience is a great asset in managing a drilling project.

(2) Assess the environment before drilling to identify any likely problems.

(3) Develop experience at drilling in and managing adverse environments and have the drillers operating under an established set of rules to identify and assess boggy conditions.

(4) Maintain good communication between drill crews and supervisors.

(5) Progressively update the knowledge gained from boggy ground encounters in one borehole to assess its potential influence on ongoing boreholes.

(6) Develop a risk assessment based procedure for over-core recovery operations.

(7) Establish and maintain a suitable set of over-coring equipment including HQ rods, jaws and guides, subs, shoe bits and stuffing box.

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