Achieving Drilling-Performance Improvement in Horizontal Tight-Gasfield Development
- Adam Wilson (JPT Special Publications Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- October 2014
- Document Type
- Journal Paper
- 154 - 159
- 2014. Society of Petroleum Engineers
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- 198 since 2007
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This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 166699, "Achieving Drilling-Performance Improvement in Horizontal Tight-Gasfield Development," by Mohamed Najwani, SPE, Yaseen Najwani, SPE, and Hani Al Lawati, BP Exploration (Epsilon); Colin Cockburn, SPE, BP Exploration Operating Company; and Mohammad Reza Heidari, SPE, and Martin Sanderson, SPE, Schlumberger, prepared for the 2013 SPE/IADC Middle East Drilling Technology Conference and Exhibition, Dubai, 7-9 October. The paper has not been peer reviewed.
The full-field development plan for the Khazzan project in Oman is based on drilling approximately 300 wells targeting gas-producing horizons at measured depths of approximately 6000 m with 1000-m horizontal sections. The first attempt to drill these wells had to overcome many drilling challenges, including wellbore instability and drilling dysfunctions. This paper shows how the application of existing technologies and processes is leading to performance gains and improvements in wellbore quality.
BP has embarked on an appraisal drilling campaign that targets a tight gas reservoir in northern Oman. The subject field is an area of approximately 2800 km2 and contains the Cambrian Barik, Miqrat, and Amin reservoirs.
The field-development plan is based on a deep-horizontal-well design. When the appraisal phase began, there was very limited experience within the country in drilling deep horizontal gas wells. Other operators in Oman were mostly drilling vertical gas wells. There were no analog data available on horizontal wells in the Barik reservoir.
The wells will be drilled vertically to approximately 4000-m measured depth before building up and landing to horizontal in the Barik or Amin reservoir. An 8½×8?-in. 1000-m horizontal interval is drilled, and a 7×4½-in. tapered liner is cemented in place before fracturing operations. Figs. 1 and 2 are schematics of the well designs.
The targeted reservoir is either Barik or Amin sandstone, both of which have a high unconfined compressive strength (exceeding 35,000 psi). The Barik sandstone is at the upper margins of the global rock-strength envelope. Indeed, when core samples were analyzed by the bit manufacturer, the strength far exceeded any of their global stock of reference rock samples.
Horizontal drilling in these hard-rock conditions presents several challenges:
- Hard rock and slow rate of penetration (ROP)
- High levels of shock and vibration
- Polycrystalline-diamond-compact (PDC) -bit cutter durability
- Drillpipe fatigue
- Wellbore stability
- Torque and drag management
- High downhole static temperatures up to 143°C
|File Size||371 KB||Number of Pages||4|