First Shale Gas Experience in Saudi Arabia: Lessons Learned.

摘要

Influenced by the success of shale gas production worldwide and to meet requirements for clean energy supply, a multidisciplinary team of petroleum specialists was established in Saudi Aramco. Meeting the growing requirement in industrial consumption and especially electricity production is a driving force for developing unconventional gas reserves. “The initial focus is in the northwest and in the area of Ghawar, where gas infrastructure exists. Initial knowledge building from similar plays in North America is being supplemented with internal technical studies and research programs to help solve geological and engineering challenges unique to Saudi Arabia and to locate specific wells planned for 2011. The company is innovatively combining knowledge and research to maximize gas reserves and production from conventional and unconventional resources in order to meet growing domestic demand” (1). During years 2010 – 2011 major international petroleum industry players – Schlumberger, Halliburton and Baker Hughes – were invited to share their experience in a series of workshops held in Dhahran. Exchange of expert ideas developed into appreciation of complexity of the shale gas reservoir and helped to identify the scope of work for the first Silurian Qusaiba shale gas well. The SHALE-1 well was drilled in 2007 as a gas exploration well. Recent drilling and geophysical data obtained in the well were beneficial for detailed sidetrack and fracture stimulation design. The Multidisciplinary Saudi Aramco - Halliburton SHALE-1 task group was established and positioned in Dhahran. This allowed them to have regular face-to-face meetings and improve the most critical criteria of any new venture – communication. The draft work plan was developed 8 months before actual operations commenced on the well site. Thorough examination of the draft work plan progressed to the final work plan with a number of improvements. For example, “R” Nipples were dropped from the monobore 4-1/2” completion string. The Frac Stimulation design was fine-tuned, involving expertise from Saudi Aramco and Halliburton. The Complete Well on Paper exercise involved over 25 specialists from both companies and helped to rectify remaining completion/stimulation design issues, and put everyone on the same page in terms of the work program. Well site operations commenced in May 2011; the well was successfully re-entered and window cut in 7” liner. An S-shaped 5-7/8” hole was drilled in the direction of minimum horizontal stresses, to the required depth in Qusaiba Shale with a maximum DLS of 4°. The well was completed with a 4-1/2” cemented liner and monobore 4-1/2” string to surface. The Hot Qusaiba interval was perforated, frac stimulated with mixed results, and successfully flowed. A temporary isolation ceramic (easily drilled) plug was set above the perforation interval. The Warm Qusaiba interval was perforated, successfully frac stimulated, and flowed with mixed results. Finally, the plug was drilled out with CTU and both intervals flowed and required production log runs were made. All targets set for the SHALE-1 re-entry well were successfully achieved and the well was suspended for future utilization as an observation well.