Designing an Appropriate Drilling Fluid to Alleviate the Problems Associated with the Drilling of Shaly and Marly Formations


Ahwaz Faculty of Petroleum, Petroleum University of Technology, Ahwaz


      Collapse of shaly and marly formations is a major problem in petroleum well drilling. This problem can result in stick pipe situations owing to improper cleaning of the well and accumulation of cuttings in the well. Carefully designed drilling muds need to be used to prevent time and cost from being wasted as a result of this problem. This study presents a research on 40 samples from problematic shaly-marly formations in Marun wells. Initially the formations were characterized from drilling engineering and geological perspectives. XRD analysis was then applied to determine the mineralogical features of the samples. Uniform tablets were prepared from the formations. The tablets were then tested with a variety of solutions, including HF acid, HCl acid and methyl alcohol. The most favorable fluid with the most suitable rheological properties was identified after detailed analysis considering the amount of swelling, corrosion, mineral solubility, etc. Results show that the best anti-sticking fluid can be obtained when HF acid is used as the main dispersant, HCl is used to solve impurities and establish contact surface for the main acid, and alcohol is used as the catalyzer.


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