Successful Implementation of Nanoparticle Deformable Sealing Polymer to Eliminate Differential Sticking of Zeit Sand- A Case Study from Gulf of Suez

Abstract This paper will describe a successful application of Nano deformable sealing polymer to mitigate a high risk of differential sticking while drilling weak sand of Zeit formation with 17.2 ppg mud weight with overbalance up to 2,500 psi. While trying to combine Zeit and S.G formation with 17.2 ppg mud weight. Two cases in offsets had differential sticking that resulted in well re-spud and isolate Zeit formation by casing string. In the subjected well, it was deeper, so it was impossible to sacrifice casing string to mitigate differential sticking. Application of Nano deformable sealing polymer to decrease the pore pressure transmission by filling the interspaces between bridging material and greatly improve the quality of the filter cake to be thin and impermeable. In addition to drilling fluid enhancement, the condition of the differential sticking was analyzed and improvement in the BHA contact area, BOP stack configuration, and well profile. In this paper engineering principles, laboratory tests of chemicals and actual field results of these improvements will be presented. It was the first time to use Nanoparticles in the Gulf of Suez, extensive laboratory tests and simulation modeling was performed to formulate the right bridging material and Nanoparticles concentration that fit the characteristics of Zeit sand. The bridging material was decreased from a commonly used value in the field of 50 lb/bbl to 20 lb/bbl to decrease the filter cake's thickness while achieving an HTHP value of less than 2 ml/30 min and spurt loss of zero. PPA test was performed daily during the execution phase that reflected the optimum quality of the actual sample filter cake and also matches the laboratory test performed in the planning stage. In case of a well control event, the BOP stack was supported by a back annular to continue reciprocation of the drilling string while repairing the main annular element if failed. BHA contact area was decreased by optimizing the directional plan to keep a low angle across Zeit sand and by minimizing BHA’s un-stabilized length.17-1/2" hole was drilled successfully using 17.2 ppg mud weight without any issue relating to differential sticking even after losses experienced in Zeit sand. Due to the successful application of Nano deformable sealing polymer and engineering approaches, it was the first time in GOS to drill Zeit sand with mud weight of 17.2 ppg successfully saving one section in the well design and achieving the well objective. The work described in this paper will help in drilling high permeable sands with a high value of overbalance while eliminating the risk of differential sticking.