The design of high-pressure high-temperature pipelines (HPHT pipelines) is mainly governed by pipe-soil interaction. Over the past few years, independent research groups utilized different test setups and methodologies to characterize the pipe-soil interaction. Laboratory approaches based on tilt table and interface direct shear tests and the in-situ FUGRO Smartpipe represent the current state of practice. The tilt table relies on gravity loading and allows for the reproduction of low confinement conditions and relatively large displacements resulting in reliable measurements of the drained residual interface shear resistance. Direct shear devices are custom-fabricated and modified to allow for reliable testing at low confining pressure and repeated cycles/reversals are needed to allow for the mobilization of residual conditions. This paper aims at proposing a first generation innovative, cost-effective and reliable test setup to quantify the pipe-soil interface resistance in-situ. As a first step in achieving this aim, a laboratory proof of concept experimental setup that could be adapted/automated in future work to become an independent field test setup is designed and implemented. Such a setup could potentially provide an alternative to the more costly FUGRO Smartpipe testing system. The scope of work presented herein is limited to the design and validation of the basic mechanisms/components of the proposed in-situ test setup. Preliminary pipe-clay interface interaction results are compared to results from tilt table and interface direct shear tests on similar clay and interface coating. Results showed that the proposed setup can reliably quantify the drained residual interface friction angle and thus may be further modified/prototyped for insitu deployment.
Roba Houhou, Rayan Bou Mjahed, Elie Shammas, Shadi Najjar and Salah Sadek
Keywords: pipe-soil interaction, in-situ test, offshore pipelines
Publisher: DFI