Models to Predict the Rate of Penetration of Insulator-Coated Pipe into Very Soft Clays Simulating Deepwater Subsea Conditions

As oil and gas production move into deeper water, the network of pipelines needed for the operation represents an increasingly significant part of the facility cost. The risers and pipelines laid on very soft seabed soils partially penetrate into the soil based on the method of placement, submerged self-weight of the pipelines, and shear strength of the soil. Based on the type of insulation used, steel or plastic outer surface will come into contact with the soil. Hence in this study, plastic pipes representing insulator-coated pipes, with outer diameter of 63 mm (2.5 in.) and 88 mm (3.75 in.) were tested in a somewhat large soil box containing very soft soils. The shear strengths of the soils used in this study were 0.3 kPa and 1.1 kPa. Several mathematical models have been developed to predict the pipe penetration into the soil without taking the loading rate into account, which is considered to be a major limitation of these analytical models. Movement of the pipes also results in the formation of soil berms in the vicinity of the pipes, which will restrict future pipe movements. Hence a need exists to better quantify the soil resistance during vertical pipe movements at various loading rates with the formation of soil berms. In this study, two analytical models have been developed to verify the physical model tests. The laboratory model tests were focused on better quantifying the relationship between pipe penetration resistance with the rate and the soil properties. The new analytical models predicted the vertical force-pipe penetration relationship very well by taking into account the rate and depth of penetration.

Language

  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: pp 549-560
  • Monograph Title: Pipelines 2014: From Underground to the Forefront of Innovation and Sustainability

Subject/Index Terms

Filing Info

  • Accession Number: 01536303
  • Record Type: Publication
  • ISBN: 9780784413692
  • Files: TRIS, ASCE
  • Created Date: Aug 4 2014 3:01PM