PEMEX

Project: PEMEX – 2003 Geophysical and Geotechnical Campaign
June 2003 to April 2004
Location: Gulf of Mexico, Mexico
Client: Petroleos Mexicanos/Foundex Explorations Limited
M+EG provided geotechnical engineering services to Foundex Explorations Limited for the site characterization and preliminary design of driven steel pipe piles for 49 proposed offshore platform sites in the Gulf of Mexico.  Water depth at the sites ranged between 10 m and 200 m.  Engineering analyses were performed to assess foundation performance for temporary on-bottom stability, installation and in-place conditions of piled jacket foundations. 

The M+EG scope of work included the following:

  • Field Investigation – supervision of site investigation for 49 sites covering geotechnical boreholes, piezocone penetration tests (PCPT) and field vane tests with final penetrations below seabed between 120 m and 130 m.  A geotechnical testing laboratory was set up on two drill ships to perform initial classification and strength testing;
  • Onshore static and dynamic testing of soil samples to achieve characterization of soils at each offshore site.  Results presented in preliminary engineering report for each site;
  • Earthquake Hazard Analysis - a seismic hazard study was performed for the 49 platform locations to provide input to the dynamic site response and soil-structure interaction analyses for an earthquake return period of 200 years;
  • Incorporation of geophysical survey results into the geotechnical assessment of the 49 platform sites and four pipeline alignments;
  • Geotechnical considerations for the axial and lateral design capacity for offshore piles as well as driveability assessments; 
  • Geotechnical considerations for the installation of four separate pipeline sections were also provided;
  • Presentation of separate static and dynamic geotechnical engineering reports in Spanish and English for all platform and pipeline locations.
Project Highlights:
  • Site-specific dynamic laboratory testing including resonant column and cyclic DSS to provide dynamic characterization (shear modulus degradation and damping curves) of deep clay and carbonate sand.  The results of the dynamic laboratory testing indicated that the use of published modulus and damping curves may underestimate the site response at deep soil sites. 
  • Earthquake Hazard Analysis – local seismic zoning, seismic design spectra and acceleration records generated for a return period of 200 years including local site effects and soil degradation under cyclic load.
  • Foundation design under static loads includes axial pile capacity, t-z and Q-z static curves, p-y static and cyclic curves, mudmats, and soil resistance to driving (SRD) for five different pile diameters ranging from 36” to 60” inches.
  • Foundation design under dynamic loading, including dynamic soil characterisation, seismic site response analyses, assessment of liquefaction potential, soil/pile interaction, and dynamic adjustment factors for p-y, t-z, and Q-z curves.
  • Submission of 148 reports over a period of 18 months summarizing the results of the site investigation and the geotechnical recommendations for structural design.