When China National Petroleum Corporation (CNPC), one of the world's largest oil companies, initiated the design and construction of a 900-kilometre natural gas pipeline from China to the border between Turkmenistan and Uzbekistan, Fugro undertook a geographically and logistically challenging project.
The pipeline alignment through Uzbekistan, Tajikistan and Kyrgyzstan crosses one of the most active tectonic regions of the world. We provided consultancy for a quick turn-around feasibility-level geohazards investigation and detailed topographical and geophysical data acquisition. To meet CNPC’s ambitious project schedule, we implemented an integrated data acquisition and interpretation plan utilising airborne data acquisition and remote sensing data interpretation services.
Topographic and geophysical data supported ongoing construction planning and additional detailed geohazard characterisation. High resolution topographic information was acquired using our FLI-MAP® system for LiDAR surveys. Mounting the laser system on Russian Mi-8 helicopters presented one of several new challenges and our engineers adapted the equipment using local resources for cost and schedule savings.
We also established 80 pairs of concrete markers and 250 topographic markers and undertook river bathymetry surveys at planned pipeline crossings and field completion.
For the Tajikistan and Kyrgyzstan segments of the pipeline route, acquired electromagnetic (EM) data were processed daily in near real-time to provide estimates of soil thickness over bedrock and soil properties with depth along the alignment. The EM data was then integrated with desktop geohazard mapping to refine interpretations and guide borehole layout planning efforts.
Desktop geohazard screening included mapping of geohazards (faults, landslides and liquefaction) within a five kilometre-wide corridor as part of a fatal flaw screening study. We prepared geohazard maps for CNPC to guide and make necessary modifications to pipeline alignment.
A probabilistic seismic hazard assessment (PSHA) was completed by establishing a project-specific seismotectonic model characterising rates, magnitudes and style of faulting that impact the project area. The seismic hazard results were deaggregated to identify the key contributors to the hazard in terms of earthquake magnitude and distances to, and types of, seismogenic sources.
Our project deliverables also included a geohazard-focused borehole layout to optimise sampling of different geologic units and potential hazards. Recommendations for geotechnical borehole locations optimised the drilling programme for subsurface data collection and correlation.
Integrating the geohazard mapping results with the EM data reduced the number of boreholes required (compared to an evenly spaced drilling approach) while increasing the informational value of each borehole location. This in turn produced significant schedule and cost efficiencies for CNPC, while maintaining a sound scientific approach to satisfy engineering input requirements.
The results of Fugro’s LiDAR and EM aerial survey along with the geohazard investigation meet the basic requirements for the detailed design of the next step. It has helped to accelerate the process of project implementation and has provided a basis for future large, long distance pipeline digital construction and maintenance.
HOW WE CAN HELP YOU
Our geohazard investigation services together with our detailed topographical and geophysical data acquisition can assist in the design and construction of even the most challenging pipeline route projects.