Chapter 15 DYNAMIC GEOHAZARD MANAGEMENT IN CHALLENGING ENVIRONMENT

The Sabah Sarawak Gas Pipeline (SSGP) is a 521 km × 36” O.D. Grade X 70 onshore natural gas pipeline that was completed in 2013 to transport 750 MMscfd of gas from the Sabah Onshore Gas Terminal (SOGT) to the LNG Complex at Bintulu, Sarawak. SSGP traverses through many different types of terrain. Two separate pipe parted incidences in August 2014 and January 2018 resulted in PETRONAS reevaluating its pipeline integrity management system for pipeline constructed in difficult terrain.

The pipe parted incidences triggered a reassessment of the terrain along the whole SSGP pipeline route. In order to manage the geohazards located along the pipeline a comprehensive Geohazard Management Plan was developed to provide immediate actions (prior to gas in), intermediate actions (during commissioning stage) & for more permanent solutions at high risk locations.

This paper presents PETRONAS unique experiences and new solutions developed to assess the difficult terrain and associated stresses impacting the pipeline. The efforts put in place in mitigating and managing geohazards are described not only for purpose of integrity management of the current SSGP pipeline condition but also for longer term aim to further enhance the integrity and reliability of the pipeline.

Summary of geomorphological terrain assessments using Geo Slope Monitoring Assessment and Repair Management (GeoSMART) findings, geomorphological mapping and engineering use of LiDAR, aerial surveillance and ground movement monitoring data incorporated via Intelligent Geohazard Management System (iGeMS) database and details of Inspection Maintenance Monitoring and Repair (IMMR) methods and procedures are presented.

The basic description of SSGP terrain in which the pipeline parted incidences occurred is described herein. Aspects of the site investigation and assessment activities undertaken are shared. Soil information used to assess slope stability analyses, description of geomorphology that causes ground movement or impart additional stresses are described. The method used to qualitatively assess geohazards and terrain impacting pipeline risk are presented.

This paper presents aspects of geohazard assessments, mitigations and management to put in place solutions to enable lower likelihood of failure. Due to experiences, data gathered, analysed and managed via monitoring programmes, costly terrain repairs are able to be rationalized and optimised to ensure geohazard risks are ALARP.

This paper presents PETRONAS updated practices in managing geohazards and their impacts to SSGP pipeline. The comprehensive work done and improvement to the Geohazard Management Plan demonstrates: 1) PETRONAS overall advancement in assessment and monitoring of the SSGP pipeline that can be affected by external stresses due to ground movement, 2) Engineers innovativeness to overcome technical challenges via GeoSMART, iGeMS and IMMR in-house solutions to raise PETRONAS confidence in managing pipeline in challenging terrain and 3) PETRONAS capability to predict pipeline overstressing occurrence and face more complex and demanding pipeline integrity issues in locations with geohazards.