Due to the importance for the Oil and Gas Industry to have a technical document that consolidates the knowledge on management of geohazards for Latin America, the Geotechnics Project Team (EPGEO under its acronym in Spanish) of the Regional Association of Oil, Gas and Biofuels Sector Companies in Latin America and the Caribbean (ARPEL) developed the “Guidelines for Monitoring and Inspection of Pipeline Integrity Management to Face Geohazards” between 2014 and 2016. These guidelines contain the experience of the different operators in the region, given the highly-complex geological-geotechnical pipeline routes (due to the mountain range of the Andes in South America or the Central System in Central America), as well as the high technical requirement derived from the dynamics of the triggering agents in equatorial and tropical areas. In this respect, this document presents the main results of such consolidation and its dissemination, some relevant aspects to be taken into account in interdisciplinary works with reference to third parties, as well as the new guidelines that the EPGEO has proposed to develop that complement the management of geohazards in a Pipeline Transportation System (PTS).

The experience gained during the operation and maintenance activities on the Camisea Pipeline Gas Transport System (SDT) owned by TGP in Peru — which goes from the Amazon rainforest in the region of Cusco to the Pacific coast near Lima, along 729 Km — has led to the evolution and the optimization of the design, construction and maintenance processes regarding works focused on the stabilization of the slopes along the right of way of the pipeline carrying natural gas and natural gas liquid. This section of the right of way is 95 km long and crosses tropical mountains in the Amazon rainforest, in a transitional area between the Manugaly valley and the basin top boundary. It was noticed since 2005 that the right of way had being affected by a land slide consisting of a horizontal crack in the ground, between both pipelines and along them. So, after number of in-site inspections, the team concluded that the area was being affected by a large ground removal event. As a consequence, traces of geotechnical instability were found on the right side of the right of way, consisting of stress cracks, transverse settlements and leaks. All of those were affecting the stability conditions of the ground. From the annual in-site follow-up, monitoring and geotechnical testing, the team established that this process affecting the right of way was caused by a large mass removal process directly related to the increase of the imbalance rate of an old colluvial deposit below the entire area, triggered by the heavy rainfall in the area — ca. 3 500 mm a year, mainly between October and April. It is to be mentioned that the axis of the NG and NGL pipelines is located on the top of this colluvial deposit, which is susceptible to landslides. This is noticeable because of cracks present in the place. Local geomorphology and heavy deforestation — caused by locals — triggers an increase of the rainfall water filtration rate into the ground, thus speeding up the slide processes. Piezometers installed in the area showed high levels of the local water table. Movement readings are: top length: 70 m; length: 250 m; width: 150 m. Criteria for the construction of landslide mitigation structures in the pipeline área are being established based on a permanent land survey monitoring system — including inclinometers, piezometers and strain-gages — as this is a large regional movement. This control action allowed the operation to continue free of damages to the pipelines and under controlled costs.

To ensure the integrity of pipelines in failure mode Geotechnical, TRANSPETRO and the TBG perform underwater inspections of pipelines in the main crossings of rivers, lakes, dams, canals and permanently flooded areas. The inspections are designed to locate guideline and measure the covering the pipelines from the margins and underwater depth, identify any exposure of the pipelines, map the occurrences of blocks of rock or debris on the channel and evaluate the anthropic influence on stability of the sections inspected. Among the crossings rivers inspected, in the Atibaia V, with approximately 27.3 m in length, was observed a high erosive potential, which resulted in the loss cover of 3 (three) pipelines of crossing river, besides the fiber optic cable. The lengths uncovered resulted in approximately 33.0 m, with suspended pipes, damage in the concrete jacket and presence of blocks of rocks in the channel. The pipeline in the most critical situation went vain of 6.0 m, with gap up to 0,2 m in relation the background. The crossing river was studied with bathymetric survey and designed cover the pipelines with mechanical protection and anti-erosive. The pipes were supported with sacks of granular material, sequentially, the margins and pipelines were protected with geotextile filled with concrete, installed with the help of divers. The working conditions of 4.0 m depth, currents of up to 0.8 m/s, temperature and low visibility waters were challenges overcome during execution, in which the divers took turns in short periods. Due to the characteristics of the bedrock, the blankets went stylized and stitched on the field by the team, with dimensions taken on site. After positioning the blankets in the background began the underwater concreting, which occurred in stages monitored by the volume pumped and divers strategically placed. The crossing river was re-inspected approximately 1 (one) year after their stabilization and was found in good conditions. The occurrence improved the procedures for geotechnical monitoring and treatment of pipelines uncovered in crossings rivers, being who the efficiency and safety of the work performed currently serve as a reference for the design of similar works.

After a period of heavy rainfall, the landslide of a mass of residual soil in the side slope to the Pipeline Range of PETROBRAS occurred, in which two oil pipelines and gas pipeline connecting a terminal to a refinery. On the day following the event in field inspection performed by the TRANSPETRO team, it was found that due to the landslide, the gas pipeline was exposed, with a Section of approximately 8.0 meters apparent in a slope at risk of undergoing deformations with the movement of unstable soil. In the course of the inspection several indications soil movement were observed, such as cracks in the ground, breaks and located cracks in reinforced concrete structures of the drainage system. Surge flow of water or soil saturation was not found, despite the high rate of rainfall during the period. Thus one ruled out the possibility of the presence of a high water table which could have caused sliding. It is assumed that this may have begun on lower slopes due to deficiencies in the surface drainage system, which caused the accumulation of rainwater and its collapse. Hence, ruptures allegedly have occurred progressively upstream until it reaches the side of the pipeline range. To ensure the integrity of the gas pipeline and operational safety and prevent the evolution of the incidents with more serious consequences, a contingency group responsible for coordinating emergency actions to contain the slope and protecting the pipeline exposed was called. The first actions consisted of protecting the slope using a plastic tarpaulin to prevent the infiltration of more rainwater, metal profile riveting to contain side soil movement to the pipelines and finally to the implementation of contention with soil nailing technique with shotcrete on the surface of the slope where the pipeline was exposed found. Repairs to the surface drainage system of the range and slopes, which had been damaged during landslide were made. In parallel to emergency actions, a campaign of geotechnical surveys using Standard Penetration Test (SPT) aiming at providing grounds for stability studies for the preparation of final stabilization project of the slope.

The Camisea Pipeline Transmission System (PTS) in Peru consists of two parallel pipelines, a Natural Gas (NG) pipeline and a Natural Gas Liquids (NGL) pipeline. The NG pipeline is 834 km long, including a 105 km loop. The NGL pipeline is 557 km long. Since 8 years ago and as a part of the current operation of the system, maintenance activities are being carried which, within its objectives for improvement, seek to establish a preventive approach instead a corrective approach. The involved areas in this new Management approach are geo-technics, pipelines, environment, communities and integrity. This paper describes the process named Integral Plan for Operating Risks. This process is a result of the updating of the geological-geotechnical base-line, in relation to the environmental and social context, allowing a comprehensive analysis of the status of the relation between the works and its environment, as well as planning prevention tasks able to guarantee the stability of the right of way (RoW) and the pipeline Integrity. This job is performed by both desk work (remote interpretation) and field work conducted by multidisciplinary teams, which ensures a transverse communication flow. All of this is backed by a digital database and a geographical information system (GIS). A Technical Atlas is constructed as a graphic document containing a series of cartographic and text cards regarding the sector under study as a useful instrument of preventive management for intervention in a given area. To date, a comprehensive remote analysis of the RoW has been completed and an in-site field analysis has started, upon which strategies are being developed in order to control items such as geological hazards, geological architecture, vegetation architecture, RoW stability, etc. Jobs were competed along the first 12 km as a pilot experience, which is being replicated all along the RoW.

In February 2009 a pipeline rupture occurred along a sloped section of the Oleoducto de Crudos Pesados (OCP) Ecuador S.A. pipeline. The spill resulted in crude oil flowing down the hillside and into the Rio Santa Rosa. Post rupture investigations were initiated to identify the geotechnical factors that may have contributed to the incident and what mitigation may be necessary to ensure future pipeline integrity. The investigation consisted of several activities including detailed site reconnaissance by a geotechnical engineering team and installation of slope inclinometers to assess ground movements. The intent of the slope inclinometers was to determine the depth, areal extent and rate of ground movement, if any. The post rupture site reconnaissance identified a number of terrain features consistent with shallow ground movement mechanisms. The presence of hummocky terrain could be the result of ground movement or an artifact of the use of the slope as cattle pasture. Five slope inclinometers were installed to assess the slope movements within the project site. Four slope indicators were installed up-slope of the pipeline right-of-way to provide some lateral boundary to the ground movement area. The slope inclinometers showed that in the months following the pipeline rupture the terrain upslope of the pipeline right-of-way was moving at a relative constant rate of about 0.45 mm/day. As a result of the geotechnical investigations an integrity mitigation plan was developed. This included ongoing slope movement monitoring, regular site reconnaissance and placement of the pipeline above ground on “sleepers” to isolate the pipeline from the underlying creeping slope. To-date, these mitigations have been successful in reducing strain on the pipeline.