Predictive control of the starting pressure of the main oil pipeline

The article calculates the starting pressures and the time of safe shutdown of the pipeline during the transportation of high-viscosity and high pour point oils, the rheological properties of which depend on temperature. When the oil temperature decreases, its viscosity increases and paraffins are released, forming a strong structure, for which additional stress is necessary to shift. To start a stopped oil pipeline transporting oil with such characteristics, the pressure developed by the pumps may not be enough. In this regard, it is necessary to determine the safe time of stopping the oil pipeline. The relevance increases with an increase in the share of high-viscosity and high pour point oil in the total production volume. Predictive control, based on the analysis of data on the characteristics of the transported product and forecasting the nature of their changes, is an intelligent tool for managing the efficiency of technological transport enterprises. Predictive control allows you to choose the optimal way to ensure reliable and trouble-free operation of the main equipment of hydrocarbon transport systems.A numerical experiment was carried out for the effect of seasonal cooling devices to protect permafrost soils from thawing, at the time of a safe shutdown of the oil pipeline. The values of starting pressures have been determined. Dependence of the pressures on the duration of the safe shutdown of the pipeline has been established. It was revealed that due to the operation of seasonally operating cooling devices, the difference between the temperature soil and oil increases during cooling, and the cooling rate increases. More pressure will be required to launch such an oil pipeline.

Supervised Learning Algorithms Applied in the Zoning of Susceptibility by Hydroclimatological Geohazards

Cenit Transporte y Logística de Hidrocarburos (CENIT), operator of about 7000 km of hydrocarbon transport systems, which constitutes it the largest operator in Colombia, has developed a strategic alliance to structure an adaptive geotechnical susceptibility zoning using supervised learning algorithms. Through this exercise, has been implemented operational decision inferences with simple linguistic values. The difficulties proposed by the method considers the hydroclimatology of Colombia, which is conditioned by several phenomena of Climate Variability that affect the atmosphere at different scales such as the Oscillation of the Intertropical Convergence Zone - ITCZ (seasonal scale) and the occurrence of macroclimatic phenomena such as El Niño-La Niña Southern Oscillation (ENSO) (interannual scale). Likewise, it considers the geotechnical complexity derived from the different geological formation environments, the extension and geographical dispersion of the infrastructure, and its interaction with the climatic regimes, to differentiate areas of interest based on the geohazards of hydrometeorological origin, when grouped into five clusters. The results of this exercise stand out the importance of keep a robust record of the events that affect the infrastructure of hydrocarbon transportation systems and using data-guided intelligence techniques to improve the tools that support decision-making in asset management.

Towards a Structured Maintenance and Integrity Management Program of Hydrocarbon Transport Systems - Emphasis on Geohazards

The main objective of the integrity and maintenance professionals of hydrocarbon transportation companies is to ensure the integrity and availability of transportation systems by monitoring and controlling the risks to which they are exposed. This article presents a series of aspects that give scope to a structured maintenance and integrity management program, and that can be established in each company based on its organizational structure and culture. Some examples are presented to take into account in geohazard management and that focus on achieving a holistic and prospective view of the professionals who manage geotechnical risk.

Diffusion-Based Modeling of Gas Transport in Organic-Rich Ultratight Reservoirs

Summary The complex pore structure and storage mechanism of organic-rich ultratight reservoirs make the hydrocarbon transport within these reservoirs complicated and significantly different from conventional oil and gas reservoirs. A substantial fraction of pore volume in the ultratight matrix consists of nanopores in which the notion of viscous flow may become irrelevant. Instead, multiple transport and storage mechanisms should be considered to model fluid transport within the shale matrix, including molecular diffusion, Knudsen diffusion, surface diffusion, and sorption. This paper presents a diffusion-based semianalytical model for a single-component gas transport within an infinite-actingorganic-rich ultratight matrix. The model treats free and sorbed gas as two phases coexisting in nanopores. The overall mass conservation equation for both phases is transformed into one governing equation solely on the basis of the concentration (density) of the free phase. As a result, the partial differential equation (PDE) governing the overall mass transport carries two newly defined nonlinear terms; namely, effective diffusion coefficient, De, and capacity factor, Φ. The De term accounts for the molecular, Knudsen, and surface diffusion coefficients, and the Φ term considers the mass exchange between free and sorbed phases under sorption equilibrium condition. Furthermore, the ratio of De/Φ is recognized as an apparent diffusion coefficient Da, which is a function of free phase concentration. The nonlinear PDE is solved by applying a piecewise-constant-coefficient technique that divides the domain under consideration into an arbitrary number of subdomains. Each subdomain is assigned with a constant Da. The diffusion-based model is validated against numerical simulation. The model is then used to investigate the impact of surface and Knudsen diffusion coefficients, porosity, and adsorption capacity on gas transport within the ultratight formation. Further, the model is used to study gas transport and production from the Barnett, Marcellus, and New Albany shales. The results show that surface diffusion significantly contributes to gas production in shales with large values of surface diffusion coefficient and adsorption capacity and small values of Knudsen diffusion coefficient and total porosity. Thus, neglecting surface diffusion in organic-rich shales may result in the underestimation of gas production.

Sand Dune Migration Monitoring for Pipeline Hazard Risk Mitigation: The Peru LNG Coastal Section Case

Pipelines often cross challenging terrains where natural hazards are the main risk for their integrity. Environmental conditions can also worsen over the infrastructure lifetime. To reduce the risk of disasters, integrity programs are developed implementing tools for early detection of threats that can lead to a failure with dramatic social, environmental and economic consequences. Fiber optic (FO) monitoring solutions have been widely used and implemented as one of the most efficient prevention tools of these programs. These solutions include geotechnical monitoring, third party intrusion detection and eventually small or pinhole like leak detection. FO based geotechnical monitoring has been successfully operated along the Sierra section of the Peru LNG pipeline since 2010, detecting minor landslides and erosion events. It has also been implemented along other hydrocarbon transport systems to allow the early detection of such events. However, these natural hazards are not the only ones threatening the pipeline. In fact, the coastal section experiences other phenomenon such as sand dune migration and eolian erosion that put the pipeline at risk. Recently, the FO monitoring was extended to the coastal region using the existing communication fiber optic cable to sense temperature changes. Very localized events are thermally detected, their spatial and temporal signature analyzed. The comparison of this data with thermal models identified sections that are close to be exposed or whose soil cover is less than 50cm over a spatial extension that does not exceed a couple of meters. Depth of cover of 10 to 30cm is estimated from such analysis. These results are confirmed by past and ongoing site inspections. Such positive results again illustrate the potential value of fiber optic sensing to mitigate geohazard risks. It not only enhances the efficiency of the integrity program detecting and localizing threats, it also improves and rationalizes the maintenance activities as focused surveys can be conducted.

Estimation of the resource of pipes of the main circulation pipeline of a NPP by the criterion of crack resistance with account of operational degradation of properties

The results of an experimental determination of the characteristics of cyclic crack growth resistance of specimens made of stainless steel 08Kh18N12T are given. Compact samples 20 mm thick cut from Du 550–30 pipes of the primary circuit of the main circulation pipeline (MCР) were studied under eccentric tension in the initial state and after 100 thousand hours of operation in the conditions of the Novo-Voronezh NPP. Using a new engineering approach based on measuring the specimen tightening and constructing a cyclic elastoplastic fracture diagram for a specimen with a crack in the coordinates “tightening – the stress intensity factor, calculated taking into account the plasticity correction”, a calculated life estimation is given for the pipe of Du 550–30 MCР NPP, made of 08Kh18N12T steel, according to the criterion of cyclic crack growth resistance, taking into account operational degradation of properties caused by the running time of 100 thousand hours. The life (survivability), expressed in a number of cycles of change in internal pressure, for a pipe with the most dangerous defects (surface semi-elliptical crack and combined defect “pitting + crack”) is determined. An analysis of the influence of the level of initial damage and the type of hazardous defect on the survivability of the pipes is made. The results can be used to analyze damage and predict the life of pipes made of ductile metals and alloys, in cooling systems of reactors, as well as main pipelines of hydrocarbon transport.