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Production Operations and Flow Assurance
Published in Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović, Practical Nanotechnology for Petroleum Engineers, 2019
Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović
Flow assurance is a production subdiscipline in which engineers strive to maintain “a reliable, manageable, and profitable flow of fluids from the reservoir to the sales point” (Denney 2002). With the advent of deepwater exploration and production, particularly in the Gulf of Mexico, subsea infrastructure design has become increasingly focused on preventing flow assurance problems and allowing easy access for intervention if necessary (Forsdyke 1997). Typical deepwater development in the Gulf of Mexico involves placing tens of kilometers of pipeline in water with temperatures of roughly 4°C and traversing changes in water depth of 300–400 m (e.g., Gudimetla et al. 2006). The changes in pressure and temperature experienced by fluids as they flow through these pipelines can include precipitation of hydrates, wax, and asphaltenes, since multiple hydrocarbon phases along with water are typically present, with associated complex phase behavior (Forsdyke 1997). If any of these substances accumulate in the pipeline, flow can be inhibited or even stop completely, posing safety, environmental, and economic risks.
Offshore Pipeline
Published in Sukumar Laik, Offshore Petroleum Drilling and Production, 2018
The term ‘flow assurance’ was first used by Petrobras in the early 1990s in Portuguese as ‘Garantia do Escoamento’, meaning literally ‘guarantee of flow’. Thus, it is defined as the technology and ability to ensure the successful and economical flow of the hydrocarbon stream from the reservoir to the point of sale. Flow assurance addresses broad aspects of the problems and solutions of flow distortion, including solid depositions of waxes, hydrates, asphaltenes and scales. The deepwater production environment and transportation through longer pipelines and flowlines provides conditions that brought about flow assurance challenges. These flow assurance challenges are as illustrated in Figure 8.19. For effective subsea production, it is important to identify the potential for and quantify the extent of any solid deposition in the system. Some flow assurance challenges such as wax and hydrate formation and deposition are very common in subsea pipeline because of the favourable subsea pressure and temperature conditions. The asphaltene and scale deposition also cause problems. A brief discussion on each of these problems follows.
Conclusions, Current Research, and Future Directions
Published in Francisco M. Vargas, Mohammad Tavakkoli, Asphaltene Deposition, 2018
S. Enayat, F. Lejarza, R. Doherty, A. T. Khaleel, C. Sisco, J. Kuang, M. I. L. Abutaqiya, N. Rajan Babu, M. Tavakkoli, F. M. Vargas
Most reservoir fluids contain waxes, which are normal paraffins, slightly branched paraffins, and also naphthalenes with long paraffinic chains (Pedersen et al. 2006). Like asphaltenes, waxes can precipitate out of solution, deposit in pipelines, and cause major flow assurance problems. This is particularly problematic in low-rate wells, where the oil has a greater residence time in the wellbore. The increase in flow time allows a greater heat loss, decreasing the oil temperature, which in turn can lead to wax precipitation and deposition (Weingarten and Euchner 1988). Wax appearance temperature (WAT), also known as cloud point, and wax content can be measured using different techniques such as microscopy, differential scanning calorimetry (DSC), pulsed NMR, microfluidic and rheometry techniques, among others (Zhao et al. 2015; Japper-Jaafar et al. 2016; Molla et al. 2016).
Investigation of gas hydrate phase equilibria in bulk and in a large particle size natural quartz sand for methane, carbon dioxide and natural gas
Published in Petroleum Science and Technology, 2023
Lucila Cruz-Castro, Edgar Ramirez-Jaramillo, Apolinar Albiter-Hernández
The CH4 hydrates are the most common in nature (Sloan and Koh 2008) as well as the natural gas mixtures, where CH4 is generally the component with highest proportion, so they are considered as a potential resource for energy supply. Recently, an onshore gas-condensate field with evidence of an aquifer was discovered in southeast of Mexico, which is particularly relevant due to its production potential. However, in short term it could present flow assurance problems in the reservoir and pipelines, derived from the formation of organic solids, in particular waxes and gas hydrates. It is known that when the temperature and pressure drop in a gas-producing well, it can condense forming a liquid phase, which contains paraffinic components that can precipitate into a solid phase, generating a complex solid–liquid–gas multiphase mixture. Also, the presence of water in the reservoir could generate emulsions that would affect the operating conditions of the well and surface lines. In addition, the water in the reservoir can promote nucleation and gelation in the wax deposit at different intensities when low temperatures are reached, which depends on the degree of emulsification of the water (Wang and Yunfei 2022). Therefore, it is necessary to study the thermodynamic behavior of the fluid produced from the reservoir to the surface, to determine the P–T conditions at which the problem could arise.
Experience and lessons in crude oil pipeline pigging: Case studies from field practices
Published in Petroleum Science and Technology, 2022
Weidong Li, Wenda Wang, Jirong Ran, Huiyuan Li, Jianxun Liu
Wax deposition is an intractable flow assurance challenge for waxy crude oil production and transportation (see Figure 1) (Wang et al. 2017, 2019; Bell et al. 2021). It occurs at low ambient temperatures where the oil temperature drops below its wax appearance temperature (WAT), which helps to establish a negative radial temperature gradient to drive the molecular diffusion. Wax deposition decreases the oil flow passage, harms the pipeline transportation capacity and increases the pumping cost. Due to the low seawater temperature, wax deposition of offshore pipes could be more severe than onshore pipes. The consequent underwater repair treatment is prohibitively expensive (Wang et al. 2015). For wax remediation, multiple methods have been proposed. For example, mechanical pigging removes the deposited wax off the pipe wall with the scrapers on pig; inductive heating inductively heats the wax plugging section of the pipe through an external coil positioned over the line; cold flow allows wax precipitation to form solid slurry in the first section of the pipe to be transported in a stable way without further solid deposition; chemical injection inhibits, dissolves or heats wax deposits; biological treatment provides continuous control of wax deposition in pipelines through constant biodegradation (Aiyejina et al. 2011; Adebiyi 2020). Among these techniques, mechanical pigging is the most widely used one for its convenience, efficiency and economy (Halstensen et al. 2013).
Experimental and numerical investigation on convective heat transfer in actively heated bundle-pipe
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Ola Karar, Sampath Emani, Ramasamy Marappa Gounder, Maung Maung Myo Thant, Hilmi Mukhtar, Mohsen Sharifpur, Milad Sadeghzadeh
Rapid growth in hydrocarbon demand and crude oil production has directed the explorations towards offshore operations ranging from shallow to ultra-deepwater. However, due to the extreme ambient conditions of low temperature and high pressure, hydrate formation and solid depositions became major challenges in the upstream operations. The drop in temperature and pressure of crude oil when being transported provide a friendly environment for the formations of hydrates and other solids such as wax, which grow into larger aggregates overtime/length of the pipeline. Wax formation in the pipeline has a direct effect on fluid flow and heat transfer. The aggregates of wax increase fluid viscosity which causes critical flow issues such as huge pressure drop inside the flow lines, high pumping power requirements, reduced permeability, change in oil rheology, clogging the flow line, fittings, control valves, and unplanned disruptions in production (Mansourpoor et al., 2019). A reduction in the thermal conductivity due to wax aggregates leads to a reduction in convective heat transfer coefficient and heat transfer in the pipe. Therefore, designing and operating offshore pipelines require advanced risk management techniques to mitigate these potential adverse effects (Kenny, 2018). Flow-related issues such as hydrates formation, wax, and asphaltenes deposition, slugging, scales, corrosion, erosion, and emulsions were the motivation to introduce flow assurance techniques in the 1990s (Camargo et al., 2004). Flow assurance aims to achieve profitable, safe, and reliable operations in the given oil & gas price scenario (Arcangeletti et al., 2019).