How to address precipitation of Wax deposits in Oil transmitting Pipilines etc., (original) (raw)
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Determination of wax content in crude oil.pdf
Wax deposition is one of the chronic problems in the petroleum industry. The various crude oils present in the world contain wax contents of up to 32.5%. Paraffinwaxes consist of straight chain saturated hydrocarbons with carbons atoms ranging fromC18 to C36. Paraffin wax consists mostly with normal paraffin content (80–90%), while, the rest consists of branched paraffins (isoparaffins) and cycloparaffins. The sources of higher molecular weight waxes in oils have not yet been proven and are under exploration. Waxes may precipitate as the temperature decreases and a solid phase may arise due to their low solubility. For instance, paraffinic waxes can precipitate out when temperature decreases during oil production, transportation through pipelines, and oil storage. The process of solvent dewaxing is used to remove wax from either distillate or residual feedstocks at any stage in the refining process. The solvents used, methyl-ethyl ketone and toluene, can then be separated from dewaxed oil filtrate stream by membrane process and recycled back to be used again in solvent dewaxing process.
Naturally occurring hydrocarbons in the earth's crust contain varying amounts of certain molecules generally called asphaltenes and waxes. Asphaltenes exhibit ~ behavior .at some thermodynamic states called flocculation. That IS, asphaltene particles or micelles present in crude oils aggregate or flocculate into larger aggregates or flocs. The locus of .all thermodynamic points in a P-T-x phase diagram at which flocculation occurs is called the Asphaltene Deposition Envelope (ADE). Paraffin waxes present in crude oils, on the other hand, at some thermodynamic states, exhibit the phenomenon of crystallization. The locus of all thermodynamic points in a P-T-x phase diagram at which wax crystallization occurs is called the Wax Deposition Envelope (WOE). Paraffin waxes are rather a polar molecules and their interactions are expected to be van der Waals or London dispersion type, whereas asphaltene molecules are polar in nature and, as a result, are expected to have polar, hydrogen bond type, or associative type molecular interactions. Asphaltene flocculation and wax crystallization are two mechanisms via which organic deposition takes place from crude oils. Paraffin deposition problems have been recognized as one of the main challenge in oil and gas industry during production and transportation of crude oil. Paraffin could be deposited anywhere along the production system, from near the wellbore region to production tubing, flow lines, pipeline, and processing facilities such as separators and leading to the reduced production and transportation rate, equipment damage, and production shut down. Hence, several methods such as mechanical, thermal, and chemical have been used to remove and prevent the formation of paraffin deposits. This study aims at getting acquainted with the causes and mechanism of wax deposition along with magnitude of the problem and its impact on the petroleum sector. 2 2 | P a g e
Occurrence and Characterization of Paraffin Wax Formed in Developing Wells and Pipelines
Energies
Deposition and precipitation of paraffin wax in pipelines are major problems in the production, transfer, storage, and processing of crude oil. To prevent complete clogging, it is necessary to minimize and remove deposited wax in pipelines and tubing. Significant research has been done addressing the mechanisms of wax formation and its composition. In this review, the status of research and perspectives on the occurrence and characterization of the paraffin wax that forms in crude oil developing wells and pipelines has been critically reviewed. Several approaches for detecting paraffin wax and managing wax formation damage during oil recovery were discussed. This review also highlighted the effects of temperature and crude oil type on wax formation.
Introduction to Wax Deposition
Int J Petrochem Res, 2018
This work is presents in brief an introduction to wax deposition process to give a general understand of this problem because of arising the challenges of growing wax deposition in the hydrocarbon pipelines by increasing production in the cold environment due to increasing demand for energy. Background and identification of wax deposition problem in the hydrocarbon pipelines are presented. Mitigation methods are used to address this problem, such as chemical, mechanical and thermal methods, but despite the available inhibition methods, many oil companies currently suffer from wax deposition problems and are still looking for a good solution to solve this issue. This research presents some of the case studies of wax deposition around the world and the methods followed to mitigate wax deposition of each case study. Numerous researchers have used various different types of chemical inhibitors, such as polyacrylate polymer, copolymer esters, polyethylene, olefin/ester copolymers, ethylene/vinyl acetate copolymers, ester/vinyl acetate copolymers, polymethacrylates, alkyl phenol resins, xylene and toluene, to studying their influence on the rheology of crude oil and to evaluate the suitable inhibitor for the waxy crude oil that provides the desired results in preventing wax deposition. The decent understanding and managing of wax deposition phenomena before it happens is strongly required in order to overcome the challenges in production and transportation of pipelines in the cold environment.