Wax In Pipelines Research Articles

Применение растворителя для удаления асфальтосмолопарафиновых отложений из морского трубопровода нефти

PA-B off-shore pipeline wax deposits have been analyzed and researched (Piltun-Astokh oil field, Sakhalin island). It is found out that crude oil includes 2.1% paraffins, basically consisting of normal hydrocarbons with carbon number of 28 to 46. Wax dissolver has been selected, which application allows keeping design pipeline capacity.

Occurrence and Characterization of Paraffin Wax Formed in Developing Wells and Pipelines

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.

Pipeline wax deposition modeling: A sensitivity study on two commercial software

This paper presents the results of a sensitivity study carried out to investigate the performances of two commercial codes, OLGA and LedaFlow, used to model the wax deposition process in pipelines under multiphase flow. Reliable simulations of the phenomenon are essential to properly design pipelines and to adopt cost-effective strategies for prevention and removal of wax deposits, reducing the risks of blockage. The main limit of the available models is that their predictions depend on a number of parameters which are usually adjusted to fit the experimental data obtained from laboratory deposition tests. Since a reliable upscale criterion has not been developed yet, model predictions have been more suitably validated using real field data, reported in literature. The performances of the commercial codes in modelling wax precipitation and deposition have been compared to each other.

Effect of drag reducer and pour point depressant on the wax deposition of crude oil pipeline

ABSTRACTIn this paper, the data of wax precipitation before and after the addition of the additives showed that the addition of the drag reducing agent (DRA) and the pour point depressant (PPD) cannot change the wax appearance temperature (WAT) of crude oil. When the dosage of DRA is small, the DRA cannot increase, stop, or slow down the precipitation of wax crystals. The addition of PPDs has no influence on the amount of precipitated wax crystals. From the GPC analysis, the molecular weight of the wax deposit samples in Linpu pipeline is from 500 to 76,800, which indicates that there is no enrichment of DRA in wax deposit samples. The results of IR show that the C˭O group was not detected in the wax deposit sample of the Wei Jing pipeline, which indicates that there is no enrichment of the PPDs in wax deposit samples. The results showed that the DRA and PPD have no obvious effect on crude oil pipeline wax deposition.

Effect of the Flow Field on the Wax Deposition and Performance of Wax Inhibitors: Cold Finger and Flow Loop Testing

Chemical inhibition is one of the methods to mitigate deposition of wax in pipelines; however, the efficiency of the inhibitors needs to be validated in the laboratory prior to field applications. Cold finger, as the most commonly used experimental setup in the field, has quite a different shear regime and temperature field compared to the flow loop and field production pipeline. This paper investigates the flow field (cold finger and flow loop) effect on the wax deposition and the performance of wax inhibitors under the same initial temperature difference and comparable shear stress conditions. The normalized deposit mass, wax content, carbon number distribution, and wax mass flux were investigated in these two different flow fields, and the performance of wax inhibitors was also investigated. Moreover, the results from this study are expected to serve as a basis for selecting proper inhibitors for field applications based on laboratory testing.

Design of novel chemical solvent for treatment of waxy crude

Deposited wax in pipelines and well bores are not easily recoverable due to its solidification over time. This is responsible for losses in production. In this paper, chemical solvent derived from laboratory was used to recover the solidified wax. Twelve chemical solvents and three commercial dispersants were mixed in different volumetric proportions to study their solubility effect on waxy crude oil. Optimised solvent mixture capable of dissolving wax material was used on a laboratory prototype experiment to measure the recovery of deposited wax at different temperatures (pour point of crude oil to 90°C). Optimum composition of solvent was based on its toxicity, flammability, availability and other contributing factors like cost and recoverability. The formulated solvent dissolved about 72% and 83% wax after three hours and six hours of soaking time respectively at 25°C. Results implied that formulated solvent have immense potential to recover solidified wax in wellbores and in pipelines. [Received: January 10, 2016; Accepted: March 13, 2016]

Prediction of Wax Deposition in an Insulation Crude Oil Pipeline

This study establishes an insulation crude oil pipeline wax deposition experimental device and describes the experimental method for insulation crude oil pipeline wax deposition. The experimental program is based on the operational plan of Tieling–Huludao insulation crude oil pipeline. The data are analyzed according to the effect of varying oil temperature, insulation thickness, and flow on wax deposition. Using SPSS software, a Daqing crude oil wax deposition rate model is derived from the linear regression. The use of the wax deposition rate model forecasts the wax deposition of the Tieling–Huludao insulation crude oil pipeline during different seasons.

Technology Focus: Production and Facilities (December 2014)

Technology Focus Two points stand out in the development and status of technology for production and facilities. The first is the amount of innovative ongoing work related to piping, pipelines, and materials for severe service. The second is the amount of work involving the use of digital simulations, including computational fluid dynamics (CFD). Pipes are the arteries and veins of production and facilities, yet too few of us are concerned about their technical status. Fortunately, others among us are concerned about this topic. As oil production moves to increasingly hostile and remote environments, the need is increasing for reliable yet affordable pipeline technology that meets the demands of severe environments. Because of the scale and the environmental severity experienced by high-pressure/high-temperature (HP/HT) and other severe service, pipelines can be prohibitively expensive to duplicate in testing facilities. Research and development increasingly uses experience-validated digital simulations and modeling, sometimes synergistically. The technical community continues to respond to severe-service challenges with research and development on, for example, how to implement corrosion-resistant-alloy (CRA) technology, how to specify and use composite materials for pipelines, and how to better install and maintain piping (including deep-sea risers and subsea lines) constructed with conventional metallurgies. Of the papers I considered for this feature, one reported on an investigation of the fatigue aspects of CRA welds for pipes in HP/HT service using finite-element analysis, while another reported on the development of an understanding of welding residual stress with the use of computational-welding-mechanics simulations. Another group of investigators provided an overview of research on the use of composite flowlines, risers, and pipework in offshore applications. An improved understanding of vortex- induced vibration was presented by another group of investigators, who used 3D dynamic CFD simulations. In a transition from the pipeline to facilities design, other investigators developed a methodology for sizing two-phase separators and slug catchers by use of a combination of dynamic pipeline modeling and CFD. But the use of digital simulations and modeling does not stop here. Operator training and process safety are being enhanced by the use of plant simulators and virtual reality. Flow assurance is taken to a new level by the development of a fully compositional wax-deposition model to help explain the location and physical character of pipeline wax deposits. Overall, it is clear that digital-simulation capabilities are quietly revolutionizing the way in which technology is developed and deployed within our industry. The fundamental understanding afforded by a variety of digital simulations is unprecedented and will continue, allowing for the rapid development and deployment of more reliable, better-performing piping and facilities technologies. JPT Recommended additional reading at OnePetro: www.onepetro.org. OTC 24797 Modeling the Shearing Effect of Flowing Fluid and Wax Aging on Wax Deposition in Pipelines by Xiaohong Zhang, Infochem-KBC, et al. OTC 25039 Welding Residual Stress and Pipeline Integrity by R. Tornqvist, DNV GL, et al. OTC 25063 Numerical Studies of Vortex-Induced Vibration of a Circular Cylinder at High Reynolds Number by M. Mobassher Tofa, Universiti Teknologi Malaysia, et al.

Direct electric heating: an environmentally friendly flow-assurance tool

In subsea flowlines, water in the line can form an ice-like structure called a hydrate plug. Wax appearance in flowlines also is a common flow assurance issue. Hydrate and wax appearance can reduce or stop production for weeks. Preventing hydrate and wax in pipelines is a major concern for the oil and gas industry. Direct electric heating (DEH) is a modern and environmentally friendly flow-assurance tool that can reduce capital expenditures (CAPEX) and operating expenditures (OPEX) in field development, reduce the probability of pollution, and reduce handling of toxic disposals as a result of traditional chemical flow assurance methods. DEH is based on using the pipeline as part of the electrical circuit, generating losses in the steel pipe to keep the pipeline and its content above the critical temperatures. Use of DEHs also increases the efficiency at the process plant after planned or unplanned production stops. For marginal fields and fields with heavy or waxy oil, DEH is a flow-assurance method that can enable these fields to be developed profitably. DEH is now a mature technology used for 13–14 years on the Norwegian continental shelf and technology implemented and used in West Africa recently. How successful this technology has been can be summarised by the Tyrihans field where Statoil quoted that they—on this project alone—saved about $USD175 million by implementing DEH. Wärtsilä has been part of the DEH development in Norway since the 90s, and undertakes design and supply of the complete topside power package in addition to electric and optical protection specially developed for DEH systems.

Online estimation of wax deposition thickness in single-phase sub-sea pipelines based on acoustic chemometrics: A feasibility study

Wax deposition in sub-sea oil producing pipelines is a concern to the oil producing companies. The deposition of wax in pipelines can cause serious economic implications if not monitored and controlled. Several researchers have developed models and investigated the deposition of wax in crude oil pipelines. As of today, there is no off the shelf instrument available for reliable online estimation of the wax deposition thickness in sub-sea pipelines. Acoustic chemometrics was applied to investigate the potential for online estimation of wax deposition thickness in sub-sea pipelines. This feasibility study was carried out as a so called piggy back on experiments performed at Statoil research centre in Porsgrunn, Norway with real crude oil or waxy gas condensate. The first investigations focused on the repeatability of the acoustic chemometric technique followed by online prediction of the wax deposition thickness in a single-phase oil flow pipeline. A partial least squares regression model was calibrated and validated with a totally independent data set. The calibrated model had a root mean squared error of prediction of 0.28mm with a final wax deposition thickness of 3.36mm, a slope of 0.91 and R2 of 0.83 which were satisfactory results. The effect of varying oil flow rates on the wax deposition thickness was also investigated. The preliminary results showed the need for further investigations based on a robust experimental design and sample pre-processing. The general conclusion that can be drawn from this feasibility study was that the potential of adapting the acoustic chemometric technique for online estimation of the wax deposition thickness exist and must be further investigated.

Study on the Pipeline Wax Deposition Mechanism and Influencing Factors

The phenomenon of wax deposition is an extremely important issue in the petroleum industry. Researching it is of great help for the oil exploration, gathering, and transportation. This paper described the phenomenon of wax deposition, discussed the mechanism, analyzed the influencing factors and proposed the positive significance of the phenomenon of wax deposition on crude oil production and safe operation in oil gathering and transportation pipeline.

The Importance of Wax-Deposition Measurements in the Simulation and Design of Subsea Pipelines

Summary Conventional practices for estimating the amount of deposited wax in pipelines are usually based on predictions made with simulation packages using limited stock-tank-oil (STO) deposition data collected under laminar-flow conditions in bench-scale flow loops. Such practices are conservative and often lead to nonoptimal designs of pipelines and surface facilities. For optimized designs, laboratory-scale deposition measurements made under realistic conditions are required to calibrate flowline models. In this work, a high-pressure deposition cell that operates on the Taylor-Couette (TC) flow principle is used to generate more deposition data with live reservoir fluids under turbulent flow similar to the conditions encountered in many flowlines. The analogy between TC flow and pipe flow is explained, and a scalability flow chart for linking the laboratory-scale deposition data from TC configuration to pipe configuration is presented. Through a case study, the scaled-deposition data are then used to tune a wax-deposition model in the OLGA®5 simulation package. Next, the tuned model is applied to predict wax deposition under actual production and transportation conditions. The importance of tuning the deposition models with live fluid data under turbulent-flow conditions is also shown by comparing results obtained from conventional dead-oil low-shear data.

Low-Temperature Oxidation Characteristics of Pipeline Wax

Four samples of pipeline wax from a North Sea crude oil pipeline have been examined in a microcalorimeter across a range of temperatures. The samples, which weighed a little under a gram, gave heat-release rates up to about 20 μW, and the initial temperature history is such that there is a small amount of melting which is manifest as a negative microcalorimeter signal. Esti mated activation energies for the oxidation are of the expected order of magni tude, though a little low.

Towards an alternative criterion for the shipping safety of activated carbons

A previous paper developed a criterion for the shipping safety of activated carbons focused on heat-release rate at criticality. This was shown to be an improvement on current test procedures, based on critical ignition temperature, which can be shown, on theoretical grounds, to be reliable only if the material under examination has a particular value for the activation energy of reaction, actually 90 kJ/mol. The tests are however often applied in total ignorance of the value of E, in which case they cannot be expected to give a reliable prediction. The previous paper compared predicted safety, in terms of supercriticality or subcriticality in a 3 m 3 shipping hold, on the basis of the two criteria: heat-release rate at criticality and critical ignition temperature. These are respectively: q=0.002 W/kg where q=heat-release rate at 38°C, and CIT=140°C where CIT=critical ignition temperature for a 10 cm 3 . Comparison were made between q values and CIT values for a suite of 11 activated carbons of various manufacturing histories. In this paper, we take the ideas and findings further in the following ways: (1) The comparisons between the predictions on the two criteria are examined in the light of the activation energies of the respective activated carbon samples. (2) The heat-release rate at criticality is estimated for three other types of solid substrate - bituminous coals, sawdust and crude oil pipeline wax - and the values compared with measurements by microcalorimetry.