Paraffin Deposition Research Articles

Modeling and prediction of asphaltene-resin-paraffinic substances deposits in oil production wells

In the oil industry today, the issue of combating deposits of asphaltene-resin-paraffinic substances (ARPD) remains relevant. At the moment, the most common method in the Perm Territory for removing ARPD in wells operated by electric centrifugal pumps is mechanized (mechanical dewaxing units). This method is the main one in the fight against wax deposits, but does not provide absolute protection. The least costly way to deal with ARPD is the use of flushing with hot oil or water, but this also does not always provide sufficient efficiency. The effectiveness of technologies will depend on the depth of deposition, the intensity and thickness of the formed layer of paraffin deposits, respectively, to select an effective technology for each specific well, knowledge of these parameters is required. To solve this problem, computational hydraulic models were created, hydrodynamic modeling and simulation of paraffin deposits when lifting fluid in a well was carried out using the example of five wells of one of the oil fields of the Perm Territory. Based on the calculations, recommendations were given on the choice of the method for removing and preventing ARPD for the analyzed wells. The proposed measures have been implemented at the wells and to date have led to a reduction in the costs of their implementation and significantly reduced oil shortages. In three wells, the change in annular pressure led to a decrease in foaming and stabilization of the dynamic level, while the main problem was solved – ARPDs are not formed in the annulus.

Исследование причин образования асфальтосмолопарафиновых отложений товарной нефти в условиях эксплуатации магистральных нефтепроводов

The results of investigations of the main causes and the most significant factors of intensification of paraffin deposition in main oil pipelines are presented. A comprehensive analysis of the composition and properties of commercial oils and their sediments was carried out, according to which phase diagrams of equilibrium of oil dispersed systems were obtained using the example of commercial oils from Bashkir fields. Based on the phase diagrams, a curve of wax oil saturation was constructed, the analysis of which confirms that the existing thermobaric conditions during the operation of main oil pipelines do not allow transporting oil without the risk of waxing. It was noted a special influence of the value of the temperature gradient in the near-wall zone and the imbalance of the ratio of high-molecular oil components in commercial batches formed in the process of joint pumping on the intensity of waxing of sections of oil pipelines complicated by deposits, which was confirmed by statistical data on the frequency of pigging. The regularities obtained in this way are proposed to be used as an express method for predicting complications associated with intensive waxing of main oil pipelines. In order to quickly assess the risks of waxing of sections of main oil pipelines, an indicator is introduced that characterizes the ratio of the content of solid paraffins to the total content of resins and asphaltenes of oil, called the criterion of instability of a commercial oil batch.

Numerical simulation of conjugated heat exchange in laminar motion of oil fluid in a well

A mathematical model of conjugate heat transfer during the laminar movement of oil fluid in the well is proposed. The motion of a gas-liquid medium in a two-dimensional axisymmetric stationary formulation is described by the equations of the boundary layer. A case of well operation in which oil is lifted to the surface due to reservoir energyis considered. A three-component medium is presented as a mixture of two components: formation of oil with dissolved gas and formation of water. The results of numerical modeling are presented, which make it possible to analyze the thermobaric state of the well under the condition of the developing flow in the pipe at the initial stage of stabilization and taking into account the phase transition associated with the formation of paraffin deposits.

Application of Pineapple Skin Waste as a Source of Biosolvent for Use as Wax Inhibitor

Wax paraffin deposition is a problem faced in the pipeline for petroleum industries that they blockage the partial or full inside the pipe, which will decrease the production rate. One of the treatments is to use the preventive methods called wax inhibitors which are expected to inhibit the crystallization of paraffin wax, and bio-solvent is included. Hydrolysis and fermentation technique are used to produced bio-solvent. Hydrolysis aims to break lignin and hemicellulose, damage the crystal structure, and increase the porosity of the material. At the same time, the occurrence of pentose changes and some glucose into ethanol is present in the fermentation process. Then, purified by the distillation process to obtain bio solvent products that are applied with waxy crude oil can reduce the pour point value of crude oil. From the hydrolysis process with five variations of acid percentage, the amount of reducing sugars increase. By increasing temperature from 50 ° C to 100 ° C, the reducing sugars continues to increase until it reaches the optimal point of 18.2 ° Brix. The amount of inoculant also affects the level of bio-solvent where the optimum results using inoculants are 0.015 g/mL, which produces 6% levels of bioethanol. The high ethanol content of 2% had a density value of 0.979 g/mL. The best °API at 5% is 13.901, and the average value is about 13.0945, where the best viscosity values for ethanol content of 6% are 0.814. Bioethanol testing using waxy crude oil is carried out with the bioethanol content of 6%. The addition of the ethanol contents only decreased the pour point 2-3℃. At sample, #LGK19 experienced a 3°C drop in pour point from 45°C to 42°C. Therefore, it can be concluded that bioethanol used as a solvent can potentially inhibit paraffin deposition.

INVESTIGATION OF THE EFFECT OF THE PERMANENT MAGNETIC FIELD OF THE MAGNETIC ANTI-PARAFFIN DEVICE ON THE STRUCTURE ASPHALT-RESIN-PARAFFIN SEDIMENT

The limited world oil reserves force to actively develop and use fields with relatively low debit wells, as well as fields with difficult oil production conditions, with high-viscosity oil and with a significant content of foreign inclusions. One of the most unpleasant and serious complications in oil equipment is asphalt-resin-paraffin deposits. Therefore, one of the most important tasks is to study the mechanism and conditions of formation of asphalt-resin-paraffin deposits, as well as the development of effective methods to combat them. Analysis of wells in which asphalt-resin-paraffin deposits are observed, shows that the presence of paraffin, regardless of its amount in oil, poses many technological and technical tasks related to the elimination of complications associated with asphalt-resin-paraffin deposits. The presence of asphalt-resin-paraffin deposits leads to a decrease in the flow rate of wells due to clogging of pores and deterioration of filtration of oil-saturated formations. During downhole oil production, asphalt-resin-paraffins accumulate in the form of deposits on the walls of pump-compressor pipes (tubing) and oilfield equipment, thereby reducing the cross section of pipelines and lead to a decrease in the flow rate of wells. In a given hour, there are close to twenty new ways of fighting with embedded paraffin. Leather with methods of combating paraffin waxing in the process of choosing effective methods for preserving and visualizing paraffin waxes without preserving the trivial mid-repair period of robotics in the drill holes, for improving the efficiency of mathematics. The use of magnetic oil treatment devices is effective in preventing these problems. The high practical efficiency of such devices is evidenced by the increasing attention paid to the development of these devices and their patenting by various foreign firms. One such device, called a magnetic anti-paraffin device, will be discussed in detail in this paper. The device was tested at the Boryslav field from 2002 to 2007, where it gave good results in contrast to other methods. MAP has significantly reduced the percentage of asphalt-resin-paraffin deposits formation in the production area and transferred the process of their utilization to the refinery №10 in Boryslav, which in turn allows to preserve valuable components of asphalt-resin-paraffin deposits for their further use and improve the environmental condition of oil fields. The use of magnetic antiparaffin device can be effective both in the gushing of the well and in the operation of its deep-rod centrifugal and diaphragm pumps, as well as on oil pipelines. The maintenance period due to the use of magnetic antiparaffin device, in particular at OJSC Ukrnafta, increased 1.5-2.6 times. The advanced MAP device differs from other magnetic devices for liquid processing in that no power supply to the device is required for work as it works on permanent magnets. Keywords: pipeline transportation of petroleum products, trunk oil pipelines, high viscosity oil, paraffin deposition, permanent magnetic field.

Studies on the Efficiency of the Impact of Paraffin Inhibitors on Lowering the WAT Temperature and Reducing the Amount of Paraffin Deposit

This paper discusses the issues of the impact of pressure and temperature on the precipitation of paraffin deposits from reservoir fluids in the presence of previously prepared paraffin inhibitors. Using a properly modified PVT apparatus, the temperature of the beginning of paraffin precipitation (wax appearance temperature—WAT) has been determined, below which the solid paraffin phase was captured on a specialized filter in various temperatures. Based on the conducted experiments, a boundary has been established separating the paraffin area (the presence of paraffins as their solid phase) from an area without paraffin. Measurements of the amount of paraffin using the filter allowed the determination of the WPC (wax precipitation curve), due to which additional data is provided regarding the amount of precipitated paraffin deposit below the WAT. The developed methodology enables to conduct the measurements within a wide range of pressures using the sample saturated with reservoir gas, which can test the crude oil sample that corresponds to the actual production conditions. Most known research methods do not allow such preparation of a sample and conducting the measurements under pressurized conditions; therefore, the produced results are subject to errors. The paper describes also the studies of efficiency and differences in the action of various paraffin inhibitors. Based on the performed research, a comparison was made involving the action of agents under the pressureless conditions of dead oil and pressurized crude oil samples saturated with gas. The performed studies allowed the determination of equilibrium conditions (in a pressure–temperature system), under which deposition of the solid paraffin phase occurs during the use of three various inhibitors. Based on the performed experiments, an area with a paraffin hazard was determined, along with an area without paraffins. Due to the separation of the precipitated solid paraffin phase, an increase in the mass of the paraffin deposit associated with a temperature drop was determined (wax precipitation curve), as well as the impact of the applied inhibitors on its course.

Dynamic Experimental Study on the Paraffin Deposition Prevention Performance of Tungsten Alloy Coating Pipe in Simulating Vertical Wellbore.

In this study, a self-designed apparatus was used to provide a quantitative evaluation of the wax prevention effect of tungsten alloy-coated tubing compared with ordinary tubing in oil production. The paraffin deposition of both pipes at different temperatures and different flow rates was studied. The efficiency of paraffin deposition prevention of the tungsten alloy coating pipe was analyzed. The results show that using this apparatus can efficiently and accurately calculate the wax prevention rate and can accurately obtain the wax deposit and wax thickness of the inner wall. The paraffin deposition of both pipes reaches the highest point at 290.15 K, and it reduces with the increase of flow rate. The use of the tungsten alloy coating pipe results in about 30% reduction in paraffin deposition. It provides a promising method for the paraffin inhibition to extend the wax removal cycle.

A new type of experimentally proposed in situ heat/gas clean foam fracturing fluid system

When cold fluid is injected into low-temperature, low-pressure, low-permeability reservoirs containing wax-bearing heavy oil, cryogenic paraffin deposition and heavy oil condensation will occur, thus damaging the formation. Moreover, the formation pressure coefficient is low and the working fluid flowback efficiency is low, which affects the fracturing stimulation effect. Therefore, an in situ heat/gas clean foam fracturing fluid system is proposed. This system can ensure that conventional fracturing fluid can create fractures and carry proppant in the reservoir, generate heat in situ to avoid cold damage, reduce the viscosity, and improve the fluidity of crude oil. The in situ heat fracturing fluid generates a large amount of inert gas while generating heat, thus forming foam-like fracturing fluid, reducing fluid loss, improving proppant-carrying performance, improving gel-breaking performance, effectively improving crack conductivity, and is clean and environmentally friendly. Based on the improved existing fracturing fluid system, in this paper, a new type of in situ heat fracturing fluid system is proposed, and a system optimization evaluation is conducted through laboratory experiments according to the performance evaluation standard of water-based fracturing fluid. Compared with the traditional in situ heat fracturing fluid system, the fracturing fluid system proposed in this study generates a large amount of inert gas and form foam-like fracturing fluid, reduces fluid loss, enhances the proppant-carrying capacity and gel-breaking performance, improves crack conductivity, the gel without residue and that the gel-breaking liquid is clean and harmless.

Coriolis flowmeter for commercial accounting of crude oil

Commercial accounting of oil and petroleum products is carried out using the so-called CQCSs or crude quality control systems. The main measurement tool in the CQCS is a flowmeter: volumetric one for the indirect dynamic method and mass flowmeter for the direct dynamic method. The operation of any oil flowmeter varies depending on conditions of its verification in flow labs and depends on a large number of mutually affecting external factors. The total additional error from their action can significantly exceed the error declared in the measuring instrument type description. Therefore, studies of the influence of both experimental factors and through mathematical models are relevant. The article simulates a change in the operation of a sensitive element of a Coriolis flowmeter - a flow tube - due to the deposition of paraffin on its inner surface, which is released under certain conditions from crude oil. The calculations performed on the model in the Aspen HYSYS software environment showed that deposits having accumulated within one year cause an error comparable with the requirements of regulatory documents for the accuracy of commercial accounting. Therefore, it is recommended to carry out additional monitoring of metrological characteristics in the verification interval in case of accounting of highly paraffinic oils.

Studying dispersed and rheological properties of hydrocarbon-containing acid emulsions and their efficiency in removing asphalt-resin-paraffin deposits

Currently, the treatment of the bottomhole formation zone with acidic compositions is one of the most common methods to intensify the oil inflow. The use of various modified acid compositions increases the efficiency of acid treatments on the bottomhole formation zone. Acid compositions, including those containing hydrocarbon solvents, which contribute to more efficient removal of organic colmatants, affect the reaction rate of the reagent with the rock and processing equipment, change the reservoir properties, etc.The article presents the results of experimental studies, which are aimed at establishing the effect of the composition of hydrocarbon-containing acidic emulsions consisting of an aqueous solution of hydrochloric acid, toluene and Neonol AF 9-10 on their dispersed and rheological properties, as well as their efficiency in removing paraffin deposits.

Systematic Study of Temperature and Different Types of Mixing in Paraffin Deposition Test Methods.

Paraffin fouling deposition is a common issue in oil production that leads to constrictions within the system wherever the system temperature drops below the wax appearance temperature (WAT). Chemical mitigation of these issues often relies on various laboratory equipment for product selection, but often the test conditions chosen are not representative of the field; therefore, the resulting deposit generated may give misleading results. In this article, our aim is to investigate how the use of different laboratory techniques can be utilized to generate a field-representative wax deposit. Our study includes the traditional cold finger (CF) apparatus, the coaxial shear cold finger (CSCF), and the dynamic paraffin deposition cell (DPDC), a test method developed in house. The pieces of equipment use similar temperature-driven deposit formation to measure fouling but with very different mixing conditions. The study of paraffin deposition at narrow temperature gradients with these techniques showed similar trends for deposit weight when compared to the fouling factor obtained using a common oil and the Para-window technique presented in a previous study. Significantly, it was observed that for all of the laboratory techniques used, different sample homogenization/mixing mechanisms did not affect the carbon chain distribution of the most insoluble and problematic high-molecular-weight wax (≥n-C35) but did affect the shorter chain composition (i.e., those that are most prevalent in the parent crude oil). The results confirm that temperature is the main driver dictating the nature of the most field-representative deposit characteristics using the laboratory test systems available. This presents the opportunity to gain better insights into paraffin deposition in the laboratory and prepares us to develop better screening capabilities in order to meet current and future paraffin challenges faced in the field.

A comparison study on the removal of paraffin wax deposition plug by ultrasound treatment, chemical demulsifier and combination of ultrasound and chemical demulsifier

Removing the paraffin deposit plugs has always been a technical problem in petroleum production process. In recent years, ultrasonic treatment technique has attracted much attention because of low cost and pollution-free. In this article, the ultrasonic treatment for removing paraffin wax was systematically investigated. The effectiveness of factors on the core paraffin wax removal were analyzed through experiments. The results demonstrate that chemical agent and ultrasonic treatment method for the removal of paraffin wax can produce obviously synergetic effects. The effect of removing the paraffin wax deposition by ultrasonic-chemical method is better than that by single chemical or ultrasonic method.

Research on Efficiency of Solvents of Paraffin Deposits

Differential scanning calorimetry has been used to study the phase transition of commercial paraffins in asphaltene-resin-paraffin deposits (ARPD). Paraffin deposits have been collected from the surface of oil field equipment in the Irelyakhskoye oil and gas field (Sakha Republic (Yakutia). Gas condensate (GC) that is currently used in this field to remove deposits, as well as its mixture with cyclohexane and p-xylene, have been studied as ARPD solvents. The degree of crystallinity (DC) of paraffins has been identified to depend on the degree of aliphaticity of the mixed solvents used, with an increase in the degree of aliphaticity of the solvent, the DC of paraffins increases. Paraffins in the triple solvents are found to possess low DC and high melting points. The results of the research led to the conclusion that it is necessary to use GC with addition of aromatic concentrate to remove paraffin deposits in the oil field.

Choice of the Effective Solvent to Remove Paraffin Deposits in Conditions of Abnormally Low Reservoir Temperatures

The results of research on dissolution kinetics of petroleum paraffins and asphaltene-resin-paraffin deposits (ARPD) of the paraffin type in aliphatic, aliphatic-aromatic, and aliphatic-naphthenic-aromatic systems within the temperature range from 10 to 60° C have been discussed. The half-life periods, order of reactions, dissolution rate constants and activiation energy of destruction of paraffins and ARPD have been calculated. Differential scanning calorimetry has been used to study the phase transitions of petroleum and commercial paraffins in aliphatic and mixed hydrocarbon solvents. Based on the conducted research, recommendations for selection of an effective solvent to remove paraffin deposits at low temperatures of reservoirs have been proposed.

Recovery Throughput of Technological Pipelines and Useful Volume of Tanks for a Long Time Operated Pump Stations

The paper discusses the problems of cleaning technological pipelines and tanks to restore the capacity and useful volume capacity of oil pumping stations. The world experience of using chemical reagents for cleaning oil pipelines from asphalt-resinous paraffin deposits is considered, the disadvantages and advantages of the method are determined taking into account the restrictions that exist at the facilities of the main oil pipeline transport. The analysis of the results of experimental laboratory studies and pilot tests of the chemical washing technology at the existing facilities of Transneft PJSC is presented. Recommendations are given on improving the technology to reduce the consumption of chemicals and time costs. Particular attention is paid to the shortcomings and features of the use of hydrocarbon solvents for cleaning technological lines from pipes of small diameter and large tanks. The expediency of an additional physical effect is substantiated to increase the efficiency and rate of destruction and removal of hard-to-remove deposits, for which the use of ultrasonic resonators providing flow homogenization and dispersion is proposed.

RESEARCH OF LOADS ON DRIVE OF ROD INSTALLATIONS IN LOW SPEED MODE AT HIGH-VISCOUS OIL PRODUCTION

Reliability and power consumption of the rod installations are largely determined by the drive balancing rate. Today, due to the increasing share of hard-to-recover reserves, issues of balance during the extraction of high viscous and paraffinic products, characterized by increased loads on the rod string due to increasing forces of hydrodynamic friction, paraffin deposition on the walls of sucker rods and pipes, are becoming urgent. The effect of the viscosity of the pumped liquid and the degree of paraffinization of the bore of the elevator pipes on the magnitude of the loads on the drive and power consumption of the rod systems, as well as on the optimal position of balancing crank loads, is studied. As a balance criterion, the minimization of the maximum torque on the crank shaft is taken. A mathematical model of the rod installation based on the analytical model of the balancing drive, taking into account the specified kinematics of the four-link mechanism of the rocking machine is developed. When calculating the hydrodynamic friction loads, the Navier-Stokes equations are used for the steady-state fluid flow in the annular space between the rods and tubing. A study of the loads on the drive at various viscosities and degrees of overlap of the cross section of the elevator pipes showed that an increase in the product viscosity (up to 200 mPa ∙ s) and intensive paraffin deposition on the walls of the rods and elevator pipes (overlapping up to 50 % of the cross section of the elevator lift) leads to an increase in the required torque up to 50 % on the crank shaft of the gearbox (the torque applied to the crank and created by the electric motor) and an increase in the consumed electricity and power up to 100 %, i.e. 2 times.

Technology Focus: Artificial Lift (March 2020)

Technology Focus Since I began writing this feature 2 years ago, I have purposely avoided discussing the elephant in the room, but it seems that now the time is right to give the topic its due. Just as the unconventional revolution has transformed our industry during the past decade, it has also dominated the world of artificial lift. In fact, it can be difficult to find an artificial lift paper or presentation these days that does not address, in some way, the design and operation of artificial lift systems in unconventional shale oil wells. Challenges abound for operators attempting to deploy artificial lift systems in unconventional applications. As always, operators set a variety of challenging business and operational goals for themselves: minimize capital and operational expenditures; maximize drawdown over the well’s life; and minimize downtime, failure frequency, and intervention frequency. The unique nature of these wells can make it challenging to achieve many of these goals, let alone all of them. Because the wells are drilled directionally (and often in a hurry), the wellbore may feature small-diameter casing, high dogleg severity, and high tortuosity. The production profile of these wells can vary dramatically over a short period of time—wells initially producing over 10,000 STB/D can produce as little as 50 STB/D just a few years later. Further complicating matters, unconventional wells often produce fluids with high gas/liquid ratios and require pumps to be set above the producing interval, making gas handling a challenge. To make matters worse, the wells typically pro-duce solids early on, and they may suffer from a variety of flow-assurance issues, including asphaltenes, paraffin deposition, hydrates, and severe slugging. All of these can make it extremely challenging—if not impossible—to achieve reliable operation with downhole pumping systems. For this reason, something surprising has happened: Gas lift has emerged as the lift method of choice in new onshore completions in these basins. While gas lift may be the “easy button,” it is not without its share of challenges. In many areas, there is a lack of adequate supply gas or compression equipment. Hydrates are common in the winter months. Limited injection pressure combined with a rapidly varying production profile can lead to frequent, costly interventions. Because the gas lift method is new to these producing basins, there is often a lack of local expertise needed to support such systems. Although gas lift may be relatively immune to the previously mentioned operational challenges, it generally provides less drawdown than what might be achieved with an optimally sized pumping system. If I sound overly pessimistic about the prospects for artificial lift in unconventional wells, I’m actually not. Engineers thrive when they have challenging problems to solve, and unconventional resources provide artificial lift engineers with ample opportunities for innovation. In recent years, I have witnessed a windfall of new technologies, including improved electrical-submersible-pump stage design, the use of permanent magnet motors, improved downhole gas-separation techniques, tailpipe systems for slug management, a variety of new automation techniques, surface-controlled gas lift valves, modular high-pressure compression systems, novel downhole completion designs, and more. I am thrilled with the array of new artificial lift technologies that the unconventional revolution has prompted, and I can’t wait to see what the future holds. Recommended additional reading at OnePetro: www.onepetro.org. SPE 194396 Downhole Gas Separation in a High-Gas/Liquid-Ratio CO2 Application by B.L. Nicholson, Occidental SPE 196146 First Digital Intelligent Artificial Lift Production Optimization Technology in UAE Dual-String Gas Lift Well—Business Case and Implementation Plan by Ahmed Alshmakhy, Abu Dhabi National Oil Company, et al. SPE 194408 Electrical Submersible Pump Powered Injection Systems Enable the Development of West-of-the-Nile Egypt Assets by Miguel Munoz, Qarun Petroleum, et al.

Increasing Efficiency of Waste Water Treatment of Wine-Making Enterprises with Simultaneous Production of Bio Surface for Oil Industry

A method for pre-treatment of wastewater with the simultaneous production of biological surface-active substances (bio-surfactants) by deep cultivation of the microscopic fungus Hypomyces odoratus in the wastewater of a winery has been developed. In wastewater after cultivation of the fungus under aerobic conditions for 12 hours, a steady decrease in BOD was observed by 2.5 times, COD by 3 times, the content of suspended solids, sulfates, phosphates, ammonium ions, nitrates, nitrites, anionic surfactants decreased significantly substances (ACAS), cationic surfactants (CAS), wastewater in chemical composition began to approach the indicators of municipal sewage. The complexity of the composition obtained during the cultivation of the biomass fungus and the isolated exopolysaccharide contributed to a decrease in the surface tension of the oil and indicated that the fungus synthesizes the bio-surfactant complex. After contact with a 12-hour mass of fungus or exopolysaccharide obtained from biomass in highly viscous, water-flooded bituminized oil, an improvement in rheological indices was noted, and the water cut and content of paraffin deposits decreased.

Hydromechanical device to clean the inside of pipes from paraffin deposits

Hydromechanical device to clean the inside of pipes from paraffin deposits

Parametric Study on the Determinants Affecting Paraffin Deposition in Producing Oil Field Facilities

Parametric Study on the Determinants Affecting Paraffin Deposition in Producing Oil Field Facilities