High Paraffin Content Research Articles

The influence of thixotropy in start-up flow of yield stress fluids in a pipe

In oil production in ultra-deep water fields, difficulties can appear in the transport of oils with high paraffin content. If the production stops and the produced fluid cools down inside the pipeline, paraffin crystals may appear and form an interlocking gel-like structure, usually exhibiting a thixotropic yield-stress behavior. The restart of the production line should be designed with reasonable precision, taking into account the complex behavior of the gel formed. The start-up flow represents the transient response due to a differential pressure applied to a single fluid initially at rest, and is highly dependent on the fluid rheological behavior and other properties. In the present work, we present experimental and numerical results of the start-up flow of yield stress fluids in a horizontal pipe. The experiments are performed using a flow loop and two different fluids, one thixotropic and another non-thixotropic. Rheological data and velocity profiles are obtained and related to the pressure drop, yield stress and thixotropy. Secondly, numerical results are obtained using the finite volume method to solve the mass and momentum conservation equations. A constitutive model based on the Oldroyd-B equation for viscoelastic fluids, is used to describe the thixotropic fluid behavior. The numerical results captured the main physical features of the flow, and showed a fair agreement to the experimental results.

EVALUATION OF HYDRAULIC AND THERMAL LOSSES IN OIL PIPELINES IN COLD AREAS

This article considers the problem of reducing energy costs for transportation of oil with high paraffin content in cold areas. A theoretical calculation of the thermal losses in the oil pipeline was carried out, depending on the speed of the oil movement through the pipe, the material and the thickness of the thermal insulation, and the ambient temperature. Theoretical research of the temperature influence and the speed of oil movement on the pressure drop along the length of the pipeline was carried out. The options for maintaining the oil temperature along the length of the pipeline by installing a fuel element on the surface of the pipeline under thermal insulation in order to create a condition for blocking the heat flow from oil to the thermal insulation of the main pipeline by counter heat flow from an additional source of heat located on the inside of the thermal insulation. Although such a solution eliminates the reduction of thermal losses from thermal insulation to the environment, however, the temperature and viscosity of oil along the pipeline will not change, which ultimately leads to a reduction in hydraulic losses and energy costs for oil transportation. This caused a reduce in pressure losses in the oil pipeline, which lead to an increase in the distance between the oil pumping stations.

A Prospective Method to Increase Oil Recovery in Waxy-Shallow Reservoir

Waxy oil has been the main characteristics of The X field. Initial screening criteria studies indicated that cyclic steam stimulation (CSS) would be the optimum option because favorable reservoir condition. Based on this method we would like to know how much oil gain and the effect of steam for the stimulated and surrounding well. The injection of steam was done for 7 days followed by 14 days of soaking period. 39,000 liter of Marine fuel oil was used to generate steam for stimulation with an average produce steam quality about 80%. Average of 255 MMBTU of steam was injected each day with total steam injected was about 1.7 BBTU. The oil production was increased four times from 5 bopd into 21 bopd. Proper well candidate and high permeability are some reason for this method successfully increase oil production. Additional heat from steam reduced the damage near wellbore due to wax deposition. This is verifying by increasing productivity index from 3 bbl/psi to 4 bbl/psi. From results and observation data, this method can be a platform for typical shallow depth reservoir with high paraffinic content especially other reservoir in Sihapas formation.

Environmental Issues and Challenges of Chinese Abandoned Oil Pipelines

China energy pipeline industry commonly faced with aging and abandonment problem. The research on pipeline abandonment was still in preliminary state, because there are no pipeline abandonment standards and guidelines. The foreign developed countries formulated pipeline abandonment standards, advanced experience and technology of residual cleaning and the crossing section grouting. But it not totally suitable for china because of difference between china and foreign country, such as the pipeline residual has a very high paraffin and resin-asphaltenes content. It is very hard to remove. So china pipeline company faced with many environmental issues and challenges in the pipeline abandonment. Study on abandonment of pipeline was conducted by pipeline company of Petrochina from 2013. A case of Petrochina abandonment pipeline was introduced in the paper, and it showed good effect. Some experience and technology of chemical cleaning were formulated from previous study and several pipeline abandonment projects. The first China industry standard on abandoned pipeline is applying for by pipeline company of Petrochina. This standard will assist pipeline company make pipeline abandonment plan to ensure public safety and environment protection.

Technological Efficiency of Implementation of Dual Completion of Objects

Нефти Удмуртии характеризуются как трудноизвлекаемые, с повышенной вязкостью, высоким содержанием парафина и смол. Большинство разрабатываемых месторождений ОАО «Удмуртнефть» на сегодняшний день находятся на третьей и четвертой стадии разработок. Характерными особенностями данных стадий разработок является высокий темп снижения добычи углеводородов и значительный рост обводненности скважинной продукции. Для увеличения объемов добычи предложена технология одновременно-раздельной эксплуатации объектов добычи нефти (ОРЭ). Внедрение ОРЭ позволит: подключить другие объекты пластов за счет уплотнения сетки без бурения дополнительных скважин и повысить рентабельность добычи; вести раздельный учет добычи нефти по каждому пласту. В работе выявлены критерии эффективности применения технологий одновременно-раздельной добычи нефти глубинно-насосным оборудованием на месторождении ОАО «Удмуртнефть» с высоковязкими нефтями; предложена оценка технологической применимости ОРЭ на месторождении, проведены расчеты технологической эффективности внедрения технологии одновременно-раздельной эксплуатации объектов добычи нефти на месторождении. Доказана целесообразность ее внедрения.

Production of oil with potential energetic use by catalytic co-pyrolysis of oil sludge from offshore petroleum industry

Oil sludge from offshore petroleum industry in Brazil was pyrolyzed to produce oil with potential energetic use. It was studied the effect of the temperature and the addition of an acid catalyst (K-10® clay) and polyethylene (PE) wastes on the production of pyrolytic oil. The quality of the pyrolytic oil was evaluated based on the hydrocarbon composition determined by NMR and GC–MS analysis. Increasing the temperature from 450 to 500°C, the yield of pyrolytic oil and gases was increased by 15% while the residues decreased by 50%. The production of gas at 450°C was increased by 50% when K-10 clay (5 or 10% w/w) was added. GC–MS analysis showed that thermal and catalytic pyrolysis is able to convert the oil sludge into a pyrolytic oil with a light hydrocarbon content higher than 95%. Hydrocarbon-type analysis showed that both thermal and catalytic pyrolysis produced pyrolytic oil with high paraffin content (higher than 80% v/v) and low aromatics and olefins (lower than 10% of each). The addition of PE wastes to the oil sludge decreased the oil production. The pyrolytic oil from the thermal pyrolysis of oil sludge with HDPE (5% w/w) was mainly composed of light hydrocarbons while that using LDPE was composed of 64% heavy hydrocarbons. Catalytic pyrolysis produced an oil fraction with (i) a higher content of light hydrocarbons than the pyrolytic oil from thermal pyrolysis and (ii) a low content of aromatics and olefins. The mean calorific value (44.1MJ/kg) of these pyrolytic oils was similar to the default caloric value for diesel (43.7MJ/kg). That result demonstrates that the thermal and catalytic pyrolysis can be potentially used to convert the mixture PE wastes and oil sludge into a diesel fraction oil.

Rheological properties of crude oils in Yaregskoye and Yaraktinskoye oil fields

Rotary viscometer tests of crude oil with a high content of resins and asphaltenes (Yaregskoye oil field) and crude oil with high paraffin content (Yaraktinskoye oil field) have been conducted. The typical flow curves for these oil types have been plotted. It has been detected that these oils are non-Newtonian fluids, viscosity of which is dependent on shear rate. Based on Arrhenius-Eyring equation, calculations of viscous flow activation energy and complex structural unit (CSU) sizes have been performed. It has been stated that there is a tenfold reduction in CSU size in asphaltic crude oil with the increase in shear rate in a rotary viscometer, while particle size in paraffinic crude oil does not essentially change under the same hydrodynamic conditions.

Behaviour of some hydrobionts in experimental conditions of accidental oil pollution

This work presents results on behavioral reactions and sensitivity of molluscs and fish to experimental modelling of accidental oil pollution during the first 72 hours. It is shown that mobile hydrobionts, such as fish attempt to escape the contaminated area during the first 24 hours after the oil spill. Benthic animals – molluscs are more susceptibleto pollution, they almost instantly lose their mobility, become inert and try to escape their shells further on, which serves as an evidence of death throes. Light crude with high content of paraffin was used for the present experiment.

Separation efficiency of two waste polymer fibers for oily water treatment

This work is concerned with the efficiency of two different waste polymeric materials as the filter media in a laboratory-scale bed coalescer in the horizontal fluid flow mode, operating in a steady-state regime. The applied materials are: waste polyethylene terephthalate from textile industry, BA1 and waste polypropylene from carpet industry, PP. Using these compressible fiber polymeric materials, high bed porosity (up to 98%) could be obtained. The investigation was carried out over a wide range of working conditions. Bed permeability was varied in the range from 0.18?10-9 to 5.389?10-9 m2. Operating fluid velocity was varied from 19 to 80 m/h, until the critical velocity was reached. Different oily wastewaters were used in the experiments. Oily wastewater is defined as the oil-inwater emulsion model prepared using mineral oils of different physico-chemical characteristics: crude oil (A) from Vojvodina region, two vacuum distillation fractions (A1, A4), and blended petroleum product with a high paraffinic content (P1). Both applied polymeric materials, BA1 and PP, showed high separation efficiency for treatment of all investigated oily wastewater. However, the BA1 material showed higher efficiency in a wider range of bed permeability and physico-chemical characteristics of oil.

Consolidated microcapsules with double alginate shell containing paraffin for latent heat storage

Double-shell alginate microcapsules containing paraffin phase change material (PCM) were prepared for latent heat storage by a method of repeated interfacial coacervation/crosslinking. The proposed process consisted of three main steps: (1) preparation of paraffin containing core particles by dripping an O/W emulsion of melted paraffin and aqueous sodium alginate into a calcium chloride ionic cross-linking solution, (2) encapsulation of the core particles into double alginate shell by ionic gelation/crosslinking by repeated interactions between the sodium alginate and calcium chloride solutions, and (3) consolidation of the capsule shells by contact heat treatment. The effects of process parameters such as the sodium alginate concentration, the calcium chloride concentration in certain stages of the process, and the contact time between the formed core particles and the surrounding alginate solution on the paraffin content and the mean diameter of capsules were studied by experimental design and statistical evaluations. The prepared PCM capsules had uniform sizes, core/shell structure, double-walled non-porous alginate coating, tunable void space inside the core, and suitably high paraffin content at properly selected process conditions, corresponding to 95.0J/g melting and 91.7J/g freezing latent heat capacity. Thermogravimetric analysis and repeated thermal cycling evidenced good thermal stability, and proper mechanical strength for leakage free microcapsules.

Microfluidic fabrication and thermal characteristics of core–shell phase change microfibers with high paraffin content

We have developed a facile and controllable microfluidic strategy to fabricate core–shell phase change microfibers with high paraffin Rubitherm®27 (RT27) content. Coaxial core-sheath flows consisting of a cylindrical jet of melting RT27 (core fluid) and annular jet of poly(vinyl butyral) (PVB) solution (sheath fluid) are formed in a coaxial microdevice. With the core-sheath flows as templates, the phase change microfibers with core–shell structure are fabricated after solvent extraction. The RT27 content of microfibers is precisely controlled by simply adjusting the inner flow rate. The microstructures, thermal characteristics and mechanical strengths of microfibers are studied systematically by SEM, DSC, TGA and a tensile tester. The results show that the resultant microfibers are composed of RT27 core and PVB polymer shell which effectively prevents RT27 from leaking during the phase change process. The enthalpies of microfibers increase with the increase of RT27 content in microfibers. The maximum melting enthalpy and crystallization enthalpy of microfibers are about 128.2 J g−1 and 124.0 J g−1 respectively, and the corresponding encapsulation ratio is as high as 70%. The prepared phase change microfibers exhibit stable, repeatable and satisfactory thermal characteristics especially thermal-regulating property. The results provide valuable guidance for design and controllable preparation of phase change microfibers with advanced microstructures and satisfactory thermal characteristics.

A study of relations between physicochemical properties of crude oils and microbiological characteristics of reservoir microflora

The dependence of the population and activity of reservoir microflora upon the chemical composition and viscosity of crude oils has been investigated, since it allows the problem of improvement in the technologies and enhancement of oil recovery as applied to production of difficult types of oils with anomalous properties (viscous, heavy, waxy, high-resin) to be solved. The effect of the chemical composition of the oil on the number, distribution, and activity of reservoir microflora has been studied using data on the microbiological properties of reservoir water of 16 different fields in oil and gas basins of Russia, Mongolia, China, and Vietnam. Information on the physicochemical properties of crude oils of these fields has been obtained from the database created at the Institute of Petroleum Chemistry, Siberian Branch on the physicochemical properties of oils throughout the world. It has been found that formation water in viscous oil reservoirs is characterized by a large population of heterotrophic and sulfate-reducing bacteria and the water of oil fields with a high paraffin content, by population of denitrifying bacteria.

Study on the Temperature Distribution of High Pour Point Oil by Integrated Method Based on Well Log, Geological Data and Experiment

High pour point oil reservoir contains various typical properties; such as a kind of high freezing point, high paraffin content and high cloud point temperature reservoir, while the temperature is regarded as high sensitive parameter for oil reservoirs. The current research aim is to develop and assess the effect by cold water flooding, the structure and properties model was built with the combination method of reservoir geological modeling and simulation. Various degrees of cold damage have deep relation with paraffin deposition and reservoir channel plug due to decline of temperature below the cloud point temperature. Precipitated paraffin has changed the rheological properties of crude oil, which can increase filtration resistance and reducing the oil displacement efficiency. Furthermore, model simulation analysis results compared under two different conditions cold and hot water flooding and predicted the inter well temperature field distribution belongs to reservoir through the model numerical simulation. Present study depicts that the integrated method base on log, geological data and experiment can predict and analysis the temperature variation efficiently, while thermal displacement method has efficiently improved the high pour-point oil reservoir development effect, increasing oil mobility and enhancing oil recovery.

Preparation and Characterization of High Latent Heat Thermal Regulating Fiber Made of PVA and Paraffin

A convenient method for preparing the thermal regulating fibers with high latent heat has been developed. PVA thermal regulating fibers were prepared via a wet spinning process, with paraffin being the phase change material. The structures and properties of these fibers were investigated by SEM, TGA, DSC and tensile strength tester. With the paraffin content in the fibers increasing from 30wt% to 70wt%, the latent heat of the fibers increases from 42.8J/g to 87.8J/g and the paraffin phase structures change from separation into partial interconnection. PVA matrix can not wrap paraffin effectively when the paraffin content increases up to 50wt%, so the paraffin loss in the spinning process increases. The thermal stability of fibers with low paraffin content is better than that of fibers with high paraffin content. After 100 heat-and-cool cycles, the latent heat of fibers lose a little. The tensile strength of these thermal regulating fibers is good enough for application in wrapping, filling, and nonwovens.

Study on Paraffin Precipitation for Dalaoba Condensate Gas Reservoir

High content of paraffin for condensate gas reservoir in Dalaoba and the precipitation of paraffin seriously affect the production and safety to bring about greater economic loss, therefore, it is necessary to develop the study on the precipitation of paraffin,deposition mechanism, variation discipline of phase state, prediction technology as well as the discipline for precipitation of paraffin of shaft.The paper establish the predication method on phase state simulation for paraffin precipitation. In order to better realize the site application, the predicted drawing version on paraffin precipitation of shaft is established to better predict the paraffin precipitation of shaft so as to provide the scientific basis for design on paraffin elimination and prevention on site as well as the construction and reasonable mining of condensate gas reservoir.

Timing and mechanism of reservoir forming in the Upper Triassic Halahatang Formation, Yuqi block, Tarim Basin, northwestern China

The Yuqi block is an important area for oil and gas exploration in the northern Akekule uplift, Tarim Basin, northwestern China. The Upper Triassic Halahatang Formation (T 3h) within the Yuqi block can be subdivided into a lowstand system tract (LST), a transgressive system tract (TST), and a highstand system tract (HST), based on a study of initial and maximum flood surfaces. Oil in the lowstand system tract of the Halahatang Formation is characterized by medium to lightweight (0.8075 g/cm 3–0.9258 g/cm 3), low sulfur content (0.41%–1.4%), and high paraffin content (9.65%–10.25%). The distribution of oil and gas is principally controlled by low-amplitude anticlines and faults. Based on studies of fluorescence thin sections and homogenization temperatures of fluid inclusions, reservoirs in the T 3h were formed in at least two stages of hydrocarbon charge and accumulation. During the first stage (Jurassic–Cretaceous) both the structural traps and hydrocarbon reservoirs were initiated; during the second stage (Cenozoic) the structural traps were finally formed and the reservoirs were structurally modified. The reservoir-forming mechanism involved external hydrocarbon sources (i.e. younger reservoirs with oil and gas sourced from old rocks), two directions (vertical and lateral) of expulsion, and multi-stage accumulation. This model provides a theoretical fundament for future oil and gas exploration in the Tarim Basin and other similar basins in northwestern China.

Harvesting Oil in India's Rajasthan Desert

The Thar Desert in India’s western state of Rajasthan is a desolate region characterized by wind-blown sand dunes. The state is a major tourist attraction, drawing millions of visitors annually to tour forts of medieval kingdoms and visit camel fairs. It is here that Cairn Energy, a Scottish oil company, took over a production-sharing contract (PSC) from Shell in 2003 and developed a major oilfield that has recoverable reserves of at least 1 billion BOE. The major oil companies have conducted little wildcat exploration in South Asia. From 1980 to 1991, the majors drilled 8,000 wells in Southeast Asia, but only 12 in South Asia. Indigenous exploration in Rajasthan began with an inconclusive exploration attempt by the government of India in 1955. In 1988, Oil India discovered natural gas near the town of Jaisalmer and has been producing 0.6 million sd m3/d since 1996. Floated on the London Stock Exchange in 1988, Cairn Energy first entered South Asia by signing a PSC with the government of Bangladesh. In 1997, during a swap of properties with Shell, Cairn acquired a 10% interest in the Rajasthan PSC, which Shell had initially signed with the government of India in 1995. The PSC covered block RJ-ON-90/1 consisting of an initial area of almost 12 000 km2—3111 km2 is now included in the development area, with India’s public sector oil company, Oil and Natural Gas Corporation, holding 30% ownership. After the discovery of the Guda field in 1999, Cairn increased its participation to 50% and eventually took over Shell’s remaining share in 2003 at a cost of USD 7.25 million and became the block’s operator. “Drill Till You Drop” Strategy The geology of the block in Rajasthan’s Barmer basin consists of channel sands stacked on top of one another to create a fluvial reservoir that has high permeability (1–25 darcy) and high porosity. From 2004, Cairn adopted a “drill till you drop” strategy. In January 2004, the company made its initial Mangala discovery with the 16th well in the basin. Following the drilling of appraisal wells, 3D-seismic-data analysis, and well tests, Mangala was confirmed as the largest oil discovery in India since 1985. The Mangala reservoir has a 150 m oil column of medium gravity (20–28°API) viscous crude (9–17 cp) with sulfur content of about 0.1%. The crude has high paraffin content that makes it suitable as a secondary feedstock for refineries, but pipelines and trucks carrying the crude require heating and insulation. Up to 2005, the company drilled more than 140 wells in Rajasthan with a yield of 25 discoveries. In addition to Mangala, Cairn’s major discoveries are Bhagyam and Aishwariya, with 22 other fields including Guda, Saraswati, Raageshwari, Greater Raageshwari, and Kameshwari. In August 2009, the Prime Minister of India, Manmohan Singh, joined Cairn Energy Chief Executive Bill Gammell in inaugurating oil production from the Mangala field.

Fuel Purpose Hydrotreating of Vegetable Oil on NiMo/γ-Al2O3 Catalyst

The application of biofuels has become more important in the whole world since the last decades. Intensive research has been started for the production of biofuels which can be applied in Diesel engines and has different chemical composition from the previously used ones. Among these fuels the most important one is biogasoil (normal and iso-paraffins) produced from triglycerides with catalytic hydrotreating (special hydrocracking). The aim of present study was to investigate the applicability of commercial NiMo/γ-Al2O3 catalyst for conversion of specially pretreated Hungarian sunflower oil to produce motor fuel components. The change in the hydrotreating activity of applied catalyst, the pathways of hydrodeoxigenation reactions and the effect of process parameters (T=300–360 °C, p=20–60 bar, LHSV=0.5–2.0 h-1, H2/sunflower oil volume ratio: 400 Nm3/m3) on the yield and composition of the products were also investigated. It was concluded that on the investigated NiMo/γ-Al2O3 catalyst products with relatively high (>50%) paraffin content (T=360–380 °C, p=60 bar, LHSV=0.5–1.0 h-1) could be produced. The yield of the produced target fraction was 50.7–54.5% at these advantageous process parameters. So it is necessary to separate and recirculate the heavy fraction. In case of every investigated process parameter C18-, C17-, C16- and C15 normal paraffins were formed, i.e. both the HDO and the decarboxylation/ decarbonylation reactions took place. The cetane number of the target fractions, are very high (>80, EN standard: ≥51), but the cold flow properties of this fraction are disadvantageous. To improve this disadvantageous property it is necessary to carry out selective isomerization of the target fraction.

Application of prediction models to performance of high paraffinic content oilfields: Case study Shen95 Block of Jinganbao Oilfield

Production performance was curve-fitted for prediction of production and estimation of incremental recovery for waterflooded reservoir. Arguably, simulation may yield non-unique solution or fail due to assumptions on the true effect of high-paraffin content on porosity, saturation, and fluid rheology in the entire formation caused by temperature and solubility effects. The curve-fitting models applied are Arps' rate–time models and Li–Horne mechanistic model proven applicable to waterflooded and naturally fractured reservoirs. Others are Corrêa's volumetric oil-cut decline model tested on heterogeneous, waterflooded, high viscous and heavy oil reservoirs characterized by volumetric-exponential decline and a water displacement curve method. The match periods for Arps' models were constrained by criteria from literature reviewed to ensure that decline was relatively under the influence of relative permeability and not operational changes. The models were chosen to match performance primarily of Shen95 Block, a faulted block in the Damintun depression, Liaohe basin, China, characterized by high pour point within 42–64 °C. Recovery estimate was not entirely consistent with past findings of Li–Horne model estimates falling in-between exponential and harmonic decline estimates, but consistent with harmonic decline estimates. Performance match preference was Corrêa's model, but the model was extended to specifically characterize performance trend by reciprocal decline exponent ( β = − 2) beyond the prior considered range of (− 1 ≤ β ≤ 0). The other block considered, a naturally fractured reservoir having similar fluid properties with Shen95 was also characterized by ( β = − 2). A holistic approach will require the alternate use of the models based on the strong points of each model according to theory, performance trends and operational changes.

Composition of Floccules Formed in Hydrotreated Base Oil

The composition of the floccules formed in hydrotreated base oil was investigated in detail. First, a method of solvent dilution and filtration at low temperature was employed to perform the separation of the floccules in the oil. Second, n-paraffins in the floccules were separated with urea, and carbon number distribution of the floccules was obtained by gas chromatography (GC). Finally, the composition and structure between the floccules and filtrated oils were investigated using gas chromatography–mass spectrometry (GC-MS) and infrared spectroscopy (IR), and their average molecular weights were also measured. The results indicate that the floccules were caused by some hydrocarbon compounds with large average molecular weight, high paraffinic carbon content, and high freezing point. The floccules were composed of a large amount of naphthenes and some paraffins. The naphthenes had longer side branches and lower ring numbers, and the paraffins had longer chains and lower degrees of branching. During slow cooling under static conditions, these hydrocarbon compounds formed a colloidal network, which embodied the oil and dispersed throughout the oil and formed the floccules.