Experimental Study on Wax Removal With Real Wax Deposits

2018 ◽  
Author(s):  
Weidong Li ◽  
Qiyu Huang ◽  
Xue Dong ◽  
Xuedong Gao ◽  
Lei Hou
Keyword(s):  
Test Section ◽  
Wax Deposition ◽  
Flow Loop ◽  
Gravity Settling ◽  
Experimental Apparatus ◽  
Field Practice ◽  
Force Profile ◽  
Wax Content ◽  
Wax Deposits ◽  
Wax Removal

Pipeline pigging is one of the most widely used wax remediation techniques in field practice. However, it still depends heavily on “rule-of-thumb” due to the limited understanding of wax deposit properties and wax removal mechanisms. By far, laboratory studies on pipeline pigging generally suffer a gross defect in test materials, i.e., the big discrepancy between the experimental wax samples and real wax deposits. To this end, this paper aims to explore the wax removal in pigging with naturally deposited wax, using a self-designed experimental facility. Wax deposit mass and wax content, two decisive indexes affecting wax removal, were also investigated. The experimental apparatus consists of two parts: a flow loop equipped with a detachable test section to achieve real wax deposits and a wax removal apparatus to perform pigging operations. The test section can be conveniently detached from the flow loop and/or mounted onto the wax removal apparatus for a quick conversion between wax deposition and pigging operation. The results indicate that a higher bulk flow temperature decreases the wax deposit mass and increases the wax content of deposit. Additionally, the distributions of wax content and wax layer thickness suggest that gravity settling plays no role in wax deposition. Moreover, the wax resistive force profile of naturally deposited wax presents four distinct stages, i.e., the build-up phase, the pre-plug phase, the plug phase and the production phase. To the best of the authors’ knowledge, this is the first study on wax removal with real wax deposits. It paves the way for the application of previous artificial-wax-based researches to real wax deposit scenarios.

Experimental Investigation of Wax Deposition at Different Deposit Locations Through a Detachable Flow Loop Apparatus

2014 ◽  
Author(s):  
Si Li ◽  
Qiyu Huang ◽  
Wenda Wang ◽  
Changhui Wang ◽  
Zhenjun Ding
Keyword(s):  
Temperature Interval ◽  
Flow Rate ◽  
Test Section ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Wax Deposition ◽  
Flow Loop ◽  
Deposit Thickness ◽  
Wax Content

Wax deposition has always been a focus in the research field of flow assurance. Operating conditions are among the predominant factors that control the deposition rate and the nature of the formed deposits. However, the disadvantages of the available wax thickness measurement techniques applied to laboratory flow loops limit deeper studies on this issue. In this work, the effects of operating conditions, including temperature interval and flow rate, on wax deposition at different deposit locations are experimentally studied using a detachable flow loop apparatus. With the detachable test section, it is achievable to obtain the thickness and the wax content profiles of the deposit as functions of axial location and time. The temperature fields in the test section under both temperature intervals are simulated with CFD software FLUENT to provide more information for the analysis of deposition process. As the results manifest, the low temperature interval tends to intensify deposition, relating to the inner temperature field and wax precipitated property of the oil. The larger flow rate leads to a growth in the deposit thickness under the laminar flow regime and brings about a distinct rise in the wax content of deposit at inlet. In addition, the increase in deposit thickness and wax content indicates the phenomenon of deposit aging, and the wax deposit layer is thinner but with higher wax content at the inlet, due to the strong flow scour.

Experimental Investigation of the Difference in Wax Deposition Aging Rate Between Polyethylene and Steel Pipes

2020 ◽  
Author(s):  
Rongbin Li ◽  
Yaping Li ◽  
Danfu Cao ◽  
Junfang Wang ◽  
Xin Liu
Keyword(s):  
Operating Conditions ◽  
Wax Deposition ◽  
Flow Loop ◽  
Waxy Crude Oil ◽  
Scanning Calorimetry ◽  
Aging Rate ◽  
Wax Content ◽  
The Difference ◽  
Dsc Method ◽  
Wax Deposits

Abstract Wax deposition is an intrinsic problem existing in the production and transportation of waxy crude oil. In the oilfield, non-metallic pipe especially high-density polyethylene pipe (HDPE) has been widely used to solve corrosion problems due to its excellent performance in intensity and corrosion. However, the wax deposition problem in polyethylene (PE) pipe has never been evaluated using dynamic and systemic apparatus. Only a few studies focus on the wax deposition on the coated polyethylene surface by using the cold finger apparatus in recent decades. In this study, the wax deposition experiments were performed using an in-door flow-loop with detachable PE and stainless steel (SS) test sections under the laminar flow regime at the same time to investigate the difference in wax deposition aging rate between the PE and SS pipes. The wax deposits under different operating conditions in both PE and SS pipes were sampled by three layers to study the aging rate at different radial locations during the wax deposition. The wax precipitation characteristics of the wax deposits were determined by using the differential scanning calorimetry (DSC) method. It was found that the wax contents of the wax deposits in PE pipe were lower than that in the SS pipe. And the difference of the wax content between PE pipe and SS pipe decreases with the depositing duration. Eventually, the wax contents of the wax deposits in PE pipe were almost the same as that in the SS pipe. The heat conduction and heat transfer processes in PE pipe and SS pipe were analyzed. The thermal gradient and the concentration gradient at wall were calculated and combined with the heat and mass transfer of wax during the wax deposition to illustrate the difference in wax content. It was found that the variations of the thermal and concentration gradients have significant effects on the diffusion process of wax molecules within the wax deposit layer and thus changing the aging rate. The comparisons and findings of wax deposition between the two kinds of pipes have provided a significant reference for the application of non-metallic pipe in the oilfield.

scholarly journals Review of the Factors that Influence the Condition of Wax Deposition in Subsea Pipelines

2018 ◽  
Vol 3 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Koh Junyi ◽  
Nurul Hasan
Keyword(s):  
Crude Oil ◽  
Residence Time ◽  
Flow Rate ◽  
Temperature Difference ◽  
Wax Deposition ◽  
Flow Loop ◽  
New Models ◽  
Wax Content ◽  
The Difference ◽  
Deep Depth

When crude oil is transported via sub-sea pipeline, the temperature of the pipeline decreases at a deep depth which causes a difference in temperature with the crude oil inside. This causes the crude oil to dissipate its heat to the surrounding until thermal equilibrium is achieved. This is also known as the cloud point where wax begins to precipitate and solidifies at the walls of the pipeline which obstruct the flow of fluid. The main objective of this review is to quantify the factors that influence wax deposition such as temperature difference between the wall of the pipeline and the fluid flowing within, the flow rate of the fluid in the pipeline and residence time of the fluid in the pipeline. It is found the main factor that causes wax deposition in the pipeline is the difference in temperature between the petroleum pipeline and the fluid flowing within. Most Literature deduces that decreasing temperature difference results in lower wax content deposited on the wall of the pipeline. The wax content increases with rising flow rate. As for the residence time, the amount of deposited wax initially increases when residence time increases until it reaches a peak value and gradually decreases. Flow-loop system and cold finger apparatus were used in literature investigations to determine the trends above. Three new models are generated through a regression analysis based on the results from other authors. These new models form a relationship between temperature difference, flow rate, residence time and Reynolds number with wax deposition. These models have high values of R-square and adjusted R-square which demonstrate the reliability of these models.

An Experimental Study on Mechanics of Wax Removal in Pipeline

2005 ◽  
Vol 127 (4) ◽  
pp. 302-309 ◽  
Author(s):  
Qian Wang ◽  
Cem Sarica ◽  
Tom X. Chen
Keyword(s):  
Test Section ◽  
Experimental Studies ◽  
Cost Effective ◽  
Test Facility ◽  
Flow Restriction ◽  
Cost Effective Method ◽  
Computer Based ◽  
Series Of Experiments ◽  
Wax Deposits ◽  
Wax Removal

Pigging has been recognized as the most cost-effective method for preventing flow restriction by wax deposits in subsea flowlines. However, the pigging mechanics for wax removal in pipelines is still very poorly understood. A unique test facility was designed and constructed for experimental studies on the mechanics of wax removal in pipelines. The test facility consisted of a test section, a support structure, an apparatus to pull the pig through the test pipe, and a computer-based data acquisition system. The test section was 6.4m(21ft) long and was made from 0.0762m(3in.) inner diameter schedule-40 steel pipe. The mixture of commercial wax and mineral oil was cast inside the test section at different wax thickness and oil contents. A series of experiments was performed to investigate the wax removal mechanics with three different types of conventional pigs, i.e., cup, disc, and foam pigs. The experiments showed that a typical wax removal process using a pig followed four distinct phases, namely, wax breaking, plug formation, accumulation, and production phases. Wax accumulation can be very significant and is expected to be the dominating factor for the force required for moving a pig in long pipelines. As wax thickness and hardness increases, the required force to move the pig increases. The shape and material of the pig have a profound effect on the wax removal performance. While the disc pig provides the most efficient wax removal, the force requirement is excessive, especially for thicker and harder wax deposits. The wax removal performance of a cup pig is very similar to that of a disc pig. However, the cup pig can withstand higher load without mechanical damages than the disc pig. The foam pig offers the poorest wax removal performance.

Investigation of thickness and wax content of wax deposits in polyethylene pipe using a flow loop

AIChE Journal ◽  
2020 ◽  
Vol 67 (1) ◽  
Author(s):  
Rongbin Li ◽  
Qiyu Huang ◽  
Dongxu Zhang ◽  
Xiangrui Zhu ◽  
Jinxu Shan ◽  
...  
Keyword(s):  
Flow Loop ◽  
Polyethylene Pipe ◽  
Wax Content ◽  
Wax Deposits

Full Scale Flow Loop Experiments of Hole Cleaning Performances of Drilling Fluids

2015 ◽  
Author(s):  
Jan David Ytrehus ◽  
Ali Taghipour ◽  
Sneha Sayindla ◽  
Bjørnar Lund ◽  
Benjamin Werner ◽  
...  
Keyword(s):  
Test Section ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Flow Loop ◽  
Base Oil ◽  
Hole Cleaning ◽  
Cleaning Performance ◽  
Water Based ◽  
Fluid Properties ◽  
Drilling Cost

One important requirement for a drilling fluid is the ability to transport the cuttings out of the borehole. Improved hole cleaning is a key to solve several challenges in the drilling industry and will allow both longer wells and improved quality of well construction. It has been observed, however, that drilling fluids with similar properties according to the API standard can have significantly different behavior with respect to hole cleaning performance. The reasons for this are not fully understood. This paper presents results from flow loop laboratory tests without and with injected cuttings size particles using a base oil and a commercial oil based drilling fluid. The results demonstrate the importance of the rheological properties of the fluids for the hole cleaning performance. A thorough investigation of the viscoelastic properties of the fluids was performed with a Fann viscometer and a Paar-Physica rheometer, and was used to interpret the results from the flow loop experiments. Improved understanding of the fluid properties relevant to hole cleaning performance will help develop better models of wellbore hydraulics used in planning of well operations. Eventually this may lead to higher ROP with water based drilling fluids as obtained with oil based drilling fluids. This may ease cuttings handling in many operations and thereby significantly reduce the drilling cost using (normally) more environmentally friendly fluids. The experiments have been conducted as part of an industry-sponsored research project where understanding the hole cleaning performance of various oil and water based drilling fluids is the aim. The experiments have been performed under realistic conditions. The flow loop includes a 10 meter long test section with 2″ OD freely rotating drillstring inside a 4″ ID wellbore made of concrete. Sand particles were injected while circulating the drilling fluid through the test section in horizontal position.

Flow Loop Investigation of Lubricant Concentration Effect on Mechanical Friction in Drilling Fluids

2016 ◽  
Author(s):  
Jan David Ytrehus ◽  
Ali Taghipour ◽  
Knud Richard Gyland ◽  
Bjørnar Lund ◽  
Sneha Sayindla ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
North Sea ◽  
Test Section ◽  
Drilling Fluid ◽  
Drill String ◽  
Drilling Fluids ◽  
Flow Loop ◽  
Steel Tubing ◽  
Steel Sections ◽  
Concrete Elements

A laboratory scale flow loop for drilling applications has been used for evaluating the effect of lubricants on skin friction during drilling and completion with oil based or low solids oil based fluids. The flow loop included a 10 meter long test section with 2″ OD free whirling rotating drill string inside a 4″ ID wellbore made of concrete elements positioned inside a steel tubing. A transparent part of the housing was located in the middle of the test section, separating two steel sections of equal length. The entire test section was mounted on a steel frame which can be tilted from horizontal to 30° inclination. The drilling fluids and additives in these experiments were similar to those used in specific fields in NCS. Friction coefficient was calculated from the measured torque for different flow velocities and rotational velocities and the force perpendicular to the surface caused by the buoyed weight of the string. The main objective of the article has been to quantify the effect on mechanical friction when applying different concentrations of an oil-based lubricant into an ordinary oil based drilling fluid and a low solids oil based drilling fluid used in a North Sea drilling and completion operation.

STUDY ON NEW ICE SLURRY GENERATOR USING NaCl AQUEOUS SOLUTION AT LOW CONCENTRATION

2013 ◽  
Vol 21 (01) ◽  
pp. 1350004 ◽  
Author(s):  
KOJI FUMOTO ◽  
TSUYOSHI KAWANAMI ◽  
TAKAO INAMURA
Keyword(s):  
Aqueous Solution ◽  
High Pressure ◽  
Test Section ◽  
Freezing Point ◽  
New Method ◽  
Heat Of Fusion ◽  
Test Fluid ◽  
Ice Slurry ◽  
Slurry Ice ◽  
Experimental Apparatus

A cold thermal energy storage system has been developed for HVAC. There are many ice-based cooling systems operating around the world. Ice slurry, which is a mixture of fine ice crystals and liquid water, is utilized in ice storage systems owing to its good flowability and large latent heat of fusion. For slurry ice production techniques, there are presently a number of commercially available ice slurry generators (e.g., Supercooled slurry ice generator, Scraper type generator, and Vacuum type generator, etc.). In the present study, a new method was developed to generate ice slurry without the deposition of an ice layer on a cooled surface. The basic components of the experimental apparatus is a cooling brine circulating loop, a high pressure pump, a valve, an aqueous solution flow loop containing the test section, which is made of transparent acrylic, and the associated instrumentation. This new method is based on freezing-point depression of the aqueous solution, which is maintained under high-pressure conditions. To control the timing for solidification and to generate ice slurry, we investigated the relationships among the pressure and temperature of the aqueous solution. The freezing phenomenon of the aqueous solution in the test section was observed in detail. As a result, we developed a new ice slurry generator based on the new method that controls the pressure and temperature of the aqueous solution. Experimental results showed that the characteristics of the ice slurry generation were closely related to the pressure and initial stage temperature of the test fluid. Finally, the optimum operation condition of the ice slurry generator based on visualization experiment was discussed.

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