Effect of Oil Temperature on the Wax Deposition of Crude Oil With Composition Analysis

Wax deposition is one of the most challenging flow assurance issues in oil production processes. The related problems span from reservoirs to refineries, but their consequences can be particularly challenging when the affected area is difficult to reach, such as producing wells. The wax deposition in the areas adjoining the bore, the bore face, the tubing string and the pump is the result of the cooling effect, which occurs when the oil flows from the high-pressure reservoir into the wellbore to the surface. During the depressurization the oil expands, and the heat is drawn from the oil. The temperature loss induces crystallization of the wax and the subsequent plugging of the well. In this case, wax deposition leads to the decrease of well flow rates and eventually causes total blockage. This paper sums up the main technologies applied to prevent or remediate the wax deposition formed inside the wells. A comprehensive review was presented, and the main advantages and disadvantages of these techniques were highlighted. For instance, the mechanical removal is still a widely used technique for solving wax problems inside wells, despite being a costly procedure; heating is another frequent used technique, but it can cause formation damage; bacterial treatments still require further studies on site conditions; changing the operational conditions may be undesirable due to other management field circumstances; coating and insulating materials generally are not fully efficient, being required to implement complementary techniques; cold flow was only tested in pipelines and it was not applicable to wells; finally WIT, electric and magnetic field or oscillatory motion are practical applications that have not been fully proven yet. Keywords Wax deposition inside wells • Wax prevention techniques and wax removal techniques

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“…Considering the ratio between the real and the reference pressure drop, it is possible to estimate the wax layer thickness (Quan et al 2016):…”

Section: Methods To Identify Wax Deposits Inside Wellsmentioning

confidence: 99%

Preventing and removing wax deposition inside vertical wells: a review

Sousa

Matos

Guerreiro³

2019

J Petrol Explor Prod Technol

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“…The pressure drop method is based on the concept of increasing pressure drop along the pipeline resulting from a decrease in the hydraulic diameter caused by wax deposition [36]. It can be used to estimate wax thickness without restart or depressurization the pipeline [21].…”

Section: The Pressure Drop Methodsmentioning

confidence: 99%

Crude oil and the problem of wax deposition on pipeline systems during transportation: A review

Onwumelu¹,

Onwuka²,

Nnebeana³

et al. 2022

World J. Adv. Res. Rev.

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Crude oil, the world’s major source of energy, is obtained from the earth as a Newtonian fluid and needs to be transported to refineries for further processing. Pipeline transport has proven to be the most efficient, environmental-friendly and cost effective of all modes of crude oil transportation from subsea production sites. However the formation and deposition of waxes (mainly paraffinic and asphaltenic components) along pipelines remains one of the greatest flow assurance problem in the petroleum industry. This is aided by attainment of wax appearance temperature (WAT), the crude’s hydrocarbon contents and rheological properties, and the production conditions amongst others. The deposited waxes clog the pipeline, reduces the flow diameter, converts the behavior of the fluid from Newtonian to non-Newtonian, decreases throughput, causes more work on pumps and other process equipment, increases energy consumption, and ultimately raises the cost of production thereby decreasing profits. It also leads to several downtimes and in extreme cases can cause permanent shut down of facilities. Several studies have been done to understand the nature of crude oil waxes and the various techniques for solving this problem. This paper takes a critical look at crude oil and reviews the current state of research into the causative factors, deposition mechanisms and remediation methods including the thermal, mechanical, biological and chemical techniques. At the end there is a conclusion and further research on the use of biological techniques (microorganisms) has been advised herein.

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“…On the other hand, shear is seen as important only when there is a high concentration of crystallized wax in the bulk oil, which is relevant only at temperatures significantly below the WAT . Other authors, − also using flow loops, show the impact on deposit mass and n -alkane distribution when working with temperatures below the WAT as well as using different temperature gradients.…”

Section: Introductionmentioning

confidence: 98%

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

Padula¹,

Gon²,

Russell³

et al. 2020

ACS Omega

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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-C 35 ) 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.

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Effect of Oil Temperature on the Wax Deposition of Crude Oil With Composition Analysis

Cited by 27 publications

References 14 publications

Preventing and removing wax deposition inside vertical wells: a review

Preventing and removing wax deposition inside vertical wells: a review

Crude oil and the problem of wax deposition on pipeline systems during transportation: A review

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

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