Analysis of different factors affecting cathodic protection for deep well casings

Metwally, I.A.; Al‐Badi, Abdullah

doi:10.1002/maco.200905272

Cited by 12 publications

(12 citation statements)

References 4 publications

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“…The main advantages with the use of PCP system are as follows (Bich and Bauman, 1995; Bauman, 2004):PCP power requirements are significantly lower than are those of conventional CP systems.PCP can provide current to significantly deeper levels compared with the conventional CP systems.PCP provides more uniform current distribution to the casing because of the inductive and capacitive reactance of the anode and structure system.PCP produces less stray current interference.PCP requires smaller anode beds.A problem of mutual interference can arise when a single PCP system is used to protect a group of close‐spaced wells from single anode unit (Doniguian, 1982; Metwally and Al‐Badi, 2009). This is because the spatial distances between the well casings and/or the electrical properties of the soil or other conducting medium result in one or more well casings receiving excessive current while others receive inadequate protection current.…”

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

“…The problem of protecting closely‐spaced well casings was recently resolved with the development of the multi‐module PCP system (Doniguian, 1982; Metwally and Al‐Badi, 2009). Each system contains multiple but separate PCP modules.…”

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

“…Semi‐closely spaced oil well casings would be protected with a multi‐module PCP system (Doniguian, 1982; Metwally and Al‐Badi, 2009). The layout of the PCP system for protecting four well casings would use one common PCP station and a common anode bed nearby to this station.…”

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

“…However, based on the field measurements in Oman (Metwally et al , 2007) and analyses of some modeled cases (Metwally and Al‐Badi, 2009), the protective currents was not pulsating and had a significant average DC component, which makes it act very similarly to the conventional CP systems.…”

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

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Factors affecting pulsed‐cathodic protection effectiveness for deep well casings

Metwally

Al‐Badi²

2009

Anti-Corrosion Methods and Materials

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PurposeThe purpose of this paper is to introduce a theoretical investigation of the pulse‐cathodic protection (PCP) systems to show how they behave under different operating conditions. The effectiveness of the PCP system also is highlighted for a typical large‐scale configuration. The principal technical objectives of this paper are to answer three questions: Are the PCP systems effective in the desert fields? Although they have been approved, what is the reason for their lack of effectiveness in some coastal areas? What are the operation recommendations for the currently installed PCP systems and their future application?Design/methodology/approachThe factors affecting the cathodic protection of well casings have been investigated theoretically by using a 3D field approach software package current distribution, electromagnetic fields, grounding and soil structure analysis. Cathodic interference with nearby well casings has been investigated thoroughly because corrosion of this kind is more serious than the anodic type. The performance of PCP systems has been analyzed with respect to obtaining better protection‐current distribution along the protected well casing at reduced anode current, together with reduced stray current (corrosion) at any nearby unprotected structure(s).FindingsFor uncoated well casings, protection current pulses are attenuated significantly and are smoothed out to be pure direct current after about 10 percent of the well‐casing buried length. High‐magnitude stray current can be found affecting any switched‐off well casings and hence they can be corroded faster from the top part than unprotected/remote wells, as are deeper well casings that may sustain considerable localized corrosion attack on the upper portions of the casing. Without the formation of a natural protective coating with high resistivity, the PCP system becomes malfunctioning, i.e. its performance becomes very similar to that of the conventional cathodic protection (CP) systems. This effect has been confirmed by field measurements in Oman, where magnesium hydroxide is minimally formed (in desert areas).Research limitations/implicationsIn reality, some of the PCP modules at the same station can have a slight deviation in the operating frequency and/or voltage. It is planned, therefore, that the investigation will be extended to simulate such cases and take into account the effect of multi‐layer soils.Practical implicationsKnowing the performance of PCP systems for protecting deep well casings is a critical issue for the oil industry.Originality/valueThe paper provides a sound basis on which oil producers can take decisions about the future application of the PCP systems, optimize their performance, and introduce application restrictions by studying all factors that affect PCP performance. The effectiveness of PCP in desert (sandy/rocky) soil, where calcium‐carbonate deposition predominates over magnesium‐hydroxide formation, has proven to be very similar to that of a conventional CP system. The reliability of artificial oil‐lif...

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Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

Section: Pcp Systems Effectiveness At Glancementioning

confidence: 99%

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Factors affecting pulsed‐cathodic protection effectiveness for deep well casings

Metwally

Al‐Badi²

2009

Anti-Corrosion Methods and Materials

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“…Corrosion easily happens because part of a pipeline in the soil is anodic and the other part in the air is cathodic. Therefore, the goal of cathodic protection is to apply a direct current to the steel and provide a sacrificial anode [6]. With the development of technology, the numerical modeling becomes very convenient and accurate method for dealing with SCC problems.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of buried pipelines under DC stray current corrosion

Zhang

Feng

et al. 2019

J. Electrochem. Sci. Eng.

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<p class="PaperAbstract">Corrosion of buried pipelines caused by stray currents is becoming a serious industrial and environmental problem. It is therefore necessary to study corrosion mechanisms of buried pipelines under DC stray currents in order to propose effective anti-corrosion measures. Since measurement of the potential is one of important ways to identify stray current intensity, the COMSOL Multiphysics software was used to simulate stray current corrosion dynamics of buried pipelines. It was also used to calculate the distribution and intensity changes of electrolyte potential in the cathodic protected system by solving Laplace’s three-dimensional equation. The obtained results showed that increased applied voltage leads to more positive shift of a pipeline potential, resulting in acceleration of stray current corrosion. On the contrary, increased soil resistivity can retard the corrosion process. The protected pipeline with a sacrificial anode suffers less corrosion interference than unprotected pipeline. Two crossed arrangement of pipelines makes no difference in corrosion of protected pipeline, but affects greatly on unprotected pipeline.</p>

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Effect of pulse cathodic protection on corrosion mitigation and electrochemical conditions under a simulated coating disbondment on pipeline steel

Najafi

Eslami

Golozar

et al. 2021

Materials & Corrosion

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Coating disbondments on pipeline steels are regions with high resistivity where conventional cathodic protection (CP) could not fully protect. Therefore, in an attempt to mitigate this challenge, this study investigates the effect of pulse CP on corrosion mitigation and electrochemical conditions under a simulated coating disbondment on X-52 pipeline steel. In this regard, conventional and pulse CP of −870 mV SCE were applied to the open mouth of a simulated coating disbondment.For pulse CP, frequencies of 1, 5, and 10 kHz were used. Results showed while the conventional CP was not able to fully protect the 20 cm simulated coating disbondment, for the pulse CP with increase in frequency from 1 to 5 kHz, and from 5 to 10 kHz, improve in CP potential protection under the simulated coating disbondment was achieved. This was accompanied by considerably lower corrosion and a more uniform pH distribution under the simulated coating disbondment.

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Analysis of different factors affecting cathodic protection for deep well casings

Cited by 12 publications

References 4 publications

Factors affecting pulsed‐cathodic protection effectiveness for deep well casings

Factors affecting pulsed‐cathodic protection effectiveness for deep well casings

Numerical modelling of buried pipelines under DC stray current corrosion

Effect of pulse cathodic protection on corrosion mitigation and electrochemical conditions under a simulated coating disbondment on pipeline steel

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