John D. Corney, Magtek,Inc., Inc.

Previous treatment methods such as biological, galvanic, and magnetic devices were minimal and were limited to a few geographical areas. Ceramic or alnico magnets used in the past have been replaced by the introduction of new high energy product magnetic material, which is eight to thirty times more powerful.

Magnetic fluid conditioners (MFCs) that require no external power source to treat fluids in oil wells have been classified as miracle gadgets by many well-meaning skeptics in the past. Some producers have used MFCs with great success, documenting great cost savings and, in some cases, increased production. If the success ratio were 75% or better, magnetic fluid conditioners would be an integral part of production equipment. A study of past attempts to market MFCs indicates a success ratio of less than 25% for the following reasons:

Many early designs consisted of nothing more than permanent magnetic material (ceramic or alnico) clamped around or suspended in a carbon steel case, usually a short section of production tube.

The energy product (BH) max of ceramic and alnico 5 varies from one to five G-Oe x 10°. Some rare grades of alnico are as high as 9 MG.Oe. New rare earth magnetic material is now commercially available in the 30-40 MG.Oe range.

The bulk (physical size) of the ceramic and alnico material handicapped the design. The magnetic energy developed by large clamp on ceramic magnetics first saturates the carbon steel production tube, so only a small residual amount of energy is left to do the work in the fluid passing inside the production tube.

Field tests proved that the amount and density of magnetic flux in the treatment area is one of the primary considerations in designing an MFC. The areas of treatment in an MFC are commonly referred to as intersects where the fluid is accelerated through an area of condensed magnetic flux.

The American Petroleum Institute (API) funded the Baylor University Magnetic Group to evaluate the principles of magnetic water treatment. The resulting paper was released at the 45th Annual Meeting of the International Water Conference in 1984. The group states, "A fundamental law of physics states that the motion of a conductor through a magnetic field will cause a voltage to be produced. This principle of electromagnetic induction was first demonstrated by Faraday, and applies not only to conducting solids such as wires, but also to conducting fluids such as aqueous solutions containing dissolved electrolytes." Therefore, the passage of water containing dissolved ions through an MFC should produce a voltage.

The Baylor researchers measured the magnetohydrodynamic effect of an MFC as the result of a series of electrical measurements made within the intersects of the device while various flow rates of a sodium chloride solution were circulated through it. Both voltage and current were measured. The more dense the magnetic flux, the more current flowed. Also the results of the voltage measurements indicated that the measured voltage was a linear function of solution flow rate.

The performance of MFCs placed in oil wells has proven that flux density (gauss) and the velocity of the crude oil and water in the magnetic intersect correspond with Baylor's findings.

Because some corrosion was observed on the stainless steel electrodes of the voltage measurement probes, it was thought that electrolysis was taking place. It was postulated that the electrolysis products, which result from the process, could be involved in causing preferential precipitation of calcium carbonate in the bulk of the solution rather than on plumbing surfaces. This is not the case in actual field applications where no sign of sacrificial disintegration of the MFC was found after years of use in oil wells.

Professor John Donaldson and Dr. Sue Grimes researched the effects of magnetic fields on fluids in the Chemistry Department of City University, London. They have a different approach and state; "A magnetic field will interact with any substance that carries a charge, however small, in any fluid. The nuclei on which the crystals start growing and the growing crystallites are very small and will have charged surfaces. As they pass through the magnetic field, these charged particles encounter considerable forces as the magnetic field interacts with them. The magnet field acts at the surface of the crystallites modifying the nature of the charges at the surface. This alters the growth of the crystal in general and on specific planes."

This will change the shape of the crystals as has been recorded by electron micrographs and X-ray diffraction patterns of precipitates of calcium carbonate. Before magnetic treatment, the precipitate of calcium carbonate contained calcite and aragonite in the ratio of about 4:1. After treatment, the ratio was about 1:4.

As crystals grow differently, their solubility or levels of supersaturation in fluids alters. This explains why scale starts to dissolve and the cloud point in crude oil is lowered.

The cloud point of oil is the temperature at which paraffin begins to come out or solution. Additional cooling brings more wax out of solution. Wax crystals can nucleate forming agglomerates that slowly develop an interlocking network. Eventually the crude becomes so thick it reaches its pour point.

Wax crystals normally have a needle-like shape, and if they remain as single crystals they tend to disperse in the crude instead of depositing on a surface. Nucleating centers gather crystals into bushy particles that attach and build deposits in the well tubing. Water can also become entrapped by these bushy agglomerates increasing the BS&W.

Asphaltenes, along with scales, formation fines and corrosion products can be nucleating centers for wax crystals. Cooling is the most common cause of wax deposition as it lowers its solubility in the crude oil. Loss of gas and light hydrocarbons from crude also decreases wax solubility.

The concept that a magnetic field will interact with crystallization nuclei explains most of the phenomenon observed in crude oil and water treatment.

Gruber and Carda (South Dakota School of Mines), in a research report presented at the Water Quality Association Annual Meeting in July 1991, grouped basic designs of magnetic devices into four classes as follows;

Class 1. This design is essentially magnets fastened to the outside of a pipe, sometimes snort lengths of production tubing (pup joint), so the device can be screwed into the production string. This group is the least likely to succeed.

Class II. This type of device makes provision to control the direction of flux (perpendicular to the fluid flow) and to compress the flux to increase flux density in the fluid passage. This class lends itself to more sophisticated and effective designs.

Class III. This design consists of a magnet or magnets suspended as a core in the center of a ferromagnetic tube or pipe. The magnets are usually set longitudinally with close packed opposing poles. This design does not have the benefits of flux density and control of flux direction.

Class IV. This class contains some electromagnetic types which are not practical in oil wells.

Improvements in MFC design have come from Class II.

The basic characteristics of a magnet are evident in its hysteresis curve. The suitability of magnetic material and its dimensions is calculated by formulas and information taken from its hysteresis curve. The secondary quadrant of the curve known as the demagnetization curve is the most important indicator of the characteristics of a particular magnetic material. It is important to know the amount of magnetic energy available outside the magnet. The maximum energy available is the magnetic energy product. The CGS unit of maximum energy product is the Gauss Oersted (G.Oe), but as common values are in the order of 10°, the more manageable Mega Gauss Oersted (MG.Oe) is commonly used.

The demagnetization curve, which shows the magnetic characteristics of a magnet, is usually drawn with magnetic induction (B) on the vertical axis and magnetic field strength (H) on the horizontal axis. The B-H curve compensated for down hole temperatures should be used.

Claims made by vendors about the strength of their devices need to be carefully evaluated as errors in terminology are often made. For example, magnetic induction (B) is referred to as gauss or kilo gauss, also the unit of residual inaction (Br) is gauss.

Often promoters who are not technically proficient read magnetic properties from technical data sheets such as residual induction 11,600 gauss and assume their gadget has 11,600 gauss. This is far from true,

It is the density of flux (gauss) available in the fluid treatment area that causes the desired effect. High-energy rare earth magnetic material can be as ineffective as ceramic or alnico material if it is not in properly designed circuits.

The magnetic "conduction coefficient" or "permanence coefficient" which relates to length/diameter (L/D) ratio of rare earth magnetic material allows a very compact design, ideal for limited space in oil wells.

Most "rare earth" material has a very high "intrinsic coercive force" or resistance to demagnetization forces. Physical impact, pressure, vibration and stray electrical and magnetic fields have virtually no degaussing effect.

The credibility of magnetic fluid conditioners has been seriously damaged by overrated performance claims and ineffective installations. Too often MFCs are touted as cure-alls for any problems in the oil field, instead of limiting installations to problems they can solve.

To date the 90% success rate in pumping wells that the Magtek,Inc. MFC has attained can only be attributed to sound magnetic design and rigid parameters in selecting wells for sizing tools. Magtek,Inc. will not ship an MFC to a customer until a complete information sheet has been provided for the particular well to be treated. Inaccurate information causes failures.

The following analysis details the "before" and "after" conditions in the subject wells, as well as the increase in savings and revenue.

"Before" conditions: Paraffin deposition in flowlines. Tank high bottoms.

"Before" treatment: Hot oil-treating flowlines an average of every two to four weeks to disperse paraffin. Continual chemical treating to reduce BS&W in tanks. Average monthly treatment cost per well: $274.00.

"Before" results: Flowline paraffin deposition continued. Tanks continued to be rejected frequently by buyers because of BS&W.

 

"After" conditions: No paraffin deposition in flowlines. Tank high bottoms reduced.

"After" treatment: Hot oil treatments and continuous chemical injections discontinued. Average monthly treatment cost per well: $0.00

"After" results: Flowlines clear of paraffin. No tank rejections recorded on any of the above wells since Magtek,Inc. MFC installation.

  Notes: Increased oil production attributed to downhole breakup of emulsions by MFC.