US2937112A - Method for removing paraffin from oil wells, lines, tanks, pumps and the like - Google Patents

Description

nite States Patent NIETHOD FOR REMOVING PARAFFIN FROM OIL WELLS, LINES, TANKS, PUMPS AND THE LIKE Albert J. Boyer, Kansas City, Kans.

No Drawing. Application June- 20, 1955 Serial No. 516,738

6 Claims. (Cl. 13440) This invention relates to the art of removing parafiin from equipment utilized in the production, transportation, storage or processing of petroleum products. More particularly, the invention contemplates a simple method for removing such parafiin which is both economical to perform and, in actual tests, has proven radically more effective in the accomplishment of the mentioned purpose than any method heretofore known.

The problem of formation of hardened parafiin on well tubes or casings, pipe lines, tanks, pump structures and the like, has long been one of great seriousness and concern in the petroleum industry. Such troublesome formations of parafiin inevitably are deposited from certain types of petroleum upon everything with which such petroleum comes in contact during its recovery, transportation and storage. As successive layers are deposited upon such surfaces, for instance oil well tubings, and as such deposits harden, impairment of the functioning of the apparatus upon which the deposits have accumulated obviously results. In the case of tubings, pipe or the like, a reduction in flow attended by back pressures and increased flow pressure requirements are encountered. In the case of pumps or the like, the deposits will, unless periodically removed, eventually result in the equipment being rendered inoperative.

In the past, the most common method for removing paraffin from such structures has been by means of heat, usually in the form of steam, by which the paraflin is melted down to break the same loose from the surface upon which it was deposited, followed by a flushing step in which water or the like may be used to remove the material so broken loose. In the case of pumps, complete disassembly has usually been required in order to properly accomplish the job, while in the case of lines it is normally required to disassemble and clean the line section-by-section. The situation has been even more gravely disadvantageous, if possible, in the case of well tubings where it has heretofore been necessary to remove or pull the tubing from the well in order to clean the tubing, as well as to get at the pump for cleaning of the latter.

It will be manifest that such procedures have been extremely expensive and, except for the lack of a better method, quite impractical, in view of the loss of the functioning time of the equipment occasioned by the necessity for its removal or disassembly, as well as the considerable amounts of time and labor required to accomplish the paraffin removal even after the equipment to be treated has been brought to a condition of access for such treatment by removal from its normal location and/or disassembly. Moreover, it will be evident that such methods heretofore necessarily employed have required the provision of special and expensive equipment at the place where the treatment is to be carried out.

Accordingly, it is the primary object of this invention to provide a method for the removal of paraflin from such structures and equipment which will overcome the 2,937,112 Patented May 17, 1960 above-mentioned and other disadvantages and will make it possible for paraflin to be removed from such equipment and structures without disassembly or dislocation thereof from their normal functional locations.

It is another important object of this invention to provide such a method which may be carried out by relatively unskilled labor through the use of inexpensive materials and equipment normally available at a well site, and which will yield results either as good or better than those heretofore possible by the use of previous methods.

It is another important object of this invention to provide a method for treating structures having a hardened deposit of parafiin thereon with a material adapted for removing such paraffin through settling thereof into a liquid or suspended state by means of chemical action so that same may be removed from the structure along with the material when the latter is withdrawn.

Still other important objects of this invention including the discovery and identification of the material best adapted for use in performing the method and the important conditions surrounding the performance of the method, will be made clear or become apparent as the following description of the invention progresses.

The method of this invention generally contemplates the use of a paraffin settler or, in a somewhat loose sense, solvent which is applied to a structural surface having a hardened deposit of paraflin thereon. Such application may be by spraying, painting, immersion, circulation or in other suitable fashion adapted to bring the solvent into contact with the hardened deposit of paraifin for chemical action therebetween.

In the case of well tubings and pumps, such application may be accomplished by simply introducing the material into the casing and permitting same to remain therein for the required period, or after introduction of the settler or solvent material therein, the latter may be circulated by means of the well pump or an auxiliary pump. One manner of performing the method on the internal structure of oil wells which has proven quite effective has been to introduce the settler or solvent material into the well casing and then recirculate the same up through the tubing and pump, thence back down the casing of the well.

In the case of pipe lines, the material may simply be added to a product being passed therethrough or may be recirculated through a considerable length of pipe line by means of an auxiliary pump and conduit tapped into the pipe line at points considerably spaced from each other on the latter.

In the case of pumps which are available on the surface of the ground, the method may be performed by simply filling the same with, or immersing the same in, the settler or solvent material.

With respect to tanks and the like, a quantity of the settler or solvent material may simply be introduced into the tank or, if the size of the tank would render such procedure uneconomical, the material may be sprayed, painted or otherwise suitably applied to the surfaces carrying the hardened paraffin deposits.

Before proceeding to an explanation of the various conditions under which the method is preferably performed, attention is directed to the nature of the settler or solvent material to be used, which is in large measure of the essence in connection with the success of the overall method. The material currently preferred is prepared by combining a soluble oil composition including a rosin odeate, a mineral lubricating oil and a coupling agent therefor with a petroleum solvent under conditions adapted to homogenize the same. A suitable water soluble oil composition is presently available from the Sinclair Refining Company under the trademark Satisol" and comprises as its material ingredients around 3% by weight of rosin odeate in a paraffin base type mineral lubricating oil with a minor proportion of agent for coupling the odeate in the oil. The paraflin base lubricating oil contained in Satisol" has the following physical characteristics:

Gravity (API) 22-31. Flash point Min. 300 F. Firing point Min. 350 F. Viscosity (Saybolt Universal scale) 100350 seconds. Pour point 20 F. max.

The coupling agent employed is preferably an aliphatic type alcohol while the rosin odeate serves as the emulsifier. The complete composition designated Satisol, has the following physical and chemical constants:

Gravity (API) 22-24.

Acid number 7.4.

Free fatty acid content 3.8% max. Ash 3.5% max. Water content Approx. 2%.

The preferred proportion of the soluble oil composition, which it will be obvious has the properties of an emulsifying agent by virtue of the presence of the rosin odeate therein, with the petroleum solvent is about 3 parts of the emulsifying soluble oil composition to 2 parts of the petroleum solvent, depending somewhat upon the particular solvent used. The stated proportions will be found quite suitable where such solvent comprises #2 flame distillate or the like.

In preparing the settler material the soluble oil composition and petroleum solvent are placed in proper proportions in a pressure mixture vessel and same are then subjected to blending sufficient to homogenize the solution. It has been found that subjection of the soluble oil composition and solvent mixture to agitation by five thousand revolutions per minute blades while under approximately 100 pounds per square inch of pressure for a period of about 30 minutes is satisfactory where air agitators are also used, although it is to be understood that such blending treatment may be carried on from about 20 minutes up to about an hour as may be required for stabilization of the mixture in homogenous condition.

Such settler or solvent material may be used either full strength or diluted by the addition of kerosene, flame distillate or the like thereto at the point of use in proportions ranging up to about 5 parts of kerosene to 1 part of settler or solvent for fully satisfactory results. It will be obvious that the degree of dilution, if any, of the settler or solvent material will depend to a considerable extent upon the thickness of the deposited paraffin to be removed and the time over which the method is to be carried out. For all except the most extreme cases, however, a mixture of about 3 parts of kerosene to 1 part of settler or solvent material is preferred and has been found to yield substantially optimum results.

Again, the length of time during which the paraflin deposit to be removed should be subjected to the settler or solvent material, is, in large measure, dependent upon the thickness of deposit. This may vary widely from about V2 to about 24 hours, with it being noted that during the latter named period a given quantity of the settler or solvent will normally have fully performed that degree of action of which it is capable. It is conceivable, therefore, that in a very extreme case, a repetitive treatment with a fresh quantity of settler or solvent material might be required, although such has not yet been encountered in practice.

Although the exact nature of the chemical action which occurs between the settler or solvent material and the hardened paraffin is not yet fully understood, the effect appears to involve the penetration and fimulsifi cation of the paraffin into a loosened, suspended and more or less liquid state in the settler solution. Such removed paraffin may then be dumped, pumped, washed, or otherwise removed from the equipment undergoing treatment.

It may be noted that the action of the settler or solvent material upon the paraflin is substantially speeded if such material is circulated relative to the paraffin to be removed. Tests made on the Carlson No. 2 well at Lindsborg, Kansas, have indicated that where the settler or solvent material is circulated through the well tube or pump to be treated, a period of about 3 hours is satisfactory with a solution of settler material diluted with up to about 5 equal parts of kerosene or flame distillate. Similar tests performed at the Duval well No. 6 in Welch Pool in Rice County, Kansas, have indicated that subjection of a pipe line to a 1 to 4 diluted solution of the settler or solvent material for a period of about 20 to 30 minutes resulted in decreasing the pressure required for movement of petroleum through the line approximately in half, although such tests indicated that for complete clearing of the line of hardened paraffin the period of circulation of the settler material therethrough should be for a somewhat longer period of the order of at least about 3 hours.

It has also been found that heating the diluted settler material preparation to approximately F. to F. speeds the chemical action of the preparation upon paraffin. In a trial carried out at the facilities of National Supply Co. in Chase, Kansas, it was found that badly coated pumps submerged in a preparation at said temperature of one part settler material to three parts #2 flame distillate for approximately 30 minutes completely removed all paraffin from the pumps.

Accordingly, it will be observed that the strengths and treating times for the removal of various thicknesses of hardened paralfin from different structures will depend to a fairly great extent upon such thicknesses and the nature of such structures. It will be clear in any event, however, that the times and costs involved are radically less than those by which the same job of paraffin removal could possibly be accomplished by methods heretofore known. The utility and advantages of the method will, therefore, be entirely manifest. Equally clear is the fact that the method contemplated by this invention involves an approach and solution to this problem along a dilferent line than has heretofore even been known or used.

Since certain aspects of the method can conceivably be varied and at least some benefit still derived from utilization of the general concept of this invention, it is to be understood that the invention should be deemed limited within its fair breadth and intention only by the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. The method of removing paraffin from a surface which comprises subjecting the surface having paraflin thereon to contact with a homogeneous mixture containing a Water soluble oil composition and #2 flame distillate, said composition including a paraffin base lubricating oil, rosin odeate and an aliphatic alcohol characterized by the property of coupling the rosin odeate into said lubricating oil and being present in suflicient quantity to penetrate and emulsify the paraffin on said surface; then, removing said surface from contact with said mixture.

2. The method as set forth in claim 1 wherein said composition has an API gravity of 22 to 24, an acid number of 7.4, a maximum free fatty acid content of 3.8%, a maximum ash content of 3.5% and a water content of approximately 2%.

3. The method as set forth in claim 1 wherein the parafiin base lubricating oil has an API gravity of 22 to 31, a minimum flash point of 300 F., a minimum firing point of 350 F., a Saybolt viscosity of 100 to 350 secends and a maximum pour point of 20 F.

4. The method as set forth in claim 1 wherein the References Cited in the file of this patent rosin odeate is present in said composition in the proportion of from about 2% to approximately 5% by weight. UNITED STATES PATENTS 5. The method as set forth in claim 1 wherein said 1,415,605 Newbury May 9, 1922 mixture contains approximately 3 parts of said composi- 5 1,722,211 Guardino July 23, 1929 tion to about 2 parts of said distillate by volume. 2,204,224 Limerick June 11, 1940 6. The method as set forth in claim 1 wherein said 2,358,665 Shapiro Sept. 19, 1944 mixture is heated to a temperature between approximate- 2,442,100 ShOWaIteI' May 25, 1948 1y 90 and 100 F. 2,613,186 Pickett Oct. 7, 1952 10 2,741,596 Luark Apr. 10, 1956

Claims (1)

1. THE METHOD OF REMOVING PARAFFIN FROM A SURFACE WHICH COMPRISES SUBJECTING THE SURFACE HAVING PARAFFIN THEREON TO CONTACT WITH A HOMOGENEOUS MIXTURE CONTAINING A WATER SOLUBLE OIL COMPOSITION AND #2 FLAME DISTILLATE, SAID COMPOSITION INCLUDING A PARAFFIN BASE LUBRICATING OIL, ROSIN ODEATE AND AN ALIPHATIC ALCOHOL CHARACTERIZED BY THE PROPERTY OF COUPLING THE ROSIN ODEATE INTO SAID LUBRICATING OIL AND BEING PRESENT IN SUFFICIENT QUANTITY TO PENETRATE AND EMULSIFY THE PARAFFIN ON SAID SURFACE, THEN, REMOVING SAID SURFACE FROM CONTACT WITH SAID MIXTURE.