System for removing organic deposits

Abstract

A themo-chemical system for removing organic deposits such as wax, asphaltenes, and resins in an oil well borehole, and in oil production and transportation tubing and pathways.

Claims

1. A system for treating or removing organic deposits formed oil well boreholes, oil production and transportation tubing, and pathway systems, the system comprising: a first tank containing a first heavy aromatic naphtha based solution comprising LABSA or aliphatic acids or mixtures of both; a second tank containing a second heavy aromatic naphtha based solution comprising amines; a first pump in fluid communication with the first tank; and a second pump in fluid communication with the second tank, the first and second pumps configured to inject the first and second solutions into a pathway having organic deposits disposed therein such that the first and second solutions react to produce imides and heat to remove the organic deposits.

2. The system of claim 1, wherein the first solution includes LABSA in a suitable solvent with or without additives such as corrosion inhibitors or surfactants.

3. The system of claim 2, wherein the LABSA component has four, eight, or twelve average carbon number in the alkyl side chain or mixture thereof.

4. The system of claim 2, wherein the suitable solvent is an organic solvent such as toluene, xylene, heavy aromatic solvents, diesel, naphtha, petroleum distillates or mixtures thereof.

5. The system of claim 1, wherein the first solution includes aliphatic acids such as formic, acetic and propanoic acids in a suitable solvent.

6. The system of claim 1, wherein the first solution includes acetic acid in a suitable solvent.

7. The system of claim 1, wherein the first solution is a mixture of LABSA and aliphatic acid such as formic, acetic or propanoic acid in suitable solvent.

8. The system of claim 1, wherein the first solution includes a mixture of LABSA and acetic acid in a suitable solvent.

9. The system of claim 1, wherein the second solution includes organic bases such as alkyl amines, ethylene amines and poly amines in a suitable solvent.

10. The system of claim 9, wherein the concentration of apliphatic amines, ethylendiamine, polyamines or mixture thereof is 50-80%.

11. The system of claim 1, wherein the second solution includes aliphatic amines such as ethyl, propyl, butyl, pentyl amine or mixture thereof in a suitable solvent.

12. The system of claim 1, wherein the second solution includes butyl amine amines in a suitable solvent.

13. The system of claim 1, wherein the concentration of LABSA and aliphatic acid or mixture thereof is 50-80%.

14. The system of claim 1, wherein the pathway includes bullheading tubing and the pumps are configured to inject the first and second solution into the bullheading tubing more or less at the same time.

15. The system of claim 1, wherein the pathway is selected from the group consisting of an oil production pathway, an oil transportation pathway, an oil transportation tube, an oil flow line, and an oil pipeline, and wherein the pumps are configured to inject the first and second solution into the pathway more or less at the same time.

16. The system of claim 1, wherein the pathway includes an oil well having at least production tubing and an annulus, wherein one of the first or second pump is in fluid communication with a lower part of the production tubing and the other of the first or second pump is in fluid communication with the annulus, such that the mixing of the first and second solution takes place at the lower part of the production tubing and the mixture together with the heat generated may be carried further down the well to where the organic deposits are located.

17. The system of claim 1, wherein the pathway includes an oil well having at least production tubing, an annulus, and a tube provided inside the production tubing, and wherein one of the first or second pump is in fluid communication with the tube and the other of the first or second pump is in fluid communication with the annulus such that mixing takes place at the bottom portion of the tube and the mixture together with the heat generated may be carried further down the well to where the organic deposits are located.

18. The system of claim 1, wherein the pathway includes an oil well having at least production tubing, an annulus, and a coil tubing unit (CTU) positioned within the production tubing, wherein one of the first or second pump is in fluid communication with the CTU and the other of the first or second pump is in fluid communication with the annulus such that the mixing takes place at a bottom portion of the CTU and the mixture together with the heat generated may be carried further down the well to where the organic deposits are located.

19. The system of claim 1, further comprising one or more heaters configured to heat the first and second solutions prior to their injection.

20. The system of claim 1, further comprising a third tank containing an organic solvent formulation called a pre-flush and a third pump in fluid communication with the third tank and configured to inject the pre-flush into the pathway.

21. The system of claim 1, further comprising a fourth tank containing a post-flush and a fourth pump in fluid communication with the fourth tank and configured to inject the post-flush into the pathway.

22. The system of claim 1, wherein the first and second pumps are capable of injecting at a rate of 1000-2000 lit/hr.

23. The system of claim 1, further comprising a connector capable of coupling to a well, the connector having at least a first hole and a second hole passing therethrough, and further comprising a first tube coupled to the first pump and disposed through the first hole in the connector and a second tube coupled to the second pump and disposed through the second hole in the connector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be described by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1a shows a top view, and FIG. 1b shows a side view of a connector according to an embodiment of the present invention;

(3) FIG. 2 shows an arrangement of pumps and solution tanks according to an embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION

(4) The present invention provides a solution to organic deposit problems in oil well bore, and oil production and transportation tubing and pathway in the form of a fluid formulation or combination of formulations, which can generate sufficient heat and have the capability of dissolving and dispersing the organic deposits in a way that they remain in solution/suspension to prevent their re-deposition and are easily removed. The present invention uses organic formulations which have a higher solubility for organic deposits without any adverse effect on the oil well production system and process.

(5) The present invention uses a combination of the action of heat, solvents and surfactants to remove organic deposits more effectively and has the following features: 1. The system is organic in nature; 2. The system is capable of generating sufficient heat to facilitate the dissolution and dispersion of organic deposits; 3. The reaction products should provide stable suspension at lower process temperature; and 4. The system can be adapted to tackle the different types of organic deposits.

(6) Linear alkyl benzene sulfonic acids (LABSA), also termed as linear alkyl aryl sulfonic acids are used in the formulations. LABSA are industrially produced and are available in a variety of mixtures denoted by average carbon number of the alkyl side chains. Thus LABSA having 4, 8, 12, 16 and 18 average carbon numbers in the alkyl side chains are easily available. Of these LABSA having 4, 8, and 12 carbon number side chains were found to be suitable.

(7) Aliphatic acids such as formic, acetic and propanoic acid were also examined for the purpose and found suitable.

(8) Organic bases such as alkyl amines, ethylene amines and poly amines were found to be more suitable for the purpose.

(9) Amines react exothermally with various LABSA or aliphatic acids producing imides and heat. Such reaction should not be per se considered an acid base reaction as these compounds are acidic or basic with respect to aqueous solution. Reaction of these compounds in an aqueous medium would produce ammonium or quaternary ammonium salts. But the chemical reaction in organic solvents gives very different results.

(10) The present invention is a thermo-chemical system using at least two formulations. One formulation is a solution of LABSA or aliphatic acids in organic solvents while the other is a solution of amines in organic solvents. Some additives such as corrosion inhibitors and surfactants may be added to make the formulations more suitable for application.

(11) Organic solvents such as toluene, xylene, heavy aromatic solvents, diesel, naphtha, petroleum distillates and mixtures thereof may be used.

(12) A formulation in one part may contain LABSA or aliphatic acids or a mixture thereof in the above solvents with suitable additives like corrosion inhibitors or surfactants.

(13) The concentration of LABSA and aliphatic acids or their mixtures can be 1-90% in abovementioned solvents. More appropriately, the concentration of LABSA or aliphatic acids or their mixture thereof can be 40-95%. More specifically the concentration of LABSA and aliphatic acid or mixture thereof can be 50-80%.

(14) The LABSA used in abovementioned formulation can be those containing 4, 8 or 12 carbon numbers in the aliphatic side chain.

(15) Aliphatic acids used in the above solvents can be formic, acetic or propanoic acids. More specifically, the aliphatic acid used in above formulation can be acetic acid.

(16) The second formulation on the other hand may contain aliphatic amines, ethylenediamine or polyamines or their mixture thereof in abovementioned solvents in the concentration of 1-95%. More appropriately, the concentration of aliphatic amines, ethylendiamine, polyamines or mixture thereof in above mentioned solvents can be 40-95%. Specifically the concentration of apliphatic amines, ethylendiamine, polyamines or mixture thereof in above mentioned solvents can be 50-80%.

(17) The solvents used in this formulation can be, more appropriately xylene, heavy aromatic solvents, diesel and light naphtha.

(18) In one aspect of the invention, the two formulations can be simultaneously injected into the well inside the tubing generally called bullheading so that the mixture and the heat generated in the process are carried to the part of the well affected with organic deposition.

(19) In another aspect of the invention, the two formulations can also be simultaneously injected in the well inside the flow line or pipeline so that the mixture and the heat generated in the process are carried to the part of the well, flow line or pipeline affected with organic deposition.

(20) In the wells where there is communication between lower part of the production tubing and annulus, one formulation can be injected in the production tubing and the other in the annulus in a manner that their mixing takes place at the bottom of the production tubing. The exothermic reaction between the two formulations generating heat can be further carried to the down stream part of the well where organic deposition has taken place.

(21) In the wells where another tube is provided inside the production tubing, one formulation can be injected in the tube and the other in the annulus between the production tubing and such tube in a manner that their mixing takes place at the bottom of the tube. The exothermic reaction of the mixture would generate heat which can be further carried to the down stream part of the well where organic deposition has taken place.

(22) In many oil wells, intervention equipment known as coil tubing unit (CTU) is used. The use of CTU allows insertion of coil tube inside the production tubing. In such an arrangement, one formulation can be injected in the coil tube and the other in the annulus between the production tubing and coil tube in a manner that their mixing takes place at the bottom of the coil tube. The resultant mixture which by virtue of exothermic reaction would generate heat which can be further carried to the down stream part of the well where organic deposition has taken place.

(23) To generate a higher temperature, one or both formulations can be heated prior to their injections.

(24) The injection of formulations as described above may be preceded by an organic solvent formulation called pre-flush, which helps prepare the deposit surface to interact more readily with the formulations.

(25) After simultaneous injections of the two formulations as described above, a fluid is injected into the well to carry the resultant mixture to the affected parts where solid deposition has taken place. Such a fluid is called as post-flush.

(26) After directing the resultant mixture to the targeted location by injection of post flushin calculated volumes, the resultant mixture is allowed to soak where the deposits are located for 12-24 hrs. After the soaking period, the normal production from the well or in the line may be resumed. The dissolved and dispersed organic deposits are carried away leaving the affected parts cleared of the organic deposits.

(27) The usual offshore oil production platforms are not large enough to accommodate big equipment like high capacity pumps and solution tanks, which are normally used to carry out such job. Therefore, the jobs are carried out with the help of a barge. On the other hand crane capacities at the offshore platforms are often limited. Present invention includes design of the equipment to overcome these handicaps. Multiple small pumps of 500-1500 lit/hr pumping capacity each may be used to pump the two formulations. The pumps are connected to the solution tanks separately. Any of the pump-solution tank sets can be used for injection of one of the formulations. Two or more such sets are dedicated to injection of one formulation. If one pump does not function, the application can be carried out with the remaining pump or pumps. Such a provision is necessary because the injection of the formulation should be accomplished without stoppage of the work and within the stipulated time. The pumps are chosen in such a way that their weight does not exceed more than the lifting capacity of the platform crane. The electric power can be supplied from the generators available at the platform or portable generators can be carried on to the platform.

(28) All the pumps can be connected to the production tubing (203), annulus, flow line or pipeline with the help of to inch size stainless steel tubes through a specially designed steel connector (10) having multiple holes (110a, 110b, 110c, 110d) as shown in FIG. 1a. As shown in FIG. 2, uses of such a connector (10) allows the use of separate sets of pumps solution tanks (20a, 20b, 20c, 20d) independently and use of small size stainless steel tubes which cause appreciable reduction in weight and size of equipment particularly hoses used in such application.

(29) While the present invention is directed primarily to the removal of organic deposits such as wax, asphaltenes and resins in oil well (207) borehole, and oil production and transportation tubing and pathway, the method and composition of the present invention can be used wherever there is a problem with the formation of organic deposits.

EXAMPLES

(30) The following examples are used to illustrate the present invention.

Example 1

(31) The organic deposits obtained from a well have the following characteristics:

(32) TABLE-US-00001 Sr Test Sample No. Description Test Method Unit Results 1 Physical appearance Visual Black brown colored solid 2 Loss on heating at % wt NA 100 C. 3 Melting Point ASTM D127 C. 79 4 n-pentane Insolubles ASTM 2007 % wt. 51.01 modified 5 Saturates content ASTM 2007 % wt. 29.16 modified 6 Aromatics content ASTM 2007 % wt. 6.01 modified 7 Resins content ASTM 2007 % wt. 14.70 modified

(33) A thermo-chemical system comprising of two formulations is designed for the above deposits. The first formulation contains 60% LABSA having 12 average carbon numbers in the alkyl side chain is dissolved in heavy aromatic solvent while the second formulation contains 60% n-butylamine in heavy aromatic solvent. 100 ml of first formulation and 50 ml of second formulation are poured into a 250 ml beaker containing 5 g of deposit. The resultant mixture is gently stirred and the maximum temperature generated during the reaction is measured to be around 90 C. It is observed that the deposits are easily dissolved and dispersed in the resultant mixture. The resultant mixture is allowed to cool at 40 C. It is observed that the deposits remain in the suspension at 40 C. No separation of wax is observed.

Example 2

(34) Organic deposits obtained from a well have the following characteristics:

(35) TABLE-US-00002 Sr Test Sample No. Description Test Method Unit Results 1 Physical appearance Visual Brown colored solid 2 Loss on heating at % wt 13.23 100 C. 3 Melting Point ASTM D127 C. 88 4 n-pentane ASTM 2007 % wt. 39.21 Insolubles modified 5 Saturates content ASTM 2007 % wt. 42.68 modified 6 Aromatics content ASTM 2007 % wt. 2.76 modified 7 Resins content ASTM 2007 % wt. 2.20 modified

(36) A thermo-chemical system comprising of two formulations is designed for above deposits. The first formulation contains 80% LABSA having 12 average carbon numbers in the alkyl side chain is dissolved in heavy aromatic solvent while the second formulation contains 80% n-butyl amine in heavy aromatic solvent. 100 ml of first formulation and 50 ml of second formulation is poured into a 250 ml beaker containing 5 g of deposit. The resultant mixture is gently stirred and the maximum temperature generated during the reaction is measured to be 115 C. It is observed that the deposits are easily dissolved and dispersed in the resultant mixture. The resultant mixture is allowed to cool at 40 C. It is observed that the deposits remain in the suspension at 40 C. No separation of wax is observed.

Example 3

(37) Organic deposits obtained from a well have the following characteristics:

(38) TABLE-US-00003 Sr Test Sample No. Description Test Method Unit Results 1 Physical appearance Visual Pale brown colored solid 2 Loss on heating at % wt 11.17 100 C. 3 Melting Point ASTM D127 C. 94 4 n-pentane Insolubles ASTM 2007 % wt. 71.29 modified 5 Saturates content ASTM 2007 % wt. 5.60 modified 6 Aromatics content ASTM 2007 % wt. 1.42 modified 7 Resins content ASTM 2007 % wt. 1.75 modified

(39) A thermo-chemical system comprising of two formulations is designed for the above deposits. The first formulation contains 10% LABSA having. 12 average carbon numbers in the alkyl side chain and 60% acetic acid is dissolved in heavy aromatic solvent while the second formulation contains 70% n-butyl amine in heavy aromatic solvent. 40 ml of first formulation and 60 ml of second formulation are poured into a 250 ml beaker containing 5 g of deposit. The resultant mixture is gently stirred and the maximum temperature generated during the reaction is measured to be 125 C. It is observed that the deposit are easily dissolved and dispersed in the resultant mixture. The resultant mixture is allowed to cool at 40 C. It was observed that the deposits remain in the suspension at 40 C. No separation of wax is observed.

(40) While the invention has been described m connection with certain preferred embodiments illustrated above, it will be understood that it is not intended to limit the invention to these particular embodiments. On contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined by the appended claims.