A system and process for cleaning congealed paraffin wax from a lateral portion of a well bore and formation using superheated fluid and nitrogen

Abstract

A process for cleaning congealed paraffin wax from a lateral well bore and formation. A superheated fluid is pumped to a tubing and a cleaning tool that dispenses the superheated fluid to penetrate and melt congealed paraffin wax in the lateral well bore and liquefy paraffin wax in the formation. Simultaneously to pumping the superheated fluid, an energizing substance is pumped down an annulus and mixes with the superheated fluid, creating an energized superheated fluid that is forced out of casing perforations and deep into the formation to liquefy paraffin wax. The pumping of the superheated fluid and the energizing substance are ceased and the tubing and the cleaning tool are retracted from the well bore after completing cleaning, wherein the energizing substance energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the tubing and the cleaning tool are retracted from the well bore.

Description

A SYSTEM AND PROCESS FOR CLEANING CONGEALED PARAFFINWAX FROM A LATERAL PORTION OF A WELL BORE AND FORMATION USING SUPERHEATED FLUID AND NITROGENFIELD OF THE DISCLOSURE

[0001] This disclosure generally relates to oil producing well bores and formations, and more particularly, to systems and processes for cleaning congealed paraffin wax from a lateral portion of a well bore and formation.BACKGROUND

[0002] Oil production in wells is known to be impeded by paraffin wax build up in lateral well bores and formation over time. The buildup of paraffin wax is caused by the congealing of the paraffin component of crude oil due to pressure drops and resultant cooling of the crude oil in the well bore and the nearby reservoir.

[0003] Current processes and systems for cleaning congealed paraffin wax from lateral well bore and formation require improvement as challenges remain. In one currently used process, rotary cutters clean the well bore, wherein cuttings are circulated to ground surface during the cleaning process. However, the cuttings may accumulate, seizing tubing within the casing during the cleaning process. Further, current processes and systems, the temperature of cleaning fluid used is limited as higher temperatures may cause the casing to overheat and damage. New inventive processes and systems for cleaning congealed paraffin wax from a lateral well bore and formation are required to improve the efficiency of paraffin wax removal.SUMMARY

[0004] The following presents a simplified summary of some embodiments of the techniques described herein in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key / critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented below.

[0005] Some aspects include a process for cleaning congealed paraffin wax from a lateral portion of a well bore and formation, including: pumping, with a first pump, superheated fluid to a tubing and a cleaning tool connected to a terminal end of the tubing, wherein the cleaning tool is positioned within the lateral portion of the well bore; dispensing, with the cleaning tool, the superheated fluid through at least one forward facing jet and a plurality of rear facing jets, wherein: the superheated fluid penetrates and melts congealed paraffin wax in the lateral portion of the well bore; the superheated fluid heats the formation, liquefying paraffin wax in the formation; and the superheated fluid dispensed from the plurality of rear facing jets provides a forward force to propel the tubing and the cleaning tool forwards in the lateral portion of the well bore; simultaneously to pumping the superheated fluid, pumping, with a second pump, an energizing substance from a container storing the energizing substance down an annulus, wherein: the annulus is formed of an exterior surface of the tubing and an interior surface of a casing; the superheated fluid dispensed from the jets of the cleaning tool mixes with the energizing substance pumped down the annulus, creating an energized superheated fluid; and the energized superheated fluid is forced out of casing perforations of the casing and deep into the formation, liquefying paraffin wax in the formation; ceasing the pumping of the superheated fluid and the energizing substance after the cleaning process is complete; and retracting the tubing and the cleaning tool from the well bore after the cleaning process is complete, wherein the energizing substance energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the tubing and the cleaning tool are retracted fromthe well bore.

[0006] Some aspects provide a system for cleaning congealed paraffin wax from a lateral portion of a well bore and formation, including: a cleaning tool comprising at least one forward facing jet and a plurality of rear facing jets for dispensing superheated fluid; a tubing; a first pump for pumping superheated fluid to the cleaning tool; a container for storing an energizing fluid; and a second pump for pumping the energizing substance from the second container down an annulus formed of an exterior surface of the tubing and an interior surface of a casing; wherein: the second pump pumps the energizing substance simultaneously to the first pump pumping the superheated fluid; the superheated fluid dispensed from the jets of the cleaning tool penetrates congealed paraffin wax in the lateral portion of the well bore and heats the formation, liquefying paraffin wax in the lateral portion of the well bore and formation; the superheated fluid dispensed from the plurality of rear facing jets provides a forward force to propel the tubing and the cleaning tool forwards into the lateral portion of the well bore; the superheated fluid dispensed from the jets of the cleaning tool mixes with the energizing substance pumped down the annulus, creating an energized superheated fluid; the energized superheated fluid is forced out of casing perforations of the casing and deep into the formation, liquefying paraffin wax in the formation; the pumping of the superheated fluid and the energizing substance is ceased and the tubing and the cleaning tool are retracted from the well bore after the cleaning of the lateral portion of the well bore and formation is complete; and the energizing substance energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the tubing and the cleaning tool are retracted from the well bore.BRIEF DESCRIPTION OF THE FIGURES

[0007] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with thedescription, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

[0008] FIG. 1A illustrates an example of a system for cleaning congealed paraffin wax from a lateral portion of a well bore and formation.

[0009] FIG. IB illustrates an example of a cleaning tool of the system illustrated in FIG. 1A.

[0010] FIG. 2 illustrates a flowchart of a process for cleaning congealed paraffin wax from a lateral portion of a well bore and formation.DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0011] The present inventions will now be described in detail with reference to a few embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present inventions. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and / or structures have not been described in detail in order to not unnecessarily obscure the present invention. Further, it should be emphasized that several inventive techniques are described, and embodiments are not limited to systems implanting all of those techniques, as various cost and engineering trade-offs may warrant systems that only afford a subset of the benefits described herein or that will be apparent to one of ordinary skill in the art.

[0012] In the following detailed description of exemplary embodiments of the invention, reference is made to accompanying drawings (where like numbers represent like elements), which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in art to practice the invention, but other embodiments may be utilized, and logical, mechanical, electrical, and other changes may be madewithout departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.

[0013] Some embodiments include a process for cleaning congealed paraffin wax from a lateral portion of a well bore (i.e., a lateral well bore) and formation. In preferred embodiments, the cleaning tool is initially disposed at a heel of the lateral well bore, however, may be positioned elsewhere at a beginning of the cleaning process. A first pump draws fluid (e.g., water; glycol and / or solvents that may or may not be mixed with water) from a first container (e.g., a holding tank stored on site) and pumps the fluid to a high pressure heater to generate superheated fluid. The superheated fluid is further pumped to a tubing (e.g., tubing wound around a wheel of a coiled tubing rig) inserted into the well bore and a cleaning tool connected to a terminal end of the tubing inserted into the well bore. The cleaning tool dispenses the superheated fluid through at least one forward facing jet and several rear facing jets. The superheated fluid dispensed from the rear facing jets provide a forward force to propel the tubing and cleaning tool forwards into the lateral well bore while the superheated fluid dispensed by the forward facing jet and rear facing jets of the cleaning tool penetrates and melts congealed paraffin wax in the lateral well bore. The superheated fluid provides rapid and thorough cleaning of the lateral well bore and has sufficient energy to heat the nearby formation, thereby liquefying built up paraffin wax in both the lateral well bore and the formation. At the same time as superheated fluid is dispensed by the jets of the cleaning tool, a second pump pumps nitrogen (e.g., nitrogen gas and liquid nitrogen) from a second container storing the nitrogen (e.g., mobile tank) down an annulus formed of an exterior surface of the tubing and an interior surface of a casing. In preferred embodiments, liquid nitrogen is transported on site by a nitrogen pumper unit that pressurizes, warms, and gasifies the nitrogen as it is being pumped into the annulus via an annular valve disposed on a well head of the well bore. The nitrogen within the annulus provides insulation to the casing, preventing the casing from overheating and damaging. Further, the use of nitrogen as an insulator allows for the use of higher fluid temperatures to deliver more thermal energy to a reservoir.

[0014] The superheated fluid dispensed from the jets of the cleaning tool mixes with the nitrogen pumped down the annulus near the jets, creating a nitrogen energized superheated fluid. In mixing with the superheated fluid, the nitrogen picks up the superheated fluid and carries the superheated fluid to the formation. The nitrogen energized superheated fluid is forced out of casing perforations of the casing and deep into the formation, causing congealed paraffin wax in the formation to be liquified. The cleaning tool progresses forward as the lateral well bore and formation are cleaned until reaching the toe (or another end location) of the lateral well bore. Once the cleaning process is complete, pumping of the superheated fluid and the nitrogen are ceased and the tubing and the cleaning tool are retracted from the well bore. In mixing with the superheated fluid and liquified wax, the nitrogen energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the cleaning process is completed and the tubing and cleaning tool are removed from the well bore. In contrast, other well bore cleaning processes return unwanted material (e.g., paraffin wax) to ground surface via the annulus while the cleaning process (e.g., pumping of cleaning fluid down tubing within the casing) is in progress. In such cases, some unwanted material may accumulate and seize the tubing within the casing. In the cleaning process proposed herein, the unwanted material is flowed back to ground surface after the tubing and the cleaning tool have been retracted from the well bore, providing a more efficient method for clearing of the casing and reservoir. The material flowed back to the ground surface may be handled in various ways depending on well site protocols, such as collecting the material flowed back to the ground surface within a waste material container.

[0015] Some embodiments provide a system for cleaning congealed paraffin wax from a lateral portion of a well bore (i.e., a lateral well bore) and formation, including at least: a first container (e.g., a tank stored on site) for storing fluid (e.g., water; glycol and / or solvents that may or may not be mixed with water); a first pump for pumping the fluid from the first container to a high pressure heater and onwards to a tubing (e.g., tubing wound around a wheel of a coiled tubing rig) and a cleaning tool connected to a terminal end of the tubing; thehigh pressure heater for generating superheated fluid from the fluid; the tubing for transporting the superheated fluid to the cleaning tool; the cleaning tool including at least one forward facing jet and a plurality of rear facing jets for dispensing the superheated fluid; a second container for storing nitrogen (e.g., nitrogen gas or liquid nitrogen); and a second pump for pumping the nitrogen from the second container down an annulus formed of an exterior surface of the tubing and an interior surface of a casing. Additional tubing is used for pumping fluid from the first container to the pump and the pump to the high pressure heater, for pumping superheated fluid from the high pressure heater to the tubing, and for pumping nitrogen from the second container to the annulus.

[0016] The cleaning tool type, style, design, and / or geometry (e.g., conical, bull nose, angular, etc.) may vary in different embodiments. In some embodiments, the cleaning tool comprises a design similar to available jetting tools but with a custom sized geometry. In some embodiments, the jetting tool includes a secondary mechanism for cleaning congealed paraffin wax from the lateral portion of the well bore.

[0017] The tubing used to transfer the superheated fluid to the cleaning tool may comprise endless tubing, drill pipe tubing, production tubing, or another means for transporting the superheated fluid to the cleaning tool.

[0018] In some embodiments, nitrogen is replaced or combined with another type of energizing substance, such as carbon dioxide and propane. The state (e.g., gas, liquid) of the energizing substance may vary in different embodiments.

[0019] In some embodiments, the process and system for cleaning congealed paraffin wax described herein is used for cleaning congealed paraffin wax from a vertical well bore and formation.

[0020] FIG. 1 A illustrates a system for cleaning congealed paraffin wax from a lateral portion 100 of a well bore and formation 101, including a holding tank 102 for storing fluid; a first pump 103 for pumping the fluid from the holding tank 102 to a high pressure heater 104 and onwards to a tubing 105 wound around a wheel of a coiled tubing rig 106 and a cleaning tool 107 connected to a terminal end of the tubing 105; the high pressure heater 104 for generatingsuperheated fluid from the fluid; the tubing 105 for transporting the superheated fluid to the cleaning tool 107; the cleaning tool 107 including a forward facing jet 108 and a plurality of rear facing jets 109 for dispensing the superheated fluid (see, FIG. IB); a second container 110 for storing nitrogen; and a second pump 111 for pumping the nitrogen from the second container 110 down an annulus 112 via an annular valve 113 disposed on a well head of the well bore, the annulus 112 being formed of an exterior surface of the tubing 105 and an interior surface of a casing 114, the casing 114 including casing perforations 115.

[0021] FIG. IB illustrates the cleaning tool 107 including the forward facing jet 108 and the plurality of rear facing jets 109 for dispensing the superheated fluid 116.

[0022] FIG. 2 illustrates a flowchart of a process for cleaning congealed paraffin wax from a lateral portion of a well bore (i.e., a lateral well bore) and formation. At 200, a cleaning tool is disposed at a heel of the lateral well bore. At 201a, a first pump draws fluid from a first container and pumps the fluid to a high pressure heater to generate superheated fluid that is further pumped to a tubing inserted into the well bore and a cleaning tool connected to a terminal end of the tubing inserted into the well bore. The cleaning tool dispenses the superheated fluid through at least one forward facing jet and several rear facing jets to liquefy built up paraffin wax in the lateral well bore. Simultaneously to 201a, at 201b, a second pump pumps nitrogen from a second container storing the nitrogen down an annulus formed of an exterior surface of the tubing and an interior surface of a casing, the nitrogen providing insulation to the casing. In preferred embodiments, liquid nitrogen is transported on site by a nitrogen pumper unit that pressurizes, warms, and gasifies the nitrogen as it is being pumped into the annulus via an annular valve disposed on a well head of the well bore. At 202, the superheated fluid dispensed from the jets of the cleaning tool mixes with the nitrogen pumped down the annulus near the jets, creating a nitrogen energized superheated fluid. The nitrogen picks up the superheated fluid and carries the superheated fluid to the formation, wherein the nitrogen energized superheated fluid is forced out of casing perforations of the casingand deep into the formation, causing congealed paraffin wax in the formation to be liquified. At 203, the cleaning tool progresses forward as the lateral well bore and formation are cleaned until reaching the toe (or another end location) of the lateral well bore. At 204, the cleaning process is complete, the pumping of the superheated fluid and the nitrogen are ceased and the tubing and the cleaning tool are retracted from the well bore. At 205, the nitrogen energized superheated fluid and liquified paraffin wax flow back to ground surface.

[0023] It should be understood that the various embodiments described herein are presented by way of example, and that numerous variations, modifications, or combinations of the described embodiments may be made without departing from the scope of the invention. In some instances, certain features of one embodiment may be used in combination with features of another embodiment, or multiple embodiments may be integrated together to achieve a desired result. Additionally, certain elements or steps of the described embodiments may be omitted, substituted, or altered depending on the specific implementation or application.

[0024] In various embodiments, certain components, methods, or functionalities described herein may be modified or adapted to fit specific use cases or design constraints. These modifications may be made in view of particular user requirements, environmental conditions, or regulatory considerations.

[0025] Alternative configurations of the embodiments described herein are also possible. In some cases, a particular feature described with reference to one embodiment may be utilized in other embodiments, even if not explicitly mentioned. Similarly, the order of steps in a process / method or the arrangement of components in a system or apparatus may be altered, provided that the underlying principles of the invention are maintained.

[0026] While particular embodiments have been described, it is to be understood that alternative embodiments may be employed in place of the specifically described forms. In some cases, specific components may be replaced with functionally equivalent alternatives, and in others, operational steps may be rearranged or omitted, all without departing from the spirit and scope of the invention.

Claims

CLAIMS1. A process for cleaning congealed paraffin wax from a lateral portion of a well bore and formation, comprising: pumping, with a first pump, superheated fluid to a tubing and a cleaning tool connected to a terminal end of the tubing, wherein the cleaning tool is positioned within the lateral portion of the well bore; dispensing, with the cleaning tool, the superheated fluid through at least one forward facing jet and a plurality of rear facing jets, wherein: the superheated fluid penetrates and melts congealed paraffin wax in the lateral portion of the well bore; the superheated fluid heats the formation, liquefying paraffin wax in the formation; and the superheated fluid dispensed from the plurality of rear facing jets provides a forward force to propel the tubing and the cleaning tool forwards in the lateral portion of the well bore; simultaneously to pumping the superheated fluid, pumping, with a second pump, an energizing substance from a container storing the energizing substance down an annulus, wherein: the annulus is formed of an exterior surface of the tubing and an interior surface of a casing; the superheated fluid dispensed from the jets of the cleaning tool mixes with the energizing substance pumped down the annulus, creating an energized superheated fluid; and the energized superheated fluid is forced out of casing perforations of the casing and deep into the formation, liquefying paraffin wax in the formation; ceasing the pumping of the superheated fluid and the energizing substance after the cleaning process is complete; andretracting the tubing and the cleaning tool from the well bore after the cleaning process is complete, wherein the energizing substance energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the tubing and the cleaning tool are retracted from the well bore.

2. The process of claim 1, further comprising: pumping, with the first pump, fluid stored in a container to a high pressure heater to generate superheated fluid, wherein the superheated fluid is further pumped to the tubing.

3. The process of claim 2, wherein the fluid comprises water.

4. The process of claim 1, wherein the energizing substance comprises nitrogen.

5. The process of claim 4, wherein the nitrogen comprises nitrogen gas.

6. The process of claim 5, wherein the second pump comprises a nitrogen pumper unit that pressurizes, warms, and gasifies liquid nitrogen as it is being pumped into the annulus.

7. The process of claim 6, wherein the second pump pumps the pressurized, warmed, and gasified nitrogen into the annulus via an annular valve disposed on a well head of the well bore.

8. The process of claim 1, wherein the energizing substance comprises carbon dioxide or propane.

9. The process of claim 1, wherein the cleaning tool is disposed at a heel of the lateral portion of the well bore at a beginning of the process.

10. The process of claim 1, wherein the tubing comprises endless tubing.

11. A system for cleaning congealed paraffin wax from a lateral portion of a well bore and formation, comprising: a cleaning tool comprising at least one forward facing jet and a plurality of rear facing jets for dispensing superheated fluid; a tubing; a first pump for pumping superheated fluid to the cleaning tool; a container for storing an energizing fluid; and a second pump for pumping the energizing substance from the second container down an annulus formed of an exterior surface of the tubing and an interior surface of a casing; wherein: the second pump pumps the energizing substance simultaneously to the first pump pumping the superheated fluid; the superheated fluid dispensed from the jets of the cleaning tool penetrates congealed paraffin wax in the lateral portion of the well bore and heats the formation, liquefying paraffin wax in the lateral portion of the well bore and formation; the superheated fluid dispensed from the plurality of rear facing jets provides a forward force to propel the tubing and the cleaning tool forwards into the lateral portion of the well bore; the superheated fluid dispensed from the jets of the cleaning tool mixes with the energizing substance pumped down the annulus, creating an energized superheated fluid; the energized superheated fluid is forced out of casing perforations of the casing and deep into the formation, liquefying paraffin wax in the formation;the pumping of the superheated fluid and the energizing substance is ceased and the tubing and the cleaning tool are retracted from the well bore after the cleaning of the lateral portion of the well bore and formation is complete; and the energizing substance energizes the superheated fluid and liquified paraffin wax to flow back to ground surface after the tubing and the cleaning tool are retracted from the well bore.

12. The system of claim 11, further comprising: a container for storing fluid; and a high pressure heater for generating superheated fluid; wherein the first pump pumps fluid from the container storing the fluid to the high pressure heater to generate superheated fluid that is further pumped to the tubing.

13. The system of claim 12, wherein the fluid comprises water.

14. The system of claim 11, wherein the energizing substance comprises nitrogen.

15. The system of claim 14, wherein the nitrogen comprises nitrogen gas.

16. The system of claim 15, wherein the second pump comprises a nitrogen pumper unit that warms and gasifies liquid nitrogen as it is being pumped into the annulus.

17. The system of claim 16, wherein the second pump pumps the pressurized, warmed, and gasified nitrogen into the annulus via an annular valve disposed on a well head of the well bore.

18. The system of claim 11, wherein the energizing substance comprises carbon dioxide or propane.

19. The system of claim 11, wherein the cleaning tool is disposed at a heel of the lateral portion of the well bore at a beginning of the process.

20. The system of claim 11, wherein the tubing comprises endless tubing.

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