MXPA00004080A

MXPA00004080A - Method and apparatus for viscosity reduction of clogging hydrocarbons in oil well

Info

Publication number: MXPA00004080A
Application number: MXPA/A/2000/004080A
Authority: MX
Inventors: Thomas Meeks
Original assignee: Thomas Meeks
Priority date: 1997-10-29
Filing date: 2000-04-27
Publication date: 2001-06-26

Abstract

Method and apparatus for reducing the viscosity of clogging hydrocarbons in an oil well (58). The apparatus is preferably trailer-mounted for portability. It includes a tube type heat exchanger(30) enabling heated gases to pass within feed water coils (48, 44) to heat the water to a predetermined temperature and at a pressure which prevents any flashing or phase change of the feed water within the heat exchanger (30). From the heat exchanger (30) the heated feed water passes through a conduit (54) which empties into the oil well. The well is open to atmosphere so that the feed water undergoes a phase change or flashing when it is introduced into the oil well. The resulting combined steam and hot water reduce the viscosity of the hydrocarbons sufficiently to facilitate their flow out of the oil well. One embodiment of the heat exchanger (30) includes special coil arrangements to promote heating efficiency.

Description

Method and apparatus for the viscosity eduction of clogging hydrocarbons in oil wells.

Technical Field The present invention relates to a method and apparatus for reducing the viscosity of clogging hydrocarbons in an oil well. A heat exchanger controls the instantaneous vaporization of the boiler water in steam until after the boiler water is injected into the oil well which is left open to atmospheric preion. _ Previous Technique The heated oil has been used for years to increase the production of oil wells that are marginal producers since they are clogged at their upper end or more superficial by organic solids of high viscosity or hydrocarbons such as paraffins and paraffins. asphaltenes. These obstruct the normal flow of oil from the reservoirs. The heated oil process is a comparatively low cost method for the rejuvenation of such oil wells. The heated oil is trucked into the well and introduced therein in sufficient quantity, and for a sufficient period of time, that the well chains and the adjacent formation are heated sufficiently to increase the viscosity of the binding hydrocarbons. to the point where they will flow out of the well with the oil from the field. The hot oil process is only practical to remove the upper portion of a well since the heated oil quickly loses its thermal energy as it submerges deep into the well. Steam injection is another form that has been used to treat the clogging of hydrocarbons by thermal reduction of their viscosity, particularly the hydrocarbons that clog the perforations or perforated tube where the formation joins with the diameter of the well. The characteristics of the steam make it more effective than hot oil for this kind of treatment, and also to give a moderately deeper treatment to the effects of a well. As the steam does not fall into temperature until it is completely condensed, its thermal effect goes further down the well, compared to a heated liquid such as hot oil. Its heat content per pound is approximately three times that of water. In addition, the saturated steam occupies approximately sixty times the volume of water at the same temperature and pressure, and the resulting pressure acts on the surrounding formation to help propel the oil with translated viscosity out of the formation. In a steam injection process of the prior art, described in U.S. Patent No. 5 3,288,214 issued to A.K. Win ler, boiler water containing significant amounts of minerals and impurities was used. To prevent these impurities from passing through and possibly obstruct the formation when the steam is injected into the well, a plug was placed in the pipe string to increase the • training pressures and therefore increase the pressure on • Injected boiler water would vaporize instantaneously in steam. This arrangement reduced the extension of the instantaneous vaporization or boiler water vaporization to no more than approximately 20% by weight. This apparently had the effect of transporting impurities in the steam, but the degree of vaporization also significantly reduced the available steam. Consequently, the injected water and steam were counted more as hot water or the hot oil of the • 20 previous technique and the advantages of using steam decreased the consequence. Another problem with the volume of the prior art hydrocarbon unclogging steam injection systems is that they are not portable, the boiler or The steam generator is typically located in a central location, and the field pipes extend from the steam generator through the distribution manifolds to the various wells of an oil field. Thermal losses in a system if they are high, the costs are high and the flexibility of a portable arrangement is lost. Prior art oil well steam generation equipment was also characterized by low efficiencies resulting from poor boiler design. This in turn caused high operating costs, so the useful cost of sending steam to a clogged well often exceeded the economic benefits of improved production. There is a continuing need, therefore, for a practical system to stimulate the production of secondary oil at reasonable costs.

Disclosure of the Invention In accordance with the present invention, the thermal energy delivery apparatus is provided to effectively reduce the viscosity of hydrocarbons that clog an oil well pipe and adjacent oil formation. In a preferred embodiment the apparatus has a capacity of approximately five million BTUs, and can deliver steam at approximately 500 degrees Fahrenheit to sequentially process or recondition approximately 100 wells per month. The apparatus includes a tube-type heat exchanger having a horizontally oriented main portion that is adapted to engage an extremity of a combustor. A vertically oriented chimney portion is connected to the main portion to remove the gases from the combustor. The heat exchanger is a simple pass system, which is highly efficient for various reasons, including the fact that it has no steam collector or sludge collector and therefore does not need forced or natural circulation, or flea systems common in the prior art. Only a conventional water pump is used to drive the boiler water through the heat exchanger. In accordance with the method of the invention, the boiler water is initially treated by any suitable means, such as an ion exchange system, to reduce its mineral content and impurities. The treated boiler water is then passed to a final coil of the tubes located at the end of the main portion that is opposite the end of the combustor. This initially heats the qaldera water but, more significantly, cools the associated limb so that it is not overheated by the combustor gases that traverse the interior of the main portion of the combustor.

A boiler water pipe extends from the final coil upwa from the main portion to the outside of the chimney portion. It then extends downward from the top of the chimney coil located within the chimney portion to the bottom of the chimney portion. A boiler water pipe from the bottom of the chimney spiral extends outwa from the chimney coil and along the outside of the main portion, and then at the combustor end of a main coil located in the chimney. main portion. The main spiral extends from the tip of the combustor to a position just below the interior of the chimney portion. At that point one end of a field conduit connects to the main spiral and extends to the open top end of the well. The temperature and pressure inside the heat exchanger are controlled so that boiler water vaporization does not occur upstream of the oil well. However, the set temperature and pressure are such that the instantaneous vaporization of about 40% by weight of the water occurs in the well at the present atmospheric pressure thereof. The injection of heated boiler water is continuous at atmospheric pressure to vaporize it instantaneously in steam to melt or decrease the viscosity of the clogging hydrocarbons. Then the normal pumping of the well can be resumed. The equipment used to transport the previous operation is preferably installed in a trailer or equivalent so that it can be transported to an individual well for immediate operation. The combustor is preferably supplied from bottles or fuel containers such as propane or natural gas transported in the trailer. Although other fuels such as diesel or crude could be used, this would require the use of expensive anti-pollution equipment such as gas scrubbers. All the power generation and control equipment is also installed on the trailer for immediate access. As a consequence of this arrangement, expansion joints, steam heads, steam pipes and long field sides used in the prior art to treat a number of wells dispersed at the same time from a central location are eliminated. Instead, as already indicated above, the present apparatus is simply transported to an individual well that is reconditioned, the well receives the treatment, and the apparatus then moves to the next well. This greatly reduces operating costs and the loss of thermal energy before emptying the water heated in the well.

Other aspects and advantages of the present invention SJ? will become apparent from the following more detailed description which is made in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of the apparatus of the present invention as it would be installed in a trailer for transportation to and from a well site; and "Figure 2 is a simplified longitudinal cross-sectional view of the heat exchanger of the apparatus, and a schematic view showing the connection of the heat exchanger to the field conduit carrying the heated boiler water to the well site for injection and vaporization with the upper end of a well that is open to atmospheric pressure Best Way to Carry Out the Invention Referring now to the drawings, the present "apparatus illustrated in Figure 1 is self-contained, installed in a trailer with wheels 10 for easy portability to and from a well site. Installed to the trailer, as it appears schematically, there is a water tank 12 from which the boiler water is pulled by a pump 14 to give treatment in ion exchange tanks 16, a brine tank 18 and the filters 20 a conventional ion exchanger system to reduce the level of any mineral and contaminant in the water.

A control system 22 automatically controls the upper level and the lower level of the stored boiler water, and the boiler water is turned off under predetermined conditions. A portable electric generator 24 provides power to operate the pump 14 and other electrically energized components, and a pair of propane tanks 26 provide fuel to a burner or combustor 28 that is located at the combustor end of a boiler or heat exchanger. 30. An associated control system 31 for conventional combustion management is also installed in the trailer, and to operate adequate mechanisms of safety interlocks and shutdown, including a relief valve, (does not appear) to avoid excessive pressurization of the tubes in the heat exchanger As will be appreciated, the control systems can also be computerized if desired, suitable systems for carrying out the foregoing are well known to those skilled in the art and the details of their construction and operation therefore they are omitted to obtain .brief. As will be appreciated, most fuels will be satisfied. for combustion of combustor 28, although fuels such as propane are preferred to reduce air pollution. Also, in those cases where a source of relatively high quality or * pure water is available, the purification or water treatment equipment may be omitted. As best seen in Figure 2, the boiler -or the heat exchanger 30 includes a horizontally oriented main portion 32 having a combustor end 34 to which the combustor 28 is installed, and a boiler water end 36 A helical pipeline arrangement constitutes a final spiral 38 which is suitably installed within the interior of the final wall of the boiler water end 36, and is connected to the water treatment equipment in the trailer 10 by means of a water pipe. of boiler 40. There is an opening in the main portion 32 adjacent to the final scroll 38, and the lower end of a laterally directed, vertically oriented chimney portion 42 is fixed to the main portion 32 in sealing relationship so that the interior of the main portion 42 communicates with the interior of the portion of the chimney 42. This directs the hot combustion gases from the combustor 28 to the portion p 32, and then to the chimney portion 42 to discharge to the atmosphere from the upper end of the chimney portion 42. These gases are at their highest temperature as they transition from the main portion 32 to the chimney portion. 42, and the presence of the final spiral 38 serves both to preheat the bo water when it enters the heat exchanger for the first time by means of the final spiral 38, as well as to avoid overheating and possible thermal damage to the final wall of the end of the bo water 36. Although deviators are not shown preferably, deviators are placed in the interiors of the main and chimney portions 32 and 42 to decrease the speed of the heated gases passing through the interiors, thereby improving the heat transfer from the gases to the bo water within the main and chimney spirals 44 and 48. In this regard, an object of the invention is to adjust the operating parameters so that the temperature of the gases leaving the upper part of the the chimney portion 42 are as close as possible to the temperature of the heated bo water leaving the heat exchanger 30. Achieving this The condition produces maximum operating efficiencies, and it has been found that the particular components and orientations of the components used in the described system are very close to this condition. The main and chimney portions 32 and 44 each include interior liner pipes that are spaced apart to define an annular space. The annular spaces are filled with any suitable insulation material for heat to minimize heat loss from the heat exchanger, as can be seen. A helically placed pipe arrangement constitutes a main spiral 44 which extends along the length of the main portion 32. It is suitably supported on the interior wall by a plurality of circumferentially spaced spacers 46 which are attached to the wall. A similarly supported pipe arrangement is located in the chimney portion 42 and constitutes a chimney spiral 48. A chimney bo water pipe 50 is connected to the final coil 38 and elongates vertically along the outside of the chimney. chimney spiral 48 to its upper end. From there the conduit is connected to the upper end of the chimney spiral 48 so that the bo water passes down through the chimney spiral 48. The lower end of the chimney spiral 48 is connected to a main chimney duct 48. bo water 52 extending outwardly from the chimney portion 42 and along the outside of the main portion 32. This conduit 52 is connected to the combustor end of the main spiral 44 so that the bo water it passes to the main spiral and around the interior space through which the combustor gases pass.

The combustor end of the main spiral 44 passes outward from the main portion 32 and is connected to a discharge conduit 54 extending to the open upper end of the column of the pipe 56 of a production well 58, forming a production line that extends through the upper portion of an oil formation 60. The fact that the well 58 is open at the top causes the well interior to be at atmospheric pressure. A safety valve 62 or other suitable element is located in the discharge duct 54 to maintain a predetermined back pressure in the heat exchanger 30. The valve 62 is located in any part of the duct 54, preferably as close as possible. possible from the well 58, and if practical at the base of the conduit 5 * 4 within the pipe column 56. The safety valve A 62, the combustor 28 and the "circulation of the boiler water through the system are controlled from The boiler water in the heat exchanger 30 is maintained at a temperature and pressure such that no vaporisation of the boiler water occurs in the exchanger, consequently, there is no accumulation of scale in the coils or ducts for reason of any precipitation of minerals or other impurities in the boiler water Any vaporization or immediate vaporization of the boiler water heated to produce steam occurs inside the well 58. In this connection, the temperature and pressure of the boiler water when it reaches the The well is preferably controlled so that approximately 40% of the weight of the water vaporizes.This percentage may vary in some way under certain operating conditions, but the Preference is given to the _temperature _ of the boiler water and the pressure are monitored closely to achieve the desired minimum of 40% vaporization. Maintaining the pressure in the well at atmospheric pressure is important to achieve this desired result. In the usual application, the vaporization of injected boiler water is continued for between 5 and 10 hours, depending on the particular geological conditions of the oil formation. By then the clogging hydrocarbons are normally removed from the system, and normal pumping operations can be resumed. The treatment can be repeated as necessary, depending on the severity of the clogging of the hydrocarbons that is experienced in the well. It is anticipated that the heating of boiler water - approximately 350 to 500 degrees Fahrenheit at a pressure of approximately 750 PSIA, and the vaporization of boiler water at atmospheric pressure in the well during the indicated period of time, will produce the desired degree. of vaporization necessary to adequately heat and melt paraffin and other hydrocarbon sealing agents in an area 10 feet in diameter around the upper end of the pipe column. Various modifications and changes can be made with respect to the above detailed description without departing from the spirit of the invention.

Claims

CLAIMS 1. - Thermal energy delivery device for reducing the viscosity of clogging hydrocarbons in an oil well (58) in a secondary oil recovery operation, the apparatus comprises two points, heat exchanger element (30) including a main portion 32 and a chimney portion (42). The main portion has a combustor limb (34) which is adapted to receive hot combustion gases and furthermore has a water tip of the daldera - (36), the chimney portion extends laterally of the main portion, the interiors of the portions main and chimney that are in communication where the hot combustion gases are introduced to the end of the combustor of the main portion through the main portion and exit laterally through the interior of the chimney portion; Helical chimney (48) and main coils (44) are located in the main and chimney portions respectively; a chimney boiler water pipe (50) extends externally of the chimney portion and is connected to the upper end of the chimney spiral to direct the boiler water down through the chimney spiral; a main boiler water pipe (52) extending externally of the main portion and connected to the inner end of the chimney spiral with the main spiral adjacent to the tip of the combustor to direct the boiler water through the main spiral; a discharge assembly (54) which is connected to the main spiral adjacent to the boiler water end, the discharge conduit extends laterally and externally of the main spiral to discharge at atmospheric pressure into the open upper end of an oil well (58) to vaporize instantaneously the water heated in steam at the open upper end; and a safety valve (62) which operates to maintain the boiler water at a pressure in which boiler water vaporization does not occur substantially before the flash vaporization of the boiler water in steam at the upper end of the oil well.
2.- Autonomous device of -delivery of portable thermal energy to reduce the viscosity of clogging hydrocarbons in an oil well (58) and particularly in the upper end of the oil well in a secondary oil recovery operation, the apparatus comprises: tube type heat exchanger element (30) including a main portion (32) and a chimney portion (42), each of the portions having outer and inner cylindrical casing tubes that define between them an annular space filled with insulation material for heat, the main portion horizontally oriented and having a combustor end (34) adapted to receive hot combustion gases, and furthermore has a boiler water end located on the opposite side (36), the chimney portion 42 is located adjacent to the boiler water tip 36 and extends laterally and upwardly of the main portion (32), the interiors of the porc Main and chimney ions are in communication where the combustion gases introduced at the tip of the combustor of the main portion pass through the main portion and are directed upwards through the interior of the chimney portion and out of the upper extremity of the chimney portion; a helical spiral d receiving boiler water (38) located in the adjacent main portion of the boiler water limb; the helical chimney (48) and the main coils (44) are located in the main and chimney portions respectively; A chimney boiler water pipe (50) extends outside the chimney portion and connects to the boiler water receiving spiral with the upper end of the chimney spiral to direct the boiler water through the boiler. the chimney spiral; a main conduit water boiler (52) extends outwardly from the main portion and connected to the lower end of the spiral chimney with the main spiral at a point adjacent the end of the combustor point to direct the feedwater through of the main spiral; a discharge conduit (54) is connected to the adjacent end of boiler water main spiral, the discharge chute extends laterally and externally of the main coil to discharge at atmospheric pressure in the open upper end of an oil well ( 58) to vaporize immediately the water heated in steam in the well; and a safety valve (62) which operates to maintain the boiler water at a pressure in which substantially before the immediate vaporization of the boiler water into steam in the oil well.
3. A method for using thermal energy to reduce the viscosity of clogging hydrocarbons in an oil well (58) open to atmospheric pressure, the method comprising: Heating the boiler water in a heat exchanger 30 to a pressure and a predetermined temperature in which substantially no boiling of the boiler water occurs in the heat exchanger, the predetermined temperature is sufficient to cause the immediate vaporization of the boiler water at atmospheric pressure in steam and hot water; maintaining the oil well (58) at a substantially atmospheric temperature; introducing the boiler water heated in a duct (54) extending to an upper end of the oil well (58_); admit the hot water and steam resulting from the immediate vaporization of the boiler water heated inside the oil well (58) in the formation (60) surrounding the oil well; and continuing the previous steps until the viscosity of the oil in the oil well and in the adjacent oil formation decreases enough for the hydrocarbons to be pumped out of the well.
4. - A method according to claim 3 wherein the "predetermined temperature is selected" so that about 40% of the boiler water is vaporized instantaneously into steam in the well
5. - A method according to claim 3 in where the pressure at which the boiler water is heated is controlled by valve elements (62) located in the duct (54). "
6. A method according to claim 3 wherein the pressure at which the boiler water it is heated is controlled "by a valve element (62) located" within the duct (54) and adjacent the well (58).
7. - A method according to claim 3 wherein the heat exchanger (30) is installed in a trailer (10) that is located on the side of the oil well (58), and where the heated gas is introduced into the exchanger of heat (30) by means of a burner element (28) that uses fuel in containers (26) located in the trailer (10).
8. - A method according to claim 3 and including the step to condition the boiler water through a passage through an ion exchange system (16) before heating the boiler water in the heat exchanger (30).
9. - A method according to claim 3 wherein the clogging hydrocarbons are mainly paraffin based.