INJECTION AND PRODUCTION FLOW RATE REGULATING SYSTEM FOR SLIMHOLE WELLS
A flow rate regulating system within an oil well with casing with a diameter less than or equal to 3½ inches, wherein the flow rate regulating system comprises: at least one regulating valve, for regulating flowrate, having a generally cylindrical body with a plurality of elongated grooves, a top sub in its upper portion and a sliding sleeve inside; and a regulating and calibrating shifting tool for regulating and calibrating the position of the sliding sleeve which has a generally cylindrical collet, a block set and a pair of nuts on each side of the block set.
The present invention refers to a system that allows regulating the flow rate of fluids to be selectively injected into slimhole oil wells with the capability of measuring the injection flow rate distribution. The system consists of a tubular body with through grooves and a sliding sleeve which restricts the flow through the grooves. The system allows a gradual and variable regulation by using a shifting tool actuated from the surface by means of a Slickline or Wireline equipment, without affecting the operating condition of the well, designed so as to provide an inner diameter sufficient to introduce flow rate measurement tools. The required flow rate is defined according to the specific position of the sleeve and the groove geometry.
BACKGROUND OF THE INVENTIONThe trend in the oil industry is heading towards small diameter or slimhole installations. This is a result of either lower drilling costs due to reduced costs directly related to the rock volume to be extracted and to the diameter of the casing, as well as the use of less equipment, or to the necessity to recover injection wells with severe casing integrity problems where re-tubing with 3½-inch (or less) GRER (Glass Fiber Reinforced Epoxy Resins) or steel tubes is one of the most effective options.
Traditional selective injection systems used for secondary oil recovery use selective installations that allow injecting fluid into multiple layers or reservoirs located at different depths in an oil well. Valves comprising a calibrated orifice or choke are used to regulate the flow rate injected into each layer, so that the injection flow rate is regulated according to the diameter of the valve orifice and a spring that opens or closes the passage to keep the flow rate constant at different injection pressures. These valves are placed inside mandrels, which are components used in traditional selective injection having the characteristic of employing a minimum inner diameter that allows the use of tools to place or remove valves and measure flow rates by means of different tools, but it also requires sufficient outer space to fit the mandrel. Said space, existing between the tubing and the casing, and occupied by the mandrel does not exist in slimhole conditions, thus preventing the application of this technology.
In other cases, circulation valves with sliding sleeves are used. Said sliding sleeves are devices used to communicate the interior of the tubing with the annular space existing between the casing and the tubing, said space allowing the fluid flow between them. These valves operate in three discrete positions, namely open, closed or equalized, and they do not allow gradual openings or closings in order to regulate the flow rate therethrough.
Conventional selective injection systems, which use mandrels with valves in casings with diameters equal to or greater than 5½ inches, are installed so that they inject into the different layers of the reservoir to be swept with fluid. Each mandrel and its valve is isolated from the following one by mechanically or hydraulically sealing packers. The systems with sliding sleeves are operated by a shifting tool, which is actuated from the surface by means of a slickline or wireline equipment.
Although selective injection systems have been developed for tubed slimhole wells with 3½-inch casings, these allow injecting into a limited number of layers and do not allow measuring the flow rate distribution thereto. Currently, there are no systems or devices in the global oil industry for slimhole selective injection for an unlimited number of layers.
A selective injection system known in the art is that disclosed in patent AR 048661 B1, assigned to YPF S.A., which protects a slimhole selective installation system for injecting 3½-inch wells that uses a design of integral regulating valves that are regulated at the surface and lowered to the point of interest by means of a pulling equipment, and in case of desiring to modify the regulation or replace a valve, it is necessary to remove the entire installation from the well. This implies an intervention with pulling equipment, thereby resulting in a very expensive operation due to service costs and oil well downtime, which led to a very limited use.
U.S. Pat. No. 8,141,648 B2, assigned to Petroquip Energy Services, discloses a shifting tool for selectively positioning a mechanical sliding sleeve valve in multiple operational positions. However, the way the valve is operated implies a complex mechanism and a great number of components, thereby making necessary higher maintenance costs.
Therefore, there is a need for a system comprising a flow rate regulating device and a shifting tool for regulating the flow rate at the bottom of an oil well, wherein said oil well has a casing with a 3½-inch diameter or less, the system allowing an unlimited number of selectivity stages and the flow rate regulation per injection zone, in secondary or tertiary recovery injection wells without the need to move or remove the installation (set of valves, packers and tubing) from the well and thereby avoiding intervention with pulling equipment or another oil rig equipment.
BRIEF DESCRIPTION OF THE INVENTIONBased on the above considerations, the present invention provides a solution to the aforementioned problems by providing an injection flow rate regulating system for slimhole wells (i.e. casing of 3½ inches or less), actuated by a shifting tool without the need to intervene the well with oil rig equipment, for an unlimited number of zones of interest, the system geometrically providing an inner passage for introducing flow rate measurement tools and being suitable for regulating flow rate of fluids including gas, water (secondary recovery) and/or polymer solutions, surfactants, alkali-surfactant-polymer (ASP), etc. in enhanced oil recovery (EOR) processes.
It should be noted that the flow rate regulation system of the invention may be also applied to oil wells with casing diameters greater than 3½ inches.
Consequently, it is an object of the present invention a flow rate regulating system for flow rate regulation within an oil well, wherein the well has a casing with a diameter less than or equal to 3½ inches, wherein the flow rate regulating system comprises:
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- a) at least one flow rate regulating valve, for regulating flow rate, having a generally cylindrical body with a plurality of elongated grooves or holes, a top sub in an upper portion and a sliding sleeve within; and
- b) a regulating and calibrating shifting tool for regulating and calibrating the position of the sliding sleeve, which has a generally cylindrical collet, a block set and a pair of nuts on each side of the block set.
In a preferred embodiment of the present invention, the system comprises a flow rate regulating valve for each well layer, without any limitation regarding the number of valves to be installed in the well.
In a preferred embodiment of the present invention, the sliding sleeve has a free inner passage that allows the shifting tool and flow rate measurement tools passage in order to establish a fluid distribution therein. The obtained measures are extremely important for monitoring and tracking the reservoir.
In a preferred embodiment of the present invention, the sliding sleeve has a notch on its inner surface.
In a preferred embodiment of the present invention, the collet has a protuberance at its lower end.
In a preferred embodiment of the present invention, the shifting tool is designed so as to freely pass through the interior of the at least one flow rate regulating valve.
In a preferred embodiment of the present invention, the block set allows gradually regulating the sliding sleeve displacement according to its position in relation to the collet.
In a preferred embodiment of the present invention, the pair of nuts comprises a nut and a lock nut.
In a preferred embodiment of the present invention, the shifting tool is actuated from the surface by a slickline or wireline equipment.
In this way the invention provides a selective installation system for slimhole wells. Each of the multiple injection or production zones has a sliding sleeve for regulating the flow rate and a full passage for maneuvering the shifting tool next to wire or cable tools and being able to place or actuate other regulating valves sliding sleeves that are located in different depths in the same well, according to the characteristics of the reservoir, either for producing oil or injecting water or other fluids. The sliding sleeve also allows the passage of flow rate measurement tools in order to know the flow rate distribution, allowing in this way the monitoring of the reservoir. Likewise, there is no need of removing the installation (valves, packers and tubing) through the intervention of pulling equipment or oil rig equipment, in case it is desired to modify the regulation of any of the devices, thereby making the selective installation system economically viable.
Additionally, the flow rate regulating system of the present invention is designed to be used both in water injection wells for secondary recovery systems and tertiary recovery (EOR) systems, thus the design of the grooves or holes through which the fluid circulates towards the formation is such that it does not cause degradation of the fluid (polymer solution, surfactant, ASP, etc.), and also the system may be used in producing wells for the regulation of hydrocarbon or water flow rate at the bottom of the well.
The present invention will be described in further detail below, making reference to the appended figures illustrating exemplary embodiments of the invention which should not be construed as limiting.
In each of the figures, same numerical references are used to indicate same elements of the present invention.
As it is known by an expert in the corresponding technical field, in the oil industry the pipe diameter is a nominal diameter and the inner and outer pipe diameter depend on the thickness. This thickness is defined by the “poundage” of the pipe which is the weight thereof per linear meter.
Said flow rate regulating valve 1 is positioned at the depth in which a reservoir or layer is located to which it is desired to inject fluids, whether for secondary or tertiary recovery (EOR), or from which it is desired to produce oil; and as many flow rate regulating valves 1 as the number of reservoirs or layers which are desired to inject to or produce from, may be included for the same oil well.
The grooves 3 of the body 2 of the flow rate regulating valve 1 are responsible for channeling the fluid from the inside of the flow rate regulating valve 1 to the outside of the flow rate regulating valve 1, i.e., to the annular space between the tubing and the casing, or vice versa, whether it is the case of an injection or production well, respectively. The sliding sleeve 4 is responsible for regulating the opening of said grooves 3 allowing, as desired and by means of a shifting tool as it will be seen below, whether a complete opening, so as to obtain maximum injection or production flow rates according to the operating pressure differential; a partial blockage, by calibrating the position of the sliding sleeve 4 so as to obtain the desired flow rate; or a complete blockage which would be equivalent to closing the flow rate regulating valve 1.
On the other hand, the flow rate regulating valve 1 has a top sub 7 that works as a stop for a shifting tool when actuating the sliding sleeve 4.
The sliding sleeve 4 has a plurality of hydraulic seals 5 in its upper and lower portion and has a notch 6 on its inner surface so that it can be coupled with a shifting tool, as it will be seen below, in order to be displaced so as to regulate the flow rate.
The shifting tool 10 can be operated from the surface by means of a slickline or wireline equipment, being able to operate a flow rate regulating valve 1 that is at a certain well depth and place it in a desired position. More precisely, the shifting tool 10 can freely pass through all sliding sleeves 4 and flow rate regulating valves 1 situated in the same well, in order to regulate the valve of interest and obtain the desired flow rate, either in injection or production mode.
The protuberance 12 at the lower end of the collet 11 of the shifting tool 10 is configured so that it can be firmly coupled with notch 6 of the flow rate regulating valve 1 so that the sliding sleeve 4 can be displaced and the flow rate adjusted to the desired value.
The block set 13 is fixed in a certain position in relation to the collet 11 by a pair of nuts 14 on each side of block set 13. Said pair of nuts 14 comprises a nut and a lock nut.
More specifically, the shifting tool 10 is used not only to open, close or displace the position of the flow rate control or circulation devices, but it has a millimetric calibration function, i.e. in steps up to 1 mm, of the position where it will locate the sliding sleeve 4, said millimetric calibration function being provided by the block set 13. In other words, in addition to having the protuberance 12 for coupling with the notch 6 of the sliding sleeve 4 that is to be displaced, the shifting tool 10 has a calibration mechanism which, based on its geometry, establishes the relative position of the sliding sleeve 4 and therefore determines the total fluid passage area, thereby regulating the flow rate. The relative position of the sliding sleeve 4 determines the resulting flow rate. Changing the position of the sliding sleeve 4 produces a change in the total passage area of the fluid from the inside of the flow rate regulating valve to the outside, or vice versa.
Said flow rate regulating system is applicable to casings with 3½-inch outer diameters and 2⅞-inch inner diameters, leaving the inner passage free so that an unlimited number of sliding sleeves can be placed as required.
The calibration is aimed at setting the valve opening. For this purpose, it is necessary to establish spacing distances between the block set 13 of the shifting tool 10 and the top sub 7 of the flow rate regulating valve 1.
Particularly, the calibration consists of establishing a certain position of the block set 13 in relation to the collet 11 of the shifting tool 10 before lowering the shifting tool 10 through the well. The block set 13 can be displaced in relation to the collet 11 and fixed in another position by loosening and adjusting the nuts 14.
When the shifting tool 10 is lowered to a flow rate regulating valve 1 that is to be operated in that well, by means of a slickline or wireline equipment, the opening of the sliding sleeve 4 of the flow rate regulating valve 1 is already defined, since the block set 13 will stop at the top sub 7, and the sliding sleeve 4 will remain in a desired position according to the position in which the block set 13 was placed in relation to the collet 11.
This procedure must be done each time the tool is lowered into the well to perform an opening or closing of any flow rate regulating valve 1. This operation requires that the operator in charge of the opening, regulating or closing operation be trained personnel.
The flow rate regulating valve 1 has an internal geometry specially designed to provide a reference to the shifting tool 10 on the relative position in which the sliding sleeve 4 has to be positioned. At the same time, the sliding sleeve 4 has an internal geometry specifically designed to allow the shifting tool 10 to pass in a downward direction and to be operated in an upward direction, except in the case that it has already operated on a valve located in a deeper zone of the well.
Unless otherwise defined, all technical and scientific terms used in the present disclosure have the same meaning as commonly understood by a person skilled in the art to which the present invention belongs. As used herein, the terms “comprises”, “has” and “includes” and their conjugations, mean “including, but not limited to”.
The technical experts will recognize or be able to determine, using only routine experimentation, many equivalents of the specific procedures, embodiments, claims and examples described herein. Such equivalents are considered to be within the scope of the present invention and encompassed by the attached claims. Thus, it should be understood that although the present embodiments have been specifically described by preferred embodiments and optional features, modifications and variations thereof, may be conceived by those skilled in the art and that such modifications and variations are considered within the scope of the invention.
Claims
1. A flow rate regulating system for flow rate regulation within an oil well with a casing with a diameter less than or equal to 3½ inches, wherein the flow rate regulating system comprises:
- at least one flow rate regulating valve for regulating flow rate, having a generally cylindrical body with a plurality of elongated grooves, a top sub in an upper portion and a sliding sleeve within; and
- a regulating and calibrating shifting tool for regulating and calibrating the position of the sliding sleeve which has a generally cylindrical collet, a block set and a pair of nuts on each side of the block set.
2. The system according to claim 1, wherein the at least one flow rate regulating valve comprises a flow rate regulating valve for each well layer.
3. The system according to claim 1, wherein the sliding sleeve has a free inner passage that allows the shifting tool and flow measurement tools passage in order to establish a fluid distribution therein.
4. The system according to claim 1, wherein the sliding sleeve has a notch on its inner surface.
5. The system according to claim 1, wherein the collet has a protuberance at its lower end.
6. The system according to claim 1, wherein the shifting tool is designed to freely pass through the interior of the at least one flow rate regulating valve.
7. The system according to claim 1, wherein the block set allows gradually regulating the displacement of the sliding sleeve according to its position in relation to the collet.
8. The system according to claim 1, wherein the pair of nuts comprise a nut and a lock nut.
9. The system according to claim 1, wherein the shifting tool is actuated from the surface by a slickline or wireline equipment
Type: Application
Filed: Nov 7, 2019
Publication Date: Jun 4, 2020
Inventors: Walter MORRIS (Ciudad Autónoma de Buenos Aires), Juan Manuel GONZALEZ FERRER (Berisso), Néstor David VILCHEZ (Ciudad Autónoma de Buenos Aires), Manuela BARBERO (Ciudad Autónoma de Buenos Aires)
Application Number: 16/677,078
