1. Field of the Invention
The invention relates to ball drop injection assemblies for use at a wellsite during hydraulic fracturing operations.
2. Description of the Related Art
Frac ball injection to control fluid flow in a well has seen use in fracturing operations for some time. Frac balls are often inserted into a wellbore to control fluid flow between different sections of a well. The balls are pumped downhole along with well stimulation fluid. It has generally been determined to be time consuming and potentially hazardous for on-site personnel to manually handle frac balls around the wellbore as equipment sometimes extend high into the air and a number of high pressure lines can surround the well to pump stimulation or other fluids into the well. The industry has sought ways to limit the manual interaction required by on-site personnel when injecting frac balls at the wellbore. One option that reduces overall injection times and the amount of manual involvement by on-site personnel involves the use of frac ball dropping assemblies.
Frac ball dropping assemblies have seen greater use in fracturing operations more recently given the efficiencies that can be achieved with frac ball injection, and the additional safety factor they provide to on-site personnel. In fracturing operations it is useful to drop frac balls of varying sizes into the wellbore, where they can be pumped downhole. The frac balls can be used to control fluid flow beneath the surface in a well. This can be useful when, for example, it is more efficient to stimulate and produce from different stages of a well at a particular time in the overall fracturing operation. Over time hydraulic fracturing has seen greater use of ball drop assemblies to stimulate well production, in part because of the time savings and in part because of the reduced manual interaction required of on-site personnel.
Ball drop assemblies can require frac balls of sequentially larger diameter to be stored in a frac ball stack above the wellhead. The balls in this stack are often stored in water or other fluids and often require some degree of temperature control. Recently, dissolvable frac balls have seen increased use, dissolvable ball designs hold up better in dry and non-pressurized storage rather than in fluid and at wellbore pressure. It would be desirable to provide a dry and atmospheric pressure storage option for frac balls just prior to well injection. It would also be desirable to eliminate the need for temperature control of the ball drop apparatus.
In addition, ball drop assemblies have seen issues and often cannot function with balls of similar or substantially similar sizes coming one after another without substantially increasing the height of the ball drop assembly and adding additional structure to accommodate the configuration. Thus, it would also be desirable to provide a system that can handle the injection of substantially similar ball sizes in a sequential manner without the need to increase the height of the ball drop assembly.
The present invention provides a ball drop apparatus that allows for dry frac ball staging and storage just prior to injection while also providing flexibility in the number and size-ordering of the balls to be injected. In a preferred embodiment, an improved ball drop apparatus is provided, which includes a pressure equalization section that connects with a pressure equalization apparatus, and the wellbore through a seal pack. The general sequence of operations starts with a frac ball being inserted from a ball feeding section into an atmosphere-to-pressure ball injection chamber. The atmosphere-to-pressure ball injection chamber is connected to and a part of an injection ram assembly. The atmosphere-to-pressure ball injection chamber and frac ball are then pushed through a first seal pack and into the pressure equalization section by hydraulics connected to the injection ram assembly. In accordance with a preferred embodiment, the pressure equalization apparatus then applies pressure to the pressure equalization section, causing the pressure within the section to increase until it reaches at or near wellbore pressure. Once the pressures are close, the injection chamber and ball are pushed through the second seal pack and into the wellbore. The ball can then be pumped downhole. Following the injection of a ball, the atmosphere-to-pressure ball injection chamber is retracted into the pressure equalization section. The injection chamber can be returned to atmospheric or close to atmospheric pressure by the pressure equalization apparatus connected to the pressure equalization section by a port. In an alternate embodiment, a ball may be pushed into the pressure equalization section, and pressure may be increased only partially, not all the way to wellbore pressure. The ball may then be injected through the seal pack or packs. This embodiment may allow some pressure and/or fluid to bleed back through the pressure equalization section or ball injection chamber after injection but may be preferred for some configurations. In yet another alternate embodiment, pressure may not be equalized at all when the ball reaches the pressure equalization section. The frac ball may then be injected into the wellbore. This embodiment may also allow for pressure and/or fluid to bleed back through the pressure equalization section or ball injection chamber after injection if no pressure equalization section is configured but may be preferred for some wellsites or reduced-cost tool configurations.
This sequence can be carried out over and over again for frac balls of varying sizes or for the sequential injection of equal size or similarly sized frac balls. Dissolvable frac balls can also benefit from this design since they can be stored in a dry environment until they are placed into the frac ball injection chamber to be inserted in the wellbore, thus preserving the integrity of the dissolvable balls prior to injection and consistent results between drops.
Various aspects and attendant advantages of one or more exemplary embodiments and modifications thereto will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Exemplary embodiments are illustrated in referenced Figures of the drawings. It is intended that the embodiments and Figures disclosed herein are to be considered illustrative rather than restrictive. No limitation on the scope of the technology that follows is to be imputed to the examples shown in the drawings and discussed herein.
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One or more first seal packs 70 separate the atmosphere-to-pressure frac ball injection chamber 20 from the pressure equalization section 30 until the frac ball is to be injected. A second seal pack 80 further separates the pressure equalization section 30 from the axial passageway 60 connected to the wellbore. In an embodiment, the pressure equalization apparatus (not shown) can be spaced apart from the pressure equalization section 30 and connected by a fluid carrying line (not shown) that connects at pressure equalization port 50.
The ball drop receiver 18 can connect to a variety of ball feeding mechanisms, such as a controlled aperture ball drop as disclosed in U.S. Patent Application Publication No. 2012/0279717, a horizontal frac ball injector as disclosed in U.S. Patent Application Publication No. 2012/0211219, or other ball feeding mechanisms as known in the industry, or as may be conceived.
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The preferred embodiment of the pressure equalization apparatus (not shown), includes a pressurized piston in a closed system that can be used to add and remove pressure from the pressure equalization section 30. The pressure equalization apparatus can share a common fluid reservoir with the pressure equalization section 30 that can be connected by the fluid carrying line. Optionally, multiple fluid carrying lines can be used. When the piston of the pressure equalization apparatus actuates, it compresses the shared fluid in the common fluid reservoir and increases the pressure both in the pressure equalization apparatus reservoir and in the pressure equalization section 30. The piston can be actuated hydraulically or by other means known in the industry. For frac balls of different sizes the piston movement can vary in the amount of stroke needed to achieve a given pressure. For example, with a larger ball size the pressure equalization section would contain a smaller volume of fluid and the piston would require a shorter stroke to achieve the desired pressure for injection of the ball. Likewise, for a smaller ball size, the pressure equalization section would contain a larger volume of fluid and the piston would require a longer stroke to achieve the desired pressure for injection of the ball. Pressure sensors could optionally be installed on either the pressure equalization section, the pressurized portion of the pressure equalization apparatus, or both. This would help on-site personnel or electronic control systems control the pressure equalization operation of the system. Over time, this system may experience dirty or sandy fluid building up in the well fluid side of the pressure equalization apparatus. In an embodiment a filter and side reservoir of fluid can be connected to this well fluid section to remove any sand or other substrate that could harm the operation of the system.
In an alternate embodiment, the pressure equalization configuration can consist of a pressure bleeding pathway between the axial passageway 60 at wellbore pressure and the pressure equalization section 30 as the means to increase the pressure equalization section 30 to wellbore pressure. In this configuration a valve or other switching means for this line would be employed to control when the pressure equalization section 30 is brought up to wellbore pressure. In this embodiment, bringing the pressure equalization section 30 back to atmospheric pressure would involve bleeding the pressure equalization section 30 to an on-site container or reservoir.
In another alternate embodiment, the atmosphere-to-pressure ball injection chamber 20 and frac ball 100 or multiple frac balls can be pushed through both the first seal pack 70 and the second seal pack 80 without any pressure pre-equalization occurring. Further, in this embodiment, when the injection chamber is retracted from the wellbore, pressure can be bled off through the pressure equalization section to an onsite container before the injection chamber is returned to the ball loading position.
In an embodiment, the injection ram assembly 22 can be actuated by hydraulic means, an electric motor, a mechanical motor, or by other means known in the industry. Further, though the injection chamber described is formed by the injection ram assembly, the apparatus can also be configured with a separate injection ram and injection chamber housing. Additionally, a screw-drive, multiple screw-drives, or other similar assemblies can be substituted for the hydraulics to cause the injection chamber to move between the various described positions.
In an embodiment, multiple frac balls could be pushed through and injected at one time. The atmosphere-to-pressure ball injection chamber would have to be large enough to accommodate the balls or configured to accommodate multiple balls.
Regarding the one or more first seal packs 70 and the one or more second seal packs 80, various seal pack designs and configurations can be substituted and still achieve the intended result. For example, at least the following seal packs or a combination of seal packs in a different location or even a combination of seal packs in the same location can be configured: Chevron Vee Pack Seal, Polypack Seal, Standard O-ring Seals, Quad Ring Seals, Rubber Seals, and Polyurethane Seals, and similar seal pack configurations, can be used and/or substituted. Generally though, the preferred seal packs are v-shaped o-ring type or similar.
Additionally, the atmosphere-to-pressure ball drop apparatus provides at least the following benefits: it allows for the dry un-pressurized storage of frac balls, which is particularly beneficial to dissolvable frac balls; it reduces or eliminates the need to heat a ball drop stack during inclement weather; and it reduces or eliminates the need for an increased height ball drop stack as two or more stacks can be configured in the same height footprint as one ball drop stack of the previous designs.
Although the concepts disclosed herein have been described in connection with the preferred form of practicing them and modifications thereto, those of ordinary skill in the art will understand that many other modifications can be made thereto. Accordingly, it is not intended that the scope of these concepts in any way be limited by the above description.
This application is a continuation-in-part of U.S. patent application Ser. No. 14/329,234, filed on Jul. 11, 2014, which claimed the benefit of U.S. Provisional Patent Application Ser. No. 61/847,346 filed on Jul. 17, 2013, both of these applications are herein incorporated by reference in their entirety.
Number | Name | Date | Kind |
---|---|---|---|
3322140 | Scott | May 1967 | A |
3911724 | Grove et al. | Oct 1975 | A |
4132243 | Kuus | Jan 1979 | A |
20120152525 | McGuire | Jun 2012 | A1 |
20120211219 | McGuire et al. | Aug 2012 | A1 |
20120279717 | Young et al. | Nov 2012 | A1 |
20140360720 | Corbeil | Dec 2014 | A1 |
Entry |
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Patent Cooperation Treaty; International Search Report and Written Opinion dated Nov. 14, 2014, United States. |
Number | Date | Country | |
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20160356112 A1 | Dec 2016 | US |
Number | Date | Country | |
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61847346 | Jul 2013 | US |
Number | Date | Country | |
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Parent | 14329234 | Jul 2014 | US |
Child | 15242029 | US |