Systems And Methods For The Storage And Disposal Of Waste Cement

Abstract

A collapsible bladder system for the storage and disposal or re-use of cement returns from oil and gas wells is described. The collapsible bladder system includes a flexible storage bag having an input valve, an output valve and a vent that can be easily set up and transported by a single person. Cement returns are pumped into the flexible storage bag and allowed to harden into a cement block. The cement block covered with the storage bag can be hauled away for disposal or re-used for a secondary purpose, such as a barricade.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefits of priority under 35 U.S.C. .sctn. 119 and 120 of U.S. Provisional Patent Application No. 61/674,200 filed Jul. 20, 2012, the entire contents of which are incorporated by reference.

FIELD OF THE INVENTION

[0002] The invention relates to collapsible bladders, and specifically to collapsible bladder systems for the storage and disposal of cement returns from oil and gas wells.

BACKGROUND OF THE INVENTION

[0003] Large storage containers are frequently needed in certain industries for the transportation and disposal of waste products. In one example and specifically in the oil and gas industry, there is a need for storing and disposing of cement returns from oil and gas wells that are being cased.

[0004] As is known, after drilling an oil or gas well, an operator will typically case sections of the well in order to provide stability to one or more sections of the well for the subsequent production phases of the well. During casing, steel sections of pipe are placed in the well and then cemented in place by pumping cement through the casing and allowing the cement to flow upwardly through the annulus between the formation and exterior surface of the casing. Once the annulus has been filled, the cement will cure thereby securing the casing in place.

[0005] During the cementing operations, at the point where the annulus is fully filled with cement, cement will flow out of the top of the well thus indicating to the operator that the annulus is full. In a typical cementing operation, in order to ensure that the annulus is fully filled with cement, the operator will allow an additional volume of cement to flow out of the top of well before ceasing to pump cement down the well. This excess or waste cement, which may be substantial in volume, must be collected at surface and properly disposed of. Currently, cement returns (i.e. the waste cement) are generally disposed of in pits or in above ground containers at or near the drilling site.

[0006] In most jurisdictions, there are various regulations and standards that must be met for cement pits in order to limit the negative effect they can have on the environment. Typically, buried cement returns must not interfere with subsurface water flow and generally measures must be taken to prevent animals or the public from entering the pit. In addition, after drilling operations cease, the pit must be reclaimed to its former or equivalent land use, all of which may be a time-consuming and costly process for the operator. Moreover, a number of jurisdictions have recently tightened their rules and regulations for cement returns disposal in order to further reduce the negative environmental impacts that may be associated with them.

[0007] More specifically, as the pit disposal method typically requires a) a large pit up to 100 m.sup.3 to be dug into the ground at a well site, b) allowing the cement returns to harden and conveying them from the wellhead to the pit and c) breaking the hardened cement into smaller pieces to ensure drainage in the pit and d) the reafter covering the cement and remediating the ground, the oil and gas industry has generally been moving away from the use of cement pits as these steps require a substantial amount of work that can be costly to complete.

[0008] Another common method for the disposal of cement returns from oil and gas wells is the use of above ground containers. In this method, large lined steel containers are set up at wellheads, where cement returns are pumped into the containers and allowed to harden. As with the pit method, the cured cement must be broken into pieces prior to disposal. The full containers are then hauled to a local landfill where the hardened cement is disposed of and the empty containers are returned to the drilling site to be filled with further cement returns. While with this method drilling companies are not subjected to the same standard of land reclamation as with cement pits, the hauling and moving around of the large heavy containers containing waste cement is both labor and equipment intensive. That is, this method typically requires the use of expensive equipment including a winch tractor as well as hammering and lifting equipment.

[0009] As a result of the foregoing problems and also due to the changes to rules and regulations concerning cement returns that are being imposed in certain jurisdictions, such as Alberta, Canada, there is a need for improved cement return storage and disposal systems that have less environmental impact and that are more cost-effective by reducing the equipment and labor requirements of cement disposal.

SUMMARY OF THE INVENTION

[0010] In accordance with the invention, a collapsible bladder for the collection and storage of cement is provided comprising: a bag body having top and bottom surfaces and front and back ends; a vent located on the top surface of the bag body for the release or equalization of air pressure within the bag; a first port located on the front end of the bag body for filling the bag body with cement, the first port having a first port valve operable between an open position and a closed position; and a second port located on the back end of the bag body for expelling overflow cement from the bag body, the second port having a second port valve operable between an open position and a closed position.

[0011] In various embodiments, the bag body includes a bag portion and a cover portion operably connectable by a zipper. The cover portion may also include at least one access port for embedding a handle within the cement prior to curing.

[0012] In another embodiment, the collapsible bladder also includes at least one external form for imparting a surface texture or feature to at least one surface of the cement block. In one embodiment, the external form includes a wave profile for imparting a wave profile on at least one surface of the cement block.

[0013] In another aspect, the invention provides a system for collecting and storing cement returns at a well site comprising: a plurality of collapsible bladders, each collapsible bladder including: a bag body having top and bottom surfaces and front and back ends; a vent located on the top surface of the bag body for the release or equalization of air pressure within the bag body; a first port located on the front end of the bag body for filling the bag body with cement returns, the first port having a first port valve operable between an open position an d a closed position; and a second port located on the back end of the bag body for expelling overflow cement returns from the bag body, the second port having a second port valve operable between an open position and a closed position; wherein the plurality of collapsible bladders are positioned in a series and the second port and first port of adjacent collapsible bladders are connected by a hose to allow overflow cement returns to flow between adjacent collapsible bladders.

[0014] In another aspect, the invention provides a method for storing and disposing of cement returns comprising the steps: pumping cement returns into a bladder; and allowing the cement returns to harden inside the bladder to create a covered cement block.

[0015] In another embodiment, the bladder includes a zipper allowing the cement block to be removed from the bladder and the method further comprises the step of c) removing the bladder from the cement block. In another embodiment, prior to step a) the bladder is fixed to at least one external form thereby enabling a covered cement block from step b) to have a surface texture or feature corresponding to the external form.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is described with reference to the accompanying figures in which:

[0017] FIG. 1 is a schematic front perspective view of a collapsible bladder in accordance with one embodiment of the invention;

[0018] FIG. 2 is a schematic top view of a collapsible bladder system comprising multiple linked bladders in accordance with one embodiment of the invention;

[0019] FIG. 3 is a schematic front perspective view of various shaped bladders in accordance with the invention; and

[0020] FIG. 4. is a schematic front view of a cement-filled bladder showing external forms in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0021] With reference to the figures, a collapsible bladder system 10 for the storage and disposal of cement returns from oil and gas wells is described. Within this description, the bladder system is generally described for the storage and disposal cement returns from oil and gas wells; however, as described below, the bladder system may be used in a number of different applications.

[0022] Referring to FIG. 1, the collapsible bladder system 10 comprises a flexible bladder 12, a vent 14, an input valve 16 and an output valve 18. The bladder 12 is constructed from a lightweight flexible material, such as polyurethane, that can be folded into a compact bundle for storage and transportation. To set up the bladder for use, the folded bladder is simply unfolded from the collapsed form at the location where waste cement is located. As such, a plurality of collapsed bladders can be readily transported and set-up in an efficient manner by a single person and without the need for heavy equipment. Moreover, a single person can easily move one or more empty bladders around a well site as needed.

[0023] More specifically, in a preferred embodiment, the flexible bladder 12 is a large collapsible bag having a generally rectangular shape with rounded corners that is fabricated from a lightweight flexible material, such as polyurethane. In the preferred embodiment, the flexible bladder has a maximum internal volume that allows standard lifting equipment to lift an equivalent volume of cement. That is, it is generally not desirable for the bag to be too large such that it will be difficult to lift an equivalent volume of cured cement but also not too small so as to require a substantially larger number of bags for a typical disposal job. Thus, in one embodiment, the bladder will have a volume of approximately 1.7 m.sup.3 (61 ft.sup.3) and generally measure approximately 8 feet (2.4 m) long, 4 feet wide (1.2 m) wide and 2 feet (0.6 m) tall.

[0024] When empty, the flexible bladder having these dimensions can be folded into a compact bundle about the size of a briefcase. The flexible bladder is generally free-standing when full or partially full and does not require further supports. As is understood, and explained in greater detail below, the shape and volume of a bag can be varied to provide additional functionality and/or uses.

[0025] In operation, one or more bladders are connected to a source of waste cement such as a casing operation via input valve 16. Each bladder is positioned such that the vent 14 is located on the top of the flexible bladder to allow for air pressure to be equalized as the bladder is being filled. The input valve 16 and output valve 18 are preferably located on opposite ends of the bladder and generally nearer the top of the bladder. Both the input valve and output valve are equipped with appropriate valve and connection fittings 16a, 18a that allow the valves to be manually moved between open and closed positions and allow hoses and/or of her elements to be secured in an airtight manner to the valves. In order to fill a bladder with waste cement, the input valve is opened and is connected to a hose or pipe (not shown) that conveys cement returns from the well into the bladder. If a single bladder is being used, the output valve is closed, otherwise, if a plurality of bladders 10a, 10b, and 10c (FIG. 2) are being connected together, a hose 20 is used to connect the output valve 18 of one bladder to the input valve 16 of the next bladder in series with each valve being placed in the open position. As such, any number of bladders can be connected in this manner, depending on the volume of cement returns from the well.

[0026] In a multi-bladder configuration, generally as the first bladder 10a fills with cement and the cement reaches the level of the output valve 18, cement will flow through the hose 20 into the second bladder system 10b. Upon reaching the level of the output valve 18b of the second bladder 10b, the cement will flow into the third bladder 10c, and so on. While the bladders are filling with cement, further bladder systems can be connected to the last bladder in the series as needed to handle the volume of cement returns. If only one bladder system is being used or the bladder system is the last in a series of bladder systems, i.e. bladder system 10c in FIG. 2, the output valve is preferably closed.

[0027] When a bladder is full, the cement returns are allowed to harden within each bladder thereby forming a large cement block enclosed in the bladder. The block of cement, with or without the bladder, can be hauled away in one piece to a disposal site such as a landfill. It is generally not necessary to break the cement into smaller pieces or remove the cement from the bag. However the bag can be removed from the cement block if desired and the block broken into pieces. In one embodiment, to facilitate removal of a cement block and re-use of the bladder, the bladder may be fabricated as interconnected pieces including a bag portion 12a and lid portion 12b interconnected via a zipper 12c extending around the circumference of the upper edge of the bag portion. In this case, if the bladder is removed from a cured cement block, the bladder may be used again.

[0028] Furthermore, the lid portion 12b may be provided with ports 12d that may be opened prior to curing to enable lifting handles (not shown) to be embedded in the uncured cement that will subsequently harden into place within the cured cement block.

[0029] In further embodiments, and depending on the shape and volume of the bladders, the cement blocks that are formed can be used for secondary purposes, such as barricades around the well head or elsewhere at the drilling site. Similarly, cement blocks can also be transported to other locations for secondary uses at those locations. Furthermore in various embodiments, multiple cement blocks can be stacked upon one another or positioned adjacent one another as needed.

[0030] As can be appreciated, the shape and size of the hardened cement block is determined by the shape and size of the bladder. The bladder can be made in various shapes and sizes to create a cement block as needed for a secondary purpose. FIG. 3 shows a variety of bag shapes each of which may have a specific secondary function. For example, a cylinder 31 or half cylinder 33 may be formed for use as a post or barricade, and a flat cylinder 32 or cube 34 may be used as a barricade and/or to enable effective stacking of blocks.

[0031] In addition, and as shown in FIG. 4, before the bladder is filled with cement, it may be placed on an exterior form that shapes the bladder as it fills with cement and hardens. The mold 30 may be placed underneath the bag, or it may extend up the sides and/or along the top of the bag, depending on the desired shape of cement block. For example, molds may be used to create cement blocks with longitudinal ridges or waves 30a along the top and/or bottom to facilitate vertical or offset stacking.

[0032] In another embodiment, if concrete blocks with substantially flat surfaces are desired, stiffening members can be secured to any of the outside edges of the unfilled bag to prevent the bag walls from bowing outwards as the bag fills with cement. In another embodiment, the bladder includes a base member having a series of longitudinal slots extending across the length or width of the bladder to enable lifting straps and/or forklift tines to be readily inserted beneath the bladder to assist in the movement of the cured bladders.

[0033] In another embodiment, reflective material is attached to the outside of the bag such that the bag is visible for secondary uses, such as a barricade. The bag may also have text and/or images on its exterior surface, which may include warning messages, instructions or advertising.

[0034] The collapsible bag can also be used for the storage and/or disposal of other well fluids, such as drilling fluids, water, fracturing fluids etc.

[0035] Further still, the exterior of the bladders may be provided with additional fixtures such as straps and/or strap loops or the like to facilitate the interconnection of adjacent bladders when filled with cement.

[0036] Although the present invention has been described and illustrated with respect to preferred embodiments and prefer red uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.

Claims

1. A collapsible bladder for the collection and storage of cement comprising: a bag body having top and bottom surfaces and front and back ends; a vent located on the top surface of the bag body for the release or equalization of air pressure within the bag; a first port located on the front end of the bag body for filling the bag body with cement, the first port having a first port valve operable between an open position and a closed position; and a second port located on the back end of the bag body for expelling overflow cement from the bag body, the second port having a second port valve operable between an open position and a closed position.

2. A collapsible bladder as in claim 1 wherein the bag body includes a bag portion and a cover portion operably connected to one another by a zipper.

3. A collapsible bladder as in claim 2 wherein the cover portion includes at least one access port for embedding a handle within the cement prior to curing.

4. A collapsible bladder as in claim 1 further comprising at least one external form for imparting a surface texture or feature to at least one surface of the cement block.

5. A collapsible bladder as in claim 4 wherein the external form includes a wave profile for imparting a wave profile on at least one surface of the cement block.

6. A system for collecting and storing cement returns at a well site comprising: a plurality of collapsible bladders, each collapsible bladder including: a bag body having top and bottom surfaces and front and back ends; a vent located on the top surface of the bag body for the release or equalization of air pressure within the bag body; a first port located on the front end of the bag body for filling the bag body with cement returns, the first port having a first port valve operable between an open position and a closed position; and a second port located on the back end of the bag body for expelling overflow cement returns from the bag body, the second port having a second port valve operable between an open position and a closed position; wherein the plurality of collapsible bladders are positioned in a series and the second port and first port of adjacent collapsible bladders are connected by a hose to a llow overflow cement returns to flow between adjacent collapsible bladders.

7. A method for storing and disposing of cement returns comprising the steps: a) pumping cement returns into a bladder; and b) allowing the cement returns to harden inside the bladder to create a covered cement block.

8. The method as in claim 7 wherein the bladder includes a zipper allowing the cement block to be removed from the bladder and the method further comprises the step of c) removing the bladder from the cement block.

9. The method as in claim 7 wherein prior to step a) the bladder is fixed to at least one external form thereby enabling a covered cement block from step b) to have a surface texture or feature corresponding to the external form.