Patent Application
20140050528
Oil and gas exploration, completion, and production operations often require the handling, transfer, and storage of large fluid volumes. Hydraulic fracturing techniques can require more than five million gallons of water per well. This large volume can be stored on site prior to and between fracturing operations, for storage, reuse and/or treatment and disposal. In addition, wells may produce large quantities of water during production. Due to environmental concerns, this water must be stored in a manner which will prevent contamination of the surrounding environment.
Often, large open pits are dug near the wells and used to store the water on or close to the well site. Environmental concerns are beginning to limit this practice. In addition to being unsightly, these pits can cause groundwater contamination, and are potential hazards to local livestock or wild animals long after drilling, completion, and production operations. Another option is the construction of steel tanks on site for storing fluid. The cost of construction, maintenance, and removal makes these options impractical in many cases.
As an alternative to pits and tanks, large fleets of tanker trucks, sometimes known as frac tanks have been employed to store fluid on a well site. Though these tanks can be redeployed from site to site recouping some of their cost more efficiently than built on site tanks, the enormous amount of resources necessary to move a fleet of tanks from site to site reduces the potential cost savings. Further, in environmentally sensitive areas, the movement of such large amounts of equipment may have serious consequences to roads and the local environment as well as create a disturbance to communities in which this equipment comes into contact.
A recent solution to the above problems has been the use of temporary tanks built on site for the storage of fluids. The problem with construction on site is that it can be costly and time consuming. A preferred method is to prepare a surface, erect a retaining wall of appropriate dimensions and then line the tank with a waterproof liner. The liner is heavy and difficult to install. Due to the thickness of the material used in the liner, it may take ten to twenty men and heavy equipment to maneuver the liner in place, and then lift the liner in small sections to secure it to the top of the wall.
Liners are large and bulky, and a full inspection can be extremely time consuming, if it can be accomplished at all. Due to the industrial environment and the large impact a small leak can have on the surroundings, it is often desirable to utilize more than one liner as a safety measure further increasing the effort and expense of erecting such a container. Liners are typically only used once and need to be disposed of after the tank is moved. This adds a significant cost to the storage operation and creates an additional waste stream. In the case that these tanks are used to store anything other than fresh water (such as produced or fracturing fluid flow back water), two or more liners are usually required, significantly increasing the overall cost of storage.
The oil and gas industry would be better served with fluid storage solutions which have the following attributes:
low manpower requirements for installation,
reusable components leading to cost reductions,
minimal environmental impact,
100% liner contingency,
ability to test liner integrity,
ability to store
Described herein is an alternative to the large bulky single or multiple liners of a built tank. The innovation described allows construction of a large holding tank or pit on site with multiple liners to significantly reduce the probability of leaks and a method to leak test the liner while allowing the complete system to be installed in less time and with less man power than that required with previous systems.
In one embodiment, a base is prepared as with previous systems. Such a base should be relatively flat and smooth so as not to create a puncture hazard for the liner and to be stable enough to support the weight of the tank when full. The preferred method is to grade and level the existing ground at the desired location, removing any large rocks, wood, or other materials which may puncture the liner. Optionally the base may be covered with a protective material such as, sand, earth, mulch, fabric, pads, or other materials which would be obvious to one skilled in the arts.
Next, the retaining wall is constructed around the perimeter of the tank. The retaining wall may be constructed of one or more sheet materials erected into a vertical wall fashion, joined at corners to form the desired shape, and optionally reinforced along the top edge and at various locations along the walls. One skilled in the arts would appreciate that a tank could be constructed in many configurations to accommodate the environment and surrounding structures with a plurality of sides and corners which may be right angles, or may be obtuse or acute angles. Further, a single side may be curved to avoid any angled corners. For ease of discussion the presumed shape described herein will be that of a rectangular tank and specifically a substantially square tank. One skilled in the arts would appreciate that a dug earthen pit could be used instead of above ground retaining walls.
In the preferred method utilized by the inventors, a plurality of blocks or panels are utilized to construct a wall around the perimeter of the desired tank. The blocks comprise a mating system which joins upper and lower blocks, and optionally horizontally adjacent blocks. In one embodiment the joining is accomplished by a tongue like protrusion along the top middle of the blocks which mates with a groove-like indention along the middle of the block's bottom side. In the preferred embodiment, the blocks have a plurality of additional grooves along the bottom side oriented perpendicular to the main groove and allowing for the interlocking of multiple blocks oriented perpendicular to one another to form a structurally reinforced corner of approximately ninety degrees (90°).
In one embodiment the blocks are hollow forms with capped openings in the bottom, or lower edge of one side, and at the top. The blocks are formed such that they have an inner compartment and an outer surface. The outer surface is structured as previously described, and the inner compartment may be filled with a weighted substance after positioning, giving the block, additional weight and inertia to prevent it from moving. The block may be filled with any flowable substance examples of which may include, but not be limited to water, sand, mud, drilling fluids.
The liner is constructed with a dual sheet membrane which is sealed around the edges to create an air pocket which is substantially rectangular in shape and the approximate size of the base of the tank or of one of the interior walls of the tank. The liner has vents which allow the liner to be inflated. One skilled in the arts would appreciate that other shapes are achievable in accordance with the teachings given here. Reinforcing strips throughout the interior space created by joining the edges of the dual membrane keep the liner in a semi-flat state such that the membranes remain in a substantially parallel arrangement rather than expanding out further in some area than in others. One skilled in the arts would appreciate that other configurations would be in accordance with the teaching such as multiple vertical compartments or multiple vertical compartments joined together to form a single larger compartment, either with individual inflation points, or a single shared inflation point.
The inflation of the liner helps to position it by allowing the force of the air to unfurl, unroll, or otherwise spread out the liner without the need of large amounts of man power or heavy equipment. In the preferred embodiment, the liner consist of a bottom compartment, and four side compartments, each of the side compartments being joined on the vertical edges with their neighboring wall compartments, and being joined on the lower horizontal edges with the edges of the bottom compartment to form a box like shape. In the preferred embodiment each of the bottom and the wall compartments has individual single inflation points and each of the compartments may be inflated and deflated separately.
The liner constructed as described above has the advantage that it can be aligned in the center of the tank's base prior to wall construction, or lowered over the wall after wall construction or lowered into an earthen pit. Inflating the bottom compartment causes it to spread over the base and positions the wall compartments, which are attached to the edges of the base, against the walls of the tank. Then by inflating the walls one at a time, the pressure causes them to erect themselves and support one another thus raising the liner to the upper edge of the tank's supporting walls. Once the liner's wall compartments are erected by air pressure it takes minimal man power to secure the top edge of the liner's walls to the tank's supporting walls.
The liner may then be maintained under pressure for a prescribed time to ensure there are no leaks, or to allow for the identification and repair of leaks. Once the integrity of the liner's membrane has been verified, the bottom compartment may be deflated prior to filling of the tank with fluid. The wall compartments may be deflated after securing them to the top of the supporting walls, or may be deflated slowly as the tank is filled with fluid. By deflating as the tank is filled, the air in the wall compartments will be forced up by the fluid's pressure further stretching the walls up the side of the tank.
Turning to the figures,
The diagrams in accordance with exemplary embodiments of the present invention are provided as examples and should not be construed to limit other embodiments within the scope of the invention. Illustrations of the components within different figures can be added to or exchanged with other components in other figures. Further, specific numerical data values (such as specific quantities, numbers, categories, etc.) or other specific information should be interpreted as illustrative for discussing exemplary embodiments. Such specific information is not provided to limit the invention. As an example
The diagrams in accordance with exemplary embodiments of the present invention are intended to illustrate an embodiment if the invention, not necessarily the only embodiment, and are provided as examples which should not be construed to limit other embodiments within the scope of the invention. For instance, heights, widths, and thicknesses may not be to scale and should not be construed to limit the invention to the particular proportions illustrated. Additionally some elements illustrated in the singularity may actually be implemented in a plurality. Further, some element illustrated in the plurality could actually vary in count. Further, some elements illustrated in one form could actually vary in detail. Further yet, specific numerical data values (such as specific quantities, numbers, categories, etc.) or other specific information should be interpreted as illustrative for discussing exemplary embodiments. Such specific information is not provided to limit the invention.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
