Not applicable.
This invention relates generally to an apparatus and method for drying sand used in fracking.
Frac sand is a pure quartz sand with durable round grains and is a crush-resistant material used by the petroleum industry. It is used in a hydraulic fracturing process, known as “fracking”, to produce petroleum fluids including natural gas, oil from rock formations which lack adequate pore space for these petroleum fluids to flow to a well. The hydraulic fracturing process generates fractures in the rock by drilling a well into the rock, sealing the well in the petroleum-bearing zone of the well and pumping liquid into the petroleum-bearing zone of the well. The liquid is treated with chemicals and has frac sand mixed therein. Large pumps above ground increase the pressure in the sealed portion of the well until the pressure exceeds the breaking point of the rocks. When the rocks fracture, the liquid containing frac sand enters the fractures. The pressure is then relieved by turning the pumps off. The frac sand inside the rock fractures must be great enough to keep the fractures open. Because the frac sand props the fractures open, it is known as a “proppant” in the industry. Frac sand is a highly pure silica sand ranging in diameter from 0.1 millimeter to over two millimeters.
The demand for frac sand has increased in the past few years because more and more oil and natural gas wells use fracking. A hydraulic fracturing job on one well can require a few thousand tons of sand.
Frac sand requires processing after being mined to optimize its performance. At a processing plant, the frac sand is washed to remove fine particles. After washing, the sand is stacked in piles to allow the water to drain through the pile faster. However, such drainage takes time and often does not dry the frac sand adequately. After being partially dried, the sand is placed in a rotary dryer. Operating a rotary dryer requires a great deal of energy because the frac sand entering the rotary dryer is wetter than desired. Its moisture content would preferably be lower entering the rotary dryer, thereby reducing the time required for the frac sand to be inside the rotary dryer to achieve the desired moisture content.
Therefore, there is a need for a drainage system for drying frac sand in less time than known drainage systems.
There is further a need for a drainage system for drying frac sand which uses gravity and costs less than known systems.
There is further a need for a method of drying frac sand which uses less energy than known drying methods.
According to one aspect of the invention, a drainage system for drying frac sand without heat comprises multiple layers above a waterproof liner. The system may be any desired size, but is typically at least one acre. The bottom waterproof layer keeps ground water from entering the drainage system and fluid used to wash the frac sand from entering the ground water.
The top layer is a perforated layer comprising sheets of high density polyethylene welded together. The layer immediately below the perforated top layer comprises a woven monofilament geotextile fabric layer. The woven monofilament geotextile fabric layer comprises woven monofilament geotextile fabric sheets sewn together. The woven monofilament geotextile fabric sheets have openings therethrough. The next lowest layer comprises a cellular confinement layer below the woven monofilament geotextile fabric layer. The cellular confinement layer comprises sections joined together with keys. Each section comprises panels joined together. When the sections of the cellular confinement layer are expanded, cells between the wave-shaped plastic panels are filled with rocks. Perforated collection pipes reside below the cellular confinement layer for capturing liquid and carrying the captured liquid to a collection pond for reuse. Rocks at least partially surround the collection pipes.
A watertight liner resides below the perforated collection pipes and below the rock containment layer. The drainage system further comprises protective layers above and below the watertight liner to prevent the rocks from damaging the watertight liner.
In a second aspect, a drainage system for drying frac sand without heat comprises a perforated top layer at the top of the drainage system. A woven monofilament geotextile fabric layer is located below the perforated top layer, the woven monofilament geotextile fabric layer comprising woven monofilament geotextile fabric sheets having openings sewn together. A cellular confinement layer is located below the woven monofilament geotextile fabric layer, the cellular confinement layer comprising wave-shaped panels joined together. Cells between the wave-shaped plastic panels are filled with rocks. Perforated collection pipes are located below the cellular confinement layer for capturing liquid and carrying the captured liquid to a collection pond for reuse. Rocks at least partially surround the collection pipes. A watertight liner resides below the perforated collection pipes and below the cellular confinement layer. Protective layers are above and below the watertight liner to prevent the rocks from damaging the watertight liner. The protective layers are preferably made of non-woven geotextile fabric.
In a third aspect, a method of drying frac sand without heat comprises constructing a drainage system, placing sand on top of the drainage system and washing the sand. The drainage system comprises a perforated top layer. A woven monofilament geotextile fabric layer having openings therethrough resides below the perforated top layer. The woven monofilament geotextile fabric layer comprises woven geotextile fabric sheets sewn together. The third layer down comprises a cellular confinement layer below the woven monofilament geotextile fabric layer. The cellular confinement layer comprises wave-shaped plastic panels joined together. The cells between the wave-shaped plastic panels are filled with rocks. Perforated collection pipes are located below the cellular confinement layer for capturing liquid and carrying the captured liquid to a collection pond for reuse. Rocks at least partially surround the collection pipes. The drainage system further comprises a watertight liner below the perforated collection pipes and below the cellular confinement layer. Protective layers above and below the watertight liner prevent the rocks from damaging the watertight liner. The protective layers are each made of non-woven geotextile fabric.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the summary of the invention given above, and the detailed description of the drawings given below, explain the principles of the present invention.
Referring first to
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The drainage system 10 may be any desired size, but is typically between one to three acres in size. Any of the drainage systems described or shown herein is strong enough to support a piece of sand moving equipment 5 weighing thousands of pounds. See
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Each of the high density polyethylene sheets 26 has multiple openings 30 therethrough, meaning each of the high density polyethylene sheets is perforated. Although the openings 30 are illustrated being circular, they may be any desired shape and any desired size. For purposes of this document, the word “perforated” means that fluid may flow through the object being described. Thus, fluid may flow through each high density polyethylene sheet 26 described as perforated. It is preferable that each of the high density polyethylene sheets 26 be perforated. However, it is within the scope of the present invention that not all of the high density polyethylene sheets 26 be perforated.
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The woven monofilament geotextile fabric sheets 32 are preferably made of polypropylene, but may be made of other perforated material. The woven monofilament geotextile fabric sheets 32 are typically fifteen (15) feet wide, but may be any desired width. The woven monofilament geotextile fabric sheets 32 are typically 300 feet in length, but may be any desired length. The process of sewing the woven monofilament geotextile fabric sheets 32 together along prayer seams occurs on site, in other words at the site of the drainage system 10. The woven monofilament geotextile fabric sheets 32 are trucked onto the site in rolls and unrolled at the site of the drainage system 10.
The core layer of the drainage system 10 is a cellular confinement layer 40 located below the woven monofilament geotextile fabric layer 30. As best shown in
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Additional rocks 64 surround each of the perforated collection pipes 56 (only one being shown) below the cellular confinement layer 40. The additional rocks 64 are preferably the same types of rocks as those of the cellular confinement layer 40. However, the additional rocks 64 below the cellular confinement layer 40 may be different than the rocks 50 within the cellular confinement layer 40. Fluid from inside the perforated collection pipes 56 (only one being shown) flows into an exit pipe 66 which flows into a collection pond (not shown) for reuse.
The next layer moving from top to bottom is an upper protective layer 68 comprising upper protective sheets 70 sewn together along sewn lines 71 at the site of the drainage system 10. See
The next layer moving from top to bottom is a liner layer 72 comprising liner sheets 74 welded together along weld lines 75 at the site of the drainage system. The liner sheets 74 are made with high density polyethylene having a thickness of between 40 mils (0.040 inches) and 60 mils (0.060 inches). The liner sheets 74 are not perforated and fluid may not pass through the liner layer 72. The liner sheets 74 are each typically 22.5 feet wide, but may be any desired width. The liner sheets 74, are typically 600 to 900 feet in length, but may be any desired length. The process of heat welding the liner sheets 74 together occurs on site, in other words at the site of the drainage system 10. The liner sheets 74 are trucked onto the site in rolls and unrolled at the site of the drainage system 10. Liner sheets which have proven satisfactory are available from Solmax International Incorporate of Quebec, Canada.
The next layer moving from top to bottom is a lower protective layer 78 comprising lower protective sheets 80 sewn together along sewn lines 76 at the site of the drainage system. Each of the lower protective sheets 80 is preferably made of non-woven geotextile fabric having a weight of eight ounces per square yard available from Hanes Geo Components, a Leggett & Platt company.
The upper and lower protective sheets 70, 80 are each typically fifteen (15) feet wide, but may be any desired width. The upper and lower protective sheets 70, 80 are typically 1500 feet in length, but may be any desired length. The process of sewing the upper and lower protective sheets 70, 80 together occurs on site. In other words, at the site of the drainage system 10. The upper and lower protective sheets 70, 80 are trucked onto the site in rolls and unrolled at the site of the drainage system 10. It is preferable that each of the upper and lower protective sheets 70, 80 be needle punched. However, it is within the scope of the present invention that not all of the upper and lower protective sheets 70, 80 be needle punched.
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Similarly, the liner layer 72 has a peripheral portion 88 which extends parallel the peripheral portion 86 of the upper protective layer 68 inside the anchor trench 14 below the peripheral portion 84 of the upper protective layer 68. Like the peripheral portions of the layers above and below it, the peripheral portion 88 of the liner layer 72 is held in place by the weight of the anchor of dirt 20 after assembly of the drainage system 10.
Similarly, the lower protective layer 78 has a peripheral portion 90 which extends parallel the peripheral portion 88 of the liner layer 72 inside the anchor trench 14 below the peripheral portion 88 of the liner layer 72 and below the anchor of dirt 20 after assembly of the drainage system 10.
Although not shown, it is within the scope of the present invention that two or three support walls be used as part of any of the drainage systems described herein.
The various embodiments of the invention shown and described are merely for illustrative purposes only, as the drawings and the description are not intended to restrict or limit in any way the scope of the claims. Those skilled in the art will appreciate various changes, modifications, and improvements which can be made to the invention without departing from the spirit or scope thereof. The invention in its broader aspects is therefore not limited to the specific details and representative apparatus and methods shown and described. Departures may therefore be made from such details without departing from the spirit or scope of the general inventive concept. For example, the faces of the boards may show different time periods than those illustrated. The invention resides in each individual feature described herein, alone, and in all combinations of any and all of those features. Accordingly, the scope of the invention shall be limited only by the following claims and their equivalents.
This is a divisional application claiming priority to and the benefit of U.S. application Ser. No. 15/850,203, filed Dec. 21, 2017 now U.S. Pat. No. 10,634,4217, and entitled “Drainage System and Method of Drying Frac Sand,” which is hereby incorporated by reference herein.
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Number | Date | Country | |
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20200217586 A1 | Jul 2020 | US |
Number | Date | Country | |
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Parent | 15850203 | Dec 2017 | US |
Child | 16818983 | US |