Patent Application
20180202277
This application relates generally to systems and processes for well stimulation, and in particular for stimulating subsurface hydrocarbon reservoirs by the introduction or injection of liquid and/or gel monopropellants.
The oil industry has increasingly relied upon enhanced oil recovery methods, including well stimulation methods, for accessing and extracting oil. Stimulation methods typically include injecting a treatment fluid (e.g., water) down a well to create a hydraulic fracture in a subsurface structure. In some applications, in situ combustion is sometimes used. For instance, solid propellant charges have been used for many years to create sufficient pressure via the treatment fluid for fractures in oil, gas, and water formations surrounding wells.
It is desired to have increased control of propellant charges for creating adequate pressures for extending fractures into the surrounding formations. It is further desired to use less treatment fluid to create such factures.
According to one aspect and example, an apparatus for fracturing wells is provided. In one example, an apparatus includes an electric liquid monopropellant device including a volume of electric liquid monopropellant, and a detonation cord in proximity to the electric liquid monopropellant device to ignite the volume of electric liquid monopropellant. The detonation cord is adapted to ignite the electric liquid monopropellant at pressures exceeding 200 psi, and in some examples, exceeding 500 or 1,000 psi. The detonation cord can be wrapped around the electric liquid monopropellant device in a variety of configurations to increase combustion rates and/or shape the event pulse of the combustion. Further, the liquid monopropellant devices are adapted to combust at temperatures less than 300 degrees Celsius.
In some examples, a plurality of electric liquid monopropellant devices can be disposed within a well tool, and the plurality of electric liquid monopropellant devices in proximity to the detonation cord. Further, at least one shaped charge device may be disposed within the well tool and in proximity to the detonation cord to combust upon activation of the detonation cord.
In some examples, electrically conductive wires are disposed in contact with the electric liquid monopropellant for sensitizing the electric liquid monopropellant prior to combustion.
In another aspect, an apparatus includes a container including an electric liquid monopropellant therein. The container may include a bag, tube, or other package for containing the electric liquid monopropellant. The apparatus can further include a detonation cord, an electrode, and/or an electric match to initiate combustion.
In another aspect, an exemplary process is provided for fracturing wells. In one example, a process includes introducing an electric liquid monopropellant into a well and igniting the electric liquid monopropellant in the well. In some examples, the liquid monopropellant is ignited when the pressure exceeds 200 psi, and in some examples when the pressure exceeds 500 or 1000 psi. The electric liquid monopropellant can be introduced via a well gun.
The present application can be best understood by reference to the following description taken in conjunction with the accompanying figures, in which like parts may be referred to by like numerals.
The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments. Descriptions of specific devices, techniques, and applications are provided only as examples. Various modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the present technology. Thus, the disclosed technology is not intended to be limited to the examples described herein and shown, but is to be accorded the scope consistent with the claims.
In one example of the present invention, an electric liquid monopropellant is used. The electric liquid monopropellant may be contained in a device or package (e.g., a container, bag, receptacle, etc.) and in close proximity to a detonation or ignition cord. For instance, a detonation cord can be at least partially wrapped around the electric liquid monopropellant device such that upon ignition of the detonation cord, the electric liquid monopropellant within the device or package detonates. In some examples, one or more electric liquid monopropellant devices can be disposed with one or more conventional shaped charge devices and proximate (e.g., wrapped) to a common detonation cord. In such examples, the shaped charge devices detonate at a faster rate than the electric liquid monopropellant, thereby providing a perforation of a well tool, well bore, and/or surrounding structure, prior to detonation of the electric liquid monopropellant.
In other examples, electric liquid monopropellant can be introduced or pumped into well structures directly, e.g., via a well or gun tool, without a device or package containing the liquid. This allows the electric liquid monopropellant to flow into cracks and other structures of the well. In some examples, the well bore can then be capped or otherwise pressurized and the electric liquid monopropellant detonated, thereby creating new fractures and/or extending existing fractures.
Additionally,
Further, a detonation cord 112 is shown running adjacent to and/or through SC 102 and ELP devices 100. Upon ignition of detonation cord 112 the SC 102 and ELP devices 100 combust. Typically, SC 102 detonate more quickly than the ELP devices 100, perforating the casing of the well gun and/or structures within the well, which is followed by combustion of the ELP devices 100.
ELP devices 100 may include an electric liquid monopropellant, such as green electric monopropellant, e.g., a HAN based liquid monopropellant that can be electrically ignited. One such liquid monopropellant is sold under the product name “GEM Mod 3 Green Electrical Monopropellant,” and sold by Digital Solid State Propulsion Inc., which generally comprises Hydroxylammonium Nitrate/2,2′-dipyridyl/Ammonium Nitrate/Water/1,2,4-triazole/1H-pyrazole (see also, e.g., https://www.dsspropulsion.com/propellant-products/). Similar electric liquid monopropellants are described in U.S. Pat. No. 9,328,034, entitled “Liquid Electrically Initiated and Controlled Gas Generator Composition,” granted on May 3, 2016, the contents of which are incorporated herein by reference in its entirety. In some examples, the electric liquid monopropellant may also be in a gel form.
Such exemplary electric liquid monopropellants can further be gelled for use in such devices described herein. For example, gelling materials may include fumed silica, polyvinyl alcohol, and the like. Progressively thicker gels will cause the propellant to burn more slowly. Exemplary liquid propellants can also be foamed using such gelling agent described above and Nitrogen gas. For example, rapid mixing, high speed blending or other methods can be used to entrain and suspend small nitrogen bubbles in the propellant gel. The propellant can also be made to burn faster by adding silica micro-balloons. These bubbles or balloons will cause the propellant to burn faster in the tool because of the additional surface area created.
Such exemplary electric liquid monopropellants at normal surface temperatures and pressures typically require electrical power to ignite, however, at pressures typically found within wells, e.g., greater than 200 psi, and often greater than 500 or 1000 psi, the electric liquid monopropellant is ignitable via conventional detonation cords. Accordingly, in one example, electric liquid monopropellant can be packaged as discrete devices, e.g., ELP devices 100, and ignited via detonation cords within a well. ELP devices 100 can include plastic containers, bags, tubes, cylinders, hoses, and the like to package and contain electric liquid monopropellant as discrete propellant charges.
Further, in some examples, a down hole power source may be used for igniting propellant. In one example, one or more capacitors can be used and slowly charged over time and rapidly discharged to ignite the propellant.
Further, in some examples, low density ceramic proppants can be suspended within the electric liquid propellant and transported/dispersed into the newly formed rock fractures during the combustion event. Further, ignition of the electric liquid monopropellant can be initiated via a submerged container of catalyst that is thermally or mechanically breached to release the catalyst.
The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the techniques and their practical applications. Others skilled in the art are thereby enabled to best utilize the techniques and various embodiments with various modifications as are suited to the particular use contemplated.
Although the disclosure and examples have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosure and examples as defined by the claims.
This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/447,294, titled “USE OF LIQUID AND GEL MONOPROPELLANTS FOR WELL STIMULATION,” filed Jan. 17, 2017. The contents of which are incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62447294 | Jan 2017 | US |
