1. Technical Field
Embodiments of the subject matter disclosed herein generally relate to methods and systems and, more particularly, to mechanisms and techniques for generating seismic waves.
2. Discussion of the Background
During the past years, the interest in developing new oil and gas production fields has dramatically increased. Thus, the industry has now extended drilling to locations that are environmentally sensitive or with limited vehicular access (e.g., riparian areas), which appear to overlay oil and gas reserves. Traditionally, hand drilled explosives or heavy mechanized sources are used for surveying the subsurface. However, in the environmental sensitive areas, the use of explosives is restricted or banned. For those land areas that are difficult to be accessed by vehicles, the challenge of deploying the necessary equipment for producing the seismic waves is high. However, those undertaking the drilling in this area need to know where to drill in order to avoid a dry well.
Seismic data acquisition and processing generate a profile (image) of the geophysical structure of the target area. While this profile does not provide an accurate location for the oil and gas, it suggests, to those trained in the field, areas where there is a likely presence or absence of oil and/or gas. Thus, providing a high resolution image of the structures (subsurface) under the surface of the Earth is an ongoing process.
During a seismic gathering process, as shown in
However, the traditional seismic sources 12 need to be deployed by a vehicle 10 as they weigh too much to be portable. As the environmentally sensitive areas prohibit or strictly limit the access of heavy duty equipment or vehicles, the existing methods for generating seismic waves are not suitable for these areas. Alternatives sources for generating the seismic waves, e.g., explosives, may also be restricted in these areas. Thus, there is a need to develop a new seismic source that overcomes the above noted problems and drawbacks.
According to one exemplary embodiment, there is a portable seismic source for generating seismic waves or energy in the ground. The portable seismic source includes an impact generator device configured to produce impulsive energy; a casing configured to house the impact generator device; a base plate configured to be placed on the ground; and a stabilizing foot mechanism configured to be provided between the casing and the base plate. The stabilizing foot mechanism includes a stabilizer which is fixed relative to the casing and configured to be placed on the base plate and a stanchion that is configured to move relative to the stabilizer when impacted by the impact generator device and to enter through the stabilizer and apply a force on the base plate.
According to another exemplary embodiment, there is a portable seismic source for generating a seismic source underground. The portable seismic source includes a casing; a combustion chamber provided inside the casing; a piston provided inside the combustion chamber to divide the combustion chamber in a first chamber and a second chamber; compression means provided between the piston and a disk of the casing so that the piston is biased towards the first chamber; a base plate configured to be placed on the ground; and a stabilizing foot mechanism configured to be provided between the casing and the base plate. The piston is configured to prevent air from the second chamber moving into the first chamber through the piston and air from the first chamber moving into the second chamber through the piston.
According to still another exemplary embodiment, there is a method for generating a seismic wave. The method includes injecting air and fuel in a combustion chamber; igniting the air and fuel to generate a high pressure in the combustion chamber; and displacing a piston provided inside the combustion chamber to transfer momentum to a base plate via a stanchion for generating the seismic wave. The piston divides the combustion chamber in first and second chambers and the piston is configured to prevent air from the second chamber moving into the first chamber through the piston and air from the first chamber moving into the second chamber through the piston.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:
The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of a portable propane powered seismic source. However, the embodiments to be discussed next are not limited to this structure, but may be applied to other structures that need to apply a force to the ground to provide a seismic source and also be portable.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
According to an exemplary embodiment there is a seismic source that is portable and does not require a vehicle to be carried to a desired destination. In addition, the novel seismic source does not use explosives. Thus, this novel seismic source complies with strict environmental requirements and can be transported by one or more persons to the desired location. In one application, the seismic source is a hammer that is activated by a fuel source, e.g., propane.
According to an exemplary embodiment shown in
Before discussing the details of the combustion chamber and other various elements of the seismic source 40, it is noted in another exemplary embodiment shown in
For preserving the portability of the entire seismic source 40, the platform 60 may be easily removed from the casing 42 and may be carried by another person than the person that carries the remainder of the seismic source 40. For illustrative purposes, a weight of the seismic source 40 is between 50-100 lbs and a weight of the platform 60 is in the range of 5-15 lbs. Thus, as the seismic source 40 may be transported by one person, and the platform 60 may be carried by another person, the novel seismic source 40 is totally portable, does not necessarily require a motorized vehicle for transportation and also does not need explosives to function. The platform 60 is foldable, i.e., may be folded from the position shown in
A cut-through view of the seismic source 40 is shown in
The casing 42 may be provided with a handle 70 for providing a point of stability to the operator that is on the platform 60 and operates the seismic source 40. Inside the casing 42 there is the combustion chamber 72 in which a piston 74 is provided. Piston 74 divides the combustion chamber 72 into a first chamber 72a and a second chamber 72b. Fuel is handled by the gas delivery system 52 (shown in
The control module may also be configured to store (e.g., memory 94) information about one or more impacts. This information may be measured, for example, by one or more sensors (see 150 in
In one application, both the nozzles 86 and the valve 90 are provided at the head 42a of the casing 42. Plural holes 98 are formed through the combustion chamber 72, in the second chamber 72a so that the exhaust from the burning process is released outside the combustion chamber. The ignition control module 54 is shown being connected to one or more spark plugs 100 that are in direct contact with an atmosphere inside first chamber 72a. The ignition control module 54 is also electrically linked to the processor 82. Thus, the processor 82 is able to control and coordinate the fuel supply, air intake, and the ignition of the mixture of air and fuel.
Returning to
The stabilizing foot mechanism 44 is interposed between disk 114 and base plate 46 as discussed next. As shown in
The stabilizing foot mechanism 44 includes the top cap 130 that is configured to interact with piston 74 as noted above. The top cap 130 may be made of stainless steel. The top cap 130 continues with a stanchion 132 that may be made of aluminum. In one application, the top cap 130 is fixedly attached to the stanchion 132. The stanchion 132 together with top cap 130 may freely move through the ring 114. The stanchion 132 is configured to enter a stabilizer 134 that may be made of aluminum. The stabilizer 134 is configured to be optionally attached to the casing 42. For example, screws may be inserted through the tail end of the casing 42 into holes 136 formed in a neck portion 138 of the stabilizer 134. Alternately, the weight of the operator standing on platform 60 can be employed to hold the casing 42 in contact with the stabilized 134. The stanchion 132 is configured to slide along direction Y relative to the stabilizer 134.
For reducing a frictional force between the stanchion 132 and the neck portion 138 of the stabilizer 134, a sleeve 140 may be provided inside the neck portion 138. The sleeve 140 may be made of Ultra-high-molecular-weight polyethylene (UHMW). The stanchion 132 is welded or attached by other means to the base plate 46. For maintaining the base plate 46 next to the flexible material 120, a skirt 146, as shown in
An operation of the portable seismic source 40 is now discussed with reference to
The stanchion 132, by moving downward under the momentum from the top cap 130, forces the base plate 46 to be driven downwards on the ground and so produces a seismic wave in step 806. The exhaust produced by the burnt fuel is primarily evacuated from the combustion chamber through holes 98 in step 808. The exhaust is also evacuated when the piston 74 moves upwards, in the negative direction of the axis Y. This secondary evacuation takes place through the valve 90 and is coordinated by processor 82. Air is inserted into the chamber 72a through the valve 90 which acts as a dual purpose air/exhaust port. The intake of air may be naturally aspirated or a mechanism for achieving forced air to assist in the evacuation of exhaust from the chamber above 42a may be used. This mechanism may include the use of compressed air or a fan. The secondary evacuation is enhanced by the piston 74 moving upward under the bias provided by the compressible means 110. In this regard, it is noted that the compressible means 110 were compressed when piston 74 moved downwards. In step 810, the process is repeated for as long as the operator desires, or as programmed into the control circuit.
The following features of the seismic source are noted. The piston 74 does not have an internal valve and there is no mechanical means inside the first chamber 72a that is activated by piston 74 for allowing the air and/or fuel to enter the first chamber 72a. The platform 60 attaches to the casing 42 and not to the base plate 46. There is a regulator 78 that maintains the pressure of the fuel at a predetermined level when the pressure in the power source 50 decreases. The seismic source 40 may be considered to act as a hammer, i.e., the piston 74 moves downwards to hit top cap 130 similar to a hammer hitting the head of a nail. This hammer action may be controlled by the operator to be continuous or in series, i.e., with a controlled time interval between two hammer actions. This interval is programmed into the control circuit.
One or more of the exemplary embodiments discussed above advantageously provides a seismic source that exhibits a cycle time for 100 hits per 60 s, or maximizes an energy transfer between the piston, base plate and the ground, or improves a bandwidth of the signal to be about 75% of a typical hand drilled dynamite slot, or maintains a low weight so that the whole assembly may be carried by one or two persons, or eliminates secondary events. According to an exemplary embodiment a weight of the whole assembly may be around 50 kg and an average cycle time may be about 600-1000 ms.
A cross-section view of a fully assembled portable seismic source 200 is illustrated in
The disclosed exemplary embodiments provide a portable system and a method for generating a seismic source that propagates underground. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
The present application is related to and claims the benefit of priority of U.S. Provisional Application 61/431,963, having the title “Portable Device and Method to Generate Seismic Waves,” and being authored by J. Jurok et al., the entire content of which is incorporated herein by reference.
Number | Date | Country | |
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61431963 | Jan 2011 | US |