Patent Publication Number: US-2018031731-A1

Title: System and method for incorporating ground penetrating radar equipment on seismic source

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 62/082,737 filed on Nov. 21, 2014, entitled “Radar Attached to a Vibrator,” which is incorporated by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to seismic exploration tools and processes and, more particularly, to systems and methods for incorporating ground penetrating radar equipment on seismic source. 
     BACKGROUND 
     In the oil and gas industry, geophysical survey techniques are commonly used to aid in the search for and evaluation of subterranean hydrocarbon or other mineral deposits. Generally, a seismic energy source, or “seismic source,” generates a seismic signal that propagates into the earth and is partially reflected by subsurface seismic interfaces between underground formations having different acoustic impedances. The reflections are recorded by seismic detectors, or “receivers,” located at or near the surface of the earth, in a body of water, or at known depths in boreholes, and the resulting seismic data can be processed to yield information relating to the location and physical properties of the subsurface formations. Seismic data acquisition and processing generates a profile, or image, of the geophysical structure under the earth&#39;s surface. While this profile may not directly show the location for oil and gas reservoirs, those trained in the field can use such profiles to more accurately predict the location of oil and gas, and thus reduce the chance of drilling a non-productive well. 
     In some seismic land data acquisitions, seismic vibrators, sometimes referred to as “vibroseis,” are used to impart the seismic waves into the earth. In land-based implementations, the seismic source signal is generally generated by a servo-controlled hydraulic vibrator, or “shaker unit,” mounted on a mobile base unit. 
     Another technique for performing geophysical surveys is the use of electromagnetic surveying (“EM”) techniques. EM surveying methods measure the response of subsurface formations to the diffusion or the propagation of naturally or artificially generated electromagnetic fields. Frequencies higher than approximately ten MHz are considered to be in the propagation domain. Frequencies lower than approximately 10 MHz are considered to be in the diffusive domain. GPR equipment working in the range of frequencies higher than approximately ten MHz is considered to be in the propagative domain. 
     One technique for performing EM surveys is the use of ground penetrating radar (“GPR”). GPR uses radar pulses to image the very near-surface layers or geophysical structure under the earth&#39;s surface. For example, GPR data can be used to characterize the geometry of sedimentary deposits near the surface of the earth. Near-surface layers may be more severely affected by environmental changes than other layers. For example, factors such as changes in moisture, and shifting particles may change the velocity, amplitude, or other aspects of wave propagation, and certain of these factors may disproportionately affect near-surface layers. Such changes may hinder the ability of seismic images to reflect the underground structures and structural changes. During a GPR acquisition, lower frequencies result in deeper investigations. However, lower frequencies also result in data with lower resolution. Higher frequencies result in shallower investigations, but with higher data resolution. The depth of a GPR investigation is mainly dependent on the water or clay content of investigated ground and the penetration of radar waves depends on the resistivity of the rocks. For example, the radar waves penetrate the subsurface less when the rocks are conductive (such as clay or salty layers). 
     In some GPR acquisitions, a radar transmitter emits electromagnetic energy that propagates into the earth and is partially reflected by subsurface seismic interfaces between underground formations. A radar antenna detects the reflected signals and the reflected signals are recorded by a recorder. The GPR data is used to generate a profile, or image, of the geophysical structure under the earth&#39;s surface. 
     The profile generated using GPR data may be used to characterize the weathered or weathering layer, referred to as the “V0” layer. The weathered layer is a layer of the earth&#39;s subsurface near the surface and is typically a low velocity layer and has a thickness ranging from less than one meter to up to 50 meters or more. Lateral and vertical velocity variations exist in the weathered layer, therefore an accurate characterization of the weathered layer is used to apply static corrections to seismic data to create an accurate image of the earth&#39;s subsurface. 
     SUMMARY 
     In accordance with some embodiments of the present disclosure, a ground penetrating radar system is disclosed. The system includes a transmitter configured to emit electromagnetic signals, an antenna configured to receive reflected electromagnetic signals, a recorder configured to record reflected electromagnetic signals, and at least one piece of mounting equipment configured to couple the antenna to a seismic source platform. 
     In accordance with another embodiment of the present disclosure, a seismic exploration system is disclosed. The system includes a seismic source platform, a seismic source coupled to the seismic source platform and configured to emit a seismic signal, a transmitter coupled to the seismic source platform using at least one piece of mounting equipment and configured to emit electromagnetic signals, an antenna coupled to the seismic source platform using at least one piece of mounting equipment and configured to receive reflected electromagnetic signals, and a recorder coupled to the seismic source platform and configured to record reflected electromagnetic signals. 
     In accordance with a further embodiment of the present disclosure, a method for joint acquisition of seismic and ground penetrating radar data is disclosed. The method includes emitting a seismic signal by a seismic source mounted to a seismic source platform, obtaining a seismic dataset corresponding to the seismic signal emitted by the seismic source, emitting a radar signal by a ground penetrating radar equipment located in proximity to a seismic source line, and obtaining a ground penetrating radar dataset corresponding to the ground penetrating radar signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features and wherein: 
         FIG. 1  illustrates a perspective view of a geophysical exploration system including a seismic source platform and GPR equipment in accordance with some embodiments of the present disclosure; and 
         FIG. 2  illustrates a flow chart of an example method for joint acquisition of seismic and ground penetrating radar data in accordance with some embodiments of the present disclosure; and 
         FIG. 3  illustrates an elevation view of an example seismic exploration system configured to produce images of the earth&#39;s subsurface geological structure in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Ground penetrating radar (“GPR”) systems use one or more GPR transmitters to emit an electromagnetic signal. Portions of the electromagnetic signal are reflected off of media in the earth&#39;s subsurface and are received by a GPR antenna. The signals received by the GPR antenna are recorded by a data recorder and later processed to create an image of the earth&#39;s subsurface. In another embodiment, the signals received by the GPR antenna may be instantaneously visible to an operator of the GPR equipment as an image of the near surface of the earth&#39;s subsurface. The GPR equipment, including the transmitter, antenna, and recorder, may be installed on a seismic source platform, such as a vibrator truck, that includes a seismic source used for seismic exploration. The installation of the GPR equipment on the seismic source platform may increase the efficiency of the geophysical survey and provide GPR data coverage at the same locations as the seismic data coverage. 
       FIG. 1  illustrates a perspective view of a geophysical exploration system including a seismic source platform and GPR equipment in accordance with some embodiments of the present disclosure. Geophysical exploration system  100  includes seismic source platform  102 . Seismic source platform  102  is shown in  FIG. 1  as a vibrator truck, but it can be any other suitable platform that includes a seismic source. Seismic source platform  102  includes vibratory equipment that emits seismic signals. Additionally, seismic source platform  102  may include GPR equipment  104  that emits electromagnetic signals and receives reflected electromagnetic signals. In some embodiments, GPR equipment  104  includes a transmitter and an antenna housed in a single piece of equipment, as shown in  FIG. 1 . In other embodiments, the transmitter and antenna may be separate pieces of equipment installed on seismic source platform  102 . In yet a further embodiment, GPR equipment  104  includes a single radar antenna that both emits electromagnetic signals and receives reflected electromagnetic signals. During a GPR acquisition, GPR equipment  104  may emit electromagnetic signals at lower frequencies to result in a deeper investigation and lower data resolution or at higher frequencies to result in a shallower investigation and higher data resolution. The depth of a GPR investigation may depend on the type of material below surface  112  such as the water or clay content and the resistivity of the material. In some embodiments, GPR equipment  104  may include an internal battery to provide power to the components of GPR equipment  104 . 
     GPR equipment  104  may be installed at any suitable location on seismic source platform  102  including the front of seismic source platform  102  (as shown in  FIG. 1 ), the back of seismic source platform  102 , or either side of seismic source platform  102 . In some embodiments, GPR equipment  104  may be installed on the front of seismic platform  102  such that the operator of seismic platform  102  can monitor the position of GPR equipment  104  when moving seismic platform  102 . GPR equipment  104  may be installed in an orientation such that the antenna in GPR equipment  104  is oriented parallel surface  112 . GPR equipment  104  may be attached to seismic source platform  102  using mounting equipment  122 . Mounting equipment  122  may provide stability to GPR equipment  104  during the GPR acquisition such that vibration experienced by GPR equipment  104  is minimized and provide proper positioning of GPR equipment  104  relative to seismic source platform  102 . For example, mounting equipment  122  may be used to position GPR equipment  104  parallel to surface  112 . Mounting equipment  122  may couple GPR equipment  104  to seismic source platform  102 . For example, mounting equipment  122  may be a rectangular piece of material, such as plastic, composite, fiberglass, Teflon, aluminum or any other suitable material that is light, corrosion resistant and nonmagnetic or any combination thereof, that may be coupled to GPR equipment  104  at one end and coupled to seismic source platform  102  at another end. As another example, mounting equipment  122  may be a flat plate of material attached to seismic source platform  102  and have protrusions extending from the plate to which GPR equipment  104  may be coupled. Mounting equipment  122  may be stiffened with any suitable stiffening support such as support arms, braces, or ribs, to reduce vibrations and movement that is transferred to GPR equipment  104  when seismic source platform  102  is performing a seismic acquisition or while seismic source platform  102  is maneuvering around the seismic survey area. In some embodiments, mounting equipment  122  may couple to GPR equipment  104  and seismic source platform  102  using any suitable fastener such as a screw, a pin, a bolt, a clamp, or any other suitable fastener. In some embodiments, mounting equipment  122  may be coupled to GPR equipment  104  and seismic source platform  102  using an interference fit, an adhesive, or other suitable coupling mechanism. Mounting equipment  122  may be designed to avoid interference with the seismic acquisition and the GPR acquisition such as avoiding metallic or magnetic materials. 
     Mounting equipment  122  may adjust the position of GPR equipment  104  above surface  112  by adjusting the height, orientation, and location of GPR equipment  104  relative to surface  112 . Height  110  at which GPR equipment  104  is located above surface  112  of the earth may be based on the requirements of the GPR acquisition. For example, height  110  may be selected to ensure GPR data quality and avoid perturbations between seismic source platform  102  and GPR equipment  104 . In some embodiments, height  110  may be based on the terrain of the seismic exploration area such that seismic source platform  102  has adequate clearance when traveling from one location to another. In some embodiments, height  110  may be based on the signal strength of GPR equipment  104  such that height  110  may be reduced to increase the signal strength. For example, height  110  may be any distance between approximately zero centimeters to approximately one meter. In some embodiments, mounting hardware  122  may be movable such that height  110  may be adjusted throughout the GPR acquisition. For example, mounting hardware  122  may rotate to lower GPR equipment  104  to be in contact with surface  112  or raise GPR equipment  104  to be a distance above surface  112  of the earth. Height  110  may be recorded for use during data processing. 
     GPR equipment  104  may be communicatively coupled to recorder  108  located on seismic source platform  102  via any suitable method for transmitting data between two devices including wired and wireless protocols. For example, any short range wireless protocol may be used to communicatively couple GPR equipment  104  and recorder  108  including Wi-Fi, near field communication (NFC), Bluetooth, infrared (IR), ultra-wideband (UWB), and ZigBee or any other suitable communication protocol. 
     Recorder  108  may be installed at any location on seismic source platform  102 . For example, recorder  108  may be located in operator cabin  106 . GPR equipment  104  or recorder  108  may be installed such that the distance between GPR equipment  104  and recorder  108  is within an effective distance for the communication protocol used to couple GPR equipment  104  and recorder  108 . 
     Recorder  108  may be communicatively coupled with global positioning system (“GPS”) system  114  via any suitable method for transmitting data between two devices including wired and wireless protocols. For example, any short range wireless protocol may be used to communicatively couple GPS system  114  and recorder  108  including Wi-Fi, NFC, Bluetooth, IR, UWB, and ZigBee or any other suitable communication protocol. GPS system  114  may be installed at any location on seismic source platform  102  where GPS system  114  has a line of sight to GPS satellites. GPS system  114  may be used to record the location of seismic source platform  102  and/or GPR equipment  104  during the geophysical exploration of data from both the seismic acquisition and the GPR acquisition. The height difference between GPS system  114  and GPR equipment  104  may be used during data processing to calculate the elevation of GPR equipment based on the elevation recorded by GPS system  114 . Distance  116  is the distance between height  118 —the distance GPS system  114  is above surface  112 —and height  110 . 
     During seismic and GPR acquisitions, the vibration equipment on seismic source platform  102  may create seismic signals and GPR equipment  104  may be simultaneously emitting electromagnetic signals. The seismic signals emitted by the seismic equipment on seismic source platform  102  and the electromagnetic signals emitted by GPR equipment  104  do not interfere with one another such that the data from both acquisitions is usable. However, in some embodiments, GPR equipment  104  may be shielded to reduce the noise received by the antenna and increase the signal to noise ratio in the GPR data. For example, GPR equipment  104  may include a directional antenna such that the antenna is oriented to receive signals from the direction of surface  112  or GPR equipment  104  may include additional materials, such as insulating foam around the antenna, to reduce the noise received by the antenna. Shielding may allow the antenna to record only reflected waves from below surface  112  and not waves reflected off structures or equipment located above surface  112  (referred to as “air waves”). The orientation of GPR equipment  104  may be adjusted to reduce the noise in the GPR data and may be adjusted based on noise testing. The noise received by the antenna may be caused by interference between the radar equipment, GPS equipment  114 , the seismic acquisition equipment, or seismic source platform  102 . 
     During a seismic acquisition, an operator of seismic source platform  102  may activate recorder  108  at the beginning of the acquisition. Recorder  108  may then activate GPR equipment  104  such that GPR data is continuously recorded during the acquisition. The operator can then perform the seismic acquisition without additional interaction with GPR equipment  104  thus reducing the potential for operator error during the GPR acquisition. In some embodiments, the operator of seismic source platform  102  may turn recorder  108  on and off during the seismic acquisition such that the GPR data is recorded discontinuously. 
     At intervals throughout the seismic acquisition, such as at the end of each day, data from recorder  108  may be downloaded, stored, and used for subsequent processing to create an image of the weathered layer of the earth&#39;s subsurface. In some embodiments, data from recorder  108  may be wirelessly transmitted to a data processing system (not expressly shown) via any suitable wireless protocol such as Wi-Fi, NFC, Bluetooth, IR, UWB, and ZigBee or any other suitable communication protocol. The image can be used for near field static correction of the seismic data and for determining the thickness of the weathered layer. 
       FIG. 2  illustrates a flow chart of an example method  200  for joint acquisition of seismic and ground penetrating radar data in accordance with some embodiments of the present disclosure. The seismic and GPR data may be used to generate images of the earth&#39;s subsurface. The steps of method  200  may be performed by a user, seismic acquisition equipment, GPR acquisition equipment, or any combination thereof. Collectively, the user, the seismic acquisition equipment, and the GPR acquisition equipment may be referred to as “acquisition equipment.” 
     The method  200  may begin at step  202 , where the acquisition equipment may emit a seismic signal. The seismic signal may be emitted by any suitable seismic source, such as a seismic source located on seismic source platform  102  shown in  FIG. 1 . The seismic source may be any suitable vibratory seismic source that provides the ability to control the phase and amplitude of the emitted seismic signal, such as hydraulic, pneumatic, electric, or magnetorestrictive actuators; a piezoelectric source; or an electrodynamic linear motor actuator source. An example of a seismic source may be shown and discussed in further detail in  FIG. 3 . 
     In step  204 , the acquisition equipment may obtain a seismic dataset corresponding to the seismic signal emitted in step  202 . The seismic dataset may be recorded by receivers from reflected or refracted seismic waves emitted by the seismic source in step  202 . The seismic dataset may be processed using any suitable data processing technique. 
     In step  206 , the acquisition equipment may emit a GPR signal. In some embodiments, the GPR signal may be emitted by a GPR antenna mounted on the seismic source platform, such as GPR equipment  104  shown in  FIG. 1 . In other embodiments, the GPR signal may be emitted by a GPR antenna located in proximity to a seismic source line. The GPR signal may be emitted at the same time as the seismic signal emitted in step  202 , may be emitted during the time intervals between individual seismic signal emissions, or both. For example, an operator of the acquisition equipment may turn on the GPR equipment at the beginning of a seismic acquisition and allow the GPR equipment to run continuously throughout the acquisition. 
     The acquisition equipment may adjust the height at which the GPR equipment is located when the GPR equipment emits the GPR signal. For example, the GPR equipment may be lowered closer to the earth&#39;s surface or may be raised based on the parameters of the GPR acquisitions. The acquisition equipment may record the height of the GPR equipment for use during processing of the GPR dataset obtained in step  208 . 
     Optionally, the acquisition equipment may determine a frequency at which to emit the GPR signal. For example, the GPR equipment may emit electromagnetic signals at lower frequencies to result in a deeper investigation and lower data resolution or at higher frequencies to result in a shallower investigation and higher data resolution. The frequency at which the GPR signal is emitted may be based on a survey plan of the acquisition area. The depth of a GPR investigation may depend on the type of material below the earth&#39;s surface such as the water or clay content and the resistivity of the material. 
     In step  208 , the acquisition equipment may obtain a GPR dataset corresponding to the GPR signal emitted in step  206 . The GPR dataset may be recorded by receivers from reflected or refracted GPR waves emitted by the GPR equipment in step  206 . The GPR dataset may be processed using any suitable data processing technique. 
     In step  210 , the acquisition equipment may determine whether the seismic acquisition is complete. If the seismic acquisition is complete, method  200  is complete; otherwise method  200  may return to step  202  to emit the next seismic signal. As stated above, steps  206  and  208  may be performed continuously throughout method  200 . 
     Modifications, additions, or omissions may be made to method  200  without departing from the scope of the present disclosure. The order of the steps may be performed in a different manner than that described and some steps may be performed at the same time. For example, steps  206  and  208  may be performed before, after, or simultaneously with steps  202  and  204 . Additionally, each individual step may include additional steps without departing from the scope of the present disclosure. Further, more steps may be added or steps may be removed without departing from the scope of the disclosure. 
     The seismic source platform with attached GPR equipment described with reference to  FIG. 1  is used to enhance the effectiveness of a system used to emit seismic signals, receive reflected signals, and process the resulting data to image the earth&#39;s subsurface.  FIG. 3  illustrates an elevation view of an example seismic exploration system  300  configured to produce images of the earth&#39;s subsurface geological structure in accordance with some embodiments of the present disclosure. The images produced by system  300  allow for the evaluation of subsurface geology. System  300  may include one or more seismic energy sources  302  and one or more receivers  314  which are located within a pre-determined exploration area. The exploration area may be any defined area selected for seismic survey or exploration. Survey of the exploration area may include the activation of seismic source  302  that radiates an acoustic wave field that expands downwardly through the layers beneath the earth&#39;s surface. The seismic wave field is then partially reflected or refracted from the respective layers as a wave front recorded by receivers  314 . For example, seismic source  302  generates seismic waves and receivers  314  record seismic waves  332  and  334  reflected from interfaces between subsurface layers  324 ,  326 , and  328 , oil and gas reservoirs, such as target reservoir  330 , or other subsurface structures. Subsurface layers  324 ,  326 , and  328  may have various densities, thicknesses, or other characteristics. Target reservoir  330  may be separated from surface  322  by multiple layers  324 ,  326 , and  328 . As the embodiment depicted in  FIG. 2  is exemplary only, there may be more or fewer layers  324 ,  326 , or  328  or target reservoirs  330 . Similarly, there may be more or fewer seismic waves  332  and  334 . Additionally, some seismic source waves will not be reflected, as illustrated by seismic wave  340 . In addition, in some cases other waves (not expressly shown) may be present that may be useful in imaging a formation or for computing seismic attributes such as refracted waves or mode converted waves. 
     Seismic energy source  302  may be referred to as an acoustic source, seismic source, energy source, and source  302 . In some embodiments, seismic source  302  is located on, or proximate to surface  322  of the earth within an exploration area. A particular seismic source  302  may be spaced apart from other similar seismic sources. Seismic source  302  may be operated by a central controller that coordinates the operation of several seismic sources  302 . Further, a positioning system, such as a GPS, may be utilized to locate and time-correlate seismic sources  302  and receivers  314 . Multiple seismic sources  302  may be used to improve data collection efficiency, provide greater azimuthal diversity, improve the signal to noise ratio, and improve spatial sampling. The use of multiple seismic sources  302  can also input a stronger seismic signal into the ground than a single, independent seismic source  302 . Seismic sources  302  may also have different capabilities and the use of multiple seismic sources  302  may allow for some seismic sources  302  to be used at lower frequencies in the spectrum and other seismic sources  302  at higher frequencies in the spectrum. 
     Seismic source  302  may comprise any type of seismic device that generates controlled seismic energy used to perform reflection or refraction seismic surveys, such as seismic vibratory sources such as a seismic vibrator, vibroseis, an air gun, a thumper truck, marine vibrators, magnetic vibrators, piezoelectric vibrators, or any source suitable for emitting a controlled seismic signal. In some embodiments, seismic source  302  may be a piezoelectric source, an encoded pulsed source, or other similar system, designed to generate a monofrequency. For example, seismic source platform  102  shown in  FIG. 1  may include seismic source  302 . 
     Seismic source  302  may radiate varying frequencies or one or more monofrequencies of seismic energy into surface  322  and subsurface formations during a defined interval of time. Seismic source  302  may impart energy through a sweep of multiple frequencies or at a single monofrequency, or through a combination of at least one sweep and at least one monofrequency or through the use of pseudorandom sweeps. In some embodiments, seismic source  302  may be part of an array of seismic sources and may emit a series of frequencies such that no source in the array emits the same signal at the same time. A seismic signal may be discontinuous so that seismic source  302  does not generate particular frequencies between the starting and stopping frequency and receivers  314  do not receive or report data at the particular frequencies. 
     Seismic exploration system  300  may include monitoring equipment  312  that operates to record reflected energy seismic waves  332 ,  334 , and  336 . Monitoring equipment  312  may include one or more receivers  314 , network  316 , recording unit  318 , and processing unit  320 . In some embodiments, monitoring equipment  312  may be located remotely from seismic source  302 . 
     Receiver  314  may be located on, buried beneath, or proximate to surface  322  of the earth within an exploration area. Receiver  314  may be any type of instrument that is operable to transform seismic energy or vibrations into a signal compatible with the data acquisition system, for example a voltage signal, a current signal, or an optical signal. For example, receiver  314  may be a vertical, horizontal, or multicomponent geophone, accelerometers, or optical fiber or distributed acoustic sensor (DAS) with wire or wireless data transmission, such as a three component (3C) geophone, a 3C accelerometer, hydrophone, or a 3C Digital Sensor Unit (DSU). Multiple receivers  314  may be utilized within an exploration area to provide data related to multiple locations and distances from seismic sources  302 . Receivers  314  may be positioned in multiple configurations, such as linear, grid, array, or any other suitable configuration. In some embodiments, receivers  314  may be positioned along one or more strings  338 . Each receiver  314  is typically spaced apart from adjacent receivers  314  in the string  338 . Spacing between receivers  314  in string  338  may be approximately the same preselected distance, or span, or the spacing may vary depending on a particular application, exploration area topology, or any other suitable parameter. 
     One or more receivers  314  transmit raw seismic data from reflected seismic energy via network  316  to recording unit  318 . Recording unit  318  transmits raw seismic data to processing unit  320  via network  316 . Processing unit  320  performs seismic data processing on the raw seismic data to prepare the data for interpretation. Although discussed separately, recording unit  318  and processing unit  320  may be configured as separate units or as a single unit. Recording unit  318  or processing unit  320  may include any equipment or combination of equipment operable to compute, classify, process, transmit, receive, store, display, record, or utilize any form of information, intelligence, or data. Recording unit  318  may collect the GPR data from recorder  108  shown in  FIG. 1  and processing unit  320  may process the GPR data. For example, recording unit  318  and processing unit  320  may include one or more personal computers, storage devices, servers, or any other suitable device and may vary in size, shape, performance, functionality, and price. Recording unit  318  and processing unit  320  may include random access memory (RAM), one or more processing resources, such as a central processing unit (CPU) or hardware or software control logic, or other types of volatile or non-volatile memory. Additional components of recording unit  318  and processing unit  320  may include one or more disk drives, one or more network ports for communicating with external devices, one or more input/output (I/O) devices, such as a keyboard, a mouse, or a video display. Recording unit  318  or processing unit  320  may be located in a station truck or any other suitable enclosure. 
     Network  316  may be configured to communicatively couple one or more components of monitoring equipment  312  with any other component of monitoring equipment  312 . For example, network  316  may communicatively couple receivers  314  with recording unit  318  and processing unit  320 . Further, network  314  may communicatively couple a particular receiver  314  with other receivers  314 . Network  314  may be any type of network that provides communication, such as one or more of a wireless network, a local area network (LAN), or a wide area network (WAN), such as the Internet. For example, network  314  may provide for communication of reflected energy and noise energy from receivers  314  to recording unit  318  and processing unit  320 . 
     The seismic survey conducted using seismic source  302  may be repeated at various time intervals to determine changes in target reservoir  330 . The time intervals may be months or years apart. Data may be collected and organized based on offset distances, such as the distance between a particular seismic source  302  and a particular receiver  314  and the amount of time it takes for seismic waves  332  and  334  from a seismic source  302  to reach a particular receiver  314 . Data collected during a survey by receivers  314  may be reflected in traces that may be gathered, processed, and utilized to generate a model of the subsurface structure or variations of the structure, for example 4D monitoring. 
     Seismic source  302  may additionally include GPR equipment  342  used to generate an image of near surface layer  344 . GPR equipment  342  may emit electromagnetic signals and receive reflected electromagnetic signals. For example, GPR equipment  342  emits an electromagnetic signal  346  and receives reflected signal  348  that is reflected off layers in near surface layer  344 . During a GPR acquisition, GPR equipment  342  may emit electromagnetic signals at lower frequencies to result in a deeper investigation and lower data resolution or at higher frequencies to result in a shallower investigation and higher data resolution. The depth of a GPR investigation may depend on the type of material below surface  322  such as the water or clay content, the resistivity of the material, and the depth of a water table below surface  322 . 
     As the embodiment depicted in  FIG. 2  is exemplary only, there may be more electromagnetic signals  346  and  348 . Reflected signal  348  may be recorded by a recorder (such as recorder  108  shown in  FIG. 1 ) on seismic source  302 . The recorder may collect GPR data. Periodically during a seismic acquisition, the GPR data may be transmitted to processing unit  320  via a wireless network using any suitable wireless protocol such as Wi-Fi, NFC, Bluetooth, IR, UWB, and ZigBee or any other suitable communication protocol. Processing unit  320  performs GPR data processing on the raw GPR data to prepare the data for interpretation and to generate an image of the weathered layer. 
     GPR equipment  342  may be used to simultaneously perform a GPR acquisition during the seismic acquisition or may be used to perform GPR acquisitions during the periods of time between emissions of seismic waves by seismic source  302 , thus increasing the efficiency of the acquisition. For example, once GPR equipment  342  is mounted to seismic source  302 , at the beginning of each day during a seismic acquisition, the operator of seismic source  302  may power-on GPR equipment  342  and record data continuously during the day. At the end of the day, the operator may power-off GPR equipment  342  and download the data or transmit the data to processing unit  320 . 
     This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. For example, a receiver does not have to be turned on but may be configured to receive reflected energy. 
     Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. For example, a computer processor may process the GPR data to generate an image of the weathered layer. 
     Embodiments of the present disclosure may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a tangible computer-readable storage medium or any type of media suitable for storing electronic instructions, and coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     Although the present disclosure has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present disclosure encompass such changes, variations, alterations, transformations, and modifications as fall within the scope of the appended claims. Moreover, while the present disclosure has been described with respect to various embodiments, it is fully expected that the teachings of the present disclosure may be combined in a single embodiment as appropriate. Instead, the scope of the present disclosure is defined by the appended claims.