Multi-station seismic sensor strings

Methods, apparatuses, and systems are disclosed for multi-station sensor strings. One example apparatus includes a sensor string. The sensor string includes a connector and a common data transmission channel configured to be in communication with a data acquisition unit through the connector. The sensor string also includes a first seismic sensor configured to provide sensed seismic data to the common data transmission channel, and a second seismic sensor also configured to provide sensed seismic data to the common data transmission channel.

TECHNICAL FIELD

The present invention relates generally to seismic exploration, and more specifically to multi-station seismic sensor strings.

BACKGROUND

Seismic surveys are conducted by deploying a large array of seismic sensors over a target area. Typically, these arrays may cover many square miles and may include thousands or tens of thousands of seismic sensors. An energy source is activated thereby causing a seismic wave to propagate through the subsurface structures of the earth. A portion of the seismic wave is reflected at discontinuities, and these reflections are sensed at the surface by the seismic sensors and recorded for later processing. Such sensing and recording are referred to as seismic data acquisition. In some instances, seismic data may be acquired passively—that is, without an active source.

Many different seismic data acquisition architectures exist. In one example, a point-to-point cable connection is used to connect each seismic sensor to a data acquisition unit. The data acquisition unit relays the signals from the sensors to a central recording location via either a wired or wireless connection. The data acquisition units and various cables connecting the sensors, data acquisition units, and the central recording location may be collectively referred to as ground electronics, and constitute a substantial portion of the overall cost and energy draw of a seismic data acquisition system.

In some instances, multiple sensors may be connected to a single data acquisition unit in order to reduce the ground electronics cost per seismic sensor. For example, a plurality of seismic sensors may be coupled to a plurality of receiver line takeout connections on a receiver line, or a plurality of seismic sensors may be integrally formed within a “link” style receiver line. Single seismic sensors coupled to takeout connections typically have a large amount of ground electronics equipment per sensor. “Link” style systems, on the other hand, may have lower ground electronics equipment per sensor but can be prone to complicated field debugging issues and increased labor demands. “Link” style systems are also heavy and may require connectivity on both sides of the link to operate. “Link” style segments are also inherently noisy—external forces (for example wind) may induce vibration or other forms of mechanical energy into the receiver line which is directly coupled into the sensors.

In both single-seismic-sensor-per-takeout systems and “link” style systems, the ground electronics equipment can account for upwards of seventy-five percent of total system cost. In addition to initial capital expenditure costs, ground electronics equipment typically requires ongoing power and labor resource during the seismic survey, which also adds to the costs of seismic data acquisition.

SUMMARY

An apparatus, e.g., for seismic data collection, comprises a set of sensor elements or sensor string. Depending on the embodiment, the sensor string may have a connector, a common data transmission channel configured to be in communication with a data acquisition unit through the connector, and first and second seismic sensors. The first seismic sensor can be configured to provide sensed seismic data to the common data transmission channel. The second seismic sensor can also be configured to provide sensed seismic data to the common data transmission channel.

In various embodiments, the sensor string may define a first housing enclosing the first seismic sensor and a second housing enclosing the second seismic sensor, and each of the first and second housings may comprise an upper portion and a lower portion. The common data transmission channel may be positioned in the upper portions of the first and second housings, and the first seismic sensor can be positioned in the lower portion of the first housing, with the second seismic sensor positioned in the lower portion of the second housing, and the respective electrical couplings provided between the respective first and second seismic sensors and the common data transmission channel. The upper portions of the first and second housings can be formed together, with a cable defining the common data transmission channel.

The apparatus may include a third seismic sensor, also configured to provide sensed seismic data to the common data transmission channel. The first, second, and third seismic sensors can be serially positioned relative to one another, thereby forming a linear structure for the sensor string.

Depending on the embodiment, the first seismic sensor may provide sensed seismic data to the common data transmission channel during a first time slot and the second seismic sensor may provide sensed seismic data to the common data transmission channel during a second time slot, where the first and second time slots may not overlap. The first seismic sensor and the second seismic sensor may also provide seismic data to the common data transmission channel using multiplexing, for example one or more of time-division multiplexing, frequency-division multiplexing, or wavelength-division multiplexing.

In some embodiments, the connector of the sensor string can be configured to be coupled to one of a plurality of takeout connections of a receiver line connected to a cabled data acquisition unit. The connector of the sensor string can also be configured to be coupled to a wireless data acquisition unit.

The common data transmission channel can comprise a twisted pair, for example a twisted pair that is also configured to provide power to any one or more of the first, second and third seismic sensors. The common data transmission channel can also be a continuous transmission medium, and each or any one or more of the first, second and third seismic sensors may be electrically coupled to the continuous transmission medium. The common data transmission channel may also comprise a plurality of segments. For example, a first of the plurality of segments of the common data transmission channel may be positioned between the connector and the first seismic sensor, and a second of the plurality of segments of the common data transmission channel may be positioned between the first seismic sensor and the second seismic sensor.

Any one or more of the first, second and third seismic sensors may comprise a receiver and a transmitter, and can be configured to provide its own sensed seismic data to the data acquisition unit via the transmitter, and/or further configured to receive sensed seismic data from the second seismic sensor via the receiver and provide the sensed seismic data received from the second seismic sensor to the data acquisition unit via the transmitter. Any one of the first, second and this seismic sensors may comprise a first, second or third termination board, respectively, and any one or more of the first, second and third segments of the common data transmission channel may be coupled between the connector or connectors and the first, second, and third termination boards, respectively. In some examples, any one or more of the first, second and third termination boards may be encoded with a first, second and third binary code, respectively. In still other examples, the first binary code identifies or auto identifies the first seismic sensor and the second binary code identifies or auto identifies the second seismic sensor position on the common data transmission channel.

In seismic data acquisition system embodiments, the system may comprise a data acquisition unit configured to transmit data to a central recording unit, a receiver line coupled to the data acquisition unit and defining a takeout connection, and a sensor string (e.g., a set of a plurality of seismic sensors or sensor nodes). Depending upon the example, the sensor string may comprise a connector coupled to the takeout connection, a common data transmission channel communicatively coupled to the data acquisition unit through the connector, and a plurality of seismic sensors, each of the plurality of seismic sensors configured to provide sensed seismic data to the common data transmission channel.

In some embodiments, the plurality of seismic sensors may be or comprise digital sensors. The sensor string may further comprise at least one terminator configured to reduce reflections, and the plurality of seismic sensors can be configured to be disposed at different ground locations away from the receiver line. For example, the sensor string may generally define a T-shaped structure.

Each of the plurality of seismic sensors may comprise a housing that is unique in color. Alternatively, any one or more of the plurality of seismic sensors may comprise a housing that is unique in color.

In some embodiments, the sensor string generally defines an in-line shaped or linear structure. In embodiments where a T-shaped sensor string is used, each of the plurality of seismic sensors can be arranged or laid out in the field in either of at least two in-line directions from the data acquisition unit or in either of two linear segments of the T-shaped structure, wherein each of the linear segments is arranged in a different direction from the data acquisition unit. In some embodiments, the first seismic sensor is configured to provide sensed seismic data to the common data transmission channel preceded by a first position data header, and the second seismic sensor is configured to provide sensed seismic data to the common data transmission channel preceded by a second position data header. The first seismic sensor may also be configured to provide sensed seismic data to the common data transmission channel in a first time slot, and the second seismic sensor is configured to provide sensed seismic data to the common data transmission channel in a second time slot. The first seismic sensor may also be configured with a first positional encoding, and the second seismic sensor is configured with a second positional encoding.

Additional seismic data acquisition systems may comprise a wireless data acquisition unit and a sensor string. The sensor string may comprise, for example, a connector coupled to the wireless data acquisition unit, a common data transmission channel communicatively coupled to the wireless data acquisition unit through the connector, a first seismic sensor can be configured to provide sensed seismic data to the common data transmission channel, and a second seismic sensor can also be configured to provide sensed seismic data to the common data transmission channel.

In such embodiments, the first seismic sensor can be configured to provide sensed seismic data to the common data transmission channel preceded by a first position data header, and the second seismic sensor can be configured to provide sensed seismic data to the common data transmission channel preceded by a second position data header. A third seismic sensor can also be provided, and configured to provide sensed seismic data to the common data transmission channel preceded by a third position data header

Depending on the application, the first seismic sensor can be configured to provide sensed seismic data to the common data transmission channel in a first time slot, and the second seismic sensor is configured to provide sensed seismic data to the common data transmission channel in a second time slot. Alternatively, each of the first, second, third and/or ensuing seismic sensors can be configured to provide sensed seismic data to the common data transmission channel in corresponding first, second, third and/or ensuing time slots.

The first seismic sensor can be configured with a first positional encoding, and the second seismic sensor can be configured with a second positional encoding. Alternatively, each of the first, second, third and/or ensuing seismic sensors can be configured with positional encoding.

In method embodiments, the method may comprise acquiring a first seismic data sample using a first seismic sensor of a sensor string, acquiring a second seismic data sample using a second seismic sensor of the sensor string at substantially the same time as acquiring the first seismic data sample using the first seismic sensor, and transmitting the first and second seismic data samples to a data acquisition unit via a common data transmission channel of the sensor string. The first seismic data sample can be transmitted via the common data transmission channel using a first portion of available data communication resources of the common data transmission channel, and the second seismic data sample can be transmitted via the common data transmission channel using a second non-overlapping portion of available data communication resources of the common data transmission channel.

The first seismic data sample can also transmitted via the common data transmission channel during a first transmission period, and the second seismic data sample can be transmitted via the common data transmission channel during a second transmission period that does not overlap with the first transmission period. Alternatively, each of the seismic data samples from first, second, third and/or ensuing seismic sensors of the sensor string may be transmitted via the common data transmission channel during respective transmission periods that do not overlap.

Alternatively or in combination, the first seismic data sample can transmitted via the common data transmission channel at a first frequency, and the second seismic data sample can be transmitted via the common data transmission channel at a second frequency. For example, each of first, second, third and/or ensuing seismic data samples from corresponding seismic sensors of the sensor string may be transmitted respective frequencies. The respective frequencies may be different for one or more of the seismic sensors, or for each of the seismic sensors; for example, the frequencies may be unique to each of the seismic data samples, and/or to each of the seismic sensors in the sensor string.

Depending on the application, a sample rate of acquiring seismic data using the first and second seismic sensors may be less than a transmission rate of transmitting the first and second seismic data samples via the common data transmission channel. In addition, relative locations of the first, second, third and/or ensuing seismic sensors may be determined based on physical dimensions of the sensor string and a connection point of the sensor string. Additionally, the first and second seismic data samples may be transmitted via the common data transmission channel by at least transmitting the first seismic data sample from a first transmission channel segment associated with the first seismic sensor to a second transmission channel segment associated with the second seismic sensor, and transmitting the first and second data samples together from the second transmission channel segment towards the data acquisition unit.

DETAILED DESCRIPTION

FIG. 1Aillustrates one example of a sensor string100A. The sensor string100A includes a connector102and a common data transmission channel104that is configured to be in communication with a data acquisition unit through the connector102. The sensor string100A also includes a first seismic sensor106configured to provide sensed seismic data to the common data transmission channel104, and a second seismic sensor108also configured to provide sensed seismic data to the common data transmission channel104. Although two seismic sensors106,108are shown in the sensor string100A ofFIG. 1A, it will be appreciated that a sensor string may include any number of a seismic sensors, a few examples of which are shown inFIGS. 1B and 1Cand described below.

Returning toFIG. 1A, the seismic sensors106,108may be any type of sensor capable of sensing seismic data, including for example a digital microelectromechanical (or MEMS) acceleration or digital velocity sensor. The first seismic sensor106may be enclosed within a first housing137defined by the string100A, and the second seismic sensor108may be enclosed within a second housing140also defined by the string100A. The first housing137may include an upper portion138and a lower portion139, with the common data transmission channel104positioned in the upper portion138of the first housing137and the first seismic sensor106positioned in the lower portion139of the first housing137. Similarly, the second housing140may include an upper portion141and a lower portion142, with the common data transmission channel104positioned in the upper portion141of the second housing140and the second seismic sensor108positioned in the lower portion142of the second housing140. As will be shown and described below, respective electrical couplings may be provided between the first and second seismic sensors106,108and the common data transmission channel104. Also, in some examples, the upper portions138,141of the first and second housings137,140may be formed together with a cable149defining the common data transmission channel104.

In some embodiments, and as illustrated inFIG. 1A, spikes110may be coupled to respective lower portions139,142of the first and second housings137,140for the first and second seismic sensors106,108in order to improve coupling of the housings137,140with the ground. The spikes110may be removable and replaceable to facilitate replacement of spikes110and/or storage/transportation of the sensor string100A.

As mentioned above, the sensor string100A illustrated inFIG. 1Aincludes a common data transmission channel104to which the first and second seismic sensors106,108are electrically coupled. The common data transmission channel104may be a continuous transmission medium such as a twisted pair, a fiber optic cable, etc., or generally any single, continuous medium over which data and/or power can be transmitted to and/or from multiple ones (i.e., both) of the seismic sensors106,108. In embodiments where the common data transmission channel104is a single, continuous transmission medium, the first and second seismic sensors106,108may be electrically coupled directly to the continuous medium—e.g., one or more wired connections may be established between the first and second seismic sensors and the common data transmission channel104, as explained for example below with reference toFIGS. 2A and 2B. Also, although the common data transmission channel104may be a single, continuous transmission medium, with the first and second seismic sensors106,108coupled thereto, the sensor string100A may nonetheless define a plurality of portions. For example, as illustrated inFIG. 1A, the sensor string100A may define first and second portions116,118. The first portion116of the sensor string100A may include a length of the common data transmission channel104between the connector102and the connection of the first seismic sensor106, while the second portion118of the sensor string100A may include a length of the common data transmission channel104between the connection of the first seismic sensor106and the connection of the second seismic sensor108.

In some embodiments, the common data transmission channel104may be formed from a plurality of separate and individual segments. The separate and individual segments may in some examples correspond with the one or more portions116,118of the sensor string100A described above. For example, referring toFIG. 1A, a segmented common data transmission channel104may include a first segment positioned between the connector102and the first seismic sensor106, and corresponding with the first portion116of the sensor string100A. The segmented data transmission channel104may also include a second, separate segment positioned between the first seismic sensor106and the second seismic sensor108, the second, separate segment corresponding with the second portion118of the sensor string100A. The first and second segments in these embodiments may form distinct transmission mediums which, when coupled together, form the common data transmission channel104. As with the single, continuous transmission medium described above, a common data transmission channel104including a plurality of segments forms a medium over which data and/or power can be transmitted to and/or from both of the first and second seismic sensors106,108. In embodiments where the common data transmission channel104comprises a plurality of segments, each of the first and second seismic sensors106,108may provide a link between the segments (e.g., a termination board that connects the segments) of the common data transmission channel104, as described below.

The first and second seismic sensors106,108may provide seismic data to the common data transmission channel104using multiplexing in some embodiments. The multiplexing may be any type of multiplexing protocol, including, but not limited to, time-division multiplexing, frequency-division multiplexing, and/or wavelength-division multiplexing. In one example, the first seismic sensor106may provide a first seismic data sample to the common data transmission channel104during a first time slot, and the second seismic sensor108may provide a second seismic data sample to the common data transmission channel104during a second time slot. The first time slot and the second time slot may be independent and non-overlapping. In another example, a first seismic data sample may be transmitted via the common data transmission channel104at a first frequency, and a second seismic data sample may be transmitted via the common data transmission channel104at a second frequency. More generally, the first seismic data sample may be provided to and transmitted via the common data transmission channel104using a first portion of available data communication resources of the common data transmission channel104, and the second seismic data sample may be provided to and transmitted via the common data transmission channel104using a second, non-overlapping portion of available data communication resources of the common data transmission channel104. Available data communication resources of the common data transmission channel104include, but are not limited to, time, frequency, and wavelength available on the common data transmission channel104.

Referring still toFIG. 1A, the seismic sensors106,108of the sensor string100A may be configured to be disposed at different ground locations when the sensor string100A is deployed. In some embodiments, the seismic sensors106,108may be disposed away from, for example, a receiver line, a data acquisition unit, etc. For example, the connector102of the sensor string100A may be attached to a takeout connection of a receiver line, or directly to a data acquisition unit, and the slack provided by the first portion116of the sensor string100A may be used to position the first seismic sensor106at some distance away from the receiver line or data acquisition unit. Similarly, the slack provided by the second portion118of the sensor string100A may be used to position the second seismic sensor108at some distance away from both the first seismic sensor106and the receiver line or data acquisition unit. In some embodiments, the first seismic sensor106and the second seismic sensor108may be positioned serially relative to each other (as shown inFIG. 1A, for example), thereby forming a linear structure that runs parallel to, for example, a receiver line (see, e.g.,FIG. 7). In this manner, the seismic sensors106,108may run along the receiver line, but may be mechanically decoupled from the receiver line in order to reduce transmission of mechanical noise on the receiver line to the seismic sensors106,108.

Once positioned, the relative locations of the seismic sensors106,108may be determined based on the physical dimensions of the sensor string100A (i.e., the lengths of the first and second portions116,118) and the connection point of the sensor string100A itself. In other words, if it is known that a certain sensor string100A is connected to, for example, a receiver line at a certain absolute position, and it is known that the first and second seismic sensors106,108are positioned in a certain manner relative to the connector102, then the absolute locations of the first and second seismic sensors106,108can be determined. Of course, the locations of the seismic sensors106,108may also be determined using other techniques, such as GPS.

With reference now toFIG. 1B, another example of a sensor string100B is shown. The sensor string100B is generally similar to the sensor string100A shown inFIG. 1A, except that the sensor string100B inFIG. 1Bincludes a third seismic sensor112that is also configured to provide sensed seismic data to the common data transmission channel104. Also, the sensor string100B inFIG. 1Bmay define a third portion120between the first seismic sensor106and the third seismic sensor112, while the second portion118is defined between the third seismic sensor112and the second seismic sensor108.

With reference toFIG. 1C, yet another example of a sensor string100C is shown. The sensor string100C is generally similar to the sensor string100A shown inFIG. 1Aand the sensor string100B shown inFIG. 1B, except that the sensor string100C inFIG. 1Cincludes a fourth seismic sensor114that is also configured to provide sensed seismic data to the common data transmission channel104. Also, the sensor string100B inFIG. 1Bmay define a fourth portion122between the third seismic sensor112and the fourth seismic sensor114. It will be appreciated fromFIGS. 1A through 1Cthat, in general, a sensor string may include any number of seismic sensors, such as 2, 3, 4, 5, 6, 7, 8, or even more.

With reference now toFIGS. 2A and 2B, two examples of the electrical connections of sensor strings200A,200B with a continuous common data transmission channel204will be described. For illustration purposes, the sensor strings200A,200B shown inFIGS. 2A and 2Band described herein include three seismic sensors206,212,208, similar to the sensor string100B illustrated inFIG. 1Band described above. As shown inFIG. 2A, in some embodiments, the common data transmission channel204of a sensor string200A may have a single one-way link or segment274that only allows data to be sent from the sensors206,212,208to a data acquisition unit through the connector202. In these embodiments, each of the first, second, and third seismic sensors206,212,208are electrically coupled to the one-way segment274via a connection270. The connections270between the first, second, and third sensors206,212,208and the one-way segment274may allow sensed seismic data from the first seismic sensor206, sensed seismic data from the second seismic sensor208, and sensed seismic data from the third seismic sensor212to be transmitted via the one-way segment274to the data acquisition unit246through the connector202. Referring still toFIG. 2A, in some examples, power may be provided to the seismic sensors206,212,208via the connector202, whereas in other examples the seismic sensors206,212,208may be independently powered.

With reference now toFIG. 2B, in some embodiments the common data transmission channel204of a sensor string200B with three seismic sensors206,212,208may have two one-way links or segments274,276, thus forming a two-way data transmission channel204. In these embodiments, each of the first, second, and third seismic sensors206,212,208are electrically coupled to the first one-way segment274via respective first connections270and are electrically coupled to the second one-way segment276via respective second connections272. The respective first connections270between the first, second, and third sensors206,212,208and the first one-way segment274may allow sensed seismic data from the first seismic sensor206, sensed seismic data from the second seismic sensor208, and sensed seismic data from the third seismic sensor212to be transmitted via the one-way segment274to the data acquisition unit246through the connector202. The respective second connections272between the first, second, and third sensors206,212,208and the second one-way segment276may allow power and/or control/commands to be sent to the first, second, and third seismic sensors206,208,212from the data acquisition unit246through the connector202.

With reference now toFIGS. 3A and 3B, two examples of the electrical connections of sensor strings300A,300B with a segmented common data transmission channel304will be described. For illustration purposes, the sensor strings300A,300B shown inFIGS. 3A and 3Band described herein include three seismic sensors306,312,308, similar to the sensor string100B illustrated inFIG. 1Band described above.

Referring first to the embodiment of a sensor string300A illustrated inFIG. 3A, each of the three seismic sensors306,312,308may have a respective transmitter324,328,332, and at least the first and third seismic sensors306,312may also have a respective receiver326,330. As illustrated inFIG. 3A, in some embodiments, the segmented common data transmission channel304of a sensor string300A may include a plurality of one-way segments382,384,386. The first one-way segment382may be coupled between the transmitter324of the first seismic sensor306and the connector, the second one-way segment384may be coupled between the transmitter328of the third seismic sensor312and the receiver326of the first seismic sensor306, and the third one-way segment386may be coupled between the transmitter332of the second seismic sensor308and the receiver330of the third seismic sensor312. Each of the respective one-way segments382,384,386allows data to be sent from the sensors306,312,308towards the data acquisition unit. For example, sensed seismic data from the second seismic sensor308is sent over the third one-way segment386from the transmitter332of the second seismic sensor308to the receiver330of the third seismic sensor312. That data received from the second seismic sensor308, together with sensed seismic data from the third seismic sensor312, is sent over the second one-way segment384from the transmitter328of the third seismic sensor312to the receiver326of the first seismic sensor306. The data received from both the second and third seismic sensors308,312, together with sensed seismic data from the first seismic sensor306, is sent over the first one-way segment382from the transmitter324of the first seismic sensor306to the connector302and on to the data acquisition unit. In this daisy-chain type of connection, data from the plurality of the seismic sensors306,312,308is thus provided to, for example, a data acquisition unit via the common data transmission channel304.

With reference now toFIG. 3B, the electrical connections for another example of a sensor string300B will now be described. The sensor string300B illustrated inFIG. 3Bis generally similar to the sensor string300A illustrated inFIG. 3A, except that the sensor string300B inFIG. 3Bincludes additional one-way segments383,385,387, and the second seismic sensor308includes a receiver333. The additional one-way segments383,385,387may be used to send control/commands and/or power to the seismic sensors306,312,308. For example, if the data acquisition unit needs to send timing information to the second seismic sensor308, the timing information may be sent first to the receiver326of the first seismic sensor306via the fourth one-way segment383. The timing information may then pass from the transmitter324of the first seismic sensor306to the receiver330of the third seismic sensor312via the fifth one-way segment385, and then pass from the transmitter328of the third seismic sensor312to the receiver333of the second seismic sensor308. In this manner, the common data transmission channel304may be a two-way daisy chain connection. Of course, other control/commands may similarly be provided to each of the seismic sensors306,312,308, and power may also be provided to the seismic sensors306,312,308via the common data transmission channel304in some embodiments.

With reference toFIGS. 2A through 3B, it will be appreciated that one or more terminators may be included in the common data transmission channel204,304of a sensor string to reduce or eliminate reflections. Also, whileFIGS. 2A and 2Bhave illustrated two embodiments of a continuous common data transmission channel204, it will be appreciated that other types of continuous data transmission channels may be used, such as a single two-way link or segment that allows for power and control/commands to be provided to the sensors and for data from the sensors to be provided to a data acquisition unit through the connector. Similarly, whileFIGS. 3A and 3Bhave illustrated two embodiments of a segmented common data transmission channel304, it will be appreciated that other types of segmented common data transmission channels may be used. In general, any type of continuous or segmented data transmission channel may be used, including those illustrated in any ofFIG. 2A, 2B, 3A, or3B in constructing a seismic sensor string according to the present disclosure.

Turning now toFIG. 4, a simplified cross-sectional view of a portion of a sensor string400is shown. The sensor string400shown inFIG. 4may be the sensor string100A shown inFIG. 1Aor the sensor string100B shown inFIG. 1B, for example, with similar reference numbers referring to similar parts. The common data transmission channel404of the sensor string400inFIG. 4is illustrated with a two-way segmented common data transmission channel404, like that described above with reference toFIG. 3B. However, as described above with reference toFIGS. 2A, 2B, and 3A, other forms of a common data transmission channel may be used, and that shown inFIG. 4is merely one example of how the common data transmission channel may be constructed.

As illustrated inFIG. 4, a first termination board434is enclosed within the first housing437of the first seismic sensor406. A plurality of segments482,483,484,485of the common data transmission channel404are connected to the first termination board434, which may include a transmitter and a receiver, like those shown inFIG. 3B. The first portion416of the cable449defining the common data transmission channel404includes a one-way segment482coupled between the connector of the sensor string400and the termination board434of the first sensor406, with the one-way segment482providing a medium for sending data from the first sensor406to the connector of the sensor string400and on to a data acquisition unit, for example. The first portion416of the cable449also includes another one-way segment483also coupled between the connector of the sensor string400and the termination board434of the first sensor406, which provides a medium for sending power and/or control/commands to the first sensor406. As illustrated inFIG. 4, once the cable449enters the upper portion438of the first housing437of the first sensor406, the one-way links482,483are exposed and electrically coupled (e.g., soldered) to the first termination board434.

Still referring toFIG. 4, the third portion420of the cable449defining the common data transmission channel404includes a one-way segment484coupled between a termination board of the third sensor (not shown) and the termination board434of the first sensor406, with the one-way segment484providing a medium for sending data from the third sensor412to the first sensor406towards the connector of the sensor string400and on to the data acquisition unit, for example. The third portion420of the cable449also includes another one-way segment485also coupled between the termination board of the third sensor and the termination board434of the first sensor406, which provides a medium for sending power and/or control/commands to the third sensor. As illustrated inFIG. 4, the one-way links484,485are exposed within the upper portion437of the first housing438and electrically coupled (e.g., soldered) to the first termination board434.

Still referring toFIG. 4, the second portion418of the cable449defining the common data transmission channel404includes a one-way segment486coupled between a termination board436of the second sensor408and the termination board of the third sensor (not shown), with the one-way segment486providing a medium for sending data from the second sensor408to the third sensor412towards the connector of the sensor string400and on to the data acquisition unit, for example. The second portion418of the cable449also includes another one-way segment487also coupled between the termination board of the third sensor and the termination board436of the second sensor408, which provides a medium for sending power and/or control/commands to the second sensor408. As illustrated inFIG. 4, the one-way links486,487are exposed within the upper portion431of the first housing440and electrically coupled (e.g., soldered) to the second termination board436.

In some embodiments, and as illustrated inFIG. 4, overmolds491A,491B may be formed over the cable449of the common data transmission channel404at the entry points to the upper portion438of the first housing437to secure the cable449to the first housing437, and similar overmolds may be formed at the cable449entry points for the housings of the other sensors. The overmolds may form at least a partially protective seal to help prevent moisture and particles from entering the first housing437at the entry points of the cable449. In some embodiments, a potting material (not visible inFIG. 4) may be used to further secure the one-way segments482,483,484,485within the interior of the upper portion438of the first housing437(and also for the segments within the interior of the housings of the other sensors), further forming a moisture and particle barrier. In some examples, the termination board434may also be secured within the potting material (in which case electrical leads may extend downward from the termination board434and protrude out of the potting material towards other circuitry of the first sensor406), whereas in other examples the one-way segments482,483,484,485may extend below the potting material so that the termination board434can be positioned below the potting material.

With reference now toFIGS. 4 and 5, the seismic sensors of a sensor string may in some embodiments be configured with positional encoding. For example, the first termination board434of the sensor string400inFIG. 4may be encoded with a first binary position code and the second termination board436may be encoded with a second binary position code. As described below with reference toFIG. 6, the positional encoding for each sensor of the sensor string may be used to identify the respective seismic sensor from which a certain seismic data sample originated. The positional encoding may be helpful because, as described above, sensed seismic data from a plurality of different seismic sensors is provided to the common data transmission channel. If a position code is added to each seismic data sample (e.g., as a header), with the position code corresponding to the seismic sensor that sensed that seismic data sample, then a data acquisition unit or central recording unit can determine the location corresponding to that seismic data sample for use in processing that seismic data sample based on the relative positioning of the seismic sensors.

Table568inFIG. 5shows one example of positional encoding that may be used. As shown in table568, position1may be associated with binary code10and may have pin connections of open, ground. Position2may be associated with binary code01and may have pin connections of ground, open. Position3may be associated with binary code00and may have pin connections of ground, ground. The positional encoding may be any combination of pin connections and binary coding, including combinations not described above. Using the positional encoding of table568, the termination board of a first seismic sensor may be configured with the position1encoding, the termination board of a second seismic sensor may be configured with the position2encoding, and so on. In some instances, the termination board for each respective seismic sensor in the sensor string may be encoded with a distinct, non-overlapping positional encoding.

FIGS. 6A and 6Billustrate one example of the transmission of seismic data from a plurality of seismic sensors on a common data transmission channel of a sensor string, such as the sensors strings100A,100B,100C,200A,200B,300A,300B,400described above. As mentioned above, a plurality of seismic sensors may provide seismic data to the common data transmission channel of a sensor string using multiplexing protocols, such as time-division, frequency-division, or wavelength-division multiplexing. One example of time-division multiplexing is shown inFIG. 6A, with a first seismic data sample658being transmitted via the common data transmission channel during a first transmission slot (e.g., a time slot for time division multiplexing), a second seismic data sample660being transmitted via the common data transmission channel during a second transmission slot, and a third seismic data sample662being transmitted via the common data transmission channel during a third transmission slot. The first seismic data sample658transmitted during the first transmission time slot may be from a first seismic sensor of a sensor string, the second seismic data sample660transmitted during the second transmission time slot may be from a second seismic sensor of the sensor string, and the third seismic data sample662transmitted during the third transmission time slot may be from a third seismic sensor of the sensor string.

The seismic sensors may be configured to provide sensed seismic data to the common data transmission channel during these respective time periods. For example, the first seismic sensor may be configured to only transmit sensed seismic data on the common data transmission channel during the first transmission slot, the second seismic sensor may be configured to only transmit sensed seismic data on the common data transmission channel during the second transmission slot, and the third seismic sensor may be configured to only transmit sensed seismic data on the common data transmission channel during the third transmission slot. The transmission slots during which respective seismic sensors transmit sensed seismic data may be predefined or may be configurable. For example, in some examples, the positional encoding of the termination boards (seeFIG. 5) may define a transmission slot during which a particular seismic sensor will transmit sensed seismic data. In another embodiment, control signals may be provided to the seismic sensors providing commands to transmit sensed seismic data during certain transmission slots. Also, in some examples, timing signals may be provided to the seismic sensors via the common data transmission line, and/or independent timing signals can be generated at or provided to the seismic sensors in another manner.

An enlarged portion ofFIG. 6Ais shown inFIG. 6Billustrating position data headers670,672,674that may be used during the transmission of seismic data samples on the common data transmission channel. For example, the first seismic data sample658may be sent (from the first seismic sensor) together with a first position data header670—for example, the position data header670may precede the actual seismic data sample658. Similarly, the second seismic data sample660may be sent (from the second seismic sensor) together with a second position data header672and the third seismic data sample662may be sent (from the third seismic sensor) together with a third position data header674. The position data headers670,672,674may be generated by the termination boards for each seismic sensor in some embodiments, and may be based on the positional encoding of the respective termination board.

In some examples, the position data header670may be combined with the actual seismic data sample658to be sent, whereas in other examples the position data header670may be sent separately from the seismic data sample658. Also, whileFIG. 6Ashows the position data headers670,672,674preceding the respective seismic data samples658,660,662on the common data transmission channel, in other embodiments, the position data headers670,672,674may be sent after each respective seismic data sample, or the position data headers670,672,674may be sent together before any seismic data samples are sent, thus allowing a burst of seismic data to be provided to the common data transmission channel. Also, in some embodiments, no position data headers670,672,674may be used—instead, the seismic data samples may be identified by a data acquisition unit merely based on the timing and/or position of an incoming stream of data on the common data transmission channel. Alternatively, in some examples, the seismic data samples658,660,662may be provided to the common data transmission channel at random, non-assigned times as packets. In these embodiments, the headers670,672,674may identify to which seismic sensor the respective seismic data samples correspond.

Also, whileFIGS. 6A and 6Bprimarily illustrate the transmission of seismic data samples on the common data transmission channel using time multiplexing, in other embodiments, the seismic data samples may be transmitted using other available resources of the common data transmission channel. For example, multiple frequencies of the common data transmission channel can be used to simultaneously (in time) send multiple seismic data samples using a common data transmission channel. In general, any available communication resources of the common data transmission channel can be shared among the plurality of sensors to transmit sensed seismic data.

Referring still toFIGS. 6A and 6B, in some embodiments, the sample rate of acquiring seismic data using the plurality of seismic sensors may be less than a transmission rate of transmitting the seismic data to, for example, a data acquisition unit via the common data transmission channel. For example, as illustrated inFIG. 6A, the sample interval (i.e., the time in between seismic samples sensed by the seismic sensors) is longer than the time it takes to transmit a seismic sample from a single sensor. InFIG. 6A, in fact, the sample interval is longer than the time it takes to transmit three seismic samples. It will be understood, however, than in other embodiments, the sample interval may be shorter than as illustrated inFIG. 6A. In instances where the sample interval is shorter than the time required to transmit the seismic samples from all of the seismic sensors on a sensor string, the seismic sensors may include a buffer or some other storage to temporarily store seismic data samples and may transmit the seismic data samples using a bucket-brigade type of system on the common data transmission channel.

With reference now toFIG. 7, one example of a wired seismic data acquisition system758incorporating multi-station seismic sensor strings is illustrated. The seismic data acquisition system758illustrated inFIG. 7includes a data acquisition unit746coupled to a central recording unit and a receiver line744, with the receiver line744defining a plurality of takeout connections743. The system758inFIG. 7also includes a plurality of sensor strings700-1,700-2,700-3,700-4, which may be any of the sensor strings described herein. Of course, the system758may include many more or fewer than four sensor strings in various embodiments. Each of the sensor strings700-1,700-2,700-3,700-4shown in the system758ofFIG. 7includes a respective connector702that is coupled to a respective takeout connection743of the receiver line744, a respective common data transmission channel704, and respective first, second, and third seismic sensors706,708,712configured to provide sensed seismic data to the respective common data transmission channel704of the respective sensor string700-1,700-2,700-3,700-4.

In operation, a first seismic sensor706of the first sensor string700-1of the seismic data acquisition system758acquires a first seismic data sample, and a second seismic sensor708of the first sensor string700-1may also acquire a second seismic data sample at substantially the same time as the first seismic sensor706acquires the first seismic data sample. Once the first and second seismic data samples have been acquired, they may be transmitted to the data acquisition unit746via the common data transmission channel704of the first sensor string700-1, as illustrated inFIGS. 6A and 6Bas just one example. In this time-multiplexing example, the first seismic data sample658may be transmitted via the common data transmission channel704during a first transmission period, and the second seismic data sample660may be transmitted via the common data transmission channel704during a second transmission period that does not overlap with the first transmission period. The first and second seismic data samples658,660may be preceded by respective position data headers670,672, as described above, in some embodiments.

With reference now toFIG. 8, one example of a wireless seismic data acquisition system858incorporating a multi-station sensor string is illustrated. The wireless seismic data acquisition system858inFIG. 8includes a wireless data acquisition unit850and a sensor string800. The sensor string800includes a connector802configured to couple the sensor string800to the wireless data acquisition unit850, a common data transmission channel804that is coupled communicatively to the wireless data acquisition unit850through the connector802, and first, second, and third seismic sensors806,808,812. As described above, the first, second, and third seismic sensors806,808,812may be configured to provide sensed seismic data to the common data transmission channel804. The wireless data acquisition unit850may comprise an antenna860to transmit seismic data wirelessly to a central recording unit848. The operation of the wireless data acquisition system858illustrated inFIG. 8is generally similar to that of the wired data acquisition system758illustrated inFIG. 7. Also, while a single sensor string800is illustrated inFIG. 8as being coupled to the wireless data acquisition unit850, in other examples, multiple sensor strings may be coupled to the wireless data acquisition unit850.

With reference toFIG. 9, an alternative embodiment of a sensor string900will now be described. The sensor string900illustrated inFIG. 9is generally similar to the sensor string100B illustrated inFIG. 1B—for example, the sensor string900illustrated inFIG. 9includes a connector902, a common data transmission channel904, and a plurality of seismic sensors956,952,954. Each of the plurality of seismic sensors956,952,954is configured to provide sensed seismic data to the common data transmission channel904of the sensor string. However, unlikeFIG. 1B, the sensor string900illustrated inFIG. 9defines a T-shaped structure, with the connector902coupled to the third seismic sensor952instead of the first seismic sensor956. A portion of two or more of the housings for the seismic sensors956,952,954may be unique in color in some embodiments to assist with placement of the sensors. For example, the upper portion of the housing of the first sensor956may be a first color (e.g., blue), while the upper portion of the housing of the second sensor954may be a second, distinct color (e.g., yellow). In this manner, a person positioning the sensors may know that the first sensor housing should be positioned eastward (or some other relative direction) from the third sensor housing, and that the second sensor housing should be positioned westward (or some other relative direction) from the third sensor housing.

The systems, apparatuses, and methods in accordance with the present disclosure have been described with reference to particular embodiments thereof in order to illustrate the principles of operation. The above description is thus by way of illustration and not by way of limitation. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. Those skilled in the art may, for example, be able to devise numerous systems, arrangements and methods which, although not explicitly shown or described herein, embody the principles described and are thus within the spirit and scope of this disclosure. Accordingly, it is intended that all such alterations, variations, and modifications of the disclosed embodiments are within the scope of this disclosure.

In methodologies directly or indirectly set forth herein, various steps and operations are described in one possible order of operation, but those skilled in the art will recognize that the steps and operations may be rearranged, replaced, or eliminated without necessarily departing from the spirit and scope of the disclosed embodiments.

All relative and directional references (including: upper, lower, and so forth) are given by way of example to aid the reader's understanding of the particular embodiments described herein. They should not be read to be requirements or limitations, particularly as to the position, orientation, or use of the invention unless specifically set forth in the claims. Connection references (e.g., attached, coupled, connected, joined, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other, unless specifically set forth in the claims.