WO2016094771A1

WO2016094771A1 - Seismic investigation of the earth

Info

Publication number: WO2016094771A1
Application number: PCT/US2015/065195
Authority: WO
Inventors: Andrew Hawthorn; Joel Herve Le Calvez; Colin Sayers; Jefferson ALFORD; Edward Michael TOLLEFSEN
Original assignee: Schlumberger Canada Limited; Services Petroliers Schlumberger; Schlumberger Holdings Limited; Schlumberger Technology B.V.; Smith International, Inc.; Prad Research And Development Limited
Priority date: 2014-12-12
Filing date: 2015-12-11
Publication date: 2016-06-16

Abstract

Systems capable of seismically investigating the earth can include one or more seismic sources and one or more seismic sensors located on the surface and/or included on a drill string. The seismic sources can include vibratory tools such as a vibratory hammer capable of improving rate of penetration of the drill string into a formation, and/or a vibratory agitator capable of reducing or breaking friction developed within the wellbore. Related methods can include using vibratory tools included in a drill string in seismic investigations, such as while the drill string is on-bottom or off-bottom.

Description

SEISMIC INVESTIGATION OF THE EARTH

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/091,296, entitled "SEISMIC INVESTIGATION OF THE EARTH," filed December 12, 2014, the disclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] Some embodiments described herein generally relate to systems and apparatuses for use in seismic investigations of the earth. Additional embodiments described herein generally relate to methods of conducting seismic investigations of the earth.

BACKGROUND

[0003] In the drilling of oil and gas wells, information regarding the locations and compositions of oil or gas deposits, and the locations and compositions of other neighboring geologic structures may be collected to aid in drilling the wells. Borehole seismic investigation is of interest to oil and gas exploration professionals because it can provide a deeper penetration into a formation than other available investigation techniques. Current borehole seismic investigation methods can face certain limitations, however, and can be economically

challenging.

SUMMARY

[0004] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0005] In one non-limiting embodiment, a system for seismic investigation of the earth is disclosed. The system may include a drill string including a bottom end and a drill bit at the bottom end of the drill string. The system may also include a vibratory tool in the drill string to vibrate along a longitudinal axis of the drill string. The system may also include a seismic sensor positioned in the drill string and/or located on the surface. [0006] In another non-limiting embodiment, a method of seismic investigation of the earth is disclosed. The method may include drilling a wellbore into a geologic formation. The method may also include oscillating a vibratory hammer axially with respect to the wellbore to impart vibratory forces to a drill bit and to impart a seismic wave into the geologic formation. The method may also include receiving a reflected portion of the seismic wave imparted to the geologic formation at a seismic sensor.

[0007] In another non-limiting embodiment, a method of seismic investigation of geologic structures is disclosed. The method may include drilling a wellbore into a geologic formation and imparting a seismic wave into the geologic formation along an axis coincident with a central axis of a terminal end portion of the wellbore. The method may also include receiving a reflected portion of the seismic wave.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0008] FIG. 1 depicts a drilling rig and drill string according to one or more embodiments disclosed herein;

[0009] FIG. 2 depicts a drilling rig and drill string according to one or more embodiments disclosed herein;

[0010] FIG. 3 depicts a drilling rig and drill string according to one or more embodiments disclosed herein;

[0011] FIG. 4 depicts a vibratory tool according to one or more embodiments disclosed herein;

[0012] FIG. 5 depicts a vibratory tool according to one or more embodiments disclosed herein;

[0013] FIG. 6 depicts an illustrative method of collecting seismic information according to one or more embodiments disclosed herein;

[0014] FIG. 7 depicts an illustrative method of collecting seismic information according to one or more embodiments disclosed herein; and

[0015] FIG. 8 depicts an illustrative method of collecting seismic information according to one or more embodiments disclosed herein.

DETAILED DESCRIPTION [0016] FIG. 1 illustrates a land-based platform and drilling rig 1 15 positioned over a wellbore 111, and a drill string 1 12 (on-bottom) for exploring a formation 10. In the illustrated embodiment, the wellbore 111 is formed by rotary drilling. Those of ordinary skill in the art given the benefit of this disclosure will appreciate, however, that the subject matter of this disclosure also finds application in directional drilling applications as well as rotary drilling, and is not limited to land-based rigs.

[0017] The drill string 112 is rotated by a rotary table 116, energized by means not shown, which engages a kelly 117 at the upper end of the drill string 112. The drill string 112 is suspended from a hook 1 18, attached to a travelling block (also not shown), through the kelly 117 and a rotary swivel 1 19 which permits rotation of the drill string 112 relative to the hook 118. Although depicted with a kelly 117 and rotary table 116 in FIG. 1, in some embodiments, the drill string 112 may be rotated using other methods, such as by using a topdrive.

[0018] Drilling fluid 126 (also referred to as drilling mud) is stored in a pit 127 formed at the well site. A pump 129 delivers the drilling fluid 126 to the interior of the drill string 112 via a port in the swivel 119, inducing the drilling fluid 126 to flow downwardly through the drill string 112 as indicated by the directional arrow 108. The drilling fluid 126 exits the drill string 112 via ports in a drill bit 105, and then circulates upwardly through the region between the outside of the drill string 1 12 and the wall of the wellbore 111, called the annulus, as indicated by the direction arrows 109. In this manner, the drilling fluid 126 lubricates the drill bit 105 and carries formation cuttings up to the surface as drilling fluid 126 returns to the pit 127 for recirculation.

[0019] The drill string 112 is suspended within the wellbore 111 and includes the drill bit 105 at its lower, terminal, or bottom end. The drill string 1 12 can also include a plurality of vibratory tools including vibratory agitators 130 along the length of the drill string 112 and/or a vibratory hammer 150 adjacent or coupled to the drill bit 105 or within one meter or within tens of meters of the drill bit 105. The vibratory agitators 130 are discussed in greater detail below, and may be used to break or lessen the friction within the wellbore 111, such as between an outer surface of the drill string 112 and an inner surface of the wellbore 11 1. The vibratory hammer 150 is also discussed in greater detail below, and may be used to improve a rate of penetration of the drill bit 105 into the formation 10. The vibratory hammer 150 may be used with otherwise seismically quiet drilling systems, such as systems that use a polycrystalline diamond compact cutter as a drill bit, to cause the drill bit 105 to act as both a drilling or cutting tool and a seismic source. The vibratory agitators 130 and the vibratory hammer 150, in the course of performing their respective functions, can generate seismic waves (e.g., pressure or acoustic waves traveling through the earth) which propagate from the respective vibratory tool into the formation 10, or propagate from the vibratory tool through the drill string and drill bit into the formation 10, and thus can be referred to collectively as seismic sources. Seismic sources may also include other tools and structures along the drill string 1 12, such as valves that control the flow of mud between an internal portion of the drill string 1 12 and the annulus.

[0020] In some embodiments, the downhole seismic sources generate signals ranging in frequency up to 10 kHz. Lower frequency range seismic signals attenuate less in the formation 10 than higher frequency seismic signals, but the lower frequency range seismic signals have a lower resolution than the higher frequency seismic signals. The lower frequency signals may be used to investigate large structures in the formation 10 over long distances. The lower frequency seismic signals may resolve features that are 10 to 100 meters in dimension and up to several kilometers from the seismic sources and seismic sensors, such as when using one or more of the downhole seismic sources with seismic sensors positioned on the ground surface. The higher frequency seismic signals may resolve features in the formation 10 of from a quarter meter up to several meters in dimension and hundreds of meters from the source and sensor, such as when using one or more of the downhole seismic sources with one or more of the sensors 120.

[0021] The drill string 112 also includes seismic sensors 120 along at least a portion of the length of the drill string 1 12. The seismic sensors 120 are sensors of seismic waves impacting the drill string 112, such as seismic waves generated at one or more of the seismic sources and reflected back to the drill string 112, e.g., from interfaces between geologic layers in the formation 10. In some cases, an interface between geologic layers in the formation can include a location at which the composition, structure, or physical or geologic properties change. Various suitable seismic sensors, such as hydrophones, geophones, and accelerometers, are known and commercially available. Including the seismic sources and the seismic sensors in the drill string 112 increases the efficiency of drilling processes and seismic investigations, as the drilling and seismic investigation may occur at the same time or on the same trip into the wellbore 111.

[0022] The seismic sensors 120 can transmit collected data to a receiver subsystem 190, which can be communicatively coupled to a computer processor 185 and a recorder 145. The computer processor 185 may be coupled to a monitor, which can employ a graphical user interface ("GUI") 192 through which measurements and particular results derived therefrom can be graphically or otherwise presented to the user. The computer processor 185 can also be communicatively coupled to a controller 160. The controller 160 can serve multiple functions, in particular to trigger the start of seismic data acquisition via downlink command. For example, the controller 160 and computer processor 185 may be used to power and operate the seismic sources or the seismic sensors 120. In some cases, the computer processor 185 and the controller 160 can be used to control the frequency and/or amplitude of the seismic waves generated by some or all of the seismic sources. Although depicted at the surface, the controller 160 and computer processor 185 may be configured in any suitable manner. For example, the controller 160 and/or computer processor 185 may be part of the drill string 1 12.

[0023] In some embodiments, the systems determine the distance, orientation, or

composition of geologic structures, including around the drill string 112 and ahead of the drill bit 105. In some embodiments, the systems are capable of imaging the earth and geologic structures therein up to several kilometers from the seismic sources (penetration into the surrounding formation). In some embodiments, the systems further include an electronics subsystem having data processing capabilities for determining the distance or orientation of at least a portion of the geologic structures near the drill string 1 12, for example capable of determining a first or at least a first interface between geologic layers within the region of the drill string 112, or for example up to or at least five such interfaces. In some embodiments, the systems further include data processing capabilities for determining the composition and properties of the earth, such as seismic velocity (e.g., compression and/or shear velocities), density, or elasticity.

[0024] The disclosure also provides methods for downhole seismic investigations. In some embodiments, the methods include obtaining information regarding the earth surrounding the drill string 112 and ahead of the drill bit 105.

[0025] FIG. 2 illustrates a drilling rig 200, which can have a structure similar to that of drilling rig 115, a drill string 202, which can have a structure similar to that of drill string 112, and a series of surface seismic sensors 218, which can communicate with a computer processor similar to computer processor 185 and a recorder similar to recorder 145, such as through a receiver subsystem similar to the receiver subsystem 190. FIG. 2 illustrates the drill string 202, having the drill bit 105 on-bottom in the wellbore. The drill bit 105 can be used to seismically investigate the earth surrounding the drill string 202, such as the distance and orientation of bed boundaries around the drill string 202 and ahead of the drill bit 105. In particular, the drill string 202 is shown investigating the earth including a first geologic layer 204, a second geologic layer 206, a third geologic layer 208, and a fourth geologic layer 210, as well as a first interface 212 between the first geologic layer 204 and the second geologic layer 206, a second interface 214 between the second geologic layer 206 and the third geologic layer 208, and a third interface 216 between the third geologic layer 208 and the fourth geologic layer 210.

[0026] As illustrated in FIG. 2, a vibratory agitator 130-3 can be activated to engage with the formation 10 and to vibrate, thereby generating seismic waves that travel from the vibratory agitator 130-3 into the first geologic layer 204. The vibratory agitator 130-3 can engage with the formation 10 and wellbore directly or indirectly. For example, in indirect engagement the vibratory agitator 130-3 may not be in direct contact with the sidewalls of the wellbore. The vibratory agitator 130-3 may generate seismic waves that travel through the annulus, which may contain drilling fluid or mud, and then from the annulus, through the wellbore sidewall, and into the formation 10. In some embodiments the vibratory agitator 130-3 may be in indirect engagement with the formation 10 through the drill pipe or drill string. The drill string 112 may contact the wellbore sidewalls at one or more locations along the wellbore, and vibratory agitator 130-3, located near one of these contact locations, may cause the drill string 112 to vibrate and the vibrations may be transmitted to the formation 10 at the locations where the drill string 112 contacts the wellbore sidewall.

[0027] In direct engagement, the vibratory agitator 130-3 may be in direct contact with the sidewalls of the wellbore. For example, the vibratory agitator 130-3 may include actuating stabilizers or reaming tools or passive structures such as packers that extend from the vibratory agitator and contact the wellbore sidewall. In some embodiments, the drill string 112 may contact the wellbore sidewall at the vibratory agitator 130-3, causing the vibratory agitator 130-3 to be in direct engagement with at least a portion of the wellbore sidewall.

[0028] The vibratory agitator 130 may be located or positioned in the drill string 112 a distance from the drill bit 105, for example at least 10 meters from the drill bit 105. In some embodiments, more than one vibratory agitator 130-1, 130-2, 130-3, are distributed along the drill string. In some embodiments, the vibratory agitator 130 may be located or positioned in the wellbore a distance from the terminal end of the wellbore, for example at least 10 meters from the terminal end of the wellbore. [0029] Seismic waves thus generated can travel outward through the first geologic layer 204 from the drill string 112. Some of the seismic waves 227 travel directly through the formation 10 to one or more of the seismic sensors 218, so-called direct arrival seismic waves. Other seismic waves may travel outward until they encounter an interface, such as the first interface 212, before traveling to one or more of the seismic sensors 218. For example, upon encountering the first interface 212, a portion of a seismic wave can be reflected back into the first geologic layer 204 and another portion can be transmitted into the second geologic layer 206. Reflected portions of the seismic wave (as indicated, for example, by reference numerals 220 and 221) can be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120-2, 120-3, 120-4, and/or the surface seismic sensors 218. A portion of the wave transmitted through the first interface 212 into the second geologic layer 206 can continue to travel outward through the second geologic layer 206 until the wave encounters the second interface 214, where the wave can again be partially reflected and partially transmitted. A portion of the seismic wave reflected at the second interface 214 (as indicated, for example, by reference numeral 222) can also be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120- 2, 120-3, 120-4, and/or the surface seismic sensors 218. The measured properties of the detected waves can allow the physical locations and orientations of interfaces between geologic layers, and the physical and geologic properties of those geologic layers to be determined.

[0030] The vibratory hammer 150 can be activated to vibrate, thereby generating seismic waves that travel from the vibratory hammer 150 into the third geologic layer 208. For example, the vibratory hammer 150 can cause the drill bit 105 to vibrate along the axis of the wellbore (e.g., up and down, or vertically in the illustrated embodiment) so as to impart seismic waves into the third geologic layer 208. As shown in FIG. 2, the drill bit 105 engages directly with the bottom of the wellbore through direct contact with the bottom of the wellbore (i.e., the drill bit is "on-bottom"), but the vibratory hammer 150 engages indirectly with the bottom of the wellbore through the drill bit 105. In some embodiments, the vibratory hammer 150 may include a drill bit 105; in such an embodiment, the vibratory hammer 150 may directly engage with the wellbore. In some embodiments, the drill bit 105 may directly engage with the sidewalls of the wellbore. In operation, the drill bit 105 drills a wellbore that has the same or similar diameter as the drill bit 105 and therefore, the outer circumference of the drill bit 105 may be in direct contact with the wellbore.

[0031] A seismic wave thus generated can travel outward through the third geologic layer 208 until the wave encounters the third interface 216. Upon encountering the third interface 216, a portion of the seismic wave can be reflected back into the third geologic layer 208 and another portion can be transmitted into the fourth geologic layer 210. Reflected portions of the seismic wave (as indicated, for example, by reference numeral 224) can continue to be reflected and transmitted at the second interface 214 and first interface 212, and can be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120-2, 120-3, 120-4, and/or the surface seismic sensors 218.

[0032] The vibratory hammer 150 can generate seismic waves that travel into the third geologic layer 208 through the drill bit 105, thus generating waves that travel out the end of the wellbore, or along an axis coincident with a central axis of the wellbore, or along an axis coincident with at least a terminal end portion of the wellbore (as indicated, for example, by reference numeral 226). In some cases, one or more of the seismic sensors 120 and the surface seismic sensors 218 can receive and measure seismic waves that travel into the end of the wellbore, or along an axis coincident with a central axis of the wellbore, or along an axis coincident with at least a terminal end portion of the wellbore (as also indicated, for example, by reference numeral 226).

[0033] FIG. 3 illustrates the drill string 202, having the drill bit 105 off-bottom in the wellbore, as it is used to seismically investigate the surrounding geologic structures. As illustrated in FIG. 3, the vibratory agitators 130-1, 130-2, and 130-3 can be activated to vibrate, thereby generating seismic waves that travel from the respective vibratory agitator into the first geologic layer 204. A seismic wave thus generated can travel outward through the first geologic layer 204 until the seismic wave encounters the first interface 212. Upon encountering the first interface 212, a portion of the seismic wave can be reflected back into the first geologic layer 204 and another portion can be transmitted into the second geologic layer 206. Reflected portions of a seismic wave generated by the vibratory agitator 130-3 can be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120-2, 120-3, 120-4 (as indicated, for example, by reference numeral 228), and/or the surface seismic sensors 218 (as indicated, for example, by reference numeral 230). Reflected portions of a seismic wave generated by the vibratory agitator 130-2 can be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120-2, 120-3, 120-4, and/or the surface seismic sensors 218 (as indicated, for example, by reference numeral 232).

[0034] The vibratory hammer 150 can be activated to vibrate off-bottom, thereby generating seismic waves that travel from the vibratory hammer 150 into the second geologic layer 206. As shown in FIG. 3, the drill bit 105 engages indirectly with the bottom of the wellbore through a fluid column at the bottom of the wellbore (i.e., the drill bit is "off-bottom"). The fluid column may include well cuttings, drilling fluid, mud, or other fluids. Drill bit vibrations may travel through the fluid column and induce seismic waves in the formation 10 when the vibrations encounter the bottom of the wellbore. The vibratory hammer 150 may also engage indirectly with the bottom of the wellbore through the drill bit 105 and the fluid column.

[0035] A seismic wave thus generated can travel outward through the second geologic layer 206 until the seismic wave encounters the second interface 214. Upon encountering the second interface 214, a portion of the seismic wave can be reflected back into the second geologic layer 206 and another portion can be transmitted into the third geologic layer 208. Reflected portions of the seismic wave (as indicated, for example, by reference numerals 234) can be detected and wave properties including amplitude and frequency can be measured using one or more of the seismic sensors 120-1, 120-2, 120-3, 120-4, and/or the surface seismic sensors 218. The vibratory hammer 150 can generate seismic waves that travel into the third geologic layer 208 through the drill bit 105 (e.g., through the drilling fluid or mud 126 between the off-bottom drill bit 105 and the terminal end of the wellbore), thus generating waves that travel out of the end of the wellbore, or along an axis coincident with a central axis of the wellbore, or along an axis coincident with at least a portion of the wellbore in the vicinity of the drill bit 105, or along an axis coincident with a central axis of the drill bit 105 (as indicated, for example, by reference numeral 236). In some cases, one or more of the seismic sensors 120 and the surface seismic sensors 218 can receive and measure seismic waves that travel into the end of the wellbore, or along an axis coincident with a central axis of the wellbore, or along an axis coincident with at least a portion of the wellbore in the vicinity of the drill bit 105, or along an axis coincident with a central axis of the drill bit 105 (as also indicated, for example, by reference numeral 236). [0036] Data collected by the seismic sensors 120 and the surface seismic sensors 218 can be used to determine the locations and orientations of geologic structures, such as geologic layers and interfaces, and to determine the composition or properties of the earth.

[0037] FIGS. 4 and 5 illustrate a vibratory hammer 150 according to one or more

embodiments disclosed herein. In some embodiments, one or more of the vibratory agitators 130 can have a structure the same as or similar to the illustrated vibratory hammer 150. The vibratory hammer 150 includes an outer casing 152, which may be cylindrical. A first end of the outer casing 152 is coupled to a first end plate 154 and a second end of the outer casing 152 is coupled to a second end plate 156. A central shaft 158 is coupled to and extends between the first end plate 154 and the second end plate 156. For example, a first end of the central shaft 158 can be coupled to a center of the first end plate 154 and a second end of the central shaft 158 can be coupled to a center of the second end plate 156. The first end of the central shaft 158 includes a groove 162 (also referred to as a keyway) that extends along at least a portion of the central shaft 158.

[0038] A motor 164 is mounted to the central shaft 158 such that the motor 164 can slide along the central shaft 158. The motor 164 has a protrusion (also referred to as a key) coupled to engage with the groove 162 of the central shaft 158 so as to rotationally lock the motor 164 to the central shaft 158. A moveable mass, such as an inner cylinder 166 is also mounted to the central shaft 158 such that the inner cylinder 166 can slide along and rotate about the central shaft 158. Although depicted as a cylinder, the inner cylinder 166 may be any suitable shape. The motor 164 is coupled to the inner cylinder 166 so that the motor 164 is longitudinally locked to the inner cylinder 166 along the axis of the central shaft 158, and such that actuation of the motor 164 causes the inner cylinder 166 to rotate with respect to the motor 164, and thus also with respect to the central shaft 158, first end plate 154, and second end plate 156 about the axis of the central shaft 158.

[0039] The first end plate 154 includes a plurality of magnets including at least one magnet 168 having a north pole (indicated by a plus-sign) facing the inner cylinder 166 and at least one magnet 170 having a south pole (indicated by a negative-sign) facing the inner cylinder 166. The second end plate 156 similarly includes a plurality of magnets including at least one magnet 168 having a north pole (indicated by a plus-sign) facing the inner cylinder 166 and at least one magnet 170 having a south pole (indicated by a negative-sign) facing the inner cylinder 166. The north and south poles of the magnets 168, 170 of the first end plate 154 are rotationally offset from the north and south poles, respectively, of the magnets 168, 170 of the second end plate 156 along the axis of the central shaft 158. In the illustrated embodiment, the first end plate 154 and the second end plate 156 each have four magnets 168, 170, with alternating north and south poles facing the inner cylinder 166, and the north and south poles of the magnets 168, 170 of the first end plate 154 are rotationally offset from the north and south poles, respectively, of the magnets 168, 170 of the second end plate 156 by 90°. The first end of the inner cylinder 166 includes at least one magnet 168 (two in the illustrated embodiment) having a north pole facing the first end plate 154 and the second end of the inner cylinder 166 includes at least one magnet 168 (two in the illustrated embodiment) having a north pole facing the second end plate 156.

[0040] In operation, the motor 164 can be actuated to rotate the inner cylinder 166 about the central shaft 158, and thus to rotate the magnets 168 of the inner cylinder 166 with respect to the magnets 168, 170 of the end plates. As the inner cylinder 166 so rotates, it encounters alternating magnetic forces pulling it toward the first and second end plates, due to the rotational offset between the poles of the magnets 168, 170 of the first and second end plates. The alternating magnetic forces can cause the inner cylinder 166 to shuttle back and forth along the central shaft 158. Controlling the speed at which the motor 164 spins the inner cylinder 166 can allow precise control over the movement and the frequency of oscillation of the inner cylinder 166 within the outer casing 152. In some cases, the motor 164 can be powered by various power sources, such as electrical power from a power source outside the wellbore 111, a mud turbine generator powered by the flow of the drilling fluid within the wellbore 11 1, a battery power source, or any other suitable power source.

[0041] In other embodiments, the vibratory hammer 150 includes a MAGHAMMER commercially available from Flexi drill Construction Limited, and the vibratory agitators 130 include a MAGVIBE commercially available from Flexidrill Construction Limited. In other embodiments, the vibratory hammer 150 and/or the vibratory agitators 130 vibrate or oscillate axially, radially, orbitally, or in any combination thereof.

[0042] The vibratory hammer 150 can serve at least two distinct purposes. First, the vibratory hammer 150 can induce vibrations in the drill bit 105 so as to increase the rate of penetration of the drill bit 105 into the formation 10, such as by causing oscillation of the force exerted by the drill bit 105 against the formation 10. Second, the vibratory hammer 150 can act as a source of seismic waves, such as for performing seismic investigations of the formation 10. In some cases, the vibratory hammer 150 can be actuated to serve both purposes simultaneously. That is, seismic investigations can be conducted as the drill bit 105 is used to dig the wellbore 111. In other cases, the vibratory hammer 150 can be actuated to serve both purposes, though not simultaneously. That is, drilling can be halted to conduct seismic investigations and seismic investigations can be halted to conduct drilling. Detailed methods are described below.

[0043] Similarly, the vibratory agitators 130 can serve at least two distinct purposes. First, the vibratory agitators 130 can induce vibrations in the drill string 112 so as to reduce or break friction that develops within the wellbore 1 11, such as between an outer surface of the drill string 112 and an inner surface of the wellbore 1 11. Second, the vibratory agitators 130 can act as a source of seismic waves, such as for performing seismic investigations of the formation 10. In some cases, the vibratory agitators 130 can be actuated to serve both purposes simultaneously. In other cases, the vibratory agitators 130 can be actuated to serve both purposes, though not simultaneously. Detailed methods are described below.

[0044] The vibratory hammer 150 and the vibratory agitators 130 can be oriented within the drill string 112 such that oscillations (such as of the inner cylinder 166) are oriented along the axis of the drill string 112, that is, longitudinal (axial) with respect to the drill string 1 12. Such orientation permits the vibratory hammer 150 and vibratory agitators 130 to generate p-waves that travel from the drill string 112 into the formation 10 in directions oriented in the same direction as, along, or at shallow angles with respect to the drill string 112 (e.g., as shown by arrows 184 and 186 in FIG. 1 and reference numeral 220 in FIG. 2) and s-waves that travel more directly outward from the drill string 1 12 into the formation 10 (e.g., as shown by arrow 182 in FIG. 1 and reference numeral 221 in FIG. 2). Similarly, the vibratory hammer 150 can generate s-waves and p-waves (though the s-waves are not illustrated in FIG. 1).

[0045] The systems disclosed herein can use a single wellbore or multiple wellbores. For example, in some cases, a first drill string in a first wellbore can include one or more seismic sources and/or one or more seismic sensors and a second drill string in a second wellbore can also include one or more seismic sources and/or one or more seismic sensors. Such systems can provide greater flexibility and more numerous options for relative positioning of seismic sources and seismic sensors. In some cases, multi -wellbore systems may reduce the distance between a seismic source and a seismic sensor, and in particular, facilitate the receipt of s-waves transmitted outwardly from the first wellbore toward the second wellbore.

[0046] FIG. 6 depicts an illustrative method 600 of investigating well drilling conditions or formation properties according to one or more embodiments disclosed herein. At block 610 the method 600 includes tripping a drill string into a wellbore. A drill string, for example the drill string 112, may include drill pipe, a bottom hole assembly, a drill bit, such as the drill bit 105, and a vibratory hammer 150 located up string from the drill bit 105. The drill string 112 may also include one or more vibratory agitators and seismic sensors, such as vibratory agitators 130 and seismic sensors 120, or any other tools used in a wellbore drilling or other downhole processes. In some embodiments, the trip-in process may include sending the drill string through an existing casing and/or openhole portions of the wellbore toward the bottom of an existing wellbore or the drilling of a new wellbore.

[0047] At block 620 the wellbore is drilled. For example, once the drill string reaches an existing bottom of the wellbore, the operator may begin drilling and extending the wellbore' s depth. In some embodiments, for example when a wellbore has collapsed, the operator may begin drilling the wellbore before reaching the bottom of the well. The drilling process may also include other drilling or downhole operations, such as enlarging the wellbore through reaming.

[0048] At block 630, seismic information is collected contemporaneously (or

simultaneously) with the drilling operation at block 620. During the collection of seismic information, seismic waves are emitted into a formation, such as the formation 10. The seismic waves, such as the seismic waves 220, 222 depicted in FIG. 2, travel through the formation 10 and may reflect off of one or more interface(s) between geologic layers, such as the first interface 212 between the first geologic layer 204 and second geologic layer 206, as depicted in FIG. 2. The seismic waves may be emitted into the formation 10 at a selected fixed frequency and amplitude or the frequency and amplitude may vary according to a selected function or over a selected range. For example, in some embodiments the seismic waves may vary over a frequency range, such as a frequency sweep between a first and a second selected frequency over selected period of time. In some embodiments, the seismic waves may sweep through a frequency band continuously, at periodic intervals, or at aperiodic intervals. In some

embodiments, the seismic waves may be emitted at more than one frequency at the same time, for example each of several seismic emitters may emit seismic waves at a different frequency at the same time. In some embodiments, multiple frequencies of seismic waves are emitted into the formation 10 one at a time, for example a first frequency is emitted, followed by a second frequency, followed by a third frequency, and etc.

[0049] Sensors, such as the surface seismic sensors 218 and the drill string seismic sensors 120, receive the direct and reflected seismic waves and may send information relating to the properties of the seismic waves to the computer processor 185 and the recorder 145, through for example, a surface receiver subsystem 190, or via other methods of communication or data transfer. The seismic data may be processed through known seismic data processing techniques to, for example, create visual images of the formation.

[0050] Investigating well drilling conditions or formation properties, including the collection of seismic information, which may further include transmitting and receiving seismic waves, may take place during active drilling of the wellbore and may use the same drill string for both drilling operations and the collection of seismic information. By combining the tools for drilling a wellbore and for collection of seismic information, well operators save time and expense because they can, for example, continue extending the length or depth of the wellbore while also recording information related to the properties of the formation.

[0051] At block 640 the method 600 includes tripping the drill string out of the wellbore. At least a portion of the drill string may be removed from the wellbore during the trip out.

[0052] FIG. 7 depicts an illustrative method 700 of collecting seismic information according to one or more embodiments disclosed herein. At block 710 seismic sources, such as the vibratory agitators 130 and the vibratory hammer 150, engage with the wellbore. Engagement with the wellbore may be direct or indirect. For example, in some embodiments, a drill bit, such as the drill bit 105 shown in FIG. 2, engages directly with the bottom of the wellbore through direct contact with the bottom of the wellbore, but the vibratory hammer 150 engages indirectly with the bottom of the wellbore through the drill bit 105. In some embodiments, the vibratory hammer 150 may include a drill bit 105; in such an embodiment, the vibratory hammer 150 may directly engage with the wellbore.

[0053] The vibratory agitators 130 may engage either directly or indirectly with the wellbore sidewalls. For example, in indirect engagement the vibratory agitators 130 may not be in contact with the sidewalls of the wellbore. The vibratory agitators 130 may generate seismic waves that travel through the annulus, and then from the annulus through the wellbore sidewall, and into the formation. In some embodiments, for example, in indirect engagement of vibratory agitators, engagement with the wellbore sidewalls may occur with the activation of the vibratory agitator 130.

[0054] In direct engagement, the vibratory agitators 130 may be in direct contact with the sidewalls of the wellbore. For example, the vibratory agitator 130 may include actuating stabilizers or reaming tools that extend from the vibratory agitator and contact the wellbore sidewall. In some embodiments the agitator may be directly coupled to, clamped to, or otherwise directly engaged with the formation by mechanical, hydraulic, or electrical means. For example, reaming tools may include mechanical, hydraulic, or electrical actuators that cause the reamer's cutter block to extend and engage the wellbore.

[0055] In some embodiments, the drill string, such as drill string 112, engages with the wellbore or formation directly at one or more locations along the drill string 112. For example, the drill sting 112 may be coupled to, clamped to, or otherwise engaged with the formation by mechanical, hydraulic, or electrical means.

[0056] At block 720 the seismic source is activated. Activating the seismic source causes the seismic source, such as vibratory agitators 130 and the vibratory hammer 150, to vibrate and send seismic waves through the earth. The seismic waves enter and travel through the formation. Some of the seismic waves reflect off of one or more interfaces between geologic layers, such as the first interface 212 between the first geologic layer 204 and the second geologic layer 206, as depicted in FIG. 2.

[0057] In some embodiments, the vibratory agitators 130 and vibratory hammer 150 are activated during drilling operations such that the vibratory agitators 130 and vibratory hammer 150 are generating seismic waves during the drilling process. In some embodiments, the vibratory agitators 130 are activated, but not the vibratory hammer 150, or the vibratory hammer 150 is activated, but not the vibratory agitators 130.

[0058] At block 730, seismic waves are received. Some of the seismic waves emitted by the seismic sources may eventually reach a seismic sensor, such as the surface seismic sensors 218, and the drill string seismic sensors 120, which sensors can receive the seismic waves. The seismic waves may travel through the formation 10 directly to the sensor or the seismic waves may reflect off of interfaces between geologic or other features of the formation 10 and then travel to the sensor. [0059] At block 740, the seismic sources are deactivated. The seismic sources may be deactivated after the sensor has received seismic information from the seismic waves generated by the seismic sources.

[0060] At block 750, the seismic sources are disengaged from the wellbore. In some embodiments, for example, embodiments wherein the seismic sources engage directly with the wellbore, the configuration of the seismic source changes such that the seismic source is no longer directly engaged with the wellbore. A directly engaged vibratory agitator 130 may retract the actuating stabilizers or reaming tools that were previously extended from the vibratory agitator such that they are no longer engaged with the wellbore sidewall. A directly engaged vibratory hammer 150 may be lifted off the bottom of the wellbore.

[0061] FIG. 8 depicts an illustrative method 800 of collecting seismic information according to one or more embodiments disclosed herein. In particular, FIG. 8 depicts an illustrative method 800 wherein the drill bit, for example drill bit 105, is not directly engaged with the bottom of the wellbore. At block 810, the drill bit 105 is lifted off the bottom of the wellbore. The drill bit 105 may be lifted off the bottom of the wellbore by moving the entire drill string 112 up the wellbore.

[0062] At block 820 seismic sources, such as the vibratory agitators 130 and the vibratory hammer 150, engage with the wellbore. Engagement with the wellbore may be direct or indirect. For example, in some embodiments, a drill bit, such as the drill bit 105 shown in FIG. 3, engages indirectly with the bottom of the wellbore through a fluid column at the bottom of the wellbore. The fluid column may include well cuttings, drilling fluid, mud, or other fluids. The vibratory hammer 150 may also engage indirectly with the bottom of the wellbore through the drill bit 105.

[0063] In some embodiments, the drill bit 105 may directly engage with the sidewalls of the wellbore. In operation, the drill bit 105 drills a wellbore that has the same or similar diameter as the drill bit 105 and, therefore, the outer circumference of the drill bit 105 may be in direct contact with the wellbore.

[0064] The vibratory agitators 130 may engage either directly or indirectly with the wellbore sidewalls. For example, in indirect engagement the vibratory agitators 130 may not be in contact with the sidewalls of the wellbore. The vibratory agitators 130 may generate seismic waves that travel through the annulus, and then from the annulus through the wellbore sidewall, and into the formation. In some embodiments, for example, in indirect engagement of vibratory agitators, engagement with the wellbore sidewalls may occur with the activation of the vibratory agitator 130.

[0065] In direct engagement the vibratory agitators 130 may be in direct contact with the sidewalls of the wellbore. For example, the vibratory agitator may include actuating stabilizers or reaming tools that extend from the vibratory agitator and contact the wellbore sidewall.

[0066] At block 830 the seismic source is activated. Activating the seismic source causes the seismic source, such as vibratory agitators 130 and the vibratory hammer 150, to vibrate and send seismic waves through the earth. The seismic waves enter and travel through the formation. Some of the seismic waves reflect off of one or more interferences between geologic layers, such as the first interface 212 between the first geologic layer 204 and the second geologic layer 206, as depicted in FIG. 2.

[0067] In some embodiments, the vibratory agitators 130 and vibratory hammer 150 are activated during drilling operations such that the vibratory agitators 130 and vibratory hammer 150 are generating seismic waves during the drilling process, such as during back reaming operations. In some embodiments, the vibratory agitators 130 are activated, but not the vibratory hammer 150, or the vibratory hammer 150 is activated, but not the vibratory agitators 130.

[0068] When the drill bit 105 is off bottom and the vibratory hammer 150 is activated, the drill bit may vibrate and send waves through the fluid column at the bottom of the wellbore. These waves may eventually reach the bottom of the wellbore and transfer their energy into the formation 10 in the form of seismic waves.

[0069] At block 840, seismic waves are received. Some of the seismic waves emitted by the seismic sources may eventually reach a seismic sensor, such as the surface seismic sensors 218, and the drill string seismic sensors 120, which sensors can receive the seismic waves. The seismic waves may travel through the formation 10 directly to the sensor or the seismic waves may reflect off of the interface between geologic or other features of the formation 10 and then travel to the sensor.

[0070] At block 850, the seismic sources are deactivated. The seismic sources may be deactivated after the sensor has received seismic information from the seismic waves generated by the seismic sources.

[0071] At block 860, the seismic sources are disengaged from the wellbore. In some embodiments, for example, embodiments wherein the seismic sources engage directly with the wellbore, the configuration of the seismic source changes such that the seismic source is no longer directly engaged with the wellbore. A directly engaged vibratory agitator 130 may retract the actuating stabilizers or reaming tools that were previously extended from the vibratory agitator such that they are no longer engaged with the wellbore sidewall.

[0072] In some embodiments, a drill string, such as drill string 112, may make multiple trips into and out of a wellbore. For example, a worn out drill bit may need replacement and the drill string 112 may be removed from the wellbore to replace the drill bit. In some embodiments, seismic waves may be generated and/or received while re-entering or exiting the wellbore.

[0073] A few example embodiments have been described in detail above; however, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the scope of the present disclosure or the appended claims. Accordingly, such modifications are intended to be included in the scope of this disclosure. Likewise, while the disclosure herein contains many specifics, these specifics should not be construed as limiting the scope of the disclosure or of any of the appended claims, but merely as providing information pertinent to one or more specific embodiments that may fall within the scope of the disclosure and the appended claims. Any described features from the various embodiments disclosed may be employed in combination. In addition, other

embodiments of the present disclosure may also be devised which lie within the scope of the disclosure and the appended claims. Additions, deletions and modifications to the embodiments that fall within the meaning and scopes of the claims are to be embraced by the claims.

[0074] Certain embodiments and features may have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, or the combination of any two upper values are contemplated. Certain lower limits, upper limits and ranges may appear in one or more claims below. Numerical values are "about" or "approximately" the indicated value, and take into account experimental error, tolerances in manufacturing or operational processes, and other variations that would be expected by a person having ordinary skill in the art.

[0075] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above- detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include other possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

1. A system for seismic investigation of the earth, comprising:

a drill string including a bottom end;

a drill bit at the bottom end of the drill string;

a vibratory tool in the drill string to vibrate along a longitudinal axis of the drill string; and

a seismic sensor positioned in the drill string.

2. The system for seismic investigation of the earth of claim 1, wherein the vibratory tool includes an outer casing surrounding a movable mass to oscillate along the longitudinal axis of the drill string.

3. The system for seismic investigation of the earth of claim 1, wherein the vibratory tool is adjacent to the drill bit.

4. The system for seismic investigation of the earth of claim 1, wherein the vibratory tool is located at least ten meters from the drill bit.

5. The system for seismic investigation of the earth of claim 1, wherein the vibratory tool is a first vibratory tool adjacent to the drill bit and the system further comprises a second vibratory tool positioned in the drill string and at least ten meters from the drill bit.

6. A method of seismic investigation of geologic structures, comprising:

drilling a wellbore into a geologic formation;

oscillating a vibratory hammer axially with respect to the wellbore to impart vibratory forces to a drill bit and to impart a seismic wave into the geologic formation; and

receiving a reflected portion of the seismic wave imparted to the geologic formation at a seismic sensor.

7. The method of seismic investigation of the earth of claim 6, wherein receiving the reflected portion of the seismic wave imparted to the earth at the seismic sensor includes receiving the reflected portion of the seismic wave imparted to the geologic formation at a seismic sensor located in the drill string.

8. The method of seismic investigation of the earth of claim 6, wherein the drill bit is off-bottom in the wellbore.

9. The method of seismic investigation of the earth of claim 6, wherein the drilling the wellbore occurs while receiving a reflected portion of the seismic wave.

10. The method of seismic investigation of the earth of claim 6, wherein the vibratory hammer includes a movable mass within an outer casing and wherein oscillating the vibratory hammer comprises oscillating the moveable mass axially with respect to the wellbore.

11. The method of seismic investigation of the earth of claim 10, wherein actuating the moveable mass comprises causing the moveable mass to rotate with respect to the outer casing.

12. The method of seismic investigation of the earth of claim 11, wherein a first end of the vibratory hammer includes a first plurality of magnets, a second end of the vibratory hammer includes a second plurality of magnets, a first end of the moveable mass includes a first magnet, and a second end of the moveable mass includes a second magnet, and wherein rotation of the moveable mass with respect to the outer casing causes the first plurality of magnets to interact with the first magnet and the second plurality of magnets to interact with the second magnet to cause the moveable mass to oscillate axially with respect to the wellbore within the outer casing.

13. The method of seismic investigation of the earth of claim 11, wherein the vibratory hammer further includes a central shaft coupled to a first end of the vibratory hammer and coupled to a second end of the vibratory hammer, wherein the moveable mass is mounted on the central shaft, and wherein causing the moveable mass to rotate with respect to the outer casing comprises using a motor mounted on and rotationally fixed with respect to the central shaft to cause the moveable mass to rotate with respect to the outer casing.

14. A method of seismic investigation of the earth, comprising:

drilling a wellbore into a geologic formation;

imparting a seismic wave into the geologic formation along an axis coincident with a central axis of a terminal end portion of the wellbore; and

receiving a reflected portion of the seismic wave.

15. The method of seismic investigation of the earth of claim 14, further comprising directly engaging a seismic source with a sidewall of the wellbore at a location at least ten meters from the terminal end portion of the wellbore; and

imparting a seismic s-wave into the geologic formation at the location in the wellbore at least ten meters from the terminal end portion of the wellbore.

16. The method of seismic investigation of the earth of claim 15, further comprising receiving a reflected portion of the seismic s-wave at a seismic sensor located in the drill string.

17. The method of seismic investigation of the earth of claim 14, wherein receiving a reflected portion of the seismic wave comprises receiving the reflected portion of the seismic wave along an axis coincident with the terminal end portion of the wellbore.

18. The method of seismic investigation of the earth of claim 14, wherein the seismic wave is a first seismic wave, the axis is a first axis, and wherein the method further comprises imparting a second seismic wave into the geologic formation along a second axis, the second axis not coincident with the central axis of the terminal end portion of the wellbore.

19. The method of seismic investigation of the earth of claim 14, wherein imparting a seismic wave into the geologic formation comprises using a vibratory hammer oscillating axially with respect to the wellbore to impart the seismic wave into the geologic formation.

20. The method of seismic investigation of the earth of claim 14, wherein imparting a seismic wave into the geologic formation comprises imparting a seismic p-wave into the geologic formation.

21. The method of seismic investigation of the earth of claim 14, further comprising directly engaging a seismic source with a sidewall of the wellbore.

22. A system for seismic investigation of the earth, comprising:

a drill string;

a vibratory tool in the drill string; and

one or more seismic sensors.

23. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool includes an outer casing surrounding a movable mass to oscillate along a longitudinal axis of the drill string.

24. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool vibrates axially, radially, orbitally, or in any combination thereof.

25. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool is adjacent to the drill bit.

26. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool is located at least ten meters from the drill bit.

27. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool is one of a plurality of vibratory tools, the vibratory tools positioned along the drill string.

28. The system for seismic investigation of the earth of claim 22, wherein the vibratory tool is clamped to the formation via mechanical, hydraulic, or electrical means.

29. The system for seismic investigation of the earth of claim 22, wherein the drill string is clamped to the formation via mechanical, hydraulic, or electrical means.

30. The system for seismic investigation of the earth of claim 29 wherein the drill string is clamped to the formation at multiple locations.

31. A method of seismic investigation of the earth, comprising:

drilling a wellbore into the earth;

activating a vibratory tool on the drill string to impart seismic waves into the earth; and receiving a portion of the seismic waves imparted to the earth at one or more seismic sensors.

32. The method of seismic investigation of the earth of claim 31, further comprising generating seismic waves using the vibratory tool in direct contact with the formation through a drill bit.

33. The method of seismic investigation of the earth of claim 31, further comprising generating seismic waves using the vibratory tool in indirect contact with the formation, the seismic waves traveling from the vibratory tool, through the drilling fluid, and into the formation.

34. The method of seismic investigation of the earth of claim 31, wherein receiving the portion of the seismic waves imparted to the earth includes receiving the portion of the seismic waves at one or more sensors located on a surface of the earth.

35. The method of seismic investigation of the earth of claim 31, wherein receiving the portion of the seismic waves imparted to the earth includes receiving the portion of the seismic waves at one or more sensors located in the drill string.

36. The method of seismic investigation of the earth of claim 31, wherein receiving the portion of the seismic waves imparted to the earth includes receiving the portion of the seismic waves at one or more sensors located in an adjacent wellbore.

37. The method of seismic investigation of the earth of claim 31, wherein activating the vibratory tool on the drill string to impart seismic waves into the earth occurs while the drill string is off-bottom in the wellbore.

38. The method of seismic investigation of the earth of claim 31, wherein receiving the portion of the seismic wave occurs while drilling the wellbore.

39. The method of seismic investigation of the earth of claim 31, wherein receiving the portion of the seismic wave occurs while re-entering the wellbore after drilling.

40. The method of seismic investigation of the earth of claim 31, wherein the vibratory tool includes a movable mass within an outer casing and wherein oscillating the vibratory tool comprises oscillating the moveable mass axially with respect to the wellbore.

41. The method of seismic investigation of the earth of claim 40, wherein actuating the moveable mass comprises causing the moveable mass to rotate with respect to the outer casing.

42. The method of seismic investigation of the earth of claim 41, wherein a first end of the vibratory tool includes a first plurality of magnets, a second end of the vibratory tool includes a second plurality of magnets, a first end of the moveable mass includes a first magnet, and a second end of the moveable mass includes a second magnet, and wherein rotation of the moveable mass with respect to the outer casing causes the first plurality of magnets to interact with the first magnet and the second plurality of magnets to interact with the second magnet to cause the moveable mass to oscillate axially with respect to the wellbore within the outer casing

43. The method of seismic investigation of the earth of claim 41, wherein the vibratory tool further includes a central shaft coupled to a first end of the vibratory tool and coupled to a second end of the vibratory tool, wherein the moveable mass is mounted on the central shaft, and wherein causing the moveable mass to rotate with respect to the outer casing comprises using a motor mounted on and rotationally fixed with respect to the central shaft to cause the moveable mass to rotate with respect to the outer casing.