Logging-while-drilling tool with interleaved instruments

Logging-while-drilling (LWD) tools may include multiple instruments interleaved into a compact configuration in a single drill string section that may be capable of nuclear magnetic resonance, resistivity, porosity, gamma density measurements, or any combination thereof. For example, a LWD tool may include a drill collar section containing: a nuclear magnetic resonance (NMR) electronics module and an NMR sensor module interleaved with a nuclear source and at least one nuclear detector.

BACKGROUND

The present application relates to logging-while-drilling (LWD) tools with multiple instruments.

LWD tools are commonly used to measure properties of a surrounding formation while drilling a wellbore that penetrates the formation. Various configurations of LWD tools may include one or more instruments for measuring resistivity, porosity, formation bulk density, formation photoelectric factor, and the like. As more instruments are added to the LWD tool, additional length is required. For example, some LWD tools with multiple instruments have lengths of about eighteen meters and longer. This length constrains the trajectory of the drilling operations such that any turns or deviations in the wellbore must be configured to allow for the length of the LWD tool to pass through the wellbore.

One solution to shrinking the length of LWD tools is to incorporate fewer instruments in each LWD tool. However, this limits the amount and type of characteristics of the formation that can be assessed. Therefore, LWD tools implement different sensors on different drill collars, which significantly increases the total length and the total cost of the LWD tool. Because of the extended total length, the sensors in the different collars pass the sections of the formation at different times, thereby, causing depth synchronization problem when analyzing data acquired by different LWD sensors. Additionally, because drilling fluid infiltrates the surrounding formation over time and the measurements from each instrument is at a different time, the comparison of the data from different sensor becomes onerous.

Another design parameter of LWD tools is that the measurement principles of many LWD sensors require the transmitter(s) and receiver(s) (also referred to as source(s) and detector(s), respectively) to be spaced from each other for a finite length, which is often long length, in order to effectively sense for characteristics of the formation. Typically, two signals are considered for effective sensing: (1) a signal that penetrates into the formation and (2) a signal that directly travels from source to the detector without passing through the formation. To meet the requirements of formation penetration and the direct signal isolation, the length of the individual sensor may be longer than that is required to implement the physical size of the transmitters and receivers, electronics, and the direct signal isolation elements, which may leave empty drill collar space therebetween.

DETAILED DESCRIPTION

The present application relates to logging-while-drilling (LWD) tools with multiple instruments interleaved into a compact configuration. The interleaved LWD tools described herein may be capable of nuclear magnetic resonance, resistivity, porosity, and gamma density measurements by uniquely integrating the components of corresponding instruments into a single drill string section. As used herein, the term “drill string section” refers to a single drill pipe or like structure that may be coupled to other drill pipes to form a drill string. A typical drill pipe is about 27 to 32 feet long, but longer lengths up to about 45 feet may be produced.

The problems associated with the length of prior LSW tools may be addressed by interleaving two or more of the instruments in a LWD tool.

As used herein, the term “interleaved” refers to interspersing of components. For example, two interleaved instrument modules along a drill collar would describe a first instrument module being in at least two portions along the drill collar with the second instrument module (or a portion thereof) being positioned between the at least two portions of the first instrument module. By way of further example, a first instrument module (IN) may be interleaved with more than one additional module (AM1 and AM2), such that the first instrument module has at least two portions with the two additional modules situated between the portions of the first instrument module such that: IN-AM1-AM2-IN or IN-AM1-IN-AM2-IN, etc.

Many LWD tools require portions of the instruments be separated for accurate measurements and to mitigate interference. For example, a source and a detector may be spaced apart by ten feet or more. Additionally, drill string sections may be placed between individual LWD tools to mitigate source/detector interference between the two tools. Accordingly, a drill string with multiple LWD tools each housed in individual drill string sections has significant amounts of unused space and may span several hundred feet of the drill string. The interleaved configurations described herein have the components of two or more LWD tools positioned within a single drill string section (e.g., in a tubular less than about 45 feet long) in a way that mitigates interference between the components of each of the LWD tools.

FIG. 1provides an axial cross-sectional diagram of an exemplary LWD tool10with interleaved instruments in a single drill collar (or drill string) section12(e.g., having a length of about 27 to about 45 feet long), according to at least some embodiments described. The illustrated LWD tool10includes components for measuring nuclear magnetic resonance and porosity. Along the length of the drill collar section12are the following components: a nuclear magnetic resonance (NMR) electronics module14and an NMR sensor module16interleaved with a nuclear module18(e.g., a neutron module) (illustrated as a nuclear source20(e.g., a neutron source) and nuclear detectors22,24(e.g., neutron detectors)).

In the illustrated configuration ofFIG. 1, the first nuclear detector22is positioned closer to the nuclear source20than the second nuclear detector24. This configuration of two detectors22,24provides for near and far nuclear detectors, respectively, which enables a near-to-far signal ratio analysis that is less sensitive to environmental effects than a single detector.

FIG. 2provides an axial cross-sectional diagram of another exemplary LWD tool100with interleaved instruments in a single drill collar (or drill string) section110, according to at least some embodiments described. In the illustrated LWD tool100, several instrument components are included to allow for nuclear magnetic resonance, resistivity, porosity, and gamma density measurement capabilities. Along the length of the drill collar section110are the following components: a first resistivity receiver module132(illustrated as a first z-direction resistivity receiver112and a first x- or y-direction resistivity receiver114) gamma density module116, a nuclear magnetic resonance (NMR) electronics module118, an NMR sensor module120interleaved with a nuclear module136(illustrated as a nuclear source122and nuclear detectors124,126), and a second resistivity receiver module134(illustrated as a second z-direction resistivity receiver128and a second x- or y-direction resistivity receiver130).

The LWD tool100may preferentially have at least a portion of the NMR electronics module118, the NMR sensor module120, the first resistivity receiver module132, the second resistivity receiver module134, or a combination thereof disposed along the drill collar section110between the nuclear module136and the gamma density module116. For example, as illustrated inFIG. 2, the nuclear components122,124,126and the gamma density module116are positioned at opposite axial ends of the NMR components118,120to provide sufficient spacing (e.g., about 5 to about 7 feet spacing) to mitigate interference.

In some instances, the first z-direction resistivity receiver112and the first x- or y-direction resistivity receiver114are remote receivers for investigating deeper into the surrounding formation, while the second z-direction resistivity receiver128and the second x- or y-direction resistivity receiver130are medium depth receivers. As described further herein, antennae in the NMR sensor module120may be used to investigate the resistivity of the formation at shallow depths from the tool100. In some instances, each or the foregoing receivers112,114,128,130may be duplicated (i.e., have two of each of the receivers in the LWD tool100), so that signals from the two identical receivers increase the accuracy of the resistivity measurements. For example, the phases of the signals measured by the illustrated receivers112,114,128,130and the duplicate receivers may be subtracted to assess the resistivity of the surrounding formation. The duplicate set of receivers may be spaced about 5 to about 7 feet apart from the corresponding illustrated receivers112,114,128,130with the corresponding resistivity electronics positioned therebetween.

The LWD tool100may preferentially have at least a portion of the nuclear module136, the gamma density module116, or a combination thereof are disposed along the drill collar section110between the first resistivity receiver module132configured for deeper measurements of the surrounding formation and the NMR sensor module120. For example, as illustrated inFIG. 2the gamma density module116is disposed between the first resistivity receiver module132and the NMR sensor module120. As described further herein, the antennae in the NMR sensor module120may be used as RF transmitters where the resultant signals after interaction with the surrounding formation may be measured by the two resistivity receiver modules132,134. Placement of the first resistivity receiver module132further from the NMR sensor module120may allow for deeper investigation of the surrounding formation.

While the LWD tool100includes several instrument components, in alternate embodiments, portions of the LWD tool may be excluded. For example, one or both of the two resistivity receiver module132,134may be excluded from the LWD tool100. In another embodiment, the gamma density module116may be excluded from the LWD tool100. In yet other embodiments, one or both of the two resistivity receiver module132,134and the gamma density module116may be excluded from the LWD tool100.

FIG. 3provides an exploded isometric view of an exemplary NMR sensor module200suitable for use in an LWD tool, according to at least some embodiments described herein (e.g., as the NMR sensor module16or120ofFIGS. 1 and 2, respectively). As illustrated, the NMR sensor module200may be interleaved with a nuclear source232and nuclear detectors234,236. Moreover, the NMR sensor module200may include a magnet assembly that includes four magnets202,204,206,208arranged in series and used to acquire an NMR signal. The NMR sensor module200interleaved with a nuclear source232and nuclear detectors234,236is configured with the nuclear source232positioned between the central magnet204and the third magnet206, the first nuclear detector234positioned between the third magnet206and the fourth magnet208, and the second nuclear detector236positioned at the opposite end of the fourth magnet208from the first nuclear detector234.

A central magnet area210with a central magnet204creates a primarily axial component of a static magnetic field {right arrow over (B)}O1212, and two transversal dipole antennae214and218create RF magnetic fields {right arrow over (B)}RF1216and {right arrow over (B)}RF2220, respectively. Together, these magnetic fields212,216,220produced in the central magnet area210create a first sensitive volume222that extends into a surrounding formation adjacent to the LWD tool.

The NMR sensor module200may be further configured to create a second sensitive volume224using the poles of a first magnet202and the central magnet204, which result in the generation of a static magnetic field {right arrow over (B)}O2226and an NMR antennae228(illustrated as a longitudinal-dipole antennae) may generate an RF magnetic field {right arrow over (B)}RF3230.

As illustrated, the first sensitive volume222and second sensitive volume224extend to different depths of investigation, which may be achieved by using different RF excitation frequencies when generating the corresponding {right arrow over (B)}RF1216and {right arrow over (B)}RF2220and {right arrow over (B)}RF3230. Typically, the RF excitation frequency determined by the static magnetic field strength is in the range to 0.2 MHz to about 1 MHz. NMR experiments in sensitive volumes222,224may be run simultaneously or sequentially.

The NMR antennae214,218,228are preferably also used as resistivity transmitters to perform resistivity measurements.

FIG. 4provides a schematic diagram of an alternative configuration for a portion of an NMR sensor module300suitable for use in an LWD tool, according to one or more embodiments. As illustrated, the NMR sensor module300may be interleaved with a nuclear source340and nuclear detectors342,344. The illustrated portion of the NMR sensor module300depicts the central magnet204ofFIG. 3and extends through the nuclear components of the tool. The third and fourth magnets206,208ofFIG. 3are replaced inFIG. 4with a single third magnet338having a smaller diameter. The smaller diameter third magnet338may prove advantageous in allowing for placement of the first nuclear detector342radially adjacent to the third magnet338(i.e., disposed between the third magnet338and the wall of a drill collar string346). Similar toFIG. 3, the nuclear source340may be disposed between the central magnet204and the third magnet336, and the second nuclear detector344may be positioned at the opposite end of the third magnet336from the nuclear source340.

FIG. 5provides a schematic diagram of an alternative configuration for a portion of an NMR sensor module400suitable for use in a LWD tool, according to at least some embodiments described herein. As illustrated, the NMR sensor module400may be interleaved with a nuclear source448and nuclear detectors450,452. The illustrated portion of the NMR sensor module400depicts the central magnet204ofFIG. 3and extends through the nuclear components of the tool. The third and fourth magnets206,208ofFIG. 3are replaced inFIG. 5with a single third magnet454. As illustrated, a portion of the third magnet454may be removed to provide a smaller diameter portion456. As will be appreciated, the smaller diameter portion456of the third magnet454may allow placement of a first nuclear detector450in the volume removed from the third magnet454. Similar toFIG. 3, the nuclear source448is disposed between the central magnet204and the third magnet454, and the second nuclear detector452is positioned at the opposite end of the third magnet454from the nuclear source448.

FIG. 6depicts an isometric view of an alternative configuration for a central magnet area560of an NMR sensor module500that is suitable for use in a LWD tool, according to at least some embodiments described herein. The central magnet area560includes a central magnet566and one or more transverse dipole antennae (illustrated as two transverse dipole antennae562,564) similar in function to the two transversal dipole antennae214,218ofFIG. 3. The central magnet area560may further include two longitudinal dipole antennae568,570. The at least one transverse dipole antennae (illustrated as two longitudinal dipole antennae568,570), if connected in reverse polarity, make a monopole antenna that, in combination with the at least one of the two transverse dipole antennae562,564, enable unidirectional azimuthally selective measurements572. For example, the NMR excitation may be substantially axially symmetrical using either the transversal dipole antennae562,564or the monopole antenna, while the combination of axially symmetrical sensitivity transversal-dipole antenna and the axially symmetrical sensitivity monopole antenna responses enables azimuthally resolved measurements572. The monopole antenna generates a substantially radial RF magnetic field in a corresponding sensitive volume. Due to reciprocity, the same coil arrangement will have a radial sensitivity direction as illustrated inFIG. 7.

FIG. 7illustrates a polar plot of sensitivity of the monopole and transverse dipole antennae demonstrating its unidirectional azimuthal selectivity. The radial grid of the polar plot is a normalized magnetic field intensity (unitless). The angular dependent distance from the coordinate origin (the antennae) to the plotted sensitivity illustrates the azimuthal selectivity of the antenna arrangement ofFIG. 6. Therefore, a proper combination of the responses of each of the transverse dipole antennae562,564ofFIG. 6with the response of the monopole antenna (properly connected longitudinal dipole antennae568,570) ofFIG. 6can give either one of four possible directions covering all quadrants of the transversal plane. Rotation of the drill string while drilling causes an amplitude modulation of the azimuthally selective response and, therefore, an amplitude modulation of the NMR relaxation signal (e.g., a CPMG echo train). The amplitude modulation parameters are indicative of the azimuthal variations of the NMR properties (e.g., the NMR porosity variations).

In some embodiments, all NMR antennae562,564,568,570may be used as RF transmitters where the resultant signals after interaction with the surrounding formation may be measured by the two resistivity receiver modules132,134(FIG. 2). Further, the NMR antennae562,564,568,570themselves may be further used as receivers for measuring resistivity of the surrounding formation at shallow sensitive volumes. Additional receiver or transmitter antennae may be also used. The additional antennae may be placed on the same magnetic cores under the same protection sleeves as the NMR antennae562,564,568,570. Resistivity data can be obtained by processing signals from all resistivity receivers.

In some embodiments, the monopole antenna (properly connected longitudinal dipole antennae568,570ofFIG. 6) may be used in combination with the transverse dipole antennae562,564ofFIG. 6for shallow azimuthally selective resistivity measurements. The azimuthally selective resistivity measurements are obtained by combining impedance measurements for the monopole antenna and transverse dipole antennae562,564.

The nuclear measurements as well as the gamma density measurements in the corresponding tool are also azimuthally selective with essentially the same azimuthal selectivity direction as the NMR (as illustrated inFIG. 6) and the shallow resistivity measurements. Combined azimuthally selective NMR, resistivity, nuclear, and gamma density measurements may increase the accuracy of the formation evaluation. In particular, NMR azimuthal sensitive volumes are oriented substantially the same as the density sensor orientations. As such, the NMR may assist in determining whether a change of density is due to a change in the formation matrix or porosity. Additionally, the NMR measurements and analysis may enhance the nuclear correction models by indicating washout problems.

The LWD tools described herein may further include other components of a bottomhole assembly common to the oil and gas industry. For example, a caliper tool, a natural gamma ray tool, a rotating or non-rotating stabilizer, or a combination thereof may be included in any of the LWD tools described herein.

FIG. 8illustrates an exemplary drilling assembly700suitable for implementing the LWD tools described herein. It should be noted that whileFIG. 8generally depicts a land-based drilling assembly, those skilled in the art will readily recognize that the principles described herein are equally applicable to subsea drilling operations that employ floating or sea-based platforms and rigs, without departing from the scope of the disclosure.

As illustrated, the drilling assembly700may include a drilling platform702that supports a derrick704having a traveling block706for raising and lowering a drill string708. The drill string708may include, but is not limited to, drill pipe and coiled tubing, as generally known to those skilled in the art. A kelly710supports the drill string708as it is lowered through a rotary table712. A drill bit714is attached to the distal end of the drill string708and is driven either by a downhole motor and/or via rotation of the drill string708from the well surface. As the bit714rotates, it creates a wellbore716that penetrates various subterranean formations718. Along the drill string708, a LWD tool736described herein is included.

In the present application, the LWD tool736may be capable of NMR analysis of the subterranean formation718proximal to the wellbore716. The LWD tool736may transmit the measured data wired or wirelessly to a processor738at the surface. Transmission of the data is generally illustrated at line740to demonstrate communicable coupling between the processor738and the LWD tool736and does not necessarily indicate the path to which communication is achieved.

A pump720(e.g., a mud pump) circulates drilling fluid722through a feed pipe724and to the kelly710, which conveys the drilling fluid722downhole through the interior of the drill string708and through one or more orifices in the drill bit714. The drilling fluid722is then circulated back to the surface via an annulus726defined between the drill string708and the walls of the wellbore716. At the surface, the recirculated or spent drilling fluid722exits the annulus726and may be conveyed to one or more fluid processing unit(s)728via an interconnecting flow line730. After passing through the fluid processing unit(s)728, a “cleaned” drilling fluid722is deposited into a nearby retention pit732(i.e., a mud pit). While illustrated as being arranged at the outlet of the wellbore716via the annulus726, those skilled in the art will readily appreciate that the fluid processing unit(s)728may be arranged at any other location in the drilling assembly700to facilitate its proper function, without departing from the scope of the scope of the disclosure.

Chemicals, fluids, additives, and the like may be added to the drilling fluid722via a mixing hopper734communicably coupled to or otherwise in fluid communication with the retention pit732. The mixing hopper734may include, but is not limited to, mixers and related mixing equipment known to those skilled in the art. In other embodiments, however, the chemicals, fluids, additives, and the like may be added to the drilling fluid722at any other location in the drilling assembly700. In at least one embodiment, for example, there could be more than one retention pit732, such as multiple retention pits732in series. Moreover, the retention pit732may be representative of one or more fluid storage facilities and/or units where the chemicals, fluids, additives, and the like may be stored, reconditioned, and/or regulated until added to the drilling fluid722.

The processor738may comprise a portion of computer hardware used to implement the various illustrative blocks, modules, elements, components, methods, and algorithms for analyzing the measurements described herein. The processor738may be configured to execute one or more sequences of instructions, programming stances, or code stored on a non-transitory, computer-readable medium. The processor738can be, for example, a general purpose microprocessor, a microcontroller, a digital signal processor, an application specific integrated circuit, a field programmable gate array, a programmable logic device, a controller, a state machine, a gated logic, discrete hardware components, an artificial neural network, or any like suitable entity that can perform calculations or other manipulations of data. In some embodiments, computer hardware can further include elements such as, for example, a memory (e.g., random access memory (RAM), flash memory, read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM)), registers, hard disks, removable disks, CD-ROMS, DVDs, or any other like suitable storage device or medium.

Executable sequences described herein can be implemented with one or more sequences of code contained in a memory. In some embodiments, such code can be read into the memory from another machine-readable medium. Execution of the sequences of instructions contained in the memory can cause a processor738to perform the process steps to analyze the measurements described herein. One or more processors738in a multi-processing arrangement can also be employed to execute instruction sequences in the memory. In addition, hard-wired circuitry can be used in place of or in combination with software instructions to implement various embodiments described herein. Thus, the present embodiments are not limited to any specific combination of hardware and/or software.

As used herein, a machine-readable medium will refer to any medium that directly or indirectly provides instructions to the processor738for execution. A machine-readable medium can take on many forms including, for example, non-volatile media, volatile media, and transmission media. Non-volatile media can include, for example, optical and magnetic disks. Volatile media can include, for example, dynamic memory. Transmission media can include, for example, coaxial cables, wire, fiber optics, and wires that form a bus. Common forms of machine-readable media can include, for example, floppy disks, flexible disks, hard disks, magnetic tapes, other like magnetic media, CD-ROMs, DVDs, other like optical media, punch cards, paper tapes and like physical media with patterned holes, RAM, ROM, PROM, EPROM and flash EPROM.

Embodiments disclosed herein include Embodiment A, Embodiment B, and Embodiment C.

Embodiment A is a LWD tool comprising: a drill collar section containing: a nuclear magnetic resonance (NMR) electronics module and an NMR sensor module interleaved with a nuclear source and at least one nuclear detector.

Embodiment A may have one or more of the following additional elements in any combination: Element A1: the LWD tool further comprising: a gamma density module contained by the drill collar section; Element A2: the LWD tool further comprising: a resistivity receiver module contained by the drill collar section; Element A3: the LWD tool further comprising: a gamma density module and a resistivity receiver module contained by the drill collar section; Element A4: Element A3 and wherein the resistivity receiver module comprises a z-direction resistivity receiver and an x- or y-direction resistivity receiver, and wherein the z-direction resistivity receiver, the x- or y-direction resistivity receiver, the gamma density module, the NMR electronics module, and the NMR sensor module interleaved with the nuclear source and nuclear detectors are each contained in and axially positioned in order along the drill collar section; Element A5: Element A3 and wherein the resistivity receiver module comprises a z-direction resistivity receiver and an x- or y-direction resistivity receiver, and wherein the gamma density module, the NMR electronics module, the NMR sensor module interleaved with the nuclear source and nuclear detectors, the z-direction resistivity receiver, and the x- or y-direction resistivity receiver are each contained in and axially positioned in order along the drill collar section; Element A6: Element A3 and wherein at least a portion of the NMR electronics module, the NMR sensor module, the first resistivity receiver module, the second resistivity receiver module, or a combination thereof are axially disposed along the drill collar section between the nuclear source and the at least one nuclear detector and the gamma density module; Element A7: Element A1 or Element A3 and wherein the gamma density module is at least about five feet from the nuclear source and the at least one nuclear detector; Element A8: the LWD tool further comprising: a first resistivity receiver module, a gamma density module, and a second resistivity receiver module, wherein the first resistivity receiver module investigates sensitive volumes at a deeper depth into a surrounding formation as compared to the second resistivity receiver module; Element A9: Element A8 and wherein at least a portion of the nuclear source and the at least one nuclear detector, the gamma density module, or a combination thereof are disposed along the drill collar section between first resistivity receiver module and the NMR sensor module; Element A10: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet, a first nuclear detector, a fourth magnet, and a second nuclear detector; Element A11: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet having a first nuclear detector radially adjacent thereto, and a second nuclear detector, wherein the third magnet has a smaller diameter than the first magnet and the central magnet; and Element A12: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet having a first nuclear detector radially adjacent thereto, and a second nuclear detector, wherein a portion of the third magnet has a smaller diameter than the first magnet and the central magnet and the first nuclear detector is positioned radially adjacent to the portion.

By way of non-limiting example, exemplary combinations applicable to Embodiment A include: one of Elements A10-A12 in combination with one of Elements A1-A3 and optionally Element A7; one of Elements A10-A12 in combination with Element3and one of Elements A4-A6; one of Elements A10-A12 in combination with Element A7; one of Elements A10-A12 in combination with Element A8 and optionally Element A9; Elements A3 and A7 in combination with one of Elements A4-A6; and Element A1 in combination with Element A8.

Embodiment B is a LWD tool comprising: a drill collar section containing: a resistivity receiver module, a gamma density module, a nuclear magnetic resonance (NMR) electronics module, and an NMR sensor module interleaved with a nuclear source and at least one nuclear detector, wherein the NMR sensor module includes at least one transversal dipole antenna and a monopole antenna in a configuration for obtaining azimuthally selective NMR, resistivity, nuclear, and gamma density measurements.

Embodiment B may have one or more of the following additional elements in any combination: Element B1: wherein the resistivity receiver module comprises a z-direction resistivity receiver and a x- or y-direction resistivity receiver, and wherein the z-direction resistivity receiver, the x- or y-direction resistivity receiver, the gamma density module, the NMR electronics module, and the NMR sensor module interleaved with a nuclear source and nuclear detectors are each contained in and positioned in order axially along the drill collar section; Element B2: wherein the gamma density module is at least about five feet from the nuclear source and the at least one nuclear detector; Element B3: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet, a first nuclear detector, a fourth magnet, and a second nuclear detector; Element B4: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet having a first nuclear detector radially adjacent thereto, and a second nuclear detector, wherein the third magnet has a smaller diameter than the first magnet and the central magnet; Element B5: wherein the NMR sensor module is interleaved with the nuclear source and two nuclear detectors and comprises, in order axially along the drill collar section: a first magnet, a longitudinal-dipole antennae, a central magnet coupled to two transversal dipole antennae, the nuclear source, a third magnet having a first nuclear detector radially adjacent thereto, and a second nuclear detector, wherein a portion of the third magnet has a smaller diameter than the first magnet and the central magnet and the first nuclear detector is positioned radially adjacent to the portion.

By way of non-limiting example, exemplary combinations applicable to Embodiment B include: one of Elements B3-B5 in combination with Element B1 and one of Elements B3-B5 in combination with Element B2.

Embodiment C is a system comprising: a drill bit attached to the distal end of the drill string; a LWD tool disposed according to Embodiment A or Embodiment B (including each with any suitable combinations of corresponding Elements) along the drill string; and a pump operably connected to the drill string for circulating the drilling fluid through the drill string to an annulus defined by the drill string and the wellbore

While interleaved LWD tools are described herein in terms of “comprising” various components, the interleaved LWD tools can also “consist essentially of” or “consist of” the various components.