Drill cutting lag time monitoring

Abstract

A method for estimating a cuttings lag time during a drilling operation includes circulating a drilling fluid in a wellbore for drilling. A plurality of radio frequency identification device (RFID) tags and / or colored dyes are introduced into a circulating drilling fluid while drilling. A time of arrival of the RFID tag or colored dye at the ground is evaluated to estimate a cuttings lag time.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 503,752, entitled “DRILL CUTTINGS LAG TIMEMONITORING”, filed May 23, 2023, the disclosure of which is incorporated herein by reference. Background Technology

[0003] Drilling fluid (mud) is pumped downhole while drilling into the underground wellbore. The fluid flows from the drill string at the drill bit, creating an upward flow through the wellbore annulus that carries drill cuttings to the surface. The fluid and drill cuttings are typically examined at the surface to assess the formation through which they exited the wellbore. The depth at which drill cuttings are generated can be determined from depth logging generated during drilling and the drill cuttings lag time (the time it takes for the cuttings to reach the surface).

[0004] Theoretical lag times can be calculated based on the well architecture (e.g., including wellbore and drill string diameters) and fluid flow rates. However, in practice, theoretical lag times do not provide a consistently accurate measurement of drill cuttings lag times. Therefore, drilling operators typically perform occasional lag time measurements during drilling. For example, a drilling operator may introduce particles (e.g., rice grains) into the drilling fluid and estimate the lag time based on the time it takes for the particles to reach the surface.

[0005] While the methods described above for estimating drill cuttings lag time may sometimes be commercially available, there is room for further improvement. For example, identifying introduced particles in the drill cuttings within the arriving drilling fluid can be difficult, potentially leading to errors in the estimated lag time. Furthermore, known methods are time- and labor-intensive. Improved lag time measurement methods are needed in industry. Attached Figure Description

[0006] To gain a more complete understanding of the disclosed subject matter and its advantages, reference is now made to the following description in conjunction with the accompanying drawings:

[0007] Figure 1 An example drilling rig is depicted, including the disclosed system for estimating the lag time of drill cuttings during drilling operations.

[0008] Figure 2 A flowchart is shown for an example method for estimating the lag time of drill cuttings during drilling operations.

[0009] Figure 3 An example of a packaged radio frequency identification (RFID) tag is depicted.

[0010] Figure 4A flowchart depicting another example method for estimating cuttings lag time during a drilling operation is depicted.

[0011] Figure 5 A flowchart depicting yet another example method for estimating cuttings lag time during a drilling operation without having to use RFID tags is depicted. DETAILED DESCRIPTION

[0012] Embodiments of the present disclosure include systems and methods for estimating cuttings lag time during a drilling operation. In one example embodiment, the disclosed method includes circulating drilling fluid in a wellbore while drilling. A plurality of radio frequency identification device (RFID) tags are introduced into the circulating drilling fluid while drilling. At least a portion of the plurality of RFID tags are detected in the circulating drilling fluid using first and second RFID readers, where the first RFID reader detects the RFID tags before the tags travel uphole through the wellbore annulus, and the second RFID reader detects the RFID tags after the tags travel uphole through the wellbore annulus at a surface location. A difference in detection times for selected ones of the RFID tags detected at the first and second RFID readers is evaluated to estimate the cuttings lag time.

[0013] Another example embodiment includes introducing a colored liquid tracer into the circulating drilling fluid while drilling. The colored liquid tracer is introduced into the downflowing drilling fluid in a downhole tool located above the drill bit. The colored liquid tracer can include a water-soluble dye and can be formulated to adhere to the cuttings such that it produces colored cuttings as it passes through the drill bit into the wellbore annulus. For example, the colored cuttings are detected at the surface using an optical sensor. A detection time for the colored cuttings to reach the surface is evaluated to estimate the cuttings lag time.

[0014] The theoretical lag time can generally be calculated from the flow rate of the drilling fluid and the geometry of the wellbore (e.g., including the depth of the wellbore, the diameter of the wellbore section, and the diameter of the drill string section). While the theoretical lag time can be useful in some operations, it is prone to error, particularly in operations where there is wellbore sloughing or washout, pumping difficulties, and / or hole cleaning difficulties. Such difficulties can result in significant lag time errors and corresponding cuttings depth errors (e.g., up to and over 50 meters of depth error). While methods for measuring lag time are known, these measurement methods tend to be manually intensive and prone to operator error (e.g., requiring an operator to visually identify particulate matter added to the circulating drilling fluid). Improved lag time measurement methods are needed in the industry.

[0015] Figure 1An example rig 20 including a system for estimating while-drilling cuttings lag time is depicted. Rig 20 can be positioned above a subterranean formation (not shown). Rig 20 can include, for example, a derrick and hoisting equipment (also not shown) for raising and lowering a drill string 30, as shown, which extends into a borehole 40 and includes, for example, a drill bit 32 and one or more downhole measurement tools 38 (e.g., logging-while-drilling or measurement-while-drilling tools) in a bottom hole assembly (BHA) above drill bit 32. Suitable drilling systems (e.g., including drilling, steering, logging, and other downhole tools) are well known in the art.

[0016] Rig 20 also includes a surface system 50 for controlling the flow of drilling fluid (e.g., for drilling borehole 40) used on the rig. In the depicted example rig, drilling fluid 35 is pumped downhole (as depicted at 92), for example, via a conventional mud pump 57. Drilling fluid 35 can be pumped to drill string 30, for example, through a standpipe 58 and mud hose 59 in the line. Drilling fluid 35 typically flows out of drill string 30 at or near drill bit 32 and creates an upward mud flow 94 through the borehole annulus 42 (the annular space between the drill string and the borehole wall). Drilling fluid 35 then flows through a return conduit 52 to a mud pit system 56. It should be understood that the terms drilling fluid and mud are used synonymously herein.

[0017] Circulating drilling fluid 35 is intended to perform many functions while drilling. One of the intended functions of the drilling fluid is to carry cuttings 45 generated while drilling to the surface (in upward flow 94). Cuttings 45 are typically removed from the returning mud via shale shakers 55 (or other similar solids control equipment) in the return conduit (e.g., immediately upstream of mud pit 56). Drilling fluid 35 is typically reused and recirculated downhole. Formation gases released during drilling can also migrate to the surface in the circulating drilling fluid. These gases are typically removed from the fluid, for example, via a degasser or gas trap 54 located in or near a manifold box 53, which in the example description is immediately upstream of shale shakers 55. Cuttings 45 and gases are typically examined at the surface to evaluate the formation through which the borehole was drilled. The depth at which cuttings and / or gases are generated can be determined from depth logs and lag times (the time it takes for cuttings to reach the surface) generated while drilling.

[0018] With continued reference to Figure 1The example rig 20 also includes at least one radio frequency identification device (RFID) reader 80A, 80B deployed in the surface system 50. In the depicted example, the rig includes a first RFID reader 80A and a second RFID reader 80B, where the first RFID reader 80A can be deployed near the injection port 51 located, for example, near the top drive or between the standpipe 58 and the mud hose 59 (or between the mud hose and the top drive). It should also be noted that, Figure 1 A plurality of RFID tags 85 injected into the drilling fluid at the injection port 51 are also depicted. The second RFID reader 80B can be deployed near the shale shaker 55, for example, at the exit point of the shale shaker 55. As described in greater detail below, the surface system 50 can optionally further include an optical detector 82 configured to detect a dye and / or colored tracer added to the circulating drilling fluid. The optical detector can be deployed, for example, near the degasser 54 upstream of the shale shaker 55.

[0019] The rig 20 can also include a control room 65 (e.g., a lab trailer or other facility including one or more instruments suitable for making various physical and chemical measurements of drill cuttings and formation gases in the drilling fluid). In addition, the control room 65 can include a computer system 70 configured to estimate a cuttings lag time, for example, using input from the RFID readers 80A, 80B and / or the optical detector 82, as described in greater detail below. The computer system 70 can include one or more processors (e.g., microprocessors) that can be connected to one or more data storage devices (e.g., hard drives or solid state memory) and well-known user interfaces. The computer system can also include or be configured to execute processor executable instructions stored in the data storage devices. The executable instructions can be configured to receive input from the RFID readers, for example, to estimate the cuttings lag time.

[0020] Figure 2A flowchart depicting one example method 100 for estimating cuttings lag time during a drilling operation is described. The method includes circulating drilling fluid in a wellbore while drilling the wellbore at 102. For example, the drilling can include rotary drilling in which a top drive is used to rotate the drill string from the surface or a mud motor is used to rotate the BHA. At 104, an RFID tag (e.g., an ultra-high frequency RFID tag) is introduced into the circulating drilling fluid while drilling. The RFID tag can be introduced, for example, at a fluid entry port located between the riser and the drill string. In such an embodiment, the RFID tag is transported down the drill string by the drilling fluid, through a nozzle in the drill bit, and brought back to the surface with the cuttings in the wellbore annulus. In another embodiment, the RFID tag can be introduced into the wellbore annulus downhole (e.g., from the BHA). For example, a measurement-while-drilling (MWD) tool or other downhole tool can be configured to introduce the RFID tag directly into the upward flowing drilling fluid in the wellbore annulus. In an example embodiment, a command from the surface can trigger the RFID tag to be released into the annulus. The release time can then be communicated to the surface (e.g., via conventional telemetry techniques).

[0021] With continued reference to Figure 2 The RFID tag can be detected in the flowing drilling fluid at 106 using one or more RFID readers. For example, in embodiments in which the RFID tag is injected at a fluid entry port, the RFID tag can be detected at a first RFID reader located at the injection port (or just downstream thereof) and a second RFID reader located at the shale shaker. In embodiments in which the RFID tag is injected downhole, the RFID tag can be detected at a first RFID reader located in the BHA (e.g., just uphole of the injection location) and a second RFID reader located at the shale shaker. Alternatively, the RFID tag can be detected at only a single RFID reader located at the shale shaker. The detection events (e.g., the timestamps of the various detected RFID tags) can then be evaluated at 108 to estimate the cuttings lag time. For example, the cuttings lag time can be estimated to equal or be related to the average detection time difference between the first RFID reader and the second RFID reader. In embodiments in which the RFID tag is introduced at the surface, the cuttings lag time can be estimated to equal the average detection time difference minus an estimated or calculated time taken by the tag to travel through the drill string. In embodiments in which the RFID tag is introduced into the wellbore annulus, the cuttings lag time can be estimated to equal the average detection time.

[0022] With continued reference to Figure 2, it should be understood that the RFID tags can be single-use or multi-use. In embodiments that use single-use RFID tags, it can be advantageous to inject (and detect) a large number of RFID tags to ensure that a sufficient number of tags survive the trip through the drill bit jet and the drill bit's interaction with the formation. In embodiments where the tags are reused (multi-use), a smaller number of RFID tags can be needed. Multi-use tags can be particularly suitable for operations that introduce the RFID tags downhole (as the tags do not need to traverse the drill bit jet and the drill bit's cutting region of interaction with the formation).

[0023] Those of ordinary skill in the art will readily appreciate that RFID systems generally use high frequency electromagnetic waves to communicate with RFID tags. Such RFID systems generally include RFID tags that include RF transponders and RFID readers that include RF transmitters and RF receivers. The RFID readers can be configured to transmit radio frequency pulses and receive corresponding RF signals from nearby RFID tags. Upon receiving or being triggered by the transmitted RF pulses, the RFID tags can be configured to transmit a short RF response signal, e.g., including a tag identification number. While the RFID tags can be active (e.g., include a battery) or passive (configured to receive power from the transmitted RF pulses), it should be understood that passive RFID tags can be advantageously used in the disclosed embodiments (and can be preferred as they do not introduce a battery into the drilling fluid).

[0024] In example (and sometimes advantageous) embodiments, the RFID tags can be encapsulated in an encapsulating material. Figure 3 One such example encapsulated RFID tag 85' is depicted. In the depicted example, commercially available RFID transponders 87 (e.g., including an RFID chip in a plastic coating) are enclosed or embedded in an encapsulating material 90. In example embodiments, the encapsulating material 90 can be selected so that the tags 85' have a density similar to that of the drill cuttings. Exemplary non-limiting encapsulating materials can include cement, epoxy, ceramic, etc. For example, the tags 85' can be manufactured so that they have a size and weight similar to that of an average drill cutting particle (and thus a similar density), with the goal that the tags can be carried to the surface at a similar rate to the drill cuttings. Thus, depending on the formation lithology being drilled, exemplary RFID tags can have a density in the range of 1 g / cm 3 to 5 g / cm 3 (e.g., 1.5 g / cm 3 to 3 g / cm 3The density is within the range of [specific parameters]. The RFID tag 85' may also optionally include a permanent magnet element 88, which allows the tag 85' to be retrieved at the ground (e.g., separating at least a portion of the RFID tag from drill cuttings at a shale vibrating screen). The recovered RFID tag can then be reused at a later time. The encapsulation of the RFID transponder also reduces the likelihood of the tag 85' being damaged or destroyed by the movement of the drill bit.

[0025] It should be understood that drill cuttings have a wide range of particle sizes generated during drilling operations. Furthermore, it should be understood that the rate at which a particular drill cutting particle is carried to the surface can depend on the particle size (and weight). For example, larger (heavier) particles can be carried at a lower speed (and therefore have a longer lag time) compared to smaller (lighter) particles. For this purpose, it may be advantageous to use RFID tags with a size distribution (e.g., encapsulated RFID tags 85'). For example, in one embodiment, first and second RFID tags with corresponding first and second (large and small) sizes can be used. In another embodiment, first, second, and third RFID tags with corresponding first, second, and third (large, medium, and small) sizes can be used. In operations employing such multi-size RFID tags, in method 100 ( Figure 2 The estimated lag time range or distribution is calculated from 108 points. For example, different lag times can be estimated for small, medium, and large RFID tags (corresponding to small, medium, and large drill cuttings). In an example embodiment, the RFID tag may have a diameter ranging from 0.1 mm to 10 mm (e.g., from 0.2 mm to 2 mm). In an example embodiment where the RFID tag has first and second (large and small) sizes, the large RFID tag may have a diameter greater than 2 mm, while the small RFID tag may have a diameter less than 1 mm.

[0026] Figure 4A flowchart of another example method 120 for estimating drill cuttings lag time during drilling operations is depicted. This method includes, at 122, for example, circulating drilling fluid in the wellbore while drilling, as described above. At 124, a liquid tracer is introduced into the circulating drilling fluid. The tracer may be miscible with the mud and may have a density similar to the drilling fluid to avoid buoyancy distortion in the measurement. The tracer may also be viscous (e.g., more viscous than the drilling fluid) to minimize its dispersion in the mud flow. The tracer may include colored tracers, for example, as disclosed in commonly assigned U.S. Patent 6,729,400. At 126, an RFID tag (e.g., an UHF RFID tag) is introduced into the wellbore, for example, along with or shortly after the introduction of the liquid tracer. The liquid tracer and the RFID tag may be introduced at 124 and 126, for example, at a fluid inlet port located between the mud hose and the drill string or downhole (e.g., from the BHA) into the wellbore annulus.

[0027] Liquid tracers can be detected in the drilling fluid at point 130 at the surface (after penetrating the wellbore) using, for example, an optical detector (such as a Schlumberger optical fluid analyzer). Upon detection of the liquid tracer, a second RFID reader can be triggered (by detecting the liquid tracer) to detect RFID tags at point 132 (e.g., at a shale vibrating screen). The triggering of the second RFID reader can be manual or automatic. The detection event (e.g., the timestamps of the individual detected RFID tags) can then be evaluated at point 134 to estimate the drill cuttings lag time as described above.

[0028] It should be understood that liquid tracers can advantageously include dyes selected for compatibility with common water-based drilling fluids and formation (native) water. The advantageous dyes are stable at the expected wellbore temperature and do not adversely affect any physical properties of the drilling fluid. Furthermore, the dyes can be advantageously selected to have a color easily detectable by optical detectors (e.g., blue). Liquid tracers can be added at virtually any suitable concentration to provide a dye concentration sufficient to color the drilling fluid (e.g., dye concentrations in the range of about 200 to 2000 mg / L). Advantageous liquid tracers may include Acid Blue #1 dye (EMI-600).

[0029] The tracer itself can provide an independent measurement of lag time (e.g., fluid lag time). Measuring the time difference between the moment the drilling fluid is introduced and the time of dye detection (e.g., using an optical detector) allows the operator to estimate the total travel time of the liquid phase of the drilling fluid. Cuttings transported back to the surface by the mud (e.g., drill cuttings) typically lag behind this fluid front. RFID tags can be matched to drill cuttings density (as described above) and can be expected to experience similar delays (so that they can arrive after the liquid tracer, even if they are introduced into the drilling fluid at the same time).

[0030] Figure 5 Another example method 140 is described for estimating the lag time of drill cuttings during drilling operations without the need for RFID tags. The method includes, at 142, for example, circulating drilling fluid in the wellbore while drilling, as described above. At 144, a liquid tracer is introduced into the circulating drilling fluid in the BHA. The liquid tracer may be deployed in a chamber within a downhole tool (such as an MWD or LWD tool) above the drill bit and may be introduced into the downward-flowing drilling fluid in the BHA. The liquid tracer and dye can rapidly traverse the drill bit nozzles and contact the freshly cut drill cuttings. The dye may be selected or formulated to have an affinity for the drill cuttings (and thus adsorb or otherwise adhere to them), thereby coloring the drill cuttings (or altering their appearance). It should be understood that the introduction of the liquid carrier into the drilling fluid can be triggered by a surface command (e.g., a pressure pulse or a change in drill string rotation rate).

[0031] Method 140 may further include detecting the arrival of colored drill cuttings at the surface (e.g., at a shale vibrating screen) at 146, and estimating the drill cuttings lag time at 148 from the difference between the arrival time of the colored drill cuttings and the time of introduction of the liquid tracer. The introduction time may be obtained from the downhole tool, for example, via conventional telemetry transmission, or may be considered as the time of sending the command plus a predetermined delay.

[0032] In some exemplary embodiments, an RFID tag may be introduced into the drilling fluid along with a liquid tracer at point 144. The RFID tag can then be detected at the surface, for example, as described above. It should be understood that the use of a liquid tracer and an RFID tag can advantageously provide a redundant estimate of the drill cuttings lag time.

[0033] It should be understood that this disclosure includes many embodiments. These embodiments include, but are not limited to, the following embodiments.

[0034] In a first embodiment, a method for estimating the cuttings lag time during drilling operations includes: circulating drilling fluid in the wellbore while drilling, the circulating drilling fluid traveling downhole through a drill string and uphole through the wellbore annulus, the circulating drilling fluid carrying cuttings generated by the drilling to a surface location; introducing a plurality of radio frequency identification (RFID) tags into the circulating drilling fluid during drilling; detecting RFID tags among the plurality of RFID tags in the circulating drilling fluid using a first RFID reader and a second RFID reader, the first RFID reader detecting RFID tags among the plurality of RFID tags before the RFID tags travel uphole through the wellbore annulus, the second RFID reader detecting RFID tags among the plurality of RFID tags at the surface location after the RFID tags among the plurality of RFID tags have traveled uphole through the wellbore annulus; and evaluating the detection time difference of selected RFID tags among the RFID tags detected at the first RFID reader and the second RFID reader to estimate the cuttings lag time.

[0035] The second embodiment may include the first embodiment, wherein a plurality of RFID tags are introduced into the drilling fluid at a fluid inlet port located at a ground position upstream of the drill string, and a first RFID reader is located near and downstream of the fluid inlet port.

[0036] The third embodiment may include any one of the first to second embodiments, wherein the plurality of RFID tags are introduced into the wellbore annulus through a downhole tool in the drill string, and a first RFID reader is located in the drill string.

[0037] The fourth embodiment may include any one of the first to third embodiments, wherein each of the plurality of RFID tags includes an RFID transponder embedded in the encapsulation material.

[0038] The fifth embodiment may include the fourth embodiment, wherein each of the plurality of RFID tags comprises 1.5 g / cm 3 Approximately 3 g / cm 3 Density within the range.

[0039] The sixth embodiment may include any one of the fourth to fifth embodiments, wherein each of the plurality of RFID tags includes a permanent magnet; and the method further includes separating at least a portion of the plurality of RFID tags from the drill cuttings at the shale vibrating screen.

[0040] The seventh embodiment may include any one of the fourth to sixth embodiments, wherein the plurality of RFID tags includes a first plurality of RFID tags and a second plurality of RFID tags; and each of the first plurality of RFID tags has a larger diameter than the second plurality of RFID tags.

[0041] The eighth embodiment may include any one of the first to seventh embodiments, and further includes introducing a colored liquid tracer into the circulating drilling fluid before or together with the plurality of RFID tags; and detecting the colored liquid tracer at the ground location before detecting an RFID tag among the plurality of RFID tags with a second RFID reader.

[0042] The ninth embodiment may include the eighth embodiment, wherein an optical detector is used to detect the colored liquid tracer at the ground location; and after the colored liquid tracer is detected at the ground location, a second RFID reader is automatically triggered to detect RFID tags among the plurality of RFID tags.

[0043] The tenth embodiment may include any of the eighth to ninth embodiments, and further includes evaluating the detection time of the colored liquid tracer at the ground location to estimate the fluid hysteresis time.

[0044] In an eleventh embodiment, a system for estimating drill cuttings lag time during drilling operations includes: a surface system configured to circulate drilling fluid in the wellbore during drilling, the circulating drilling fluid traveling downhole through the drill string and uphole through the wellbore annulus, the circulating drilling fluid carrying drill cuttings generated by the drilling to the surface location; a plurality of radio frequency identification (RFID) tags configured to be introduced into the circulating drilling fluid; a first RFID reader and a second RFID reader, the first RFID reader being configured to... After the ID tag is introduced into the circulating drilling fluid and before the RFID tag is carried by the drilling fluid through the wellbore annulus to the surface, a second RFID reader in the RFID reader is deployed at the surface location in the surface system and is configured to detect the RFID tag after the RFID tag is carried by the drilling fluid through the wellbore annulus to the surface; and a processor configured to evaluate the difference in detection time between selected RFID tags detected at the first RFID reader and the second RFID reader to estimate the drill cuttings lag time.

[0045] The twelfth embodiment may include the eleventh embodiment, wherein the surface system includes a fluid inlet port configured to introduce an RFID tag; the system includes a downhole tool configured to introduce the RFID tag into the wellbore annulus, the downhole tool further including a first RFID reader.

[0046] The thirteenth embodiment may include any one of the eleventh to twelfth embodiments, wherein each of the plurality of RFID tags includes an RFID transponder embedded in an encapsulation material, and the density is 1.5 g / cm³. 3 Approximately 3 g / cm 3 Within the range.

[0047] The fourteenth embodiment may include the thirteenth embodiment, wherein the plurality of RFID tags includes a first plurality of RFID tags and a second plurality of RFID tags; and each of the first plurality of RFID tags has a larger diameter than the second plurality of RFID tags.

[0048] The fifteenth embodiment may include any one of the eleventh to fourteenth embodiments, and further includes a colored liquid tracer comprising a dye and configured to be introduced into the circulating drilling fluid before or together with the plurality of RFID tags; and an optical detector configured to detect the colored liquid tracer at the ground location.

[0049] In a sixteenth embodiment, a method for estimating the lag time of drill cuttings during drilling operations includes: circulating drilling fluid in the wellbore during drilling, the circulating drilling fluid traveling downhole through a drill string and uphole through the wellbore annulus, the circulating drilling fluid carrying drill cuttings generated by the drilling to a surface location; introducing a colored liquid tracer into the circulating drilling fluid during drilling, the colored liquid tracer being introduced into the downward-flowing drilling fluid in a downhole tool located above the drill bit, the colored liquid tracer comprising a water-soluble dye and formulated to adhere to the drill cuttings such that the colored liquid tracer generates colored drill cuttings as it passes through the drill bit and enters the wellbore annulus; detecting the colored drill cuttings at the surface location; and evaluating the detection time of the colored drill cuttings to estimate the lag time of the drill cuttings.

[0050] The seventeenth embodiment may include the sixteenth embodiment, and further includes transmitting the time of introducing the colored liquid carrier into the circulating drilling fluid to the surface location; and wherein the evaluation includes evaluating the difference between the detection time of the colored drill cuttings and the time of introducing the colored liquid carrier into the circulating drilling fluid to estimate the drill cuttings lag time.

[0051] The eighteenth embodiment may include the seventeenth embodiment, wherein colored drill cuttings are automatically detected at a ground location using an optical detector.

[0052] The nineteenth embodiment may include any one of the sixteenth to eighteenth embodiments, wherein the water-soluble dye includes Acid Blue #1 (EMI-600).

[0053] The twentieth embodiment may include any one of the sixteenth to nineteenth embodiments, and further includes introducing a plurality of radio frequency identification (RFID) tags into a circulating drilling fluid having the colored liquid tracer; using an RFID reader to detect RFID tags among the plurality of RFID tags at the ground location; and evaluating the detection time of the RFID tags among the plurality of RFID tags to estimate another drill cuttings lag time.

[0054] Although drill cuttings lag time monitoring has been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

Claims

1. A method for estimating cuttings lag time during a drilling operation, the method comprising: circulating a drilling fluid in a wellbore while drilling the wellbore, the circulating drilling fluid traveling downhole through a drill string and uphole through a wellbore annulus, the circulating drilling fluid carrying drill cuttings generated by the drilling to a surface location; introducing a plurality of radio frequency identification device (RFID) tags into the circulating drilling fluid while drilling; detecting RFID tags of the plurality of RFID tags in the circulating drilling fluid using a first RFID reader and a second RFID reader, the first RFID reader detecting RFID tags of the plurality of RFID tags before the RFID tags have traveled uphole through the wellbore annulus, the second RFID reader detecting RFID tags of the plurality of RFID tags after the RFID tags have traveled uphole through the wellbore annulus at the surface location; and evaluating a difference in detection times of selected RFID tags of the detected RFID tags at the first RFID reader and the second RFID reader to estimate the cuttings lag time.

2. The method of claim 1, wherein the plurality of RFID tags are introduced into the drilling fluid at a fluid entry port at a surface location upstream of the drill string, and the first RFID reader is located proximate and downstream of the fluid entry port.

3. The method of claim 1, wherein the plurality of RFID tags are introduced into the wellbore annulus by a downhole tool in the drill string, and the first RFID reader is located in the drill string.

4. The method of claim 1, wherein each of the plurality of RFID tags includes an RFID transponder embedded in an encapsulating material.

5. The method of claim 4, wherein each of the plurality of RFID tags comprises a density in a range from 1.5 g / cm 3 to about 3 g / cm 3 .

6. The method of claim 4, wherein: each of the plurality of RFID tags includes a permanent magnet; and the method further comprises separating at least a portion of the plurality of RFID tags from the drill cuttings at a shale shaker.

7. The method of claim 4, wherein: the plurality of RFID tags includes a first plurality of RFID tags and a second plurality of RFID tags; and the first plurality of RFID tags each have a greater diameter than the second plurality of RFID tags.

8. The method of claim 1, further comprising: introducing a colored liquid tracer into the circulating drilling fluid prior to or with the plurality of RFID tags; and detecting the colored liquid tracer at the surface location prior to detecting RFID tags of the plurality of RFID tags with the second RFID reader.

9. The method of claim 8, wherein: the colored liquid tracer is detected at the surface location using an optical detector; and the second RFID reader is automatically triggered to detect RFID tags of the plurality of RFID tags after the colored liquid tracer is detected at the surface.

10. The method of claim 8, further comprising: a detection time of the colored liquid tracer at the surface location is assessed to estimate a fluid lag time.

11. A system for estimating a cuttings lag time during a drilling operation, the method comprising: a surface system configured to circulate a drilling fluid in a wellbore while the wellbore is being drilled, the circulating drilling fluid carrying cuttings produced by the drilling to a surface location; a plurality of radio frequency identification device (RFID) tags configured for introduction into the circulating drilling fluid; a first RFID reader of the RFID readers configured to detect the RFID tags after the RFID tags are introduced into the circulating drilling fluid and before the RFID tags are carried by the drilling fluid through the wellbore annulus uphole, a second RFID reader of the RFID readers deployed in the surface system at the surface location and configured to detect the RFID tags after the RFID tags are carried by the drilling fluid through the wellbore annulus uphole; and a processor configured to assess a difference in detection times of selected ones of the RFID tags detected at the first and second RFID readers to estimate the cuttings lag time.

12. The system of claim 11, wherein: the surface system comprises a fluid inlet port configured for introduction of the RFID tags; or the system comprises a downhole tool configured to introduce the RFID tags into the wellbore annulus, the downhole tool further comprising the first RFID reader.

13. The system of claim 11, wherein each of the plurality of RFID tags comprises an RFID transponder embedded in an encapsulating material and has a density in a range of 1.5 g / cm 3 to about 3 g / cm 3 .

14. The system of claim 13, wherein: the plurality of RFID tags comprises a first plurality of RFID tags and a second plurality of RFID tags; and the first plurality of RFID tags each have a greater diameter than the second plurality of RFID tags.

15. The system of claim 11, further comprising: a colored liquid tracer comprising a dye and configured for introduction into the circulating drilling fluid before or with the plurality of RFID tags; and an optical detector configured to detect the colored liquid tracer at the surface location.

16. A method for estimating a cuttings lag time during a drilling operation, the method comprising: circulating a drilling fluid in a wellbore while the wellbore is being drilled, the circulating drilling fluid carrying cuttings produced by the drilling to a surface location; introducing a colored liquid tracer into the circulating drilling fluid while drilling, the colored liquid tracer being introduced into the downhole drilling fluid flowing downward in a downhole tool in a bottom hole assembly located above a drill bit, the colored liquid tracer including a water soluble dye and being formulated to adhere to drill cuttings such that the colored liquid tracer produces colored drill cuttings as the drill cuttings pass through the drill bit into the wellbore annulus; detecting the colored drill cuttings at the surface location; and evaluating a time of detection of the colored drill cuttings to estimate the cuttings lag time.

17. The method of claim 16, further comprising: communicating a time that the colored liquid carrier is introduced into the circulating drilling fluid to the surface location; and wherein the evaluating includes evaluating a difference between the time of detection of the colored drill cuttings and the time that the colored liquid carrier is introduced into the circulating drilling fluid to estimate the cuttings lag time.

18. The method of claim 17, wherein the colored drill cuttings are automatically detected at the surface location using an optical detector.

19. The method of claim 16, wherein the water soluble dye includes Acid Blue #1 (EMI-600).

20. The method of claim 16, further comprising: introducing a plurality of radio frequency identification device (RFID) tags into the circulating drilling fluid with the colored liquid tracer; detecting an RFID tag of the plurality of RFID tags at the surface location using an RFID reader; and evaluating a time of detection of the RFID tag of the plurality of RFID tags to estimate another cuttings lag time.

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