Drill cuttings LAG time monitoring

Abstract

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

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 503,752, entitled “DRILL CUTTINGS LAG TIME MONITORING” filed May 23, 2023, the disclosure of which is hereby incorporated herein by reference.BACKGROUND

[0002] Drilling fluid (mud) is pumped downhole while drilling a subterranean wellbore. The fluid emerges from the drill string at the drill bit and creates an upward flow through the wellbore annulus which carries drill cuttings to the surface. The fluid and cuttings are commonly examined at the surface to evaluate the formation layers though which the wellbore is drilled. The depth at which the cuttings were generated may be determined from the depth log generated while drilling and the cuttings lag time (the time it takes the cuttings to reach the surface).

[0003] A theoretical lag time may be calculated from the well architecture (e.g., including the wellbore and drill string diameters) and the fluid flow rate. However, in practice the theoretical lag time does not provide a consistently accurate measure of the cuttings lag time. As such, drilling operators commonly make occasional lag time measurements while drilling a well. For example, a drilling operator may introduce particulate (e.g., rice grains) into the drilling fluid and estimate the lag time based on the arrival time of the particulate at the surface.

[0004] While the above described methods for estimating cuttings lag time may at times be commercially serviceable, there is room for further improvement. For example, identifying the introduced particulate amidst the drill cuttings in the arriving drilling fluid can be difficult such that the estimated cuttings lag time may be subject to error. Moreover, known methods are time and labor intensive. There is a need in the industry for improved lag time measurement methods.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] For a more complete understanding of the disclosed subject matter, and advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0006] FIG. 1 depicts an example drilling rig including a disclosed system for estimating the cuttings lag time during a drilling operation.

[0007] FIG. 2 depicts a flow chart of one example method for estimating the cuttings lag time during a drilling operation.

[0008] FIG. 3 depicts one example of an encapsulated radio frequency identification device (RFID) tag.

[0009] FIG. 4 depicts a flow chart of another example method for estimating the cuttings lag time during a drilling operation.

[0010] FIG. 5 depicts a flow chart of still another example method for estimating the cuttings lag time during a drilling operation without necessarily using RFID tags.DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure include systems and methods for estimating a drill cuttings lag time during a drilling operation. In one example embodiment, a disclosed method includes circulating drilling fluid in a wellbore while drilling. A plurality of radio frequency identification device (RFID) tags is 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 in which the first RFID reader detects the RFID tags prior to the tags traveling uphole through the wellbore annulus and the second RFID reader detects the RFID tags at the surface location after they have traveled uphole through the wellbore annulus. Differences in the detection times of selected ones of the detected RFID tags at the first RFID reader and the second RFID reader are evaluated to estimate the drill cuttings lag time.

[0012] Another example embodiment includes introducing a colored liquid tracer into the circulating drilling fluid while drilling. The colored liquid tracer is introduced into downwardly flowing drilling fluid in a downhole tool located above the drill bit. The colored liquid tracer may include a water soluble dye and may be formulated to adhere to drill cuttings such that it generates colored drill cuttings upon passing through the drill bit into the wellbore annulus. The colored drill cuttings at the surface, for example, using an optical sensor. A detection time of the colored drill cuttings surface arrival is evaluated to estimate the drill cuttings lag time.

[0013] A theoretical lag time can often be computed from the flow rate of the drilling fluid and the geometry of the wellbore (e.g., including the depth of the wellbore, the diameters of the wellbore sections, and the diameters of the drill string sections). While a theoretical lag time may be serviceable in some operations, it is prone to error, especially in operations in which there is wellbore caving or washout, pumping difficulties, and / or hole cleaning difficulties. Such difficulties can lead significant lag time errors and corresponding cuttings depth errors (e.g., up to and exceeding 50 meters of depth error). While methods are known for measuring the lag time, 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). There is a need in the industry for improved lag time measurement methods.

[0014] FIG. 1 depicts an example drilling rig 20 including a system for estimating the cuttings lag time while drilling. The drilling rig 20 may be positioned over a subterranean formation (not shown). The rig 20 may include, for example, a derrick and a hoisting apparatus (also not shown) for raising and lowering a drill string 30, which, as shown, extends into wellbore 40 and includes, for example, a drill bit 32 and one or more downhole measurement tools 38 (e.g., a logging while drilling tool or a measurement while drilling tool) in a bottom hole assembly (BHA) above the bit 32. Suitable drilling systems, for example, including drilling, steering, logging, and other downhole tools are well known in the art.

[0015] Drilling rig 20 further includes a surface system 50 for controlling the flow of drilling fluid used on the rig (e.g., used in drilling the wellbore 40). In the example rig depicted, drilling fluid 35 is pumped downhole (as depicted at 92), for example, via a conventional mud pump 57. The drilling fluid 35 may be pumped, for example, through a standpipe 58 and mud hose 59 in route to the drill string 30. The drilling fluid 35 typically emerges from the drill string 30 at or near the drill bit 32 and creates an upward flow 94 of mud through the wellbore annulus 42 (the annular space between the drill string and the wellbore wall). The drilling fluid 35 then flows through a return conduit 52 to a mud pit system 56. It will be appreciated that the terms drilling fluid and mud are used synonymously herein.

[0016] The circulating drilling fluid 35 is intended perform many functions while drilling. One of the intended functions of the drilling fluid is to carrying cuttings 45 that are generated while drilling to the surface (in upward flow 94). The cuttings 45 are commonly removed from the returning mud via a shale shaker 55 (or other similar solids control equipment) in the return conduit (e.g., immediately upstream of the mud pits 56). The drilling fluid 35 is generally reused and recirculated downhole. Formation gases that are released during drilling may also migrate to the surface in the circulating drilling fluid. These gasses are commonly removed from the fluid, for example, via a degasser or a gas trap 54 located in or near a header tank 53 that is immediately upstream of the shale shaker 55 in the example depiction. The cuttings 45 and gas are commonly examined at the surface to evaluate the formations though which the wellbore is drilled. The depth at which the cuttings and / or gases were generated may be determined from the depth log generated while drilling and the lag time (the time it takes cuttings to reach the surface).

[0017] With continued reference to FIG. 1, example drilling rig 20 further 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 first and second RFID readers 80A, 80B in which the first RFID reader 80A may be deployed proximate to an injection port 51 located, for example, near the rig top drive or between the standpipe 58 and mud hose 59 (or between the mud hose and the top drive). Note also that FIG. 1 further depicts a plurality of RFID tags 85 being injected into the drilling fluid at the injection port 51. The second RFID reader 80B may be deployed proximate to the shale shaker 55, for example, at an exit point of the shale shaker(s) 55. As described in more detail below, the surface system 50 may 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 may be deployed, for example, in the vicinity of the degasser 54 upstream of the shale shaker 55.

[0018] Drilling rig 20 may further include a control room 65 (e.g., a laboratory trailer or other facility including one or more instruments suitable for making various physical and chemical measurements of the drill cuttings and formation gases in the drilling fluid). Moreover, the control room 65 may include a computer system 70 configured, for example, to estimate the cuttings lag time using input from the RFID readers 80A, 80B and / or the optical detector 82 as described in more detail below. The computer system 70 may include one or more processors (e.g., microprocessors) which may be connected to one or more data storage devices (e.g., hard drives or solid-state memory) and user interfaces as is well known. The computer system may further include, or be configured to execute, processor executable instructions stored in the data storage device. The executable instructions may be configured, for example, to receive and input from the RFID readers to estimate the cuttings lag time.

[0019] FIG. 2 depicts a flow chart of one example method 100 for estimating the cuttings lag time during a drilling operation. The method includes circulating drilling fluid in a wellbore while drilling the wellbore at 102. For example, the drilling may include rotary drilling in which the drill string is rotated from the surface using a top drive or the BHA is rotated using a mud motor. RFID tags (e.g., ultra-high frequency RFID tags) are introduced into the circulating drilling fluid at 104 while drilling. The RFID tags may be introduced, for example, at a fluid inlet port located between the standpipe and the drill string. In such embodiments, the RFID tags are transported by the drilling fluid down the drill string, through the nozzles in the drill bit, and are carried back to the surface along with the drill cuttings in the wellbore annulus. In another embodiment, the RFID tags may be introduced downhole (e.g., from the BHA) into the wellbore annulus. For example, a measurement while drilling (MWD) tool or other downhole tool may be configured to introduce the RFID tags directly into the upwardly flowing drilling fluid in the wellbore annulus. In example embodiments, a command from the surface may trigger the release of RFID tags into the annulus. The release time may then be communicated to the surface (e.g., via conventional telemetry techniques).

[0020] With continued reference to FIG. 2, the RFID tags may be detected in the flowing drilling fluid at 106 using one or more RFID readers. For example, in embodiments in which the RFID tags are injected at the fluid inlet port, the RFID tags may be detected at a first RFID reader located at (or just downstream from) the injection port and a second RFID reader located at the shale shaker. In embodiments in which the RFID tags are injected downhole, the RFID tags may be detected at a first RFID readers located in the BHA (e.g., just uphole from the injection location) and a second RFID reader located at the shale shaker. Alternatively, the RFID tags may be detected at only a single RFID reader located at the shale shaker. The detection events (e.g., time stamps of the individual detected RFID tags) may then evaluated at 108 to estimate the cuttings lag time. For example, the cuttings lag time may be estimated to be equal to or related to an average detection time difference between the first and second RFID readers. In embodiments in which the RFID tags are introduced at the surface, the cuttings lag time may be estimated to be equal to the average detection time difference minus an estimated or computed time taken for the tags to traverse the drill string. In embodiments in which the RFID tags are introduced into the wellbore annulus, the cuttings lag time may be estimated to be equal to the average detection time.

[0021] With continued reference to FIG. 2, it will be appreciated that the RFID tags may be single use or multi-use. In embodiments that make use of single use RFID tags, it may be advantageous to inject (and detect) a large number RFID tags to ensure that a sufficient number of the tags survive the transit and particularly transit through the drill bit jets and the crushing action of the drill bit on the formation. In embodiments in which the tags are reused (multi-use), a smaller number of RFID tags may be required. Multi-use tags may be particularly well suited to operations in which the RFID tags are introduced downhole (since the tags do not need to traverse the drill bit jets and the cutting zone in which the drill bit interacts with the formation).

[0022] Those of ordinary skill in the art will readily appreciate an RFID system generally uses high frequency electromagnetic waves to communication with an RFID tag. Such an RFID system generally includes an RFID tag including an RF transponder and an RFID reader including an RF transmitter and an RF receiver. The RFID reader may be configured to transmit a radio frequency pulse and to receive a corresponding RF signal from nearby RFID tags. Upon receiving, or being triggered by, the transmitted RF pulse, the RFID tags may be configured to transmit a short RF response signal, for example, including a tag identification number. While RFID tags may be active (e.g., including a battery) or passive (configured to receive power from the transmitted RF pulse), it will be appreciated that passive RFID tags may be advantageously utilized in the disclosed embodiments (and may be preferred since they do not introduce a battery into the drilling fluid).

[0023] In example (and sometimes advantageous) embodiments, the RFID tags may be encapsulated in an encapsulation material. FIG. 3 depicts one such example encapsulated RFID tag 85′. In the depicted example, a commercially available RFID transponder 87 (e.g., including an RFID chip in a plastic coating) is enclosed or embedded in an encapsulation material 90. In example embodiments, the encapsulation material 90 may be selected such that the tag 85′ has a similar density to drill cuttings. Example, non-limiting encapsulation materials may include cement, an epoxy resin, a ceramic, and the like. For example, the tags 85′ may be fabricated such that they are of a similar size and weight (and therefore have a similar density) to an average drill cuttings particle with the intent that the tags may be carried to the surface at a similar rate of speed to the drill cuttings. Example RFID tags may therefore have a density in a range from 1 g / cm3 to 5 g / cm3 (e.g., from 1.5 g / cm3 to 3 g / cm3) depending on the formation lithologies being drilled. RFID tag 85′ may further optionally include a permanent magnetic element 88 that enables the tag 85′ to be retrieved at the surface (e.g., separating at least a portion of the RFID tags from the drill cuttings at the shale shaker). Recovered RFID tags may then be reused at a later time. Encapsulation of the RFID transponder may also reduce the likelihood of that the tags 85′ are damaged or destroyed by the action of the bit.

[0024] It will be appreciated that during a drilling operation, drill cuttings have a wide range of particle sizes that are generated. Moreover, it will be further appreciated that the rate at which a particular cuttings particle is carried to the surface can depend on the particle size (and weight). For example, larger (heavier) particles may be carried at a lower speed (and therefore have a longer lag time) than smaller (lighter) particles. For this reason, it may be advantageous to employ RFID tags (e.g., encapsulated RFID tags 85′) having distribution of sizes. For example, in one embodiment first and second RFID tags may be employed having corresponding first and second (large and small) sizes. In another embodiment, first, second, and third RFID tags may be employed having corresponding first, second, and third (large, medium, and small) sizes. In operations employing such multi-sized RFID tags, a range or distribution of lag times may be estimated at 108 of method 100 (FIG. 2). For example, distinct lag times may be estimated for the small, medium, and large RFID tags (corresponding to small, medium, and large cuttings particles). In example embodiments, the RFID tags may have a diameter in a range from 0.1 mm to 10 mm (e.g., from 0.2 mm to 2 mm). In example embodiments in which the RFID tags have first and second (large and small) sizes, the large RFID tags may have a diameter of greater than 2 mm while the small RFID tags may have a diameter of less than 1 mm.

[0025] FIG. 4 depicts a flow chart of another example method 120 for estimating the cuttings lag time during a drilling operation. The method includes circulating drilling fluid in a wellbore while drilling the wellbore at 122, for example, as described above. A liquid tracer is introduced into the circulating drilling fluid at 124. The tracer may be miscible with the mud and may have a similar density to the drilling fluid to avoid buoyancy-distortion of the measurement. The tracer may also be viscous (e.g., more viscous than the drilling fluid) to minimize dispersion thereof in the mud flow. The tracer may include a colored tracer, for example, as disclosed in commonly assigned U.S. Pat. No. 6,729,400. RFID tags (e.g., ultra-high frequency RFID tags) are introduced into the wellbore at 126, for example, along with or shortly after the introduction of the liquid tracer. The liquid tracer and the RFID tags 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.

[0026] The liquid tracer may be detected at 130 in the drilling fluid at the surface (after traversing the wellbore), for example, using an optical detector (such as the Schlumberger Optical Fluid Analyzer). After detection of the liquid tracer, the second RFID reader may be triggered (by the detection of the liquid tracer) to detect the RFID tags at 132 (e.g., at the shale shaker). The triggering of the second RFID reader may be manual or automatic. The detection events (e.g., time stamps of the individual detected RFID tags) may then evaluated at 134 to estimate cuttings lag time as described above.

[0027] It will be appreciated that the liquid tracer may advantageously include a dye that is selected for compatibility with common water-based drilling fluids and formation (connate) water. Advantageous dyes may be stable at the expected wellbore temperatures and will not adversely affect any of the physical properties of the drilling fluid. Moreover, the dye may be advantageously selected to have a color that is readily detected by the optical detector (e.g., blue). The liquid tracer may be added in substantially any suitable concentration to provide a dye concentration sufficient to color the drilling fluid (e.g., a dye concentration in a range from about 200 to 2000 mg / L). Advantageous liquid tracers may include Acid Blue #1 dye (EMI-600).

[0028] By itself, the tracer may offer an independent measurement of lag time (e.g., a fluid lag time). Measuring the time difference between the moment of introduction to the drilling fluid to the detection time of the dye (e.g., using the optical detector) enables the operator to estimate the overall travel time of the liquid phase of the drilling fluid. The debris (e.g., including the drill cuttings) that the mud transports back to the surface commonly lags behind this fluid front. The RFID tags may be density-matched to the cuttings (as described above) and may be expected to undergo a similar delay (such that they may arrive after the liquid tracer even when introduced to the drilling fluid at the same moment in time).

[0029] FIG. 5 depicts still another example method 140 for estimating the cuttings lag time during a drilling operation without necessarily using RFID tags. The method includes circulating drilling fluid in a wellbore while drilling the wellbore at 142, for example, as described above. A liquid tracer is introduced into the circulating drilling fluid in the BHA at 144. The liquid tracer may be deployed in a chamber in a downhole tool (such as an MWD or LWD tool) above the drill bit and may be introduced into the downwardly flowing drilling fluid in the BHA. The liquid tracer and dye may quickly traverse the drill bit nozzles and contact freshly cut drill cuttings. The dye may be selected or formulated such that it has an affinity to (and therefore adsorbs or otherwise adheres to) the drill cuttings and thereby colors (or changes the appearance) of the drill cuttings. It will be appreciated that surface command (such a pressure pulse or a drill string rotation rate change) may be employed to trigger introduction of the liquid carrier into the drilling fluid.

[0030] Method 140 may further include detecting the arrival of the colored drill cuttings at the surface at 146 (e.g., at the shale shaker) and estimating the cuttings lag time at 148 from a difference between the arrival time of the colored drill cuttings and a time at which the liquid tracer was introduced. The introduction time may be obtained, for example, from the downhole tool via a conventional telemetry transmission or may be taken to be the time at which the command was sent plus a predetermined delay.

[0031] In certain example embodiments, RFID tags may be introduced into the drilling fluid at 144 with the liquid tracer. The RFID tags may then be detected at the surface, for example, as described above. It will be appreciated that the use of a liquid tracer and RFID tags may advantageously provide a redundant estimation of the cuttings lag time.

[0032] It will be understood that the present disclosure includes numerous embodiments. These embodiments include, but are not limited to, the following embodiments.

[0033] In a first embodiment, a method for estimating a drill cuttings lag time during a drilling operation includes circulating 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 ones of the plurality of RFID tags in the circulating drilling fluid using first and second RFID readers, the first RFID reader detecting the ones of the plurality of RFID tags prior to the RFID tags traveling uphole through the wellbore annulus, the second RFID reader detecting the ones of the plurality of RFID tags at the surface location after the ones of the plurality of RFID tags have traveled uphole through the wellbore annulus; and evaluating a difference in detection times of selected ones of the detected RFID tags at the first RFID reader and the second RFID reader to estimate the drill cuttings lag time.

[0034] A second embodiment may include the first embodiment wherein the plurality of RFID tags is introduced into the drilling fluid at a fluid inlet port located at the surface location upstream of the drill string, and the first RFID reader is located proximate to and downstream of the fluid inlet port.

[0035] A third embodiment may include any one of the first through second embodiments, wherein the plurality of RFID tags is introduced into the wellbore annulus by a downhole tool in the drill string, and the first RFID reader is located in the drill string.

[0036] A fourth embodiment may include any one of the first through third embodiments, wherein each of the plurality of RFID tags comprises an RFID transponder embedded in an encapsulation material.

[0037] A fifth embodiment may include the fourth embodiment, wherein each of the plurality of RFID tags comprises a density in a range from 1.5 g / cm3 to about 3 g / cm3.

[0038] A sixth embodiment may include any one of the fourth through fifth embodiments, wherein each of the plurality of RFID tags comprises a permanent magnet; and the method further comprises separating at least a portion of the plurality of RFID tags from the drill cuttings at the shale shaker.

[0039] A seventh embodiment may include any one of the fourth through sixth embodiments, 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 larger diameter than the second plurality of RFID tags.

[0040] An eighth embodiment may include any one of the first through seventh embodiments, further comprising introducing a colored liquid tracer into the circulating drilling fluid either before or with the plurality of RFID tags; and detecting the colored liquid tracer at the surface location prior to the detecting the ones of the plurality of RFID tags with the second RFID reader.

[0041] A ninth embodiment may include the eighth embodiment, 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 the ones of the plurality of RFID tags after the colored liquid tracer is detected at the surface.

[0042] A tenth embodiment may include any one of the eighth through ninth embodiments, further comprising evaluating a detection time of the colored liquid tracer at the surface location to estimate a fluid lag time.

[0043] In an eleventh embodiment, a system for estimating a drill cuttings lag time during a drilling operation includes a surface system configured to circulate 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; a plurality of radio frequency identification device (RFID) tags configured for introduction into the circulating drilling fluid; first and second RFID readers, a first of the RFID readers being configured to detect the RFID tags after the introduction into the circulating drilling fluid and before the RFID tags are carried by the drilling fluid uphole through the wellbore annulus, a second of the RFID readers being deployed in the surface system at the surface location and being configured to detect the RFID tags after the RFID tags are carried by the drilling fluid uphole through the wellbore annulus; and a processor configured to evaluate a difference in detection times of selected ones of the detected RFID tags at the first RFID reader and the second RFID reader to estimate the drill cuttings lag time.

[0044] A twelfth embodiment may include the eleventh embodiment, wherein the surface system includes a fluid inlet port configured for introducing the RFID tags; the system includes a downhole tool configured to introduce the RFID tags into the wellbore annulus, the downhole tool further including the first RFID reader.

[0045] A thirteenth embodiment may include any one of the eleventh through twelfth embodiments, wherein each of the plurality of RFID tags comprises an RFID transponder embedded in an encapsulation material and have a density in a range from 1.5 g / cm3 to about 3 g / cm3.

[0046] A fourteenth embodiment may include the thirteenth embodiment, 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 larger diameter than the second plurality of RFID tags.

[0047] A fifteenth embodiment may include any one of the eleventh through fourteenth embodiments, further comprising a colored liquid tracer including dye and configured for introducing into the circulating drilling fluid either before or with the plurality of RFID tags; and an optical detector configured to detect the colored liquid tracer at the surface location.

[0048] In a sixteenth embodiment, a method for estimating a drill cuttings lag time during a drilling operation includes circulating 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 colored liquid tracer into the circulating drilling fluid while drilling, the colored liquid tracer being introduced into downwardly flowing drilling fluid in a downhole tool located in a bottom home assembly above a drill bit, the colored liquid tracer including a water soluble dye and being formulated to adhere drill cuttings such that it generates colored drill cuttings upon passing through the drill bit into the wellbore annulus; detecting the colored drill cuttings at the surface location, and evaluating a detection time of the colored drill cuttings to estimate the drill cuttings lag time.

[0049] A seventeenth embodiment may include the sixteenth embodiment, further comprising transmitting to the surface location a time at which the colored liquid carrier was introduced into the circulating drilling fluid; and wherein the evaluating comprises evaluating a difference between the detection time of the colored drill cuttings and the time at which the colored liquid carrier was introduced into the circulating drilling fluid to estimate the drill cuttings lag time.

[0050] An eighteenth embodiment may include the seventeenth embodiment, wherein the colored drill cuttings are automatically detected at the surface location using an optical detector.

[0051] A nineteenth embodiment may include any one of the sixteenth through eighteenth embodiments, wherein the water-soluble dye comprises Acid Blue #1 (EMI-600).

[0052] A twentieth embodiment may include any one of the sixteenth through nineteenth embodiments, further comprising introducing a plurality of radio frequency identification device (RFID) tags into the circulating drilling fluid with the colored liquid tracer; detecting ones of the plurality of RFID tags at the surface location using an RFID reader; and evaluating detection times of the ones of the plurality of RFID tags to estimate another drill cuttings lag time.

[0053] Although drill cuttings lag time monitoring has been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A method for estimating a drill cuttings lag time during a drilling operation, the method comprising:circulating 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 ones of the plurality of RFID tags in the circulating drilling fluid using first and second RFID readers, the first RFID reader detecting the ones of the plurality of RFID tags prior to the RFID tags traveling uphole through the wellbore annulus, the second RFID reader detecting the ones of the plurality of RFID tags at the surface location after the ones of the plurality of RFID tags have traveled uphole through the wellbore annulus; andevaluating a difference in detection times of selected ones of the detected RFID tags at the first RFID reader and the second RFID reader to estimate the drill cuttings lag time.

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

3. The method of claim 1, wherein the plurality of RFID tags is 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 comprises an RFID transponder embedded in an encapsulation 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 / cm3 to about 3 g / cm3.

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

7. The method of claim 4, wherein:the plurality of RFID tags comprises a first plurality of RFID tags and a second plurality of RFID tags; andthe first plurality of RFID tags each have a larger 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 either before or with the plurality of RFID tags; anddetecting the colored liquid tracer at the surface location prior to the detecting the ones 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; andthe second RFID reader is automatically triggered to detect the ones of the plurality of RFID tags after the colored liquid tracer is detected at the surface.

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

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

12. The system of claim 11, wherein:the surface system includes a fluid inlet port configured for introducing the RFID tags; orthe system includes a downhole tool configured to introduce the RFID tags into the wellbore annulus, the downhole tool further including 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 encapsulation material and have a density in a range from 1.5 g / cm3 to about 3 g / cm3.

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

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

16. A method for estimating a drill cuttings lag time during a drilling operation, the method comprising:circulating 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 colored liquid tracer into the circulating drilling fluid while drilling, the colored liquid tracer being introduced into downwardly flowing drilling fluid in a downhole tool located in a bottom home assembly above a drill bit, the colored liquid tracer including a water soluble dye and being formulated to adhere drill cuttings such that it generates colored drill cuttings upon passing through the drill bit into the wellbore annulus;detecting the colored drill cuttings at the surface location; andevaluating a detection time of the colored drill cuttings to estimate the drill cuttings lag time.

17. The method of claim 16, further comprising:transmitting to the surface location a time at which the colored liquid carrier was introduced into the circulating drilling fluid; andwherein the evaluating comprises evaluating a difference between the detection time of the colored drill cuttings and the time at which the colored liquid carrier was introduced into the circulating drilling fluid to estimate the drill 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 comprises 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 ones of the plurality of RFID tags at the surface location using an RFID reader; andevaluating detection times of the ones of the plurality of RFID tags to estimate another drill cuttings lag time.

Images