Estimating rock abrasiveness after drilling a well using PDC bit and real time bit wear prediction in drilling
Patent Information
- Application Number
- US19/184963
- Authority / Receiving Office
- US · United States
- Patent Type
- Applications(United States)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2026-10-22
Smart Images
Figure US20260328083A1-D00000_ABST
Abstract
Description
TECHNICAL FIELD
[0001] Some implementations relate to subsurface drilling. More specifically, some implementations relate to methods for determining rock abrasiveness after drilling a well using PDC bit.BACKGROUND
[0002] Knowledge of rock mechanical properties, including unconfined compressive strength and confined compressive strength, allows for accurate geomechanical evaluations. Relevant rock properties include rock abrasiveness and rock strength. The estimation of rock abrasiveness and rock strength after drilling a well may be useful in understanding dysfunctions that may have occurred in drilling and useful in selecting a bit or drilling conditions for future well drilling. Usually, these rock properties may be measured by measurement while drilling and / or logging while drilling tools indirectly.BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Implementations of the disclosure may be better understood by referencing the accompanying drawings.
[0004] FIG. 1 an elevation view (partially cross sectional) of an example well system, according to some implementations.
[0005] FIG. 2 is a block diagram of an example computer, according to some implementations.
[0006] FIG. 3 is a graphical representation of a cutter of a drill bit, according to some implementations.
[0007] FIG. 4 is a graph defining an example relationship between the cutter wear volume and energy of a cutter of a drill bit, according to some implementations.
[0008] FIG. 5 is a graphical representation of a cutter of a drill bit, according to some implementations.
[0009] FIG. 6 is a graphical illustration of a bit wear model that includes nine levels of bit wear.
[0010] FIG. 7 is a graph showing depth of cut vs. weight on bit at each of the nine bit wear levels, according to some implementations.
[0011] FIG. 8 is a graph depicting depth of cut vs. torque on bit at each of the nine bit wear levels, according to some implementations
[0012] FIG. 9 is a graph depicting depth of cut vs. drilling efficiency at nine bit wear levels, according to some implementations.
[0013] FIG. 10A is a plot depicting weight on bit vs. torque on bit at various wear levels, according to some implementations.
[0014] FIG. 10B is a plot depicting example normalized axial cutter force distribution and normalized cutter torque distribution at bit wear level zero and a depth of cut, according to some implementations.
[0015] FIG. 11A is a flow diagram illustrating operations for estimating rock abrasiveness for sections of a drilling run.
[0016] FIG. 11B is a flow diagram illustrating operations for predicting bit wear level in real time drilling.
[0017] FIG. 12 is a table showing a file 1200 indicating final dull severity for a drill bit from a drilling run.
[0018] FIG. 13 is a graph indicating a bit wear level function.
[0019] FIG. 14 includes graphs showing values for CCS and normalized abrasiveness index.
[0020] FIG. 15 includes graphs showing CCS and calibrated rock abrasiveness.
[0021] FIG. 16 is a flow diagram illustrating operations for determining energy input into primary cutters and cutter wear severity at a drilling depth.
[0022] FIG. 17 is a graph showing measured wear severity and calculated wear severity.
[0023] FIG. 18 includes graphs showing input bit energy and bit wear levels.DESCRIPTION OF IMPLEMENTATIONS
[0024] The description that follows may include example systems, methods, techniques, and program flows that embody implementations of the disclosure. However, this disclosure may be practiced without these specific details. For clarity, some well-known instruction instances, protocols, structures, and techniques may not be shown in detail.Overview
[0025] Previous techniques for determining rock abrasiveness after drilling a borehole may require information about forces on the drill bit from sensors on the drill bit. For example, some previous techniques may use data from sensors on the drill bit to determine weight on bit (WOB) and / or torque on bit (TOB) for a particular drilling operation. Using WOB and / or TOB (determined using sensors on the drill bit), these previous techniques may estimate rock abrasiveness after drilling the borehole. However, because these previous techniques require information from sensors on the drill bit, these previous techniques would not work in the absence of this sensor information. Hence, these previous techniques may not work if the bit does not have sensors that collect force information or if the sensor information is unavailable.
[0026] Instead of using information from sensors on the drill bit, some implementations may estimate rock abrasiveness and cutter wear severity along a drilling depth using rock strength, measured bit motion (such as bit rotation speed and rate of penetration), and measured cutter wear severity at the end of the drilling run. Some implementations also may utilize measured bit motion, rock strength, and previous estimates of rock abrasiveness to make real-time estimations of drill bit wear for a drill bit in a borehole. Therefore, some implementations may estimate wear of a drill bit in a borehole without drill bit sensor information indicating forces on the drill bit.Example Well System
[0027] Some implementations may be included or otherwise embodied in a well system. FIG. 1 an elevation view (partially cross sectional) of an example well system, according to some implementations. In particular, FIG. 1 is a schematic diagram of a well system 100 that includes a drill string 180 having a drill bit 112 disposed in a wellbore 106 for drilling the wellbore 106 in the subsurface formation 108. While depicted for a land-based well system, example implementations may be used in subsea operations that employ floating or sea-based platforms and rigs. The drill bit 112 is an example drill bit for which simulation of abrasive wear and damage as described herein may be performed.
[0028] The well system 100 may further include a drilling platform 110 that supports a derrick 152 having a traveling block 114 for raising and lowering the drill string 180. The drill string 180 may include, but is not limited to, drill pipe, drill collars, and down hole tools 116. The down hole tools 116 may comprise any of a number of different types of tools including measurement while drilling (MWD) tools, logging while drilling (LWD) tools, mud motors, and others. A kelly 115 may support the drill string 180 as it may be lowered through a rotary table 118. The drill bit 112 may include roller cone bits, polycrystalline diamond compact (PDC) bits, natural diamond bits, any hole openers, reamers, coring bits, and the like. As the drill bit 112 rotates, it may crush or cut rock to create and extend a wellbore 106 that penetrates various subterranean formations. The drill bit 112 may be rotated by various methods including rotation by a downhole mud motor and / or via rotation of the drill string 180 from the surface 120 by the rotary table 118. Attributes of drilling the wellbore may be adjusted to increase, decrease, and / or maintain the rate of penetration (ROP) of the drill bit 112 through the subsurface formation 108. Attributes may include weight-on-bit (WOB) and rotations-per-minute (RPM) of the drill string 180. In some implementations, the drill bit 112 may become dull and lose efficiency, thus requiring more WOB and / or RPM to maintain a target ROP. A pump 122 may circulate drilling fluid through a feed pipe 124 to the kelly 116, downhole through interior of the drill string 180, through orifices in the drill bit 112, back to the surface 120 via an annulus surrounding the drill string 180, and into a retention pit 128.
[0029] The well system 100 includes a computer 170 that may be communicatively coupled to other parts of the well system 100. The computer 170 may be local or remote to the drilling platform 110. A processor of the computer 170 may perform simulations (as further described below). In some implementations, the processor of the computer 170 may control drilling operations of the well system 100 or subsequent drilling operations of other wellbores.
[0030] An example of the computer 170 is now described. FIG. 2 is a block diagram of an example computer, according to some implementations. FIG. 2 depicts a computer 200 that includes a processor 201 (possibly including multiple processors, multiple cores, multiple nodes, and / or implementing multi-threading, etc.). The computer 200 includes a memory 207. The memory 207 may be system memory or any one or more of the above already described possible realizations of machine-readable media. The computer 200 also includes a bus 203 and a network interface 205.
[0031] The computer 200 also includes a bit wear unit 211and a controller 215. The bit wear unit 211 and the controller 215 may perform one or more of the operations described herein. For example, the bit wear unit 211 may perform operations for estimating drill bit wear, calibrating rock abrasiveness, and other operations, as further described below. The controller 215 may perform various control operations to a wellbore operation based on input from the bit wear unit 211. For example, the controller 215 may modify a drilling operation based on an estimation of drill bit wear determined by the bit wear unit 211.
[0032] Any one of the previously described functionalities may be partially (or entirely) implemented in hardware and / or on the processor 201. For example, the functionality may be implemented with an application specific integrated circuit, in logic implemented in the processor 201, in a co-processor on a peripheral device or card, etc. Further, realizations may include fewer or additional components not illustrated in FIG. 2 (e.g., video cards, audio cards, additional network interfaces, peripheral devices, etc.). The processor 201 and the network interface 205 are coupled to the bus 203. Although illustrated as being coupled to the bus 203, the components shown in FIG. 2 may have any suitable communication and / or connectivity architecture.Example Operations and Implementations
[0033] Some implementations may include a nonlinear cutter wear model for determining the step wear of a cutter and / or the nonlinear velocity of a cutter during drilling. To illustrate, FIG. 3 is a graphical representation of a cutter of a drill bit, according to some implementations. In FIG. 3, a cutter 300 includes a cutting element 301 and a body 303. In some implementations, the cutting element 301 may be composed of diamond. The body 303 may be composed of other less costly material (such as carbide).
[0034] As shown, a critical cutter energy (Ec) may be defined as the energy associated with a wear depth of the cutter 300 substantially equaling the chamfer size. A critical wear depth (Wc) may be defined as the depth wherein the cutting element 301 is worn away to a point where the body 303 is starting to be in contact with the formation being drilled.
[0035] To further illustrate, FIG. 4 is a graph defining an example relationship between the cutter wear volume and energy of a cutter of a drill bit, according to some implementations. FIG. 4 depicts a graph 400 that includes an x-axis that is the energy (E) 402 of the drill bit and a y-axis that is the cutter wear volume (V) 404 of the drill bit. The graph 400 includes a line 405 that starts at an Ec 403 (when V is zero). A first part 407 of the line 405 is based on μ (a constant), Ka (the rock abrasive factor), and Kb (the cutter wear resistance factor. A second part 409 of the line 405 is based on μ, Ka, Kb, and Kc (cutter and body element wear resistance factor).
[0036] In some implementations, the nonlinear cutter wear model for a cutter of a drill bit may be defined as follows. If E is less than Ec, V=0 (as shown in the graph 400 of FIG. 4). However, if E is not less than Ec, a determination is made of whether the cutter wear depth (Wd) is less than Wc. If Wd is less than Wc, the cutter wear volume (V) may be defined by Equation (1):V=μ Ka Kb (E−Ec) (1)
[0037] However, if Wd is not less than Wc, V may be defined by Equation (2):V=μ Ka Kb Kc (E−Ec) (2)
[0038] Also, as part of the nonlinear cutter wear model, a nonlinear velocity of the drill bit may be determined. A critical velocity (Vc) may be defined as the last cone cutter's velocity of the drill bit. Vc may be fixed in a simulation for a drill bit (even when drilling parameters are changed.
[0039] Cutter power (Pt) may be defined as follows. If the velocity (Vel) of the drill bit is less than or equal to Vc, P may be defined by Equation (3):Pt=F*(Vm) (3)wherein F is the force and m is a constant (0.5~0.75). However, if Vel is not less than Vc, P may be defined by Equation (4):Pt=F*(V) (4)Additionally, cutter energy (E) may be defined by Equation (5):E=Pt*T (5)wherein T is time.Additionally, a cutter wear severity may be defined by a cutter wear depth. To illustrate, FIG. 5 is a graphical representation of a cutter of a drill bit, according to some implementations. FIG. 5 depicts a cutter 500 having a cutter wear depth and at a back rake angle (BRa). A cutter wear depth may be a function of back rake angle, cutter diameter, chamfer size, cutter shape and cutter wear volume. For a cutter wear depth, a cutter wear severity (Sc) may be defined by Equation (6):Sc=8(cutter Wear Depth / Diameter) (6)If Sc=4, cutter wear depth=0.5 diameter. Therefore, Sc=4 may be defined as the maximal cutter wear severity. If Sc>4, the cutter may be considered lost.
[0045] Some implementations categorize bit wear into nine bit wear levels—level 0 to level 8. The levels may indicate increasing bit wear. Level 0 may indicate a bit with all sharp unworn cutters. Bit wear may increase with each level, and level 8 may indicate a highest level of bit wear. FIG. 6 is a graphical illustration of a bit wear model that includes nine levels of bit wear. In FIG. 6, a graph 600 includes a first curve 602 indicating no wear on cutters 606 of a drill bit. Hence, the first curve 602 shows the cutter wear of level zero. A second curve 604 indicates a maximum wear level on the cutters 606. Hence, the second curve 604 shows the cutter wear at level 8.
[0046] Some implementations create a bit wear matrix for a drill bit design. The bit wear matrix may include values that may be used with other drilling information to estimate bit wear, rock abrasiveness, and other values related to bit wear. Some implementations may use values from the bit wear matrix to speed-up real-time determinations about drill bit wear for a drill bit that is actively deployed in a borehole. The matrix may include one row for each of the bit wear levels 0-8 and a plurality of columns.
[0047] For each bit wear level, a cutter depth distribution and cutter wear volume distribution may be determined and stored in the bit wear matrix. For each bit wear level, there may be one or more depth of cut (DOC) levels. Some implementations calculate and store the following values for each DOC level: 1) ratio of WOB of the drill bit's primary cutter to the WOB for the drill bit (WOBp / WOB); 2) ratio of TOB of the drill bit's primary cutter to the drill bit's TOB (TOBp / TOB); 3) a normalized axial force distribution; and 4) a normalized cutter torque distribution.
[0048] Some implementations may use a bit / rock interaction model to compute the above-noted values for the bit wear matrix. The bit / rock model may select revolutions per minute (RPM) and rate of penetration (ROP) to determine DOC. The bit / rock interaction model may assign particular RPM, ROP, and rock strength (σ) values to calculate associated WOB and TOB values. The bit / rock interaction model may use one or more of these values to calculate mechanical specific energy (MSE) needed to cut through the rock. The bit / rock interaction model also may calculate bit drilling efficiency (η): η=σ / MSE. Note that σ is used in the calculation of η, but η is independent of σ. In other words, for any given σ, the ratio of σ / MSE is the same. Furthermore, the bit / rock model may use information about the drill bit design (such as material, shape, size, and more) to perform the calculations described here.
[0049] FIGS. 7-10 show how the bit / rock model may determine bit performance of the nine wear levels. FIG. 7 is a graph showing DOC vs. WOB at each of the nine bit wear levels, according to some implementations. The graph 700 includes nine plots 706—one plot for each of the nine wear levels. Each plot 706 includes ten points. The plot 708 is for level 0, and the plot 710 is for level 8. The graph includes an X-axis 702 showing DOC (in inches per revolution of the bit) and a Y-axis 704 showing WOB in kilo-pound force (klbf) for each of the nine bit wear levels. As shown, more WOB is needed to achieve a DOC as the drill bit wear level increases. In some implementations, the bit / rock model may compute values show in the graph 700.
[0050] FIG. 8 is a graph depicting DOC vs. TOB at each of the nine bit wear levels, according to some implementations. In some implementations, the bit / rock model may compute values show in the graph 800. The graph 800 includes nine plots 806—one plot for each of the nine wear levels. The plots 806 each include ten points. The graph 800 includes an X-axis 802 indicating a DOC in inches / revolution and a Y-axis 804 indicates TOB in kilo foot-pounds (kft-lb) for each of the nine bit wear levels.
[0051] FIG. 9 is a graph depicting DOC vs. drilling efficiency at nine bit wear levels, according to some implementations. In some implementations, the bit / rock model may compute values show in the graph 900. The graph 900 includes nine plots 910—one plot for each of the nine wear levels. The graph 900 includes an X-axis 902 depicting a DOC in inches / revolution and a Y-axis 904 depicting a bit drilling efficiency (Bit DE) as a percentage of a theoretical perfect drilling efficiency. A plot 906 indicates a drilling efficiency of a drill bit with a wear level of 0 as a function of cut depth, and a plot 908 indicates a drilling efficiency of a drill bit with a wear level of 8.
[0052] FIG. 10A is a plot depicting WOB vs. TOB at various wear levels, according to some implementations. In some implementations, the bit / rock model may compute values shown in the graph 1000. A graph 1000 includes plots 1006 for each of the nine wear levels. The graph 1000 includes an X-axis 1002 depicting a weight on bit (measured in klbf) and a Y-axis 1004 depicting a torque on bit measured in kft-lb.
[0053] FIG. 10B is a plot depicting example normalized axial cutter force and normalized cutter torque distribution at bit wear level zero and a depth of cut, according to some implementations. The bit / rock interaction model may compute these values shown in the graph.
[0054] In some implementations, the bit wear matrix may include information shown in FIGS. 7-10B for given values of rock strength. The bit wear unit 211 (or other component) may use the bit wear matrix to determine bit wear levels for offset wells after drilling runs have been performed and / or to determine real-time bit wear levels for drill bits deployed in boreholes. For real-time bit wear estimation, the bit wear unit 211 may have access to ROP and RPM of the drill bit, so it may calculate depth of cut. If the bit wear unit 211 knows (or assumes) rock abrasiveness, it may calculate a bit wear level using the predetermined values stored in the bit wear matrix instead of incurring delays associated with using the bit / rock model in real-time. The discussion of FIG. 11A explains how some implementations estimate rock abrasiveness (such as for an offset well). The value of rock abrasiveness may be used later for providing real-time estimates of drill bit wear for drill bits deployed in boreholes.
[0055] FIG. 11A is a flow diagram illustrating operations for estimating rock abrasiveness for sections of a drilling run. The operations in FIG. 11A may be performed after the drilling run to estimate rock abrasiveness of the drilling run. After estimating rock abrasiveness, some implementations use the estimated rock abrasiveness to provide real-time estimates of bit wear for a drill bit actively deployed in a borehole. Some implementations also may control drilling operations based on the bit wear estimates made in real-time. In some implementations, the bit wear unit 211 performs the operations shown in FIG. 11A.
[0056] In FIG. 11A, the flow 1100 begins at block 1102. The operations shown at blocks 1102 to 1118 initialize an iterative process for estimating the rock abrasive index. After initializing the process, the flow iteratively estimates a bit wear level at the end of each segment and a total bit wear level for the drilling run.
[0057] At block 1102, the bit wear unit 211 may determine a final dull severity for a drilling run. For example, the bit wear unit 211 may read a file that indicates the final dull severity. FIG. 12 is a table showing a file 1200 indicating final dull severity for a drill bit from a drilling run.
[0058] At block 1104, the bit wear unit 211 may determine an actual final bit wear level based on the final dull severity from the drilling run. The bit wear unit 211 may estimate the actual final bit wear level using information collected during the drilling run. The bit wear unit 211 may estimate the actual final bit wear level by: 1) determining the cutter dull severity (Sc) from the file 1200; 2) calculating cutter wear depth (Wc) using Sc and cutter diameter (Dc) in the formula Wc=Sc×DC / 8; 3) calculating the sum of all cutter wear depth for all the cutters on the drill bit 4) determining bit wear level using a bit wear level function. FIG. 13 is a graph indicating a bit wear level function. The graph 1300 includes a bit wear level function 1302 that relates total cutter wear depth (Y-axis) to a bit wear level (X-axis). The bit wear level function 1302 may indicate a total bit wear level at the end of a drilling run. As shown, an example calculated total cutter wear depth 1304 results in an estimated bit wear level of level 5 (slightly less wear than necessary for level 6) (see 1306). The bit wear unit 211 may implement any suitable bit wear function (such as the bit wear level function 1302). Referring to block 1104, the actual final bit wear level may serve as a reference value against which an estimated bit wear level is compared (see block 1140).
[0059] At block 1106, the bit wear unit 211 may read confined compressive strength (CCS) and abrasive index for the drilling run. This information may be contained in an available file or database. At block 1108, the bit wear unit 211 may normalize the abrasive index into a range from 0 to 1. FIG. 14 includes graphs showing values for CCS and normalized abrasiveness index. The graph 1402 shows example values of CCS and their depths. The graph 1404 shows example normalized abrasiveness indexes (values between 0 and 1).
[0060] At block 1110, the bit wear unit 211 may read the RPM and ROP for the drilling run from drilling data collected during the drilling run.
[0061] At blocks 1112 and 1114, the bit wear unit 211 may estimate a constant (λ) used for determining rock abrasiveness with the formula: rock abrasiveness=λ*normalized abrasive index (see 1114).
[0062] At block 1116, the bit wear unit 211 initializes the bit wear level to level zero because the drill bit is new. At block 1118, the drilling depth is initialized to a depth of a first segment of the drilling run.
[0063] At block 1120, the flow 1100 begins a loop that proceeds through blocks 1120-1138 to estimate a bit wear level for each segment of the drilling run. For example, if there are five segments in the drilling run, the flow 1100 will loop five times through blocks 1120 to 1138. At block 1120, the bit wear unit 211 calculates depth of cut. For example, the bit wear unit 211 may use RPM and ROP (see block 1110) and other information to calculate depth of cut.
[0064] At block 1122, the bit wear unit 211 may calculate WOB and TOB using rock strength, depth of cut and the bit wear level using the bit wear matrix. The bit wear unit 211 may use the depth of cut (see block 1120), bit wear level to look up a WOB and a TOB from the bit wear matrix. The WOB and TOB are then scaled, respectively, using the rock strength.
[0065] At block 1124, cutter axial force, for all primary cutters, may be calculated from WOB using the normalized cutter axial forces from bit matrix. Cutter torque, for all primary cutters, may be calculated from TOB using the normalized cutter torque distribution from bit matrix. Cutter drag forces for all primary cutters may be calculated using cutter torque and cutter radial locations.
[0066] At block 1126, cutter power and cutter energy may be calculated using cutter forces, cutter velocities and time spent in a drilling section.
[0067] At block 1132, the bit wear unit 211 may calculate primary cutter wear depth. The bit wear unit 211 may use the energy input into the cutters (computed at 1126) and one or more equations described herein (such as equations 1-6 described with reference to FIGS. 3-5).
[0068] At block 1134, the bit wear unit 211 may calculate bit wear level (such as a wear level 0-9). The bit wear unit 211 may use the primary cutter wear depth (calculated at 1132) and information in the bit wear matrix to determine the bit wear level. The bit wear matrix may indicate cutter wear depth at each bit wear level. The sum of cutter wear depth (or the average cutter wear depth) may be stored with each bit wear level in the bit wear matrix. The sum of cutter wear depth (or the average cutter wear depth) as a function of bit wear level is available via the bit wear level function (see also discussion of FIG. 13
[0069] At block 1136, if all segments of the drilling run have not been processed, the flow 1100 proceeds to block 1138. At 1138, the bit wear unit 211 increments the drilling depth to the depth of the next segment of the drilling run and proceeds to the next iteration of the loop. As noted, the flow 1100 repeats the loop for all segments of the drilling run. However, if all segments of the drilling run have been processed, the flow 1100 proceeds to block 1140.
[0070] At block 1140, the bit wear unit 211 determines whether the final bit wear level (computed at block 1134) is equal to the actual bit wear level (computed at block 1104). For example, both the calculated and actual bit wear levels may be “level 5”. If the bit wear levels do not match, the bit wear unit 211 adjusts λ (the constant value used to determine rock abrasiveness) and proceeds to block 1112 to re-performs the loop with the adjusted λ value. However, if the actual and calculated bit wear levels do not match, flow continues at block 1142.
[0071] At block 1142, the bit wear unit 211 calibrates the rock abrasive index using the value of λ that lead to matching actual and calculated bit wear levels. FIG. 15 includes graphs showing CCS and calibrated rock abrasiveness. The graph 1502 shows the original CCS values that may have been used in the operations of FIG. 11A. The graph 1504 shows calibrated rock abrasiveness values. Additionally, the bit wear unit 211 may save λ, the cutter wear level, and / or bit wear level for each loop iteration (each iteration corresponding to a depth of the drilling run). The bit wear unit 211 may save the cutter and bit wear levels in the bit wear matrix. From block 1142, the flow ends.
[0072] As noted, some implementations may perform the flow 1100 to determine rock abrasiveness for an offset well. The implementations may use the rock abrasiveness value to provide real-time estimates of drill bit wear for wells nearby the offset well. For example, the bit wear unit 211 may adapt the flow 1101 for real-time drilling to estimate a drill bit wear level for each segment of a drilling run.
[0073] FIG. 11B is a flow diagram illustrating operations for predicting bit wear level in real time drilling. In FIG. 11B, pre-calculations (1151) may be performed before the operations at block 1152. At block 1151, the bit wear unit 211 may pre-calculate the following values at each bit wear level and at each DOC for the current real-time drilling run: WOB; TOB; scaled cutter axial force and cutter torque for each cutter; ratio of the primary cutter's WOB and TOB to the drill bit's WOB and TOB. The bit wear unit 211 may store this information in the bit wear matrix (such as in a manner described herein). As shown in FIG. 11B, these pre-calculated values may be utilized during operations for predicting bit wear in real-time drilling.
[0074] In FIG. 11B, flow 1150 begins at block 1152. At block 1152, the bit wear unit 211 may read ROP, RPM, rock strength, and rock abrasiveness for each drilling depth (“MD”).
[0075] At block 1154, the bit wear unit 211 may initiate a loop that continues while current drilling depth is less than a maximum drilling depth (“maxMD”). The loop repeatedly executes blocks 1156-1180 until the current drilling depth equals or exceeds the maximum drilling depth.
[0076] At block 1156, the bit wear unit 211 may get a bit wear level from the bit wear matrix. Initially, the bit wear level for the drill bit may be zero, as the bit is new and sharp.
[0077] At block 1158, the bit wear unit 211 may estimate WOB and TOB using RPM, ROP, and rock strength from the bit wear matrix.
[0078] At block 1160, the bit wear unit 211 may get scaled cutter axial force distribution for the cutters of the drill bit and an axial coefficient for the drill bit from the bit wear matrix.
[0079] At block 1162, the bit wear unit 211 may estimate cutter axial force for each cutter of the drill bit.
[0080] At block 1164, the bit wear unit 211 may get scaled cutter torque distributions and torque coefficient for the drill bit from the bit wear matrix.
[0081] At block 1166, the bit wear unit 211 may estimate cutter torque for each cutter of the drill bit.
[0082] At block 1168, the bit wear unit 211 may estimate cutter drag force for each cutter of the drill bit.
[0083] At block 1170, the bit wear unit 211 may calculate cutter energy using cutter axial force and drag force for each cutter of the drill bit.
[0084] At block 1172, the bit wear unit 211 may calculate cutter wear volume using cutter energy for each cutter of the drill bit.
[0085] At block 1174, the bit wear unit 211 may calculate cutter wear depth and cutter wear severity for each cutter of the drill bit.
[0086] At block 1176, the bit wear unit 211 may estimate a bit wear level from the cutter wear severity.
[0087] At block 1178, the bit wear unit 211 unit may determine whether the current drilling depth is less than the maximum drilling depths. If the current drilling depth is less than the maximum drilling depth, the bit wear unit 211 may increment the current drilling depth level (at block 1180), so the loop may continue.
[0088] At block 1182, the bit wear unit 211 may output cutter wear severity for all cutters of the drill bit and a bit wear level for the drill bit.
[0089] FIG. 16 is a flow diagram illustrating operations for determining energy input into primary cutters and cutter wear severity at a drilling depth. In FIG. 16, a flow 1600 begins at block 1602. Some implementations may perform the flow 1600 using the concepts described with reference to the non-linear bit wear model, equations 1-6, and FIGS. 3-5.
[0090] At block 1602, the bit wear unit 211 may determine input bit energy, including WOB TOB and depth of cut.
[0091] At block 1604, the bit wear unit 211 may determine cutter forces.
[0092] At block1606, the bit wear unit 211 may determine cutter power.
[0093] At block 1608, the bit wear unit 211 may determine cutter energy.
[0094] At block 1610, the bit wear unit 211 may determine cutter wear volume.
[0095] At block 1612, the bit wear unit 211 may determine cutter wear depth.
[0096] At block 1614, the bit wear unit 211 may determine cutter wear severity.
[0097] FIG. 17 is a graph showing measured wear severity and calculated wear severity. The graph 1700 shows a first plot 1702 of the measured wear severity (also referred to as actual wear severity herein) of the cutters of a drill bit. A second plot 1704 shows the calculated wear severity of the cutters of the drill bit. The second plot 1704 is an example of cutter wear severity values calculated by the bit wear unit 211 from performing the operations of FIG. 11.
[0098] FIG. 18 includes graphs showing input bit energy and bit wear levels. The graph 1802 includes a plot 1804 of input bit energy values at associated depths. The graph 1806 includes a plot 1808 of drill bit wear levels at associated depths. The two graphs together show a relationship between input energy and wear levels at associated depths. These relationships may be used in performing the operations described herein.
[0099] FIGS. 1-18 and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. None of the implementations described herein may be performed exclusively in the human mind nor exclusively using pencil and paper. None of the implementations described herein may be performed without computerized components such as those described herein. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently. Some implementations may perform the operations with different components.
[0100] As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0101] The various illustrative logics, logical blocks, modules, circuits, and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits, and processes described throughout. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.
[0102] The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the implementations disclosed herein may be implemented or performed with a general purpose single-or multi-chip processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor or any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes and methods may be performed by circuitry that is specific to a given function.
[0103] In one or more implementations, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Implementations of the subject matter described in this specification also may be implemented as one or more computer programs, such as one or more modules of computer program instructions stored on a computer storage media for execution by, or to control the operation of, a computing device.
[0104] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The processes of a method or algorithm disclosed herein may be implemented in a processor-executable instructions which may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that may be enabled to transfer a computer program from one place to another. Storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection may be properly termed a computer-readable medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-Ray™ disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations also may be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine readable medium and computer-readable medium, which may be incorporated into a computer program product.
[0105] Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.
[0106] Certain features that are described in this specification in the context of separate implementations also may be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also may be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be removed from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
[0107] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example process in the form of a flow diagram. However, some operations may be omitted and / or other operations that are not depicted may be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described should not be understood as requiring such separation in all implementations, and the described program components and systems may be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results.EXAMPLE CLAUSES
[0108] Implementations may be described by the following clauses.
[0109] Clause 1: A method for determining wear of a drill bit without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the method comprising: assuming a first rock abrasiveness value using a constant and a normalized abrasiveness index; assuming a bit wear level equaling to zero at start of drilling; computing a respective bit wear level of the drill bit for each respective segment of a drilling run, the computing including calculating WOB and TOB using revolutions per minute (RPM) of the drill bit in the respective segment of the drilling run, rate of penetration (ROP) of the drill bit in the respective segment of the drilling run, and a rock strength value; determining cutter wear depth for all primary cutters of a drill bit based, at least in part, on the WOB and TOB and the first rock abrasiveness value; and determining a final estimated bit wear level using the cutter wear depths; in response to determining a final drill bit wear level matches a reference drill bit wear level, calibrating the first rock abrasiveness value using the constant.
[0110] Clause 2: The method of clause 1 further comprising: in response to determining the final drill bit wear level does not match the reference drill bit wear level, modifying the constant; estimating a second rock abrasiveness value using the modified constant and the normalized abrasiveness index; and re-computing the respective bit wear level of the drill bit for each respective segment of the drilling run using the second rock abrasiveness value instead of the first rock abrasiveness value.
[0111] Clause 3: The method of any one or more of clauses 1-2 further including: pre-calculating, for each respective segment of the drilling run, WOB and TOB of the drill bit, bit drilling efficiency for the drill bit, normalized cutter axial forces and normalized cutter torques for the drill bit.
[0112] Clause 4: The method of any one or more of clauses 1-3 further including: determining a depth of cut for the respective drilling segment based on the RPM and ROP.
[0113] Clause 5: The method of any one or more of clauses 1-4, wherein the reference bit wear level was measured after a well is drilled.
[0114] Clause 6: The method of any one or more of clauses 1-5, wherein the respective bit wear levels are included in a plurality predetermined bit wear levels, the method further comprising: for each of the predetermined bit wear levels, determining a cutter wear depth distribution and cutter wear volume distribution, a ration of weight on bit (WOB) of a primary cutter of the drill bit to WOB of the drill bit, a ration of torque on bit (TOB) of a primary cutter of the drill bit to TOB of the drill bit, a normalized axial force distribution, and a normalized cutter torque distribution.
[0115] Clause 7: A system comprising: a processor; one or more computer-readable mediums including computer-executable instructions for predicting a bit wear level of a drill bit in real time drilling without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the instructions including: instructions to determine a rate of a penetration (ROP), a rock strength, and a rock abrasiveness for each respective segment of a drilling run of the drill bit in a borehole; instructions to assume a bit wear level of zero at start of a drilling run; instructions to estimate WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run using revolutions per minute (RPM) of the drill bit in the respective segment, rate of penetration (ROP) of the drill bit in the respective segment, and the rock strength; instructions to calculate a scaled cutter axial force distribution and an axial force coefficient for each cutter of the drill bit for a current segment of the drilling run using the WOB of the current segment; instructions to calculate, for the current segment, a torque coefficient of the drill bit using the TOB of the respective segment; instructions to calculate, for the current segment, a respective cutter wear volume using the rock abrasiveness and a respective cutter wear depth and a cutter wear severity for each cutter of the drill bit using the axial force coefficient and torque coefficient; instructions to estimate the bit wear level of the drill bit based on the cutter wear depth; and instructions to output the cutter wear severity for each cutter of the drill bit and the bit wear level.
[0116] Clause 8: The system of clause 7, the instructions further including: instructions to estimate cutter torque of each cutter of the drill bit using the torque coefficient; and instructions to estimate cutter drag force for each cutter of the drill bit using the cutter torque of each cutter.
[0117] Clause 9: The system of any one or more of clauses 7-8, the instructions further including: instructions to calculate cutter energy for each cutter from the cutter axial force and the cutter drag force.
[0118] Clause 10: The system of any one or more of clauses 7-9, the instructions further including: instructions to calculating cutter wear volume for each cutter from the cutter energy for each cutter.
[0119] Clause 11: The system of any one or more of clauses 7-10, the instructions further comprising: instructions to pre-calculate the WOB of the drill bit and TOB of the drill bit in a pre-defined range of depth of cut and a given rock strength; instructions to pre-calculate scaled cutter axial force for each cutter of the drill bit; instructions to pre-calculate cutter torque for each cutter on the drill bit; instructions to pre-calculate a ratio of TOB of a primary cutter of the drill bit to the TOB of the drill bit; and instructions to pre-calculate a ratio of WOB of the primary cutter of the drill bit to the WOB of the drill bit.
[0120] Clause 12: The system of any one or more of clauses 7-11, the instructions further comprising: storing, in a bit wear matrix, the WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run, the scaled cutter axial force for each cutter of the drill bit, the cutter torque for each cutter on the drill bit, the ratio of TOB of a primary cutter of the drill bit to the TOB of the drill bit, and the ratio of WOB of the primary cutter of the drill bit to the WOB of the drill bit.
[0121] Clause 13: The system of any one or more of clauses 7-12, wherein the instructions to estimate WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run include instructions to receive the WOB and TOB of the drill bit from the bit wear matrix.
[0122] Clause 14: The system of any one or more of clauses 7-13, wherein instructions to calculate the axial force distribution and the axial force coefficient of the drill bit include instructions to receive the axial force distribution and the axial force coefficient of the drill bit from the bit wear matrix.
[0123] Clause 15: The system of any one or more of clauses 7-14, wherein the bit wear level is one of a plurality of predetermined bit wear levels.
[0124] Clause 16: One or more computer-readable mediums including computer-executable instructions for determining wear of a drill bit without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the instructions comprising: instructions to assume a first rock abrasiveness value using a constant and a normalized abrasiveness index; instructions to assume a drill bit wear level equaling to zero at a start of drilling; instructions to compute a respective bit wear level of the drill bit for each respective segment of a drilling run, the instructions to compute including instructions to calculate WOB and TOB using revolutions per minute (RPM) of the drill bit in the respective segment of the drilling run, rate of penetration (ROP) of the drill bit in the respective segment of the drilling run, and a rock strength value; instructions to determine cutter wear depth for all primary cutters of a drill bit based, at least in part, on the WOB and TOB using the first rock abrasiveness value; and instructions to determine a final estimated bit wear level using the cutter wear depth for all primary cutters of the drill bit; instructions to, in response to a determination that the final estimated bit wear level matches a reference drill bit wear level, calibrate the first rock abrasiveness value using the constant.
[0125] Clause 17: The one or more computer-readable mediums of clause 16, the instructions further including: instructions to, in response to a determination that the final estimated bit wear level does not match the reference drill bit wear level, modify the constant, estimate a second rock abrasiveness value using the modified constant and the normalized abrasiveness index, and re-compute the respective bit wear level of the drill bit for each respective segment of the drilling run using the second rock abrasiveness value instead of the first rock abrasiveness value.
[0126] Clause 18: The one or more computer-readable mediums of any one or more of clauses 16-17, the instructions including: instructions to pre-calculate WOB and TOB of the drill bit drilling efficiency for the drill bit, normalized cutter axial forces of the drill bit, and normalized cutter torques of the drill bit within a pre-defined range of depth of cut.
[0127] Clause 19: The one or more computer-readable mediums of any one or more of clauses 16-18, the instructions further including: instructions to determine a depth of cut for the respective drilling segment based on the RPM and ROP.
[0128] Clause 20: The one or more computer-readable mediums of any one or more of clauses 16-19, wherein the reference bit wear level was measured after a well is drilled.
Claims
1. A method for determining wear of a drill bit without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the method comprising:assuming a first rock abrasiveness value using a constant and a normalized abrasiveness index;assuming a bit wear level equaling to zero at start of drilling;computing a respective bit wear level of the drill bit for each respective segment of a drilling run, the computing includingcalculating WOB and TOB using revolutions per minute (RPM) of the drill bit in the respective segment of the drilling run, rate of penetration (ROP) of the drill bit in the respective segment of the drilling run, and a rock strength value;determining cutter wear depth for all primary cutters of a drill bit based, at least in part, on the WOB and TOB and the first rock abrasiveness value; anddetermining a final estimated bit wear level using the cutter wear depths;in response to determining a final drill bit wear level matches a reference drill bit wear level, calibrating the first rock abrasiveness value using the constant.
2. The method of claim 1 further comprising:in response to determining the final drill bit wear level does not match the reference drill bit wear level,modifying the constant;estimating a second rock abrasiveness value using the modified constant and the normalized abrasiveness index; andre-computing the respective bit wear level of the drill bit for each respective segment of the drilling run using the second rock abrasiveness value instead of the first rock abrasiveness value.
3. The method of claim 1 further including:pre-calculating, for each respective segment of the drilling run, WOB and TOB of the drill bit, bit drilling efficiency for the drill bit, normalized cutter axial forces and normalized cutter torques for the drill bit.
4. The method of claim 3 further including:determining a depth of cut for the respective drilling segment based on the RPM and ROP.
5. The method of claim 1, wherein the reference bit wear level was measured after a well is drilled.
6. The method of claim 1, wherein the respective bit wear levels are included in a plurality predetermined bit wear levels, the method further comprising:for each of the predetermined bit wear levels, determininga cutter wear depth distribution and cutter wear volume distribution,a ration of weight on bit (WOB) of a primary cutter of the drill bit to WOB of the drill bit,a ration of torque on bit (TOB) of a primary cutter of the drill bit to TOB of the drill bit,a normalized axial force distribution, anda normalized cutter torque distribution.
7. A system comprising:a processor;one or more computer-readable mediums including computer-executable instructions for predicting a bit wear level of a drill bit in real time drilling without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the instructions including:instructions to determine a rate of a penetration (ROP), a rock strength, and a rock abrasiveness for each respective segment of a drilling run of the drill bit in a borehole;instructions to assume a bit wear level of zero at start of a drilling run;instructions to estimate WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run using revolutions per minute (RPM) of the drill bit in the respective segment, rate of penetration (ROP) of the drill bit in the respective segment, and the rock strength;instructions to calculate a scaled cutter axial force distribution and an axial force coefficient for each cutter of the drill bit for a current segment of the drilling run using the WOB of the current segment;instructions to calculate, for the current segment, a torque coefficient of the drill bit using the TOB of the respective segment; instructions to calculate, for the current segment, a respective cutter wear volume using the rock abrasiveness and a respective cutter wear depth and a cutter wear severity for each cutter of the drill bit using the axial force coefficient and torque coefficient;instructions to estimate the bit wear level of the drill bit based on the cutter wear depth; andinstructions to output the cutter wear severity for each cutter of the drill bit and the bit wear level.
8. The system of claim 7, the instructions further including:instructions to estimate cutter torque of each cutter of the drill bit using the torque coefficient; andinstructions to estimate cutter drag force for each cutter of the drill bit using the cutter torque of each cutter.
9. The system of claim 8, the instructions further including:instructions to calculate cutter energy for each cutter from the cutter axial force and the cutter drag force.
10. The system of claim 9, the instructions further including:instructions to calculating cutter wear volume for each cutter from the cutter energy for each cutter.
11. The system of claim 7, the instructions further comprising:instructions to pre-calculate the WOB of the drill bit and TOB of the drill bit; in a pre-defined range of depth of cut and a given rock strength;instructions to pre-calculate scaled cutter axial force for each cutter of the drill bit;instructions to pre-calculate cutter torque for each cutter on the drill bit;instructions to pre-calculate a ratio of TOB of a primary cutter of the drill bit to the TOB of the drill bit; andinstructions to pre-calculate a ratio of WOB of the primary cutter of the drill bit to the WOB of the drill bit.
12. The system of claim 11, the instructions further comprising:storing, in a bit wear matrix, the WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run, the scaled cutter axial force for each cutter of the drill bit, the cutter torque for each cutter on the drill bit, the ratio of TOB of a primary cutter of the drill bit to the TOB of the drill bit, and the ratio of WOB of the primary cutter of the drill bit to the WOB of the drill bit.
13. The system of claim 7, wherein the instructions to estimate WOB of the drill bit and TOB of the drill bit for each respective segment of the drilling run include instructions to receive the WOB and TOB of the drill bit from the bit wear matrix.
14. The system of claim 7, wherein instructions to calculate the axial force distribution and the axial force coefficient of the drill bit include instructions to receive the axial force distribution and the axial force coefficient of the drill bit from the bit wear matrix.
15. The system of claim 7, wherein the bit wear level is one of a plurality of predetermined bit wear levels.
16. One or more computer-readable mediums including computer-executable instructions for determining wear of a drill bit without using weight on bit (WOB) and torque on bit (TOB) measured from sensors on the drill bit, the instructions comprising:instructions to assume a first rock abrasiveness value using a constant and a normalized abrasiveness index;instructions to assume a drill bit wear level equaling to zero at a start of drilling;instructions to compute a respective bit wear level of the drill bit for each respective segment of a drilling run, the instructions to compute includinginstructions to calculate WOB and TOB using revolutions per minute (RPM) of the drill bit in the respective segment of the drilling run, rate of penetration (ROP) of the drill bit in the respective segment of the drilling run, and a rock strength value;instructions to determine cutter wear depth for all primary cutters of a drill bit based, at least in part, on the WOB and TOB using the first rock abrasiveness value; andinstructions to determine a final estimated bit wear level using the cutter wear depth for all primary cutters of the drill bit;instructions to, in response to a determination that the final estimated bit wear level matches a reference drill bit wear level, calibrate the first rock abrasiveness value using the constant.
17. The one or more computer-readable mediums of claim 16, the instructions further including:instructions to, in response to a determination that the final estimated bit wear level does not match the reference drill bit wear level,modify the constant,estimate a second rock abrasiveness value using the modified constant and the normalized abrasiveness index, andre-compute the respective bit wear level of the drill bit for each respective segment of the drilling run using the second rock abrasiveness value instead of the first rock abrasiveness value.
18. The one or more computer-readable mediums of claim 16, the instructions including:instructions to pre-calculate WOB and TOB of the drill bit bit drilling efficiency for the drill bit, normalized cutter axial forces of the drill bit, and normalized cutter torques of the drill bit within a pre-defined range of depth of cut.
19. The one or more computer-readable mediums of claim 18, the instructions further including:instructions to determine a depth of cut for the respective drilling segment based on the RPM and ROP.
20. The one or more computer-readable mediums of claim 16, wherein the reference bit wear level was measured after a well is drilled.