Abstract:
A method and system for improving cuttings measurements in drilling operations includes rotating a helical screw in a trough at a first speed, measuring a first weight of a cuttings mixture within the trough, measuring a first torque required to maintain rotation of the helical screw at the first speed through the cuttings mixture, and calculating a difference between the first torque and a second torque required to maintain rotation of the helical screw at the first speed through a second weight of natural cuttings equal to the first weight.

Description:
CROSS-REFERENCE AND CLAIM OF PRIORITY TO RELATED APPLICATION 
     This application is a U.S. National Phase of International Application No. PCT/US2012/020663, which was filed on Jan. 9, 2012, and is incorporated herein by reference in its entirety and for all purposes. 
     FIELD OF THE INVENTION 
     The present disclosure relates generally to oilfield measurements, and more particularly, to systems and methods for improved cuttings measurements. 
     BACKGROUND OF THE INVENTION 
     Boreholes are created by drilling into the earth using a rig. The rig drives a bottomhole assembly (BHA) on a drill string to create a hole. The BHA comprises a drill bit, which is provided with sufficient weight-on-bit (WOB) to break the rock. The BHA also may provide directional control of the drill bit and may use sensors to take downhole measurements of actual drilling conditions. 
     Drilling fluid or drilling mud is pumped downhole through a drill pipe while drilling. The drilling fluid cools the drill bit, circulates through the borehole, and returns drill cuttings, such as sand and shale, to the surface. The cuttings are passed through a shaker which strains the cuttings from the drilling fluid, and optionally, through a centrifuge which separates cuttings such as sand from the drilling fluid. The cleaned drilling fluid is then returned downhole through the drill pipe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a rotary drilling rig according to an embodiment of the invention. 
         FIG. 2  is a flowchart illustrating the acts of a method for improved cuttings measurements according to an embodiment of the invention. 
         FIG. 3  is a plan view of a system for improved cuttings measurements according to an embodiment of the invention. 
         FIG. 4A  is a perspective view of a system for improved cuttings measurements according to an embodiment of the invention. 
         FIG. 4B  is a perspective view of a system for improved cuttings measurements according to an embodiment of the invention. 
         FIG. 5  is a schematic diagram illustrating a system of an embodiment for effecting the methods described herein. 
         FIG. 6  is diagrammatic representation of a machine having a set of instructions for causing the machine to perform any of the one or more methodologies discussed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Systems and methods for improved cuttings measurements are described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments. It is apparent to one skilled in the art, however, that embodiments of the present invention can be practiced without these specific details or with an equivalent arrangement. In some instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments. 
     As described herein, some embodiments of the invention obtain real-time, constant measurements of the amount of cuttings coming over shakers, corrected in real-time for the amount of drilling fluid carrying these cuttings. These measurements can be compared to values calculated using sophisticated lab tables, such as volumetric lag tables produced by the InSite® software package from Halliburton Energy Services Inc., that indicate a theoretical or predicted amount of cuttings created at the bit and that should be measured at the shakers. According to some embodiments, alarms can be activated to alert operators when a measured amount of cuttings differs from a predicted amount of cuttings by more than a threshold amount. 
     Referring now to the drawings,  FIG. 1  illustrates an exemplary rotary drilling rig  100  that can be employed in concert with embodiments of the invention. Boreholes can be created by drilling into the earth using drilling rig  100 . Rig  100  drives a bottom hole assembly (BHA)  150 , positioned at the bottom of drill string  175 , into earth  102 . According to some embodiments, the BHA  150  comprises a drill bit  130  and tool string  140 , which can be moved up and down within a hole as facilitated by drill line  125 . An annulus  103  is formed between the drill string  175  and the sides  104  of the hole. The drill bit  130  is provided with sufficient weight-on-bit (WOB) and torque to create the hole. According to some embodiments, the BHA  150  also provides directional control of drill bit  130 . According to some embodiments, the tool string  140  can be semi-permanently mounted with measurement tools (not shown), such as measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools, that take downhole measurements of drilling conditions, as described further herein. According to some embodiments, the measurement tools are self-contained within tool string  140 , as shown in  FIG. 1 . 
     Drilling fluid (such as mud, in this example) is pumped downhole from a mud tank  105  by a mud pump  115  (powered by a power source  120 ) through a stand pipe  170 . The mud cools the drill bit  130 , circulates through annulus  103 , and returns drill cuttings, such as sand and shale, to the surface. The cuttings and mud mixture is passed through a flow line  160  and into a trough system  190 , including shakers and an optional centrifuge (not shown). The trough system  190  is described in greater detail with respect to  FIGS. 3, 4A and 4B  herein. The shakers separate a majority of solids, such as cuttings and fines, from the mud. Cleaned mud is then returned downhole through the stand pipe  170 . Changes in various factors, such as change in rate of penetration (ROP) or formation, can be observed, analyzed and accounted for during this process. Although referenced herein for convenience as “mud,” the term “mud” can refer to both mud alone and a mud/cuttings mixture. Further, although referenced herein as “drilling fluid,” the term “drilling fluid” can refer to both drilling fluid alone and a drilling fluid and cuttings mixture. 
     Although shown and described with respect to a rotary drill system in  FIG. 1 , many types of drills can be employed in carrying out embodiments of the invention, such as, for example, Auger drills, air core drills, cable tool drills, diamond core drills, percussion rotary air blast (RAB) drills, reverse circulation drills, and the like. Drills and drill rigs used in embodiments of the invention can be used onshore (as shown and described with respect to  FIG. 1 ), or offshore (not shown). Offshore oil rigs that can be used in accordance with embodiments of the invention include, for example, floaters, fixed platforms, gravity-based structures, drillships, semi-submersible platform, jack-up drilling rigs, tension-leg platforms, and the like. Embodiments of the invention can be applied to rigs ranging anywhere from small in size and portable, to bulky and permanent. 
     Further, although described herein with respect to oil drilling, embodiments of the invention can be used in many other applications. For example, disclosed methods can be used in drilling for mineral exploration, environmental investigation, natural gas extraction, underground installation, mining operations, water wells, geothermal wells, and the like. 
       FIG. 2  is a flowchart  200  illustrating a process for improved cuttings measurements according to an embodiment of the invention. The process begins at  210 , at which point a cuttings and drilling fluid mixture is returned to the surface through the annulus, and moved into one or more shakers. The cuttings and drilling fluid mixture can be moved into the shaker by a flow line, for example, such as flow line  160  of  FIG. 1 . The shakers (and optionally, a centrifuge) separate the majority of solids, such as cuttings and fines, from the drilling fluid. The cleaned drilling fluid is returned downhole by a stand pipe, for example, such as stand pipe  170  of  FIG. 1 . 
     At  212 , a helical screw within a trough is rotated at a constant speed co. Although illustrated as occurring at a particular position within the method, it is understood that the helical screw can begin rotation at a number of different times within the method while still allowing for proper measurement of the torque required to maintain its rotation through the cuttings. 
     The discharge from the shakers, or the “discharged cuttings”, are moved into the trough at  214 . Although the cuttings and drilling fluid mixture has been substantially separated by the shakers, it is understood that an amount of drilling fluid may remain on the surface of the discharged cuttings, within depressions or holes in the discharged cuttings, between discharged cuttings, or absorbed into the discharged cuttings. 
     At  216 , the weight of the discharged cuttings, w dis , is obtained. The weight of the discharged cuttings can be obtained by measuring the discharged cuttings independently, measuring the discharged cuttings within the trough, or measuring the discharged cuttings on or within any other component having a known weight. For example, the total weight of the trough system can be measured by weight sensors below or suspending the trough. The weight of the discharged cuttings can then be determined by subtracting the weight of the trough, helical screw, and any other non-cuttings and non-drilling fluid components attached to the trough, from the total measured weight of the trough system. 
     As discussed further herein, a pre-determined graph, chart or equation illustrating a known amount of torque required to maintain a constant rotation ω of the helical screw through various weights of natural cuttings is established. At  218 , a baseline torque, τ nat , required to rotate the helical screw through the weight of the discharged cuttings, w dis , is obtained from the graph, chart or equation. Thus, the baseline torque τ nat  represents the torque that would be required to rotate the helical screw through the discharged cuttings if the discharged cuttings were natural, i.e., entirely free of drilling fluid. The word “natural” is used herein to describe cuttings that are completely separated from the drilling fluid. However, it is contemplated that such natural cuttings are not necessarily “dry”, as ordinary pore water may be present in cuttings free of drilling fluid. Thus, the phrase “natural cuttings” could refer to any cuttings separate from the drilling fluid, with or without pore water. 
     At  220 , the actual torque, τ dis , required to maintain rotation of the helical screw through the discharged cuttings at the constant speed ω, is measured. The actual torque, τ dis , can be measured by a variety of gauges, sensors or meters, such as a torque meter coupled to a motor driving the helical screw, as discussed further herein. At  224 , the difference Δτ between the actual torque and the baseline torque is determine by the equation Δτ=τ dis −τ nat . This difference Δτ represents the difference in torque required to maintain rotation of the helical screw at the constant speed ω due to the presence of fluid on the discharged cuttings as compared to natural cuttings. 
     A pre-determined graph, chart or equation illustrating a known ratio or percentage of fluid to cuttings based on a difference in torque Δτ is consulted to determine the particular ratio or percentage of drilling fluid to cuttings for the discharged cuttings at  225 . At  226 , this ratio is used to isolate the weight of the natural cuttings (i.e., cuttings without any drilling fluid), w nat , in the trough. For example, the weight of the natural cuttings w nat  can be determined through multiplication of the percentage of cuttings in the discharge by the total weight of the discharged cuttings, w dis . 
     The expected volume of natural cuttings being discharged into the trough, V expected , is obtained from volumetric lag tables, such as those produced by the InSite® software package from Halliburton Energy Services Inc. Such volumes can be predicted based upon geology, weight-on-bit (WOB), drilling speed, downhole conditions, and various other specifications. The density of the discharged cuttings, ρ dis , can be estimated from historical density data or supplied by MWD/LWD tools, for example. The expected weight of natural cuttings being discharged into the trough, w expected , can then be calculated using the equation w expected =V expected ×ρ dis , at  232 . 
     At  234 , the weight of the natural cuttings in the trough, w nat , is compared to the expected weight of natural cuttings being discharged into the trough, w expected . If the weight of the natural cuttings in the trough, w nat , is not within an established acceptable threshold of the expected weight of natural cuttings being discharged into the trough, w expected , an alarm is activated at  236  according to the illustrated embodiment, and the process proceeds to optional decision block  238  (or directly to  240 ). If the weight of the natural cuttings in the trough, w nat , is indeed within an established acceptable threshold of the expected weight of natural cuttings being discharged into the trough, w expected , the process proceeds to optional decision block  238  (or directly to  240 ). 
     At optional decision block  238 , the percentage of fluid on the discharged cuttings (determined at  225 ) is compared to an established acceptable percentage of fluid to be present on the discharged cuttings. At optional process block  240 , an alarm is activated if the percentage of fluid exceeds the established acceptable percentage of fluid, and the process continues at  242 . If the percentage of fluid is within the acceptable threshold, the process proceeds directly to  242 . At  242 , the various measurements, calculations and results are stored, and the process ends at  299 . 
     According to some embodiments, corrective action can be taken based on an activated alarm and/or stored measurements. Corrective action can be taken manually, such as by an operator; automatically, such as in automated drilling systems; or a combination thereof. In combined embodiments, the automated system can identify one or more potential problems and select one or more corrective actions based on the type of the alarm, the stored measurements and/or any other downhole conditions or measurements. The automated system can identify the potential problem(s) and suggest the corrective action(s) to an operator, who must authorize the suggested action prior to implementation of the corrective action(s). Alternatively, if the operator disagrees with one or more of the proposed corrective action(s), the operator can modify the suggested action or deny the action entirely. 
     A notable difference between the actual and expected weights of natural cuttings within the trough may indicate that downhole conditions, i.e., geology, drilling depth, drilling speed, borehole size, etc., are not as expected. A higher than expected amount of cuttings could indicate that a bigger hole is being drilled than what was originally desired or intended. A lower than expected amount of cuttings could indicate that the cuttings are not being efficiently cleaned out of the hole, which could in turn cause the pipe to get stuck. In the latter case, the method of drilling could be changed to remedy the predicted problem. For example, in the case of horizontal drilling, the rotary speed can be increased to “clean” the hole, and/or a more viscous fluid can be pumped downhole. Numerous other problems and corrective actions can similarly be identified based on their particular surrounding circumstances and measurements. 
     A percentage of fluid on the discharged cuttings within the trough higher than an acceptable threshold could also indicate various problems. For example, a greater than expected amount of fluid could indicate an inefficiency of the shakers that could be corrected by various adjustments, such as changes to screen desk angle, vibration, G-force and cuttings conveyance velocity. Such adjustments would reduce costs by maximizing fluid reclamation. Further, drilling waste would be limited, lessening the economic impact of the meticulous processing, treatment and disposal required of discharged cuttings. Further, potentially adverse environmental effects caused by fluids retained on the cuttings would be limited. 
       FIGS. 3 and 4A  illustrate exemplary trough systems for improved cuttings measurements that can be employed in concert with embodiments of the invention. As illustrated, a cuttings and drilling fluid mixture flows into shale shaker screens  1  at point A, for example. Shaker screens  1  allow the cleaned drilling fluid to flow out at point B, while discharging the cuttings into trough  2  at point C. Trough  2  comprises a helical screw  3  having a central shaft. According to some embodiments, helical screw  3  is rotationally secured with bearing  5 , for example, to trough  2  (such as is shown in  FIG. 4A , for example). Although illustrated and described with respect to bearing  5 , however, it is understood that any means for rotationally coupling helical screw  3  to trough  2  can be used. 
     As further shown in  FIGS. 4A , helical screw  3  is driven rotationally by motor  6 . Motor  6  can be, for example, an electrical, hydraulic or pneumatic motor, and is preferably certified to work in areas near rig shale shakers. A constant speed controller (not shown) is used in conjunction with motor  6 , and can be positioned either externally or internally to motor  6 . The constant speed controller ensures that motor  6  drives helical screw  3  at an uninterrupted constant speed. Further, the constant speed controller or motor  6  can internally include a gauge, sensor or meter that identifies changes in torque or power needed by motor  6  to maintain constant rotation of helical screw  3 , such as a torque meter. In another embodiment, a torque meter can be provided external to the constant speed controller or motor  6 , whilst still being operatively coupled thereto. 
     Helical screw  3  continually moves the discharged cuttings falling into trough  2  in direction D, and discharges them from trough  2  at point E. Thus, according to some embodiments, the torque measurements described herein can be taken without interruption, as it is unnecessary to empty the cuttings out of trough  2  at regular intervals. By eliminating the need to empty trough  2 , inaccuracies caused by estimating what the readings might have been during the time that trough  2  is emptied are eliminated. The torque or power required by the motor to maintain a constant rotation of the screw can therefore be measured in real-time, without interruption, and be continually sent to a computing device. 
     Weight sensors  4  under trough  2  can also take constant continuous, uninterrupted readings of the weight of the entire system, including the trough, helical screw and cuttings, and send the weight measurements to a computing device. Although shown and described with weight sensors  4  positioned under trough  2 , it is understood that weight sensors  4  can take a reading of the weight at a variety of other positions, such as through suspension. 
       FIG. 4B  illustrates an alternative embodiment of an exemplary trough system for improved cuttings measurements. In this embodiment, trough  2  comprises a helical screw  3 ′ having no central shaft. A configuration according to  FIG. 4B  performs similar functions to those described with respect  FIGS. 3 and 4A . It is contemplated, however, that different advantages may be realized by the use of different embodiments. For example, a greater volume of cuttings may be held in trough  2  of  FIG. 4B  due to the lack of a central shaft, and less torque may be required to rotate the cuttings, which are not displaced by the central shaft. However, helical screw  3 ′ may be less efficient at moving the same volume of cuttings as helical screw  3 , because the cuttings may be able to more easily displace out of the path of movement in direction D. 
       FIG. 5  illustrates a system of an embodiment for effecting the methods described above. Trough system  510  transmits and receives data via network  530  to a server  540 . According to some embodiments, trough system  510  comprises trough  512 , helical screw  514 , motor  516 , controller  517  and weight sensor  519 , and can be, for example, the trough system illustrated in  FIGS. 3, 4A and 4B  herein. 
     Either or both of server  540  and user device  550  are computer systems. In embodiments in which server  540  is used, server  540  comprises processor  542  and memory  544 , and may be an HTTP (Hypertext Transfer Protocol) server, such as an Apache server, or an FTP server. Memory  544  may be any type of volatile or non-volatile storage media that includes, for example, one or more of read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and zip drives. 
     When server  540  is used, user device  550  may be a simple receiver or display device capable of implementing visual and/or audio alarms, instead of a fully functional computer system. In either embodiment, user device  550  may comprise one or more of analog or digital interfaces, mainframes, minicomputers, personal computers, laptops, personal digital assistants (PDAs), cell phones, televisions, audio receivers, video receivers, displays, and the like. 
     Server  540  and user device  550  are characterized in that they are capable of being connected to network  530 . Network  530  may be any network for transmitting and receiving data to and/or from trough system  510 , for transmitting and receiving data to and/or from server  540 , and for transmitting and receiving data to and/or from user device  550 . For example, network  530  may be a local area network (LAN), wide area network (WAN), a telephone network, such as the Public Switched Telephone Network (PSTN), an intranet, the Internet, or combinations thereof. In other embodiments, network  530  may be a telemetry network, such as one or more of a mud pulse telemetry network, an electromagnetic telemetry network, a wired pipe network, a pipe-in-pipe network, an acoustic telemetry network, a torsion telemetry network, or combinations thereof. In still other embodiments, network  530  can be a combination of traditional and telemetry networks. 
     In use, trough system  510  measures the weight of the system using weight sensor  519 , and transmits the measurement to server  540  over network  530 . Trough system  510  also measures the torque required by motor  516  to maintain a constant-rate rotation of helical screw  514  through the cuttings via a torque meter within controller  517 , and transmits this measurement to server  540  over network  530 . These measurements can be made and transmitted constantly, without interruption, in real time. Alternatively, these measurements can be made on demand, at predetermined times, at predetermined intervals, at random times, or based on the performance of one or more conditions. 
     Although illustrated and described herein with respect to a torque meter, any of a number of other methods or devices can be used to measure or estimate torque in accordance with embodiments of the invention. For example, if motor  516  is an electric motor, the electrical power used to run motor  516  can be measured to indicate the torque required to drive helical screw  514  at a constant speed. If motor  516  is a hydraulic or pneumatic motor, the change in pressure of the fluid driving helical screw  514  at a constant speed can be measured to indicate the torque required. 
     According to some embodiments, server  540  decodes the data received from trough system  510 , if necessary, and converts it into a format usable by processor  542 , memory  544  and/or user device  550 . In an embodiment of the invention using a wired pipe network as network  530 , server  540  is again not necessarily required, and data can be transmitted directly to and from network  530  and user device  550 . In this embodiment, user device  550  can convert the electrical data signal received from network  530  into decodable computer-readable signals. 
     In embodiments where server  540  is used, server  540  can be directly wired, wirelessly connected, or a combination thereof, to trough system  510 . In one embodiment, server  540  acts merely as a receiver for user device  550  using, for example, antennas, acoustic receivers, pipe-in-pipe electrical connections, wires, etc., and can convert an electrical data signal received from network  530  into decodable computer-readable signals. 
     Although described herein with respect to server  540 , it is understood that trough system  510  may alternatively transmit and receive data directly to and from at least one user device  550 , and server  540  can be eliminated entirely. In embodiments in which server  540  is not used, user device  550  may itself include a processor and memory to perform the functions described herein with respect to server  540 . 
     According to some embodiments, processor  542  of server  540  retrieves from memory  544  stored data relating to the torque required to maintain constant rotation of helical screw  514  through natural cuttings, i.e., cuttings without any drilling fluid present. This “natural cuttings” data can initially be established by measuring the torque required to maintain rotation of helical screw  514  at a particular speed through known volumes, weights and densities of natural cuttings, and stored in memory  544 . The data points can then be plotted onto a graph, a curve can be fit to the points, and additional data points beyond the range of the collected data can be extrapolated. Data charts and equations representing this relationship can also be established. 
     According to some embodiments, processor  542  compares the measured torque required to maintain constant rotation of helical screw  514  through the cuttings in trough  512 , to the known torque required to maintain the same constant rotation of helical screw  514  through natural cuttings. Using a graph, chart or equation illustrating a known ratio or percentage of fluid to cuttings based on the difference in torque, processor  542  estimates the amount of drilling fluid on the cuttings, and the amount of cuttings themselves, within trough  512 . 
     According to some embodiments, when the discharged cuttings are measured within trough  512 , processor  542  corrects the measured weight of the cuttings to account for the weight of trough  512 , helical screw  514 , motor  516 , torsion meter  517 , weight sensor  519 , and any other components attached to trough system  510  and affecting its weight (other than the cuttings). Processor  542  then estimates the weight of the natural cuttings within the trough (i.e., cuttings without any residual drilling fluid), such as by multiplying the percentage of cuttings in the discharge by the measured weight of the discharged cuttings. 
     According to some embodiments, processor  542  retrieves from memory  544  an expected or predicted volume of cuttings to be discharged from the shakers. Such predictions can be obtained, for example, from the volumetric lag tables produced by the InSite® software package from Halliburton Energy Services Inc. According to some embodiments, processor  542  further retrieves from memory  544  the density of the discharged cuttings, then calculates the expected or predicted weight of the natural cuttings being discharged into the trough. 
     Processor  542  compares the actual weight of the natural cuttings within the trough to the expected weight of cuttings discharged from the shakers, and retrieves an acceptable range of differences or tolerances from memory  544 . This difference between estimated and predicted weights, along with other measurements and estimations relating to the cuttings in the trough (e.g., measured torque, weight of cuttings, estimated volume of drilling fluid on the discharged cuttings, estimated volume of natural cuttings) are stored in memory  544 , as well as any other relevant or associated data, such as downhole conditions, drilling parameters, environmental conditions, date and time, operator, etc. Although described herein with respect to estimated and predicted weights of cuttings, it is understood that other parameters may be used with similar results, such as estimated and predicted percentages of cuttings per volume of drilling fluid, estimated and predicted volumes of cuttings, etc. 
     According to some embodiments, if the estimated and predicted volumes differ by more than an acceptable amount, server  540  sends a signal to user device  550 , which, in turn, activates an alarm or another visual or audible indicator. In another embodiment, if the percentage of fluid on the discharged cuttings is higher than an acceptable threshold, server  540  can also send a signal to user device  550 , which, in turn, activates an alarm or another visual or audible indicator. 
     In either embodiment, server  540  can further transmit all measured, estimated and predicted data to user device  550 . For example, an operator at user device  550  can assess the data in conjunction with other relevant information (such as downhole conditions), and choose and implement appropriate remedial or corrective actions, if desired. In another embodiment, user device  550  can analyze the data in conjunction with other relevant available data, and automatically select and implement appropriate remedial actions. In still another embodiment, user device  550  can analyze the data in conjunction with other relevant available data, and suggest one or more appropriate remedial actions to the operator, who must, in turn, implement the desired actions. 
     Optionally, the measured, estimated and predicted data can further be stored in conjunction with the previously-referenced “natural cuttings” data, and plotted onto the graph. A new curve can then be fit to the data points to further refine the graph, and additional data points beyond the range of the collected data can more accurately be extrapolated. Similarly, a data chart or equation can be updated based on the new data. 
     Further, a graph of the torque required to drive the helical screw through the cuttings in the trough versus the percentage of fluid on the cuttings can be built up and refined using tried and true methods. For example, the above-described methods can be further refined for future use and reference by measuring and accounting for (A) the density of the drilling fluid at the time of measurement, (B) the density of the cuttings coming out of the borehole at the time of measurement, and (C) the density of the mixture at the time of measurement. In any case, the constant, real-time reading of power or torque can be calibrated and used as a real-time indicator of the amount of drilling fluid on the cuttings, eliminating the need for spot checks. Further, because the amount of drilling fluid that remains on cuttings can vary significantly, the accuracy of the readings is increased through constant measurement, as estimations between spot check measurements become unnecessary. 
     By determining the amount of drilling fluid remaining on cuttings, the loss of drilling fluid due to carryover, which can be substantial, can be tracked and accounted for. Further, by removing the estimated weight of remaining drilling fluid from the estimated weight of discharged cuttings, a better assessment can be made of the amount of cuttings coming over the shakers. By more accurately estimating the amount of returned cuttings and determining whether it is as expected, any build up of cuttings in the annulus can be detected earlier to prevent a number of problems, such as twist-offs and pipe sticking, that can lead to catastrophic failure. In addition, the flow rate and density of the drilling fluid can be adjusted and optimized to ensure efficient removal of cuttings from the annulus. 
     Although described with respect to the method illustrated in  FIG. 2 , it is understood that any of the methods or any portions thereof that are described herein can be similarly performed. Further, although described with particular devices, it is understood that a variety of similar devices may be employed to perform the processes described herein. Various functions of these and other embodiments can be described as modules of computer executable instructions recorded on tangible media. The modules can be segregated in various manners over various devices. 
       FIG. 6  shows a diagrammatic representation of a machine in the exemplary form of computer system  1300  within which a set of instructions, for causing the machine and/or slave devices to perform any of the one or more methodologies discussed herein, may be executed. In alternative embodiments, the machine operates as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine may operate in the capacity of, for example, a server or a client machine in server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be, for example, a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. 
     According to some embodiments, computer system  1300  comprises processor  1350  (e.g., a central processing unit (CPU), a graphics processing unit (GPU) or both), main memory  1360  (e.g., read only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.) and/or static memory  1370  (e.g., flash memory, static random access memory (SRAM), etc.), which communicate with each other via bus  1395 . 
     According to some embodiments, computer system  1300  may further comprise video display unit  1310  (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). According to some embodiments, computer system  1300  also may comprise alphanumeric input device  1315  (e.g., a keyboard), cursor control device  1320  (e.g., a mouse), disk drive unit  1330 , signal generation device  1340  (e.g., a speaker), and/or network interface device  1380 . 
     Disk drive unit  1330  includes computer-readable medium  1334  on which is stored one or more sets of instructions (e.g., software  1338 ) embodying any one or more of the methodologies or functions described herein. Software  1338  may also reside, completely or at least partially, within main memory  1360  and/or within processor  1350  during execution thereof by computer system  1300 , main memory  1360  and processor  1350  also constituting computer-readable media. Software  1338  may further be transmitted or received over network  1390  via network interface device  1380 . 
     While computer-readable medium  1334  is shown in an exemplary embodiment to be a single medium, the term “computer-readable medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “computer-readable medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present invention. The term “computer-readable medium” shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media. 
     It should be understood that processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. Further, various types of general purpose devices may be used in accordance with the teachings described herein. It may also prove advantageous to construct a specialized apparatus to perform the methods described herein. Those skilled in the art will appreciate that many different combinations of hardware, software, and firmware will be suitable for practicing the present invention. 
     The present invention has been described in relation to particular examples, which are intended in all respects to be illustrative rather than restrictive. Further, while the present invention has been described in connection with a number of exemplary embodiments, and implementations, the present inventions are not so limited, but rather cover various modifications, and equivalent arrangements. 
     Other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Various aspects and/or components of the described embodiments may be used singly or in any combination. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.