Drilling performance in a horizontal EGS development

Abstract

The present invention relates to systems and methods for improving drilling performance in horizontal enhanced geothermal system (EGS) wells. The systems and methods include techniques for drilling horizontal EGS wells developed over a series of successful drilling campaigns in which changes to drilling parameters and corresponding drilling performance outcomes were monitored and documented. Through iterative optimization across multiple drilling campaigns, sustained drilling rates of at least 70 feet per hour over run lengths of 2,800 feet in hard rock formations having unconfined compressive strength between 30-50 ksi have been achieved.

Description

DRILLING PERFORMANCE IN A HORIZONTAL EGS DEVELOPMENT CLAIM OF PRIORITY

[0001] This international application claims the benefit of U.S. Provisional Patent Application Serial No.63 / 550,299, filed on February 6, 2024, titled “DRILLING PERFORMANCE IN A HORIZONTAL EGS DEVELOPMENT,” the contents of which is incorporated by reference herein in its entirety. FIELD OF THE INVENTION

[0002] The present invention relates to improving drilling performance in industries such as oil and gas, mining, and geothermal energy. BACKGROUND

[0003] As geothermal energy becomes more widespread as a clean energy solution, the technical challenges associated with generating geothermal energy become more prevalent. For example, drilling in geothermal industries presents various technical challenges that may not be presented in other industries. Geothermal drilling involves penetrating hard, abrasive, and high-temperature rock formations, which presents technical challenges with respect to impediments to the drilling process and increased wear on equipment. Geothermal wells are drilled to depths where sufficiently high temperatures for energy production are achieved, and these depths may be deeper than those of wells drilled in other industries. Thus, there is a continuing need for technical solutions to the various technical challenges faced in geothermal industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Some examples are shown for purposes of illustration and not limitation in the figures of the accompanying drawings. In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views or examples. It should be understood that additional and alternative examples are possible without departing from the principles of the subject matter described herein.

[0005] FIG. 1 illustrates an example of a natural resource system, in accordance with examples described herein.

[0006] FIG. 2 illustrates a graph plotting drilling performance over multiple geothermal wells, in accordance with examples described herein.

[0007] FIG. 3 illustrates a graph depicting a drilling learning curve, in accordance with examples described herein.

[0008] FIG. 4 illustrates a chart showing lateral granite drilling performance metrics, in accordance with examples described herein.

[0009] FIG. 5 illustrates a chart showing time and cost performance metrics, in accordance with examples described herein.

[0010] FIG. 6 illustrates a graph plotting improvements in friction reduction, in accordance with examples described herein.

[0011] FIG. 7 illustrates an example method for drilling a geothermal well, in accordance with examples described herein.

[0012] FIG. 8 illustrates an example of a machine upon which any one or more of the techniques discussed herein may perform, in accordance with examples described herein. DETAILED DESCRIPTION

[0013] In general, a drilling learning curve describes how drilling performance may improve over time as knowledge and experience are gained. For example, the knowledge and experience gained from drilling one well may be leveraged to increase the performance in drilling another well. In geothermal applications, geothermal developments often lack the geologic consistency and the scale and continuous scope of operations to develop and leverage a drilling learning curve. These technical challenges to developing and leveraging a drilling learning curve have a sizeable impact in geothermal applications because, without developing and leveraging a drilling learning curve, drilling costs becomes prohibitive factors in a geothermal drilling campaign. Therefore, there is a need in the field of geothermal technologies for drilling techniques that promote a geothermal drilling learning curve.

[0014] The systems and techniques described herein seeks to address these and other technical challenges and limitations arising in the field of geothermal technologies. For example, techniques for drilling horizontal enhancedgeothermal system (EGS) wells have been developed over multiple successful campaigns. The techniques include utilizing a drilling system with a bottom- hole assembly with a polycrystalline diamond (PDC) drill bit. The PDC drill bit includes deep leached and shaped cutters that provide improved thermal resistance for high-temperature geothermal applications and improve depth of cut in hard rock formations. The drilling system includes a torsional vibration reduction tool that mitigates rotational vibrations experienced by the drilling system. The effectiveness of the drilling system is enhanced through addition of lubricants to the drilling mud to reduce friction between the borehole wall and the drilling system. The use of lubricants in the drilling mud is useful with hard rock formations where, for example, granite rock presents high levels of friction that impede weight transfer to the drill bit while simultaneously requiring higher than typical weight-on-bit for effective drilling. The effectiveness of the drilling system is enhanced through use of mud coolers to control inlet drilling fluid temperature. By cooling the inlet drilling fluid temperature, the mud coolers maintain lower well temperatures during bit-trips and contribute to the overall drilling performance improvements in EGS wells.

[0015] The systems and techniques described herein have achieved improved drilling performance in EGS wells. In some examples, the systems and techniques described herein achieved sustained drilling rates of at least 70 feet per hour over run lengths of at least 2,800 feet when drilling horizontal wellbore sections in granite rock formations, which is a notable improvement over prior estimates of 25 feet per hour as the representative baseline of what is achievable in granite basement drilling. With these drilling rates and these run lengths, a 60% reduction in drilling time has been achieved over initial drilling operations. As drilling time accounts for over 75% of total well costs, the improvements described herein provides significant cost reduction in drilling campaigns. Thus, the systems and techniques described herein provide for sustainably achievable improvements in drilling EGS wells.

[0016] In some examples, through multiple successful campaigns, the techniques for drilling horizontal EGS wells have iteratively improved. By monitoring and analyzing drill bit wear patterns, drilling parameters (e.g., revolutions per minute, weight on bit), connection practices, hole cleaning practices, tripping practices, and reaming practices during a drilling campaign,areas for improvement are identified for the next drilling campaign. For example, monitoring and analyzing drill bit wear patterns identifies areas of improvement in cutting structure performance and durability in hard rock formations. Monitoring and analyzing drilling parameters identifies optimal operating ranges and avoids problematic parameter combinations that trigger dysfunction. Monitoring and analyzing connection practices prevents premature bit failure and identifies optimal pick-up heights to account for pipe stretch. Monitoring and analyzing hole cleaning effectiveness identifies areas of improvement with respect to maintaining wellbore stability and optimal drilling fluid performance. Monitoring and analyzing tripping practices and reaming practices reduces nonproductive time and identifies areas of improvement with respect to maintaining smooth wellbore conditions.

[0017] In some examples, the monitoring and analyzing of drill bit wear patterns, drilling parameters (e.g., revolutions per minute, weight on bit), connection practices, hole cleaning practices, tripping practices, and reaming practices during a drilling campaign is supplemented with root cause failure analysis of drilling runs during the drilling campaign to identify drilling dysfunction and performance limiters. The root cause failure analysis involves identifying sources of drilling inefficiency to determine the source of failure initiation in failed run cases. For example, in applying root cause failure analysis to drilling runs that suffered from premature failure revealed that connection practices and transitions from slide to rotate drilling triggered reduction in performance and, in some cases, drill bit failure. Further analysis revealed that insufficient pick-up height to account for pipe stretch prevented the drill bit from fully disengaging from the hard rock formation. The insufficient pick-up height causes the drill bit to experience sever loads due to rotation at low depth of cut. Here, through root cause failure analysis, the source of drilling inefficiency and performance limiters in these drilling runs is the insufficient pick-up height. By increasing the pick-up height in subsequent drilling campaigns, overall drilling performance is improved.

[0018] In some examples, the techniques for drilling horizontal EGS wells were developed through revolutions per minute (RPM) and weight on bit (WOB) step testing to identify optimal drilling parameters and avoid RPM and WOB combinations that trigger drilling dysfunction. For example, starting with apredetermined and a predetermined WOB, RPM is increased in fixed steps (e.g., 10 RPM increase) while maintaining WOB. At each step increase in RPM, the drilling performance (e.g., rate of penetration) is measured and evaluated against the drilling performance of other steps. A step where improvements in drilling performance are disproportionately or relatively lower than other steps or a step where no improvements in drilling performance are realized indicates that an optimal RPM has been found. In general, the RPM of the step preceding the step where improvements in drilling performance is relatively lower or where no improvements are realized is the optimal RPM. This RPM step testing is repeated for increases in WOB in fixed steps. Through this RPM and WOB step testing, an optimal RPM and WOB combination can be determined.

[0019] In some examples, the techniques for drilling horizontal EGS wells were developed through standardized trial forms in which drilling system changes were documented to capture information for systematic improvements. The standardized trial forms detail base case drilling system configurations to establish a starting point for drilling system changes. The standardized trial forms specify a set of variables, such as drilling parameters, that are changed for a drilling trial and provide implementation guidance for the drilling trial based on the changed variables. By establishing a set of variables that are changed between drilling trials, the changes that result in drilling performance improvements are isolated and identified. The standardized trial forms provide information for documenting and measuring drilling performance outcomes to ensure clear and standardized performance assessments. By establishing standardized drilling performance outcomes and standardized measurements for the drilling performance outcomes, drilling performances are readily comparable to identify drilling performance improvements. The standardized trial forms identify variables that may confound measurement and assessment, and the standardized trial forms provide information on how to mitigate the potential for inconclusive results. The standardized trial forms detail risks associated with the drilling trial, operational mitigations for preventing the risks, and how to manage risks should they arise. The standardized trial forms provide drilling trial close outs with documented conclusions and recommendations for future operations. This structured documentation approach facilitates iterative optimization ofdrilling operations by providing clear explanations for drilling system changes and facilitating the identification of drilling performance limiters.

[0020] The systems and techniques described herein include a system for drilling a horizontal EGS well. The system comprises a drilling system that includes a bottom-hole assembly with a PDC drill bit. The PDC drill bit includes deep leached cutters that provide improved thermal resistance for high- temperature geothermal applications and shaped cutters that improve depth of cut in hard rock formations. The drilling system includes a torsional vibration reduction tool that mitigates rotational vibrations experienced by the drilling system. The system includes a drilling fluid system with lubricators that provide lubricants to drilling mud. The lubricants are formulated to reduce friction between the borehole wall and the drilling equipment, alleviating some of the technical challenges of drilling in hard rock formations. The drilling fluid system includes mud coolers to control inlet drilling fluid temperature, enabling effective cooling during drilling operations to reduce the risk of premature thermal failure.

[0021] In some examples, the PDC drill bit includes features that make it suitable for hard rock drilling applications. For example, the PDC drill bit incorporates cutting structure layouts specifically engineered for granite drilling, with optimized gauge length and bit hydraulics to extend operational life and improve cutting efficiency. The PDC drill bit includes deep leached cutters that are designed to provide thermal resistance, addressing the high temperatures in geothermal applications that tend to lead to premature thermal failure of cutting structures. The deep leached cutters are configured to improve depth of cut in granite, addressing the technical challenges of drilling in hard rock formations. For example, hard rock formations have unconfined compressive strength (UCS) between 30-50 ksi, which is double what most commercial hydrocarbon developments encounter. By incorporating deep leached cutters, cutting structure layouts designed for granite drilling, and calibrated gauge length and bit hydraulics, the PDC drill bit maintains sustained drilling rates of 70 feet per hour over run lengths of 2,800 feet in these conditions.

[0022] In some examples, the cutters used in the PDC drill bits are deep leached to engineered to provide improved thermal resistance in geothermal applications. For example, the leach depths of the deep leached cutters are adjusted (e.g.,ranging from 100 micrometers to 1000 micrometers) to balance between thermal stability and overall cutter toughness. In some examples, the thickness of the diamond tables of the deep leached cutters are adjusted (e.g., ranging from 2mm to 4mm) to improve thermal resistance.

[0023] In some examples, the cutters used in the PDC drill bits are shaped to improve depth of cut in hard rock formations. For example, the geometries of the cutters are engineered to cut hard rock with a shearing motion rather than a crushing motion, which improves heat distribution and thermal stability. The geometries of the cutters are engineered to cut hard rock with reduced friction to reduce heat around the cutter tips. In some examples, the shape and deep leaching of the cutters in combination improves drilling efficiency and bit durability in geothermal drilling applications.

[0024] In some examples, the torsional vibration reduction tool that manages and mitigates torsional vibrations in drilling operations by absorbing torsional oscillations and vibrations, preventing drill bit over-engagement, and balancing weight transfer. The torsional vibration reduction tool comprises an outer housing that encloses the internal components, a shaft that experiences and absorbs torsional vibrations, a rotary element that mitigates torsional oscillations, a damping mechanism (e.g., disk valve) that absorbs impact forces, and adapters or connectors to integrate the torsional vibration reduction tool with the drilling system. In general, the torsional vibration reduction tool is cylindrical and installed in line with the drill bit in the drilling system.

[0025] In some examples, the drilling fluid system incorporates mud coolers to control the inlet temperature of the drilling fluid, enabling effective cooling of the wellbore while the drilling fluid is circulating. The mud coolers promote longer well heat up times, which facilitates reduced well temperatures during bit trips. This reduces the risk of premature thermal failure of downhole tools and cutting structures. In some examples, the mud coolers manage the flow of the drilling fluid and the cooling medium (e.g., water, air, refrigerant) to improve heat transfer.

[0026] In some examples, the drilling fluid system utilizes lubricants in the drilling mud to reduce friction between the borehole wall and the drilling equipment. This reduction in friction facilitates drilling operations in hard rock formations where hardness and abrasion pose technical problems. Thelubricants (e.g., oil-based additives, synthetic oils, ester-based lubricants, graphite) are directly added and blended with the drilling mud and continuously applied to the drilling mud to maintain low friction conditions.

[0027] By reducing friction and heat when drilling in hard rock formations, the technical challenges of maintaining sustained drilling performance in these hard rock formations are addressed. For example, in horizontal wells, high friction between the borehole wall, the drill pipe, and the bottom hole assembly leads to technical challenges in moving pipe in and out of the hole, transferring weight to the drill bit for efficient drilling rates, and excessive pipe wear leading to higher maintenance costs. These technical challenges are exacerbated in hard rock formations where hardness and abrasion create high friction environments.

[0028] The subject matter described herein has application to oil and gas activities, such as waterflooding, steam flooding, steam assisted gravity drainage, and enhanced oil recovery. The subject matter described herein has application to geothermal energy activities, where thermal energy is extracted from subsurface formations by circulating a working fluid, such as water or carbon dioxide, through the formation and recovering the heated fluid. It should be understood that while the examples described herein involve the recovery of geothermal resources and hydrocarbon resources from beneath the surface of the earth, the subject matter described herein is not so limited. Thus, the subject matter described herein may find applicability in the recovery of minerals and ores, and other resources within the ground.

[0029] FIG. 1 illustrates an example 100 of a natural resource system 102, in accordance with examples described herein. For example, the natural resource system 102 may pump fluid or gas from one or more geothermal energy sources. Typically, in the production of natural resources from formations within the earth a well or borehole is drilled into the earth to the location where the natural resource is believed to be located. These natural resources may be a heat source for geothermal energy, a hydrocarbon reservoir, containing natural gas, crude oil and combinations of these; the natural resource may be fresh water; or it may be some other natural resource that is located within the ground.

[0030] Generally, when a well is drilled into these formations the natural resources rarely flow into and out of the formation, and into the well at rates, durations and amounts that are economically viable. This problem can relate tothe viscosity of the natural resource, the porosity of the formation, the geology of the formation, the formation pressures, and the perforations that place the production tubing in the well in fluid communication with the formation, to name a few.

[0031] In drilling a well, an initial borehole is made into the earth, and then, subsequent and smaller diameter boreholes are drilled to extend the overall depth of the borehole. In this manner, as the overall borehole gets deeper its diameter becomes smaller; resulting in what can be envisioned as a telescoping assembly of holes with the largest diameter hole being at the top of the borehole closest to the surface of the earth.

[0032] Typically, when completing a well, it is necessary to perform a perforation operation. In general, when a well has been drilled and casing (e.g., a metal pipe) is run to the prescribed depth, the casing is typically cemented in place by pumping cement down and into the annular space between the casing and the earth. The casing, among other things, prevents the hole from collapsing and fluids from flowing between permeable zones in the annulus. Thus, this casing forms a structural support for the well and a barrier to the earth.

[0033] Boreholes are generally formed and advanced by using mechanical drilling equipment having a rotating drilling tool (e.g., a bit). For example, when creating a borehole in the earth, a drilling bit is extending to and into the earth and rotated to create a hole in the earth. In general, to perform the drilling operation the bit must be forced against the material to be removed with a sufficient force to exceed the shear strength, compressive strength, or combinations thereof, of that material.

[0034] As illustrated in FIG.1, the natural resource system 102 can inject a fluid or a gas through a subsurface 104 via an injection well 108 to fractures 110a, 110b, 110c. The fractures 110a, 110b, 110c can be part of an enhanced geothermal system, which can be a man-made reservoir created where there is hot rock but insufficient or little natural permeability or fluid saturation. In some instances, fluid or gas can be injected through the injection well 108 to cause the fractures 110a, 110b, 110c to open or re-open to creating permeability. In some instances, fluid or gas can be injected through the injection well 108 as part of a flow through the fractures 110a, 110b, 110c. The flow through the fractures 110a, 110b, 110c can be enhanced through reservoir stimulation. Here,stimulation of multiple fractures, such as the fractures 110a, 110b, 110c, allows for an area to be stimulated in a series of smaller stimulations, minimizing local stress perturbations. The stimulation of multiple fractures provides for access to significantly more of the reservoir and provides additional flow opportunities, increasing overall flow rate. For example, through multizone stimulation flow rates of 40-80 kg / s for commercial production may be achieved where stimulation of a single fracture may fail to achieve a flow greater than 25 kg / s.

[0035] As illustrated in FIG.1, fluid or gas can flow from the fractures 110a, 110b, 110c to the natural resource system 102 through the subsurface 104 via a production well 106. The natural resource system 102 can extract energy (e.g., heat, thermal energy) from the fluid or the gas from the fractures 110a, 110b, 110c. As illustrated in FIG.1, the injection well 108 and the production well 106 can be horizontal wells. The injection well 108 and the production well 106 can have limited entry completion designs to maximize thermal sustainability. In general, limited entry completion designs refer to well stimulation techniques that effectively treat multiple zones simultaneously. Through limited entry completion designs, even stimulation and uniform flow can be achieved.

[0036] FIG. 2 illustrates a graph 200 plotting drilling performance over multiple geothermal wells, in accordance with examples described herein. The graph 200 plots a number of days (on the x-axis) to drill a measured depth (on the y-axis) from spud to total depth. In the graph 200, drilling progress for a first well 202 used about 70 days to drill to a measured depth of about 11,000 feet. Drilling progress for a second well 204 used about 60 days to drill to a measured depth of about 11,000 feet. Drilling progress for a third well 206 used about 36 days to drill to a measured depth of about 13,000 feet. Drilling progress for a fourth well 208 used about 25 days to drill to a measured depth of about 13,000 feet. Drilling progress for a fifth well 210 used about 25 days to drill to a measured depth of about 13,500 feet. Drilling progress for a sixth well 214 used about 20 days to drill to a measured depth of about 13,000 feet. Drilling progress for a seventh well 216 used about 23 days to drill to a measured depth of about 14,000 feet. Drilling progress for an eighth well 218 used about 22 days to drill to a measured depth of about 13,500 feet. The graph 200 demonstrates performance improvements over multiple drilling operations with drilling time reduced by over 60% through these drilling operations.

[0037] FIG. 3 illustrates a graph 300 depicting a drilling learning curve, in accordance with examples described herein. The graph 300 plots a number of wells (on the x-axis) against a number of days (on the y-axis) to complete a well from spud to total depth. An original estimated drilling learning curve 302 predicts improvements from about 72 days to complete a first well to about 35 days to complete a twenty-first well, representing a planned 18% learning curve. Based on the systems and techniques described herein, a revised estimated drilling learning curve 304 predicts improvements from about 72 days to complete a first well to about 25 days to complete a twenty-first well, representing a 35% learning curve. An actual performance curve 306 demonstrates that the revised estimated drilling learning curve was exceeded, with improvements from about 70 days to drill a first well to about 22 days to drill an eighth well. At the sixth well, completion of a barefoot design with no production liner capital or installation costs incurred was completed within about 20 days. At the seventh well, completion of a well with 1500 feet of additional granite drilled and casing design optimization was completed within about 23 days. The actual performance curve 306 demonstrates a 60% reduction in drilling time. Therefore, the actual performance curve 306 demonstrates that drilling learning curves are achievable in EGS developments.

[0038] FIG. 4 illustrates a chart 400 showing lateral granite drilling performance metrics across eight wells, in accordance with examples described herein. For these eight wells, the chart 400 plots average lateral footage per bit 402a, 402b, 402c, 402d, 402e, 402f, 402g, 402h, maximum lateral bit run length 404a, 404b, 404c, 404d, 404e, 404f, 404g, 404h, and number of lateral bits 406a, 406b, 406c, 406d, 406e, 406f, 406g, 406h. The chart 400 illustrates continuous improvement in drilling efficiency. For example, average lateral footage per bit 402a at the first well was about 500 ft, and this improved to about 2500 ft for average lateral footage per bit 402h at the eighth well. Similarly, maximum lateral bit run length 404a at the first well was about 500 ft, and this improved to about 3000 ft for maximum lateral bit run length 404h at the eighth well. These improvements in lateral footage per bit led to improvements in number of lateral bits, with the number of lateral bits 406a at the first well being 9 and the number of lateral bits 406h at the eighth well being 2. Thus, using the systems and techniques described herein, continuous improvements in drilling performance was realized.

[0039] FIG. 5 illustrates a chart 500 showing time and cost performance metrics across eight wells, in accordance with examples described herein. The chart 500 demonstrates the relationship between drilling time and drilling cost. As cost per feet 502 decreased from about $1000 for the first two wells to about $400 for the last four wells, the days to complete (from spud to total depth) 504 similarly decreased from about 60 to 70 days for the first two wells to about 20 to 30 days for the last four wells. Here, since drilling time accounts for 75% of total well costs, improving drilling efficiency directly provides benefits with respect to cost savings.

[0040] FIG. 6 illustrates a graph 600 plotting improvements in friction reduction, in accordance with examples described herein. The graph 600 plots hookload (on the x-axis) against bit depth (on the y-axis). In the graph 600, lubricant is added during some drilling operations at bit depths between 7,000 ft and 9,000 ft, resulting in hookloads of 220 klbf to 250 klbf at bit depths between 7,000 ft and 13,000 ft as shown in first hookload measurements 602 for lubricated drilling operations (operating at a 0.2 friction coefficient). To illustrate the improvements from adding lubricant, second hookload measurements 604 (operating at a 0.7 friction coefficient) for unlubricated drilling operations show hookloads of 390 klbf to 420 klbf at bit depths around 13,000 ft. Thus, the addition of lubricants to drilling mud demonstrates reduction in downhole friction, improving overall drilling efficiency.

[0041] FIG. 7 illustrates an example method 700 for drilling a geothermal well, in accordance with examples described herein. The operations of the example method 700 are illustrative, and the sequence may be altered without departing from the scope of the present invention. For example, the example method 700 can be performed with additional or fewer operations. The operations of the example method 700 can be performed in sequence, in parallel, or in different orders. In some examples, different components of an example device or system that implements an example technique may perform operations at substantially the same time or in a specific sequence.

[0042] At 702, the example method 700 provides a drilling system comprising a bottom-hole assembly with a drill bit having deep leached cutters and a torsional vibration reduction tool. The drilling system may be, for example, used in the drilling operations described in accordance with FIGS. 2-6.

[0043] At 704, the example method 700 reduces friction between a borehole wall and the drilling system by adding a lubricant to drilling mud. The reduction in friction may be, for example, in accordance with details provided in FIG. 6.

[0044] At 706, the example method 700 controls inlet drilling fluid temperature by using mud coolers. The mud coolers may be, for example, used with the drilling system in the drilling operations described in accordance with FIGS.2-6.

[0045] At 708, the example method 700 determines drills a horizontal wellbore section in a hard rock formation using the drilling system, the drilling comprising stabilizing the bottom-hole assembly using the torsional vibration reduction tool. The drilling may be, for example, in accordance with details provided in FIGS. 2-6.

[0046] FIG. 8 illustrates generally an example of a block diagram of a machine 800 upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform in accordance with some examples. In alternative examples, the machine 800 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 800 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machine 800 may act as a peer machine in peer-to-peer (P2P) (or other distributed) network environment. The machine 800 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing 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, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

[0047] Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities (e.g., hardware) capable of performing specified operations when operating. A module includes hardware. In an example, the hardware may be specifically configured to carry out a specific operation (e.g., hardwired). In an example, the hardware may include configurable execution units (e.g.,transistors, circuits, etc.) and a computer readable medium containing instructions, where the instructions configure the execution units to carry out a specific operation when in operation. The configuring may occur under the direction of the execution units or a loading mechanism. Accordingly, the execution units are communicatively coupled to the computer readable medium when the device is operating. In this example, the execution units may be a member of more than one module. For example, under operation, the execution units may be configured by a first set of instructions to implement a first module at one point in time and reconfigured by a second set of instructions to implement a second module.

[0048] Machine (e.g., computer system) 800 may include a hardware processor 1102 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 804 and a static memory 806, some or all of which may communicate with each other via an interlink (e.g., bus) 1108. The machine 800 may further include a display unit 810, an alphanumeric input device 812 (e.g., a keyboard), and a user interface (UI) navigation device 814 (e.g., a mouse). In an example, the display unit 810, alphanumeric input device 812 and UI navigation device 814 may be a touch screen display. The machine 800 may additionally include a storage device (e.g., drive unit) 816, a signal generation device 818 (e.g., a speaker), a network interface device 820, and one or more sensors 821, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor. The machine 800 may include an output controller 828, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0049] The storage device 816 may include a machine readable medium 822 that is non-transitory on which is stored one or more sets of data structures or instructions 824 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 824 may also reside, completely or at least partially, within the main memory 804, within static memory 806, or within the hardware processor 1102 during execution thereof by the machine 800. In an example, one or any combination of the hardwareprocessor 1102, the main memory 804, the static memory 806, or the storage device 816 may constitute machine readable media.

[0050] While the machine readable medium 822 is illustrated as a single medium, the term “machine readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, or associated caches and servers) configured to store the one or more instructions 824.

[0051] The term “machine readable medium” may include any medium that is capable of storing, encoding, or carrying instructions for execution by the machine 800 and that cause the machine 800 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non- limiting machine-readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0052] The instructions 824 may further be transmitted or received over a communications network 826 using a transmission medium via the network interface device 820 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 820 may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network 826. In an example, the network interface device 820 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 800, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software. GLOSSARY

[0053] Generally, the term “about” and the symbol “~” as used herein unless stated otherwise is meant to encompass a variance or range of ±10%, the experimental or instrument error associated with obtaining the stated value, and preferably the larger of these.

[0054] As used herein, unless specified otherwise, the terms “formation”, “reservoir”, “pay zone”, and similar terms are to be given their broadest possible meanings, and include all locations, areas, and geological features within the earth that contain, may contain, or are believed to contain, a desired resource (e.g., geothermal heat, hydrocarbons, etc.).

[0055] As used herein, unless specified otherwise, the terms “field”, “oil field”, “geothermal field”, and similar terms are to be given their broadest possible meanings, and include any area of land, sea floor, or water that is loosely or directly associated with a formation, and more particularly, with a resource containing formation. Thus, a field may have one or more exploratory and producing wells associated with it. A field may have one or more governmental body or private resource leases associated with it. A field may be directly associated with a resource containing formation.

[0056] As used herein, unless specified otherwise, the terms “geothermal”, “geothermal well”, “geothermal resource”, “geothermal energy”, and similar terms are to be given their broadest possible meanings, and include systems and operations, including wells, that recover or utilize the heat energy that is contained within the earth. Such systems and operations include enhanced geothermal well, engineered geothermal wells, binary cycle power plants, dry steam power plants, flash steam power plants, open looped systems, and closed loop systems.

[0057] As used herein, unless specified otherwise, the term “earth” should be given its broadest possible meaning, and includes, the ground, all naturalmaterials, such as rocks, and artificial materials, such as concrete, that are or may be found in the ground, including without limitation rock layer formations, such as, granite, basalt, sandstone, dolomite, sand, salt, limestone, rhyolite, quartzite and shale rock.

[0058] As used herein, unless specified otherwise, the term “borehole” should be given it broadest possible meaning and includes any opening that is created in a material, a work piece, a surface, the earth, a structure (e.g., building, protected military installation, nuclear plant, offshore platform, or ship), or in a structure in the ground, (e.g., foundation, roadway, airstrip, cave or subterranean structure) that is substantially longer than it is wide, such as a well, a well bore, a well hole, a micro hole, a slimhole, a perforation, or other term commonly used to define these types of long narrow passages. Wells would further include exploratory, production, abandoned, reentered, reworked, and injection wells. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a vertical line, based upon a level as a reference point, a borehole can have orientations ranging from 0° i.e., vertical, to 90°, i.e., horizontal and greater than 90° e.g., such as a heel and toe and combinations of these such as for example “U” and “Y” shapes. Boreholes may further have segments or sections that have different orientations, they may have straight sections and arcuate sections and combinations thereof; and for example, may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the “bottom” of a borehole, the “bottom surface” of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole furthest along the path of the borehole from the borehole's opening, the surface of the earth, or the borehole's beginning. The terms “side” and “wall” of a borehole should to be given their broadest possible meaning and include the longitudinal surfaces of the borehole, whether or not casing or a liner is present, as such, these terms would include the sides of an open borehole or the sides of the casing that has been positioned within a borehole. Boreholes may be made up of a single passage, multiple passages, connected passages and combinations thereof, in a situation where multiple boreholes are connected or interconnected each borehole would have a borehole bottom. Boreholes may beformed in the sea floor, under bodies of water, on land, in ice formations, or in other locations and settings.

[0059] As used herein, phrases of the form “at least one of an A, a B, or a C”, “at least one of A, B, or C”, “at least one of A, B, and C”, and similar phrases, should be interpreted to select at least one from the group that comprises A, B, and C. ^ Unless explicitly stated otherwise in connection with a particular instance, this manner of phrasing does not mean “at least one of A, at least one of B, and at least one of C.” ^ As used herein, the example “at least one of an A, a B, or a C” would cover any of the following selections: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, and {A, B, C}.

[0060] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense, i.e., in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words using the singular or plural number may also include the plural or singular number, respectively. The word “or” in reference to a list of two or more items, covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. Likewise, the term “and / or” in reference to a list of two or more items, covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. EXAMPLES

[0061] In view of the above-described implementations of subject matter this application discloses the following list of examples, wherein one feature of an example in isolation or more than one feature of an example, taken in combination and, optionally, in combination with one or more features of one ormore further examples are further examples also falling within the disclosure of this application.

[0062] Example 1 is a method for drilling a geothermal well, comprising: providing a drilling system comprising: a bottom-hole assembly with a drill bit having deep leached cutters; and a torsional vibration reduction tool; reducing friction between a borehole wall and the drilling system by adding a lubricant to drilling mud; controlling inlet drilling fluid temperature by using mud coolers; and drilling a horizontal wellbore section in a hard rock formation using the drilling system, the drilling comprising: stabilizing the bottom-hole assembly using the torsional vibration reduction tool.

[0063] In Example 2, the subject matter of Example 1 comprises monitoring drill bit wear patterns during the drilling; and analyzing the drill bit wear patterns to identify areas of improvement in cutting structure performance.

[0064] In Example 3, the subject matter of Examples 1 – 2 comprises monitoring drilling parameters during the drilling; and analyzing the drilling parameters to identify an operating range for drilling the hard rock formation.

[0065] In Example 4, the subject matter of Examples 1 – 3 comprises monitoring connection practices during the drilling; and analyzing the connection practices to determine a pick-up height for the drilling system.

[0066] In Example 5, the subject matter of Examples 1 – 4 comprises performing step testing with a first range of revolutions per minute and a second range of weight on bit during the drilling; and determining a first parameter for revolutions per minute and a second parameter for weight on bit based on the step testing.

[0067] In Example 6, the subject matter of Examples 1 – 5 comprises documenting drilling system changes using standardized trial forms.

[0068] In Example 7, the subject matter of Examples 1 – 6 comprises wherein the standardized trial forms comprise first information describing a base case drilling system configuration and second information describing a changed variable implemented to the base case drilling system configuration.

[0069] In Example 8, the subject matter of Examples 1 – 7 comprises wherein the standardized trial forms comprise first information describing a set of changed drilling parameters implemented to a base case drilling systemconfiguration and second information describing a set of measured drilling performance outcomes.

[0070] In Example 9, the subject matter of Examples 1 – 8 comprises wherein the standardized trial forms comprise information for a subsequent drilling operation based on a set of changed drilling parameters implemented to a base case drilling system configuration and a set of measured drilling performance outcomes.

[0071] In Example 10, the subject matter of Examples 1 – 9 comprises maintaining a sustained drilling rate of about 70 feet per hour over a run length of about 2,800 feet.

[0072] Example 11 is a system for drilling a horizontal geothermal well comprising: a drilling system comprising: a bottom-hole assembly with a drill bit having deep leached cutters; and a torsional vibration reduction tool to stabilize the bottom-hole assembly; a drilling fluid system comprising: lubricators to provide lubricants to drilling mud; and mud coolers to control inlet drilling fluid temperature.

[0073] In Example 12, the subject matter of Example 11 comprises monitoring equipment to monitor drill bit wear patterns during drilling.

[0074] In Example 13, the subject matter of Examples 11 – 12 comprises monitoring equipment to detect revolutions per minute and weight on bit during drilling.

[0075] In Example 14, the subject matter of Examples 11 – 13 comprises monitoring equipment to document changes between the drilling system and a base case drilling system configuration and to measure drilling performance outcomes of the drilling system.

[0076] Example 15 is a drilling performance monitoring system comprising: sensors to detect drilling parameters used by a drilling system while drilling a well; monitoring equipment to measure drilling performance outcomes of the drilling system; one or more processors; memory storing instructions that, when executed by the one or more processors, cause the drilling performance monitoring system to perform operations comprising: determining changes between the drilling parameters used by the drilling system and a base case drilling system configuration; and generating a standardized trial form documenting the changes and the drilling performance outcomes.

[0077] The present invention may be embodied in other forms than those specifically disclosed herein without departing from the spirit or essential characteristics of the present invention. The described examples are to be considered in all respects only as illustrative and not restrictive.

[0078] The various examples of systems, compositions, articles, uses, applications, equipment, methods, activities, and operations set forth in this specification may be used for various other fields and for various other activities, uses and examples. Additionally, these examples may be used with: existing systems, compositions, articles, uses, applications, equipment, methods, activities, and operations; may be used with systems, compositions, articles, uses, applications, equipment, methods, activities, and operations that may be developed in the future; and with such systems, compositions, articles, uses, applications, equipment, methods, activities, and operations that may be modified, in-part, based on the teachings of this specification. Further, the various examples set forth in this specification may be used with each other, in whole or in part, and in different and various combinations. Thus, for example, the configurations provided in the various examples of this specification may be used with each other; and the scope of protection afforded the present inventions should not be limited to a particular example, configuration or arrangement that is set forth in a particular example, or in an example in a particular figure.

Claims

CLAIMS What is claimed is:

1. A method for drilling a geothermal well, comprising: providing a drilling system comprising: a bottom-hole assembly with a drill bit having deep leached cutters; and a torsional vibration reduction tool; reducing friction between a borehole wall and the drilling system by adding a lubricant to drilling mud; controlling inlet drilling fluid temperature by using mud coolers; and drilling a horizontal wellbore section in a hard rock formation using the drilling system, the drilling comprising: stabilizing the bottom-hole assembly using the torsional vibration reduction tool.

2. The method of claim 1, further comprising: monitoring drill bit wear patterns during the drilling; and analyzing the drill bit wear patterns to identify areas of improvement in cutting structure performance.

3. The method of claim 1, further comprising: monitoring drilling parameters during the drilling; and analyzing the drilling parameters to identify an operating range for drilling the hard rock formation.

4. The method of claim 1, further comprising: monitoring connection practices during the drilling; and analyzing the connection practices to determine a pick-up height for the drilling system.

5. The method of claim 1, further comprising: performing step testing with a first range of revolutions per minute and a second range of weight on bit during the drilling; anddetermining a first parameter for revolutions per minute and a second parameter for weight on bit based on the step testing.

6. The method of claim 1, further comprising: documenting drilling system changes using standardized trial forms.

7. The method of claim 6, wherein the standardized trial forms comprise first information describing a base case drilling system configuration and second information describing a changed variable implemented to the base case drilling system configuration.

8. The method of claim 6, wherein the standardized trial forms comprise first information describing a set of changed drilling parameters implemented to a base case drilling system configuration and second information describing a set of measured drilling performance outcomes.

9. The method of claim 6, wherein the standardized trial forms comprise information for a subsequent drilling operation based on a set of changed drilling parameters implemented to a base case drilling system configuration and a set of measured drilling performance outcomes.

10. The method of claim 1, wherein drilling the horizontal wellbore section further comprises: maintaining a sustained drilling rate of about 70 feet per hour over a run length of about 2,800 feet.

11. A system for drilling a horizontal geothermal well comprising: a drilling system comprising: a bottom-hole assembly with a drill bit having deep leached cutters; and a torsional vibration reduction tool to stabilize the bottom-hole assembly; a drilling fluid system comprising: lubricators to provide lubricants to drilling mud; andmud coolers to control inlet drilling fluid temperature.

12. The system of claim 11, wherein the drilling fluid system further comprises: monitoring equipment to monitor drill bit wear patterns during drilling.

13. The system of claim 11, wherein the drilling system further comprises: monitoring equipment to detect revolutions per minute and weight on bit during drilling.

14. The system of claim 11, further comprising: monitoring equipment to document changes between the drilling system and a base case drilling system configuration and to measure drilling performance outcomes of the drilling system.

15. A drilling performance monitoring system comprising: sensors to detect drilling parameters used by a drilling system while drilling a well; monitoring equipment to measure drilling performance outcomes of the drilling system; one or more processors; memory storing instructions that, when executed by the one or more processors, cause the drilling performance monitoring system to perform operations comprising: determining changes between the drilling parameters used by the drilling system and a base case drilling system configuration; and generating a standardized trial form documenting the changes and the drilling performance outcomes.

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