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GLOSSARY
Glossary
Advanced Geothermal Systems (AGS)
Advanced Geothermal Systems (AGS)
Closed-loop wellbore heat exchangers extracting heat without hydraulic stimulation. Eliminates induced seismicity and water management issues.
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Advanced Technology
Automated Drilling
Automated Drilling
Real-time parameter optimization using advanced control systems. Increases ROP 15-30% while reducing human error and dysfunction.
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Advanced Technology
Autonomous Drilling
Autonomous Drilling
Self-governing systems making real-time drilling decisions. Field trials show 25-48% ROP gains over manual operations (SPE/IADC 223649).
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Advanced Technology
Autonomous Weight-on-Bit Control
Autonomous Weight-on-Bit Control
Automatic optimal force maintenance through real-time downhole adjustments. Eliminates manual weight management in hard rock and directional wells.
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Advanced Technology
Axial Vibration
Axial Vibration
Bit bounce oscillations creating 10-20x normal WOB impact forces. Severely damages equipment and reduces ROP by 15-40%.
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Performance Metrics
Baseload Power
Baseload Power
Baseload power delivers 24/7 electricity regardless of weather. Geothermal achieves 90%+ capacity factor—far exceeding solar and wind.
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Advanced Technology
Blowout Preventer (BOP)
Blowout Preventer (BOP)
Primary well control equipment sealing the wellbore during kicks. Working pressures to 20,000 psi with 30-second closure requirements per API standards.
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Safety & Well Control
Bottom Hole Assembly (BHA)
Bottom Hole Assembly (BHA)
BHA components: drill bit, motor, stabilizers, MWD. Torsional dampers reduce HFTO 100% vs offset runs (SPE-223747-MS, 2025).
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Equipment & Tools
Casing
Casing
Steel pipe providing structural integrity and zone isolation. Represents 30-40% of tangible well costs with API design safety factors governing selection.
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Equipment & Tools
Closed-Loop Control
Closed-Loop Control
Self-correcting system using output feedback to adjust inputs. Enables millisecond-response autonomous drilling optimization.
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Advanced Technology
Closed-Loop Mud System
Closed-Loop Mud System
Recycling system that removes cuttings, eliminates reserve pits, reduces environmental impact by 80%, and maintains consistent mud properties.
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Drilling Fluids
Coiled Tubing Drilling
Coiled Tubing Drilling
Continuous steel pipe eliminating connections. Sakhalin-1 achieved record CT runs to 11,680m MD (SPE-92783, 2005).
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Equipment & Tools
Differential Pressure
Differential Pressure
Difference between wellbore and formation pressure. Excessive differential causes stuck pipe—25% of drilling NPT at $250M+ annual industry cost.
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Drilling Fluids
Directional Drilling
Directional Drilling
Non-vertical wellbores accessing remote reserves. RSS reduces drilling time 50% vs motors; autonomous systems add 25-48% ROP gains (SPE-223649-MS).
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Directional Drilling
Dogleg Severity (DLS)
Dogleg Severity (DLS)
Rate of wellbore direction change (°/100ft). Industry limits 3-5°/100ft conventional; modern RSS achieve 15°/100ft (SPE-124498-MS).
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Directional Drilling
Downhole Anchoring
Downhole Anchoring
Wellbore gripping system generating thrust locally at bit. Eliminates friction losses and enables extended reach drilling.
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Advanced Technology
Downhole Automation
Downhole Automation
Autonomous bit-location control with millisecond response. Improves ROP while extending equipment life in hard rock drilling.
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Advanced Technology
Downhole Force Control
Downhole Force Control
Real-time bit force measurement and adjustment at source. Eliminates surface control delays and maintains precise operating conditions.
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Advanced Technology
Downhole Motor
Downhole Motor
Hydraulic motor near bit converting fluid flow to rotation. Enables directional drilling with precise trajectory control.
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Equipment & Tools
Drill Bit
Drill Bit
Rock-cutting tool determining drilling efficiency. PDC bits achieve 2-3× higher ROP than roller cone—FORGE program showed 400%+ improvement in hard rock.
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Equipment & Tools
Drill String
Drill String
Drill pipe, collars, and BHA transmitting power to bit. API 5DP grades E-75 to S-135; optimized designs enabled 11,943m runs (SPE-150959).
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Equipment & Tools
Drilling Automation ROI
Drilling Automation ROI
SPE/IADC studies show 25-48% ROP gains, $750M annual savings from vibration mitigation. Autonomous drilling cuts costs 20-50% vs manual operations.
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Advanced Technology
Drilling Dysfunction
Drilling Dysfunction
Inefficient energy transfer, accelerated wear, and reduced ROP. Includes stick-slip, whirl, and bit bounce conditions.
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Performance Metrics
Drilling Fluid (Mud)
Drilling Fluid (Mud)
Engineered fluid system: 5-10% of well cost ($425K-$850K for $8.5M well). Balances hole cleaning, stability, and environmental compliance.
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Drilling Fluids
Drilling Optimization
Drilling Optimization
Systematic process maximizing efficiency through parameter optimization. Leverages real-time analytics and automated systems.
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Drilling Operations
Drilling Optimization Technology
Drilling Optimization Technology
Real-time analytics and automated control optimizing WOB, RPM, and flow rate. Achieves higher ROP while extending bit life and reducing NPT.
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Advanced Technology
Drilling Simulator
Drilling Simulator
Physics-based training systems replicating drilling scenarios. Improves crew competency, safety awareness, and decision-making skills.
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Advanced Technology
Enhanced Geothermal Systems (EGS)
Enhanced Geothermal Systems (EGS)
Enhanced Geothermal Systems create reservoirs in hot dry rock via stimulation. Drilling costs (40-60% of capex) determine EGS viability.
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Advanced Technology
Equivalent Circulating Density (ECD)
Equivalent Circulating Density (ECD)
Effective density during circulation including friction losses. Must remain below fracture gradient—rheology optimization balances hole cleaning vs. ECD.
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Drilling Fluids
Extended Reach Drilling (ERD)
Extended Reach Drilling (ERD)
High horizontal-to-vertical displacement. World record: 15,000m MD with 14,129m stepout at Sakhalin-1 (Rosneft, 2020). DDI >7.0 indicates supercomplex wells.
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Directional Drilling
Formation Pressure
Formation Pressure
Pore pressure exerted by formation fluids. Prediction accuracy critical—Bowers method achieves less than 5% error vs. direct measurements.
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Formation & Geology
Geosteering
Geosteering
Real-time trajectory optimization using continuous LWD data. Keeps wellbore within productive zone for maximum reservoir contact.
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Directional Drilling
Geothermal Drilling Cost Reduction
Geothermal Drilling Cost Reduction
Cost reduction through automated control and real-time optimization. Key to making enhanced geothermal systems economically viable.
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Performance Metrics
Geothermal Drilling Technology
Geothermal Drilling Technology
Specialized techniques for extreme temperatures (175°C+), hard formations, and corrosive environments. Key enabler for EGS viability.
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Advanced Technology
Geothermal Gradient
Geothermal Gradient
Learn how geothermal gradient (25-30°C/km) affects drilling fluid, equipment, and well design. Essential for geothermal operations.
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Formation & Geology
Geothermal Well Economics
Geothermal Well Economics
Cost analysis framework for geothermal wells. Drilling represents 40-60% of project capex—technology reducing drilling time directly improves viability.
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Performance Metrics
Hard Rock Drilling Technology
Hard Rock Drilling Technology
Hard rock drilling for granite, basalt, and formations above 30,000 psi. Advanced technologies enabling economic geothermal and deep drilling.
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Advanced Technology
Horizontal Drilling
Horizontal Drilling
Wellbore running parallel to formation maximizing reservoir contact. Dramatically increases production vs. vertical wells.
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Directional Drilling
Inclination
Inclination
Angle between wellbore and vertical. MWD accuracy ±0.1-0.2° after calibration—survey intervals should not exceed 100 ft for position accuracy.
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Directional Drilling
Jarring
Jarring
High-impact technique for freeing stuck pipe. Impact force multiplier up to 8×—50% of incidents resolved within 4 hours; critical to act fast.
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Drilling Operations
Kick
Kick
Uncontrolled formation fluid influx into wellbore. 70% occur during connections—early detection systems reduce response threshold by 50%.
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Safety & Well Control
Kickoff Point (KOP)
Kickoff Point (KOP)
Measured depth where wellbore deviates from vertical and begins building angle. Critical for trajectory planning.
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Directional Drilling
Levelized Cost of Energy (LCOE)
Levelized Cost of Energy (LCOE)
Average cost per unit of electricity over plant lifetime. Key metric for comparing geothermal vs. other power generation technologies.
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Performance Metrics
Logging While Drilling (LWD)
Logging While Drilling (LWD)
Real-time formation evaluation sensors capturing resistivity, porosity, gamma ray. Optimizes well placement during drilling.
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Measurement & Data
Measurement While Drilling (MWD)
Measurement While Drilling (MWD)
Real-time trajectory, drilling mechanics, and formation data via mud pulse telemetry. Enables precise wellbore placement.
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Measurement & Data
Mechanical Specific Energy (MSE)
Mechanical Specific Energy (MSE)
Energy per unit volume of rock removed. Introduced by Teale (1965), MSE enables real-time drilling dysfunction detection.
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Performance Metrics
Modular Drilling Automation
Modular Drilling Automation
Standalone automation components integrating with existing BHA and rigs. Lower barrier to entry without full platform replacement.
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Advanced Technology
Motor Differential Pressure
Motor Differential Pressure
Pressure drop across mud motor correlating to torque output. Critical parameter for optimizing motor performance and preventing stalling.
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Performance Metrics
Mud Motor
Mud Motor
PDM converting mud flow to rotation. Lobe configurations 1:2 (high speed) to 9:10 (high torque); bent housing 1.83-2.12° achieves 15-20°/100ft build rates.
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Equipment & Tools
Non-Productive Time (NPT)
Non-Productive Time (NPT)
Time lost to failures, stuck pipe, or unplanned events. Accounts for 20-30% of drilling time, costing $250M+ annually.
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Drilling Operations
Overbalance
Overbalance
Wellbore pressure exceeding formation pressure. Industry specifies 100-200 psi margin—higher values increase formation damage and stuck pipe risk.
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Drilling Operations
Perforation
Perforation
Shaped charge process creating reservoir-wellbore communication. Shot density of 8+ SPF recommended—crushed zone can reduce permeability to 5% of original.
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Drilling Operations
Plasma Drilling
Plasma Drilling
Pulsed plasma torch at 6,000°C breaking rock via thermal shock. Contactless operation eliminates bit wear in hard formations.
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Advanced Technology
Plasma Drilling Technology
Plasma Drilling Technology
Contactless drilling using plasma pulses for thermal-mechanical rock disintegration. Eliminates bit wear in hard formations.
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Advanced Technology
Quill
Quill
Top drive rotating shaft transmitting torque to drillstring. Modern systems deliver 37,000-105,000 ft-lb continuous torque enabling 90-ft stand drilling.
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Equipment & Tools
Rate of Penetration (ROP)
Rate of Penetration (ROP)
Drilling speed in ft/hr or m/hr. SPE/IADC studies show autonomous systems achieve 25-48% ROP gains over manual operations.
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Performance Metrics
Real-Time Downhole Control
Real-Time Downhole Control
Millisecond-response parameter adjustment at bit location. Eliminates 2-4 second surface control delays for immediate dysfunction prevention.
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Advanced Technology
Real-Time Drilling Data
Real-Time Drilling Data
Continuous streaming of drilling parameters for immediate analysis. Enables proactive problem detection and remote expert support.
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Measurement & Data
Rotary Downlinking
Rotary Downlinking
Drill string rotation modulation transmitting commands to downhole tools. Enables autonomous system control without physical connections.
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Measurement & Data
Rotary Steerable System
Rotary Steerable System
Continuous drill string rotation with trajectory control. Eliminates sliding operations for faster drilling and better hole quality.
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Equipment & Tools
Stabilizer
Stabilizer
BHA component controlling trajectory and reducing vibration. Expandable designs achieve 35% MSE reduction with proper placement 30-60 ft from bit.
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Equipment & Tools
Stick-Slip
Stick-Slip
Bit stops/accelerates cyclically at 0.1-2 Hz. Velocity reaches 2× surface RPM during slip; causes $750M annual industry cost (SPE 127413).
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Performance Metrics
Supercritical Geothermal Systems
Supercritical Geothermal Systems
Geothermal systems above 374°C delivering 5-10x more power per well. Requires advanced drilling for extreme temperatures and hard rock.
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Advanced Technology
Thermal Spallation
Thermal Spallation
Rock-breaking mechanism using rapid thermal stress to cause surface spalling. Key physics behind contactless plasma drilling technology.
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Advanced Technology
Thrust Control
Thrust Control
Active downhole force management delivering up to 30,000 lbs. Overcomes friction limitations and enables optimal bit loading control.
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Performance Metrics
Torque
Torque
Rotational force transmitted to bit, measured in ft-lbs. Readings indicate bit performance, drag, and potential drilling problems.
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Performance Metrics
Torsional Vibration
Torsional Vibration
Cyclical rotational speed variation causing tool failures. Exceeds MWD reliability at 25g, causes 20-30% of failures (SPE 127413).
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Performance Metrics
Underbalanced Drilling (UBD)
Underbalanced Drilling (UBD)
Drilling with wellbore pressure below formation pressure. Achieves 3-4× ROP improvement and eliminates differential sticking in suitable applications.
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Drilling Operations
Vibration Dampener
Vibration Dampener
Tool absorbing drillstring vibrations to protect BHA. 25 g lateral threshold for MWD—20-30% of tool failures attributed to drilling dynamics.
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Equipment & Tools
Weight on Bit (WOB)
Weight on Bit (WOB)
Downward force on drill bit (klbs/kN). Friction consumes 50-70% of surface weight in directional wells (SPE 173024).
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Performance Metrics
Wellbore Stability
Wellbore Stability
Mechanical integrity of borehole. Stability issues cause 10% of drilling NPT. Autonomous systems maintain ECD within stability windows.
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Safety & Well Control
X-Ray Diffraction (XRD)
X-Ray Diffraction (XRD)
Analytical technique identifying mineralogy and crystal structures. Provides critical data for drilling fluid design.
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Measurement & Data
Yield Point
Yield Point
Drilling fluid resistance to initial flow. API range 5-3×PV lb/100ft²—higher YP/PV ratios improve cuttings transport in laminar flow regimes.
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Drilling Fluids
Zone Isolation
Zone Isolation
Preventing fluid communication between formations. Primary cement failures occur in 37% of wells—remediation increases costs 30%.
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Drilling Operations