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GLOSSARY
Glossary

A

A

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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

B

B

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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

C

C

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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

D

D

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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

E

E

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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

F

F

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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

G

G

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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

H

H

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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

I

I

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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

J

J

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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

K

K

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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

L

L

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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

M

M

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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

N

N

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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

O

O

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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

P

P

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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

Q

Q

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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

R

R

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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

S

S

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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

T

T

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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

U

U

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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

V

V

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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

W

W

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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

X

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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

Y

Y

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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

Z

Z

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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