PETE 4241-2 Geothermal Well Design & Construction Flashcards

Vocabulary practice flashcards covering core concepts, resource types, drilling mechanics, wellbore stability, lost circulation, and formula relations from Geothermal Well Design.

Earth's total surface heat flow (Davies & Davies, 2010) is about: (a) $4.7\,\text{TW}$ (b) $19\,\text{TW}$ (c) $47\,\text{TW}$ (d) $470\,\text{TW}$

(c) $47\,\text{TW}$

Mean continental surface heat flux is about: (a) $65\,\text{mW/m}^2$ (b) $650\,\text{mW/m}^2$ (c) $6.5\,\text{W/m}^2$ (d) $65\,\text{W/m}^2$

(a) $65\,\text{mW/m}^2$

Roughly what share of Earth's surface heat flow comes from radioactive decay? (a) Almost none (b) About 10% (c) About 90% (d) About half

(d) About half

The geothermal gradient equals: (a) $k / q$ (b) $q / k$ (c) $q \times k$ (d) $q \times k \times z$

(b) $q / k$

From a $20\,^\circ\text{C}$ ($68\,^\circ\text{F}$) surface, about what depth reaches $150\,^\circ\text{C}$ ($302\,^\circ\text{F}$) at a $30\,^\circ\text{C/km}$ gradient? (a) $2.2\,\text{km}$ ($7,200\,\text{ft}$) (b) $4.3\,\text{km}$ ($14,200\,\text{ft}$) (c) $5.2\,\text{km}$ ($17,100\,\text{ft}$) (d) $8.7\,\text{km}$ ($28,500\,\text{ft}$)

(b) $4.3\,\text{km}$ ($14,200\,\text{ft}$)

Drilling's share of a geothermal project's overnight capital cost is about: (a) 30–57% (b) 60–75% (c) 80–90% (d) Over 95%

(a) 30–57%

Geothermal's share of US utility-scale electricity generation in 2025 was about: (a) 0.04% (b) 0.4% (c) 4% (d) 14%

(b) 0.4%

The Geysers peaked in 1987 at about: (a) $380\,\text{MW}$ (b) $725\,\text{MW}$ (c) $1,100\,\text{MW}$ (d) $2,043\,\text{MW}$

(d) $2,043\,\text{MW}$

What is The Geysers doing to hold up reservoir pressure? (a) Drilling deeper into hotter rock (b) Injecting about 20 million gallons per day of treated wastewater (c) Converting all plants to binary (d) Shutting in half the wells every summer

(b) Injecting about 20 million gallons per day of treated wastewater

A '90%-plus' figure quoted for geothermal plants is most likely: (a) The US fleet capacity factor (b) The thermal efficiency (c) Plant availability or a design capacity factor (d) The parasitic load

(c) Plant availability or a design capacity factor

Why do data centers suit geothermal? (a) They need the cheapest possible energy (b) They need seasonal heat (c) They are always built near volcanic fields (d) They draw a near-constant load around the clock and need firm power

(d) They draw a near-constant load around the clock and need firm power

Unsubsidized geothermal LCOE in Lazard's LCOE+ v19.0 (July 2026) is about: (a) $5–15/MWh (b) $37–99/MWh (c) $67–111/MWh (d) $175–255/MWh

(c) $67–111/MWh

The three gaps between petroleum training and a geothermal well are: (a) Temperature, hardness, chemistry (b) Cost, policy, permitting (c) Depth, pressure, flow rate (d) Water, land, transmission

(a) Temperature, hardness, chemistry

Which conversion technology suits a moderate-enthalpy resource of $90\text{--}150\,^\circ\text{C}$? (a) Dry steam (b) Single flash (c) Direct use only (d) Binary (organic Rankine) cycle

(d) Binary (organic Rankine) cycle

Water becomes supercritical above $22.1\,\text{MPa}$ and about: (a) $100\,^\circ\text{C}$ (b) $221\,^\circ\text{C}$ (c) $300\,^\circ\text{C}$ (d) $374\,^\circ\text{C}$

(d) $374\,^\circ\text{C}$

Which is NOT one of the four ingredients a hydrothermal system needs? (a) A heat source (b) Dissolved methane (c) Permeable reservoir rock (d) A cap-rock seal

(b) Dissolved methane

The normal Gulf Coast hydrostatic pressure gradient used in Lecture 2 is: (a) $0.433\,\text{psi/ft}$ (b) $0.465\,\text{psi/ft}$ (c) $0.70\,\text{psi/ft}$ (d) $1.00\,\text{psi/ft}$

(b) $0.465\,\text{psi/ft}$

The pore-pressure gradient computed for Gladys McCall #1 is about: (a) $0.62\,\text{psi/ft}$ (b) $0.70\,\text{psi/ft}$ (c) $0.76\,\text{psi/ft}$ (d) $0.83\,\text{psi/ft}$

(d) $0.83\,\text{psi/ft}$

Dissolved methane measured in the DOE geopressured test wells ranged from about: (a) $24\text{--}55\,\text{scf/bbl}$ (b) $100\text{--}150\,\text{scf/bbl}$ (c) $240\text{--}550\,\text{scf/bbl}$ (d) Over $1,000\,\text{scf/bbl}$

(a) $24\text{--}55\,\text{scf/bbl}$

Why did the 2009–2011 attempt to restart the Sweet Lake geopressured well end? (a) The reservoir had depleted (b) Casing collapsed in the test well (c) Wells at $8–10 million each, no premium power purchase agreement, and no Louisiana renewable portfolio standard (d) Induced seismicity

(c) Wells at $8–10 million each, no premium power purchase agreement, and no Louisiana renewable portfolio standard

In EGS, hydraulic stimulation mostly: (a) Shears existing natural fractures (b) Opens new tensile fractures in intact rock (c) Dissolves the rock matrix (d) Seals the reservoir from the wellbore

(a) Shears existing natural fractures

Utah FORGE is best described as: (a) A commercial EGS power plant (b) A closed-loop demonstration (c) A DOE field laboratory in granitoid basement (d) A geopressured test well

(c) A DOE field laboratory in granitoid basement

Which EGS risk has not yet been measured at commercial scale? (a) Finding hot rock (b) Drilling horizontal laterals in granite (c) Water supply for stimulation (d) Multi-decade thermal drawdown

(d) Multi-decade thermal drawdown

In a closed-loop system, outlet temperature is set mainly by: (a) Circulation rate (b) Reservoir permeability (c) Contact area with the rock (lateral length) (d) Brine salinity

(c) Contact area with the rock (lateral length)

Under the INL traffic-light plan, injection stops (red) when peak ground velocity reaches about: (a) $0.05\,\text{cm/s}$ (b) $0.5\,\text{cm/s}$ (c) $3.9\text{--}9.2\,\text{cm/s}$ (d) Magnitude 2 on any scale

(c) $3.9\text{--}9.2\,\text{cm/s}$

The Lecture 2 ranking of resource options for Louisiana puts first: (a) Geopressured co-production (b) Conventional hydrothermal (c) Closed-loop systems (d) Superhot

(a) Geopressured co-production

Standard MWD/LWD electronics are rated to about: (a) $121\,^\circ\text{C}$ ($250\,^\circ\text{F}$) (b) $175\,^\circ\text{C}$ ($347\,^\circ\text{F}$) (c) $260\,^\circ\text{C}$ ($500\,^\circ\text{F}$) (d) $300\,^\circ\text{C}$ ($572\,^\circ\text{F}$)

(b) $175\,^\circ\text{C}$ ($347\,^\circ\text{F}$)

Standard BOP elastomers are rated to about: (a) $121\,^\circ\text{C}$ ($250\,^\circ\text{F}$) (b) $177\,^\circ\text{C}$ ($350\,^\circ\text{F}$) (c) $200\,^\circ\text{C}$ ($392\,^\circ\text{F}$) (d) $300\,^\circ\text{C}$ ($572\,^\circ\text{F}$)

(a) $121\,^\circ\text{C}$ ($250\,^\circ\text{F}$)

In the field-unit MSE equation, the rotary term is: (a) $WOB / A_b$ (b) $A_b \times ROP / (120 \pi N T)$ (c) $120 \pi N T / (A_b \times ROP)$ (d) $WOB \times ROP / A_b$

(c) $120 \pi N T / (A_b \times ROP)$

MSE running at several times the rock's UCS most likely points to: (a) A dull bit, poor hole cleaning, vibration, or founder (b) Rock stronger than logged (c) Perfect efficiency (d) A units error in UCS

(a) A dull bit, poor hole cleaning, vibration, or founder

'Founder' describes the point where: (a) The bit has no moving parts left (b) The bit drills faster than the mud can clean (c) Returns are lost (d) More weight on bit stops increasing ROP, so MSE rises

(d) More weight on bit stops increasing ROP, so MSE rises

PDC bits displaced roller cones in hot, hard rock mainly because PDC bits: (a) Crush rock rather than shear it (b) Have no seals or bearings to overheat (c) Are always cheaper (d) Have cutters that survive $730\,^\circ\text{C}$ formation temperatures

(b) Have no seals or bearings to overheat

What drives PDC cutter degradation near $730\,^\circ\text{C}$? (a) Seal elastomer failure (b) Bearing grease breakdown (c) Thermal-expansion mismatch between the cobalt binder and the diamond (d) Bentonite flocculation

(c) Thermal-expansion mismatch between the cobalt binder and the diamond

Lecture 3 gives the unconfined compressive strength of granite as about: (a) $10\text{--}40\,\text{MPa}$ (b) $50\text{--}100\,\text{MPa}$ (c) $125\text{--}200\,\text{MPa}$ (d) $280\text{--}350\,\text{MPa}$

(c) $125\text{--}200\,\text{MPa}$

Comparing the 2017 FORGE offset well 58-32 with the lower half of 16A(78)-32, the lecture says the biggest money saver was: (a) Mud cost (b) Feet per bit run, because it cuts trips (c) Rig day rate (d) Casing design

(b) Feet per bit run, because it cuts trips

Stick-slip severity grows with: (a) Drillstring length (deeper wells) (b) Lower rock strength (c) Higher mud weight (d) Smaller bit diameter

(a) Drillstring length (deeper wells)

Aerated fluid or foam is used where: (a) The reservoir is overpressured (b) The formation is salt (c) The reservoir is underpressured, to bring hydrostatic pressure near pore pressure (d) The bit needs extra weight

(c) The reservoir is underpressured, to bring hydrostatic pressure near pore pressure

Which fluid temperature limit could NOT be traced to a citable source in Lecture 3? (a) Bentonite flocculation near $149\,^\circ\text{C}$ ($300\,^\circ\text{F}$) (b) Formate brine stability near $190\,^\circ\text{C}$ (c) Conventional LCM degradation from $93\,^\circ\text{C}$ ($200\,^\circ\text{F}$) (d) Degradation temperatures for starch, CMC, xanthan and PHPA

(d) Degradation temperatures for starch, CMC, xanthan and PHPA

When losses start, the first question to answer is: (a) How do I stop them? (b) Am I in an interval I want to produce? (c) How much LCM is on location? (d) Should I pull out of the hole?

(b) Am I in an interval I want to produce?

A loss rate of $150\,\text{bbl/hr}$ is classified as: (a) Seepage (b) Partial (c) Severe (d) Total

(c) Severe

Overall lost-circulation treatment success in geothermal wells is about: (a) 24% (b) 45% (c) 65% (d) 90%

(a) 24%

Conventional LCM typically starts to degrade from about: (a) $38\,^\circ\text{C}$ ($100\,^\circ\text{F}$) (b) $66\,^\circ\text{C}$ ($150\,^\circ\text{F}$) (c) $93\,^\circ\text{C}$ ($200\,^\circ\text{F}$) (d) $149\,^\circ\text{C}$ ($300\,^\circ\text{F}$)

(c) $93\,^\circ\text{C}$ ($200\,^\circ\text{F}$)

Which material is used on purpose in Imperial Valley production zones because it breaks down and leaves little residue? (a) Controlled-porosity ceramic (b) Gilsonite (c) Expanded aggregate (d) Cottonseed hulls

(d) Cottonseed hulls

Fine fibre and granular background LCM seals fractures up to about: (a) $25\,\mu\text{m}$ (b) $250\,\mu\text{m}$ (c) $2.5\,\text{mm}$ (d) $25\,\text{mm}$

(b) $250\,\mu\text{m}$

IDDP-2 lost returns from about what depth to total depth? (a) $1.2\,\text{km}$ (b) $2.1\,\text{km}$ (c) $2.6\,\text{km}$ (d) $3.2\,\text{km}$

(d) $3.2\,\text{km}$

Drilling blind costs you: (a) Bit life (b) Casing strength (c) Conventional kick indicators such as pit gain (d) The mud cooler

(c) Conventional kick indicators such as pit gain

Heating the wellbore wall after circulation stops tends to cause: (a) Tensile radial cracks (b) Ballooning (c) No change in stability (d) Compressive spalling and breakout along the minimum horizontal stress direction

(d) Compressive spalling and breakout along the minimum horizontal stress direction

In the hot geothermal well example, the mud-weight window closes because: (a) Cooling lowers the fracture gradient onto the ECD (b) Pore pressure rises (c) The mud gets heavier with depth (d) The bit wears

(a) Cooling lowers the fracture gradient onto the ECD

A $0.5\,\text{ppg}$ trip margin taken from a $1.7\,\text{ppg}$ static window uses up about: (a) A third of the window (b) Half (c) Two-thirds (d) All of it

(a) A third of the window

The tool previewed at the end of Lecture 4 that holds bottom-hole pressure inside a narrow window with surface back-pressure is: (a) An LCM pill (b) Aerated mud (c) Managed pressure drilling (MPD) (d) Drilling blind

(c) Managed pressure drilling (MPD)