Methods used to survey and characterize the physical and geological characteristics along and near the wall of a well, including the temperature, pressure, fracture density, fracture orientation, porosity, rock type, casing integrity, and fluid chemistry.
Denotes the start of the well. The term originated from cable tool drilling where spudding is the act of hoisting the drill pipe and letting it fall freely so that the drill bit strikes the bottom of the well bore with sufficient force to break the rock.
Pamukkale is a western Turkish town known for the mineral-rich thermal waters that cascade over steep, white terraces that reach over 100 meters (~330 feet) high. Across the terraces, there are a total of 17 hot springs, which range in temperature from 35-100 degrees Celsius (95-212 degrees Fahrenheit) year-round. The name in Turkish means “cotton castle” as it resembles the cotton plantations in central Turkey.
However, the white terraces are not cotton – they’re travertine rock! Travertine is a form of limestone that is deposited over time by mineral waters, most commonly, hot springs. The mass of hot springs sources in the area produces high amounts of calcium carbonate in the water so when the water hits the open air, it becomes white travertine rock.
Before it was Pamukkale, the site used to be the lively Greco-Roman city Hierapolis. Hierapolis was a spa city founded in 190 BC. Just like today, it was one of Turkey’s most popular hot springs. The ruins of the city are well preserved and hold what is known as Cleopatra’s pool, who is said to have bathed there, along with many other historically famous people.
The hot springs are open to the public to swim and relax in, and they have been known to be great for healing.
The process of extracting geothermal heat by the heating of initially cold water that flows through fractures in hot rock below the surface. Heat transfer is achieved by conduction through the solid rock and convection by the flowing water.
The practice of steering the trajectory of a well during drilling from vertical to a deviated angle, including horizontal drilling used for oil and gas production from poorly permeable rocks. Directional drilling may also be used to maneuver around obstructions or to drill beneath areas that are inaccessible on the surface.
Large diameter pipe that is assembled and inserted into newly drilled intervals of a well. The upper portions of a cased well are commonly cemented in place to provide a smooth internal bore, and prevent the inflow of water and/or collapse of the hole.
A tool that is placed on the end of a string of pipe to drill a well. Rotary drill bits are commonly used in oil and gas and geothermal drilling. Coring bits are used to obtain cylindrical core samples of rock that preserve mineralogical and textural features which are commonly destroyed during rotary drilling.
Did you know... that Paris has used geothermal energy to heat the homes of more than 2 million people?
You might not think that Paris, the city of love, would be a major producer of geothermal energy – but it is! Paris has been using geothermal energy to heat houses since 1969.
Under the famous city are two deep aquifers containing hot water. Since 1969, Paris has been working on many geothermal projects. Today, there are around fifty supply networks in the city that heat almost 250,000 homes.
The main aquifer, the Dogger, is about 1,500-2,000 meters (~4,900-6,600 feet) deep. The rock that hosts the aquifer is 150-170 million years old and is made of limestone. It has a temperature of about 60 degrees Celsius. While the Dogger is full of mineral salts that make produced water unfit for consumption, the heat can be used for district heating. This geothermal resource supplies energy to buildings in the northern, eastern, and southern parts of Paris, but to the west it falls below a threshold temperature that makes drilling and production uneconomic.
Currently, SIPPEREC (the Paris intercommunal union for energy and communication networks) is exploring the idea of drilling into the Triassic rock layer, which underlies the Dogger at 2,100 meters (~6,870 feet) depth. The temperature of the water at this level is about 80 degrees Celsius – 20 degrees higher than the Dogger. If successful, utilizing the Triassic layer would allow development in the western part of the Paris region but full-scale exploration awaits approval from regulatory authorities and the state.
As of 2020, drilling into the Dogger costs about 5 million euros per well. Of course, drilling deeper costs more, and the cost of drilling into the Triassic layer is about 9 million euros per well. However, because of the hotter water temperature, production here could be cheaper as less water would be required. SIPPEREC says that network users' charge could be lowered as well.
The new heating networks are scheduled for completion in November of this year with the benefit of conserving annual emissions of 30,000 tonnes of CO2.