Horizontal drilling is a technique used to develop larger oil and gas resources from a single well.
Horizontal drilling and horizontal wells have been common practice in the oil and natural gas industries since the 1970s, but the US Department of Energy notes the concept was first introduced as early as 1929.
In Australia, horizontal or “directional” drilling has been common since the 1990s and has been used more recently to target deep shale gas resources in South Australia and NT.
Australia’s first horizontal shale gas well was drilled by Santos in SA’s Cooper Basin in 2013 and the most recent example was Origin’s Amungee NW-1H well in the Beetaloo Basin in the NT.
The Amungee well was drilled in 2015 and hydraulically fractured in 2016. It resulted in an important natural shale gas discovery for the Northern Territory.
These and other horizontal wells have been drilled safely with no impact on water resources or the environment.
Larger wells do of course use more water, sand and other additives, but the technology means fewer wells are drilled overall and the environmental impact is thus reduced.
Today, companies can drill multiple horizontal well paths from a single surface location.
Clustering wells onto a single surface location dramatically reduces the overall amount of surface land required for wells and related infrastructure.
Reducing oil and gas wells’ surface impacts while also improving production is an important advantage of horizontal drilling.
Also called deviated drilling, directional drilling involves deliberately shifting a well’s path from the vertical. Wells can be deviated until they are running horizontally. They can even be steered – in real time – upwards or downwards once the horizontal direction is established.
Reasons for directional drilling include:
- Avoiding a surface site that is operationally difficult or environmentally sensitive
- Targeting a larger gas resource from a single well
- Reducing costs or surface impact by drilling several wells in different directions from the one surface location
- Targeting an offshore resource from an onshore site
- Enhancing oil and gas production by drilling in a way that exposes more of the reservoir to the wellbore.
To steer the well path, rotary steerable equipment is mounted on the drill pipe just behind the drill bit. These systems are controlled from the surface to redirect the drill bit to steer the well on any desired path.
Directional drilling is precise. Wells kilometres deep can be directed to within centimetres of their targets.
This technology developed for the oil and gas industry is now also being used in other industry applications, including:
- construction and civil engineering
- drilling water wells
- laying water pipelines and telecommunication cables.