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Types Of Drilling & Boring In Oil & Gas

Types Of Drilling & Boring In Oil & Gas

Drilling and boring are two basic types for extracting oil and gas from the earth’s surface.  If you plan on working for the oil and gas industry in your career, then you must understand their methods and how they operate.

Drilling and boring are two methods but have many types; some are advanced and cost less, but others are old and expensive. The type of method to use depends on various factors like location, rock formation, budget available, etc.

Today we will learn about these various methods and how they work. So, let’s get started.

Common Oil Drilling Types

Various drilling methods are used for extracting and exploring oil found in underground fossil fuel formations. The best method depends on location, surface, expenses, etc. Here are a few standard methods that are used these days:

Vertical Drilling

Vertical drilling is the most commonly used method for finding and exploring oil, natural gas resources. Using this method, a well bore is drilled vertically along the surface to the target reservoir where oil or gas might be located.

Vertical drilling is a cost-effective method for finding natural resources but has proven to be inefficient as well. Sometimes the underground reservoir might extend horizontally and out of reach of the bore well. In that case, multiple vertical drilling must be done multiple times to locate the exact location or directional drilling, which is far more effective, which we will discuss later.

Percussion/Cable Drilling

Cable drilling is percussion, an old method of crushing rock through a heavy drilling bit attached to a cable. It involves repeatedly lifting and hitting the drill bit to break a rock. 

Cuttings from the borehole can be removed by submerging them in water and flushing them up to the surface following the removal of the bit.

In both unconsolidated and consolidated formations, this method of drilling is effective. Among these are sand, silt, sandstone, and gravel. It is not that commonly used these days and is less efficient too.

Rotary Drilling

Rotary drilling is a drilling technique that uses a rotating drill bit to cut through rock or other materials. It is the most common method for drilling oil and gas wells, water wells, geothermal wells, and other types of wells.

The equipment can be mounted on a platform for drilling exploration wells on land. Drilling rigs that utilize Kelly bars and hydraulic rotary drilling equipment are ideal for more significant hydraulic rotary drilling operations.

Drilling can be made more efficient by adjusting the rotational speed following the composition of the formation materials. Air-based drilling fluids have a faster penetration rate than water-based drilling fluids.

Directional Drilling

A directional drilling uses a curved path to guide the drill so that it will deepen the borehole. This technique extends the rotary drilling technique because both use the same equipment. Still, in directional drilling, additional equipment is used to track the trajectory of the well bore.

You can also classify it as ‘Directional Boring’. Using this method, oil explorers can reach deposits that would otherwise be impossible using vertical drilling. The wellbore can be deviated by angles ranging from 0 to 90 degrees.

Drilling multiple wells from one platform is a significant advantage of directional drilling. Consequently, it is much more economical since costs are greatly reduced.

Hydraulic Fracturing

Hydraulic Fracking involves injecting water, sand, and chemicals at high pressure into a well bore to fracture the rock formation. This fracturing allows oil and gas to flow more freely. Shale formations are often drilled horizontally or directionally to extract oil and gas.

Horizontal Drilling

This is a variation of directional drilling. This method drills a well horizontally through the rock formation to reach the oil and gas reservoir. This method is often used to extract oil and gas from shale formations, which have low permeability. Such formations require horizontal directional drilling combined with hydraulic fracturing to extract the resources.

Dual-Wall Reverse-Circulation Drilling

The dual-wall reverse-circulation process involves connecting two concentric drill pipes to control the flow.  The outer string is called the casing, and its purpose is to provide stability to the borehole and protect the environment from contamination. The inner string is the drill pipe, which rotates and moves the drill.

This technique is a type of rotary drilling. It uses reverse circulation, where compressed air is pumped down the drill pipe and flows back in the annular space between the casing and the drill pipe. This creates a vacuum effect that shoots the drill cuts and debris up the surface.

Geologic samples are collected using this method. This method may be applied to both rotary drilling and percussion drilling. Cuttings can be recovered from a controlled space where compressed air circulates.

This method has the advantage of a high sample recovery rate. It is also possible to penetrate alluvial or fissure rock very quickly with this method. Furthermore, it aids in delivering an accurate estimate of aquifer yield based on depth and formation type.

Offshore Drilling

The process of offshore drilling involves extracting petroleum from reserves under the oceans rather than those located on land. Over the past few years, offshore oil rigs have evolved into enormous structures operated continuously by hundreds of personnel.

The offshore drilling method is expensive and risky for extracting oil but also very profitable.

Electro Drilling

This procedure involves using electric motors to drive rotary tables, winches, and other equipment to create a borehole. This allows for a greater degree of flexibility in operations. It is a newer method of oil exploration. The motor is connected above the drill bit and below the hole to provide more direct power to the drill bit.

Electro-drilling is reliable in mud mixtures or weighted mud in complex geological conditions. Azerbaijan, Turkmenistan, and Ukraine have all implemented electro-drilling widely to reduce energy use and material waste.  

This method combines the advantages of both hydraulic and rotary motors and involves a wide range of drill-bit rotational speeds. Using this technique, you can also drill deviated boreholes through controlled drilling.


Drilling and boring methods are crucial for oil and gas exploration. These methods have evolved to become more sophisticated, efficient, and safe. Each method has its advantages and limitations.

Similarly, cable and rotary drilling have unique benefits, depending on the drilled geological formations.

The oil industry continues to invest in research and development to improve these methods and increase production efficiency. In the coming years, we can see more advanced methods that involve sustainable practices and are cost-effective at the same time.