Generalized Process of Finding Oil & Gas Reserves

Geology

Before we drill for oil or natural gas we first have to determine where gas reservoirs exist. The search begins with geologists and geophysicists who use technology and science to locate possible oil or natural gas deposits.

Geologists and geophysicists study and examine the land's surface and subsurface area while conducting seismic surveys. These surveys gather geological information underground by sending sound waves into the earth.

Geologists then record the signals that bounce back from hitting rock formations. This data helps them determine areas that might contain natural gas reserves. The area is then tested.

Land Leasing and Oil & Gas Ownership

If their findings determine oil or natural gas may exist, courthouse records are searched to determine ownership of oil and gas mineral rights. A landman then negotiates a lease with the mineral owner. Permits are obtained from state agencies once a lease is signed.

If operations require access across another property for drilling access or pipeline construction, the landman must get an easement or a right of way from those landowners.

Crews then clear the land in accordance with environmental protection agencies to make an access road so the drilling rig and other equipment can be brought to the site.

Drilling a Well

Drilling begins after the land is surveyed and tested for possible natural gas deposits. The proper permits and legal papers must then be obtained.

The decision on whether or not to drill a well is based on several factors. Geologists consider the natural formation of the area, along with the subsurface, depth and size of the area.

Crews then clear a section of the land to make an access road so the drilling rig and other equipment can be brought to the site. Once the land is cleared, drilling experts dig into the ground until they find the area where the natural gas is believed to be.

A well can be drilled using either vertical or horizontal drilling, depending on the rock formation. Horizontal drilling and fracturing are often used to extract natural gas from deep rock formations and shale.

Once the rig is set up workers drill a surface hole until just above where they believe natural gas exists. To do this they must use a drill bit, collar and drill pipe. They then run and cement the casing and put casing pipe into the hole to prevent it from collapsing.

Next workers pump cement into the casing pipe using a bottom plug, a cement slurry, a top plug and drill mud. The pressure from the drill mud causes the cement slurry to move through the casing and fill the space between the outside of the casing and the hole.

After the cement hardens, crews test it to make sure it’s aligned properly and is correctly sealed. The process of drilling and running new casings and cement continues several more times until rock cuttings reveal oil sand from the rocks.

Rock samples and measurements of the rock formation are now taken to verify the presence of oil or natural gas. If the drilled well reveals natural gas deposits, it is developed to allow the extraction of the natural gas. Production ceases if gas is not found.

Wells can be drilled horizontally or vertically. Horizontal drilling and fracturing are often used to extract natural gas from deep rock formations and shale.

Until a few years ago, wells were mostly drilled vertically, by going straight into the ground. That changed several years ago when technology and other advancements led to horizontal drilling.

Horizontal drilling is used in situations where vertical drilling is not possible or is not cost effective. There’s one main difference between horizontal and vertical drilling. Vertical drilling requires going hundreds or thousands of feet straight down from the entry point to access oil or natural gas.

Horizontal drilling is when you enter the ground and only need to go down a few feet before making a 90 degree angle. Therefore, horizontal drilling can access an oil or natural gas reserve that is not directly beneath the point of entry.

Not only is horizontal drilling economical compared to vertical drilling, it also has less impact on the environment.

Completing a Well

Completing a well is the process that makes the well ready to produce oil or natural gas.

Workers begin by lowering a perforating gun into the well. This gun contains several explosive charges that are used to create holes in the casing that will let the oil or gas flow through.

Tubing is then placed in the hole to allow the oil or natural gas to flow up the well. A piece of equipment called a christmas tree is connected to the top of the tubing. The valves on the christmas tree allow crews to control the flow of oil or natural gas from the well.

After the oil or natural gas is flowing, the rig is removed from the site and production equipment is set up so the natural resource can be extracted from the well.

Production and Delivery

If oil or natural gas is found, it must be processed for transportation. The following explains how natural gas is taken from the ground and processed for use.

Crews begin by removing the rig and place a pump on the well head. Meanwhile, well tenders constantly regulate the pressure of the Christmas tree valves to control the flow of oil or natural gas reserves.

They then connect a series of pipelines and tanks to the valves on the Christmas tree to extract the natural resource from the well.

The natural gas that is found in the ground must go through a series of steps to make it ready for use. Purity specifications are constantly adhered to.

Natural gas that is used in homes and businesses is mostly made up of methane. The raw natural gas that comes from a well must be processed to separate hydrocarbons and fluids so it can be sent through pipelines. This dry natural gas must also be purified before it can be transported.

Once purified, the natural gas travels through hundreds of miles of gas gathering pipelines until it reaches a processing plant.

Now that we've found oil or natural gas, it needs to be processed for transportation. The following explains how natural gas is taken from the ground and processed for use.

Gathering lines transport oil and natural gas from the well to a processing center. This is where water, carbon dioxide, sulfur and other impurities are removed. An odorant is then added to the gas so consumers can smell a gas leak.

The natural gas or oil is then sent through distribution lines to a meter site. The gas utility's central control center monitors the pressure and how fast the gas or natural oil flows through the system.

A service line carries the natural gas from the meter site to the home or business. Pipes inside the home or business transport the gas to appliances.

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