Oil and Gas Production

Oil and gas production is the function of the upstream segment of the oil and gas industry that brings hydrocarbons up from subsurface reservoirs to the surface.

Upstream is known as E&P, or exploration and production because it’s two key functions are the exploration for and production of oil and gas.

However upstream is segmented into these two core functions due to the technical differences between them.

Oil and gas production activities maximize the recovery of hydrocarbons and petroleum from subsurface reservoirs.

These production activities include primary, secondary, and tertiary recovery methods depending on the geography of the reservoir.

Understanding oil and gas production and facilities involves knowledge of three connected systems – the reservoir, the subsurface structures, and the surface facilities.

Production Surface Facilities

The key production surface infrastructure includes gathering, separation and storage facilities.

Traditionally, the reservoir oil, gas, and water are not transported long distances as a mixed stream, but instead are separated at a processing facility in close proximity to the wells.

Formation water is usually sent back into the ground through a re-injection well.

Once separated, the commercial oil or gas is stored to prepare for transport.

Artificial Lift

During the initial stages of a well’s producing life, the fluids are kept moving as long as the natural pressure of the reservoir fluids is higher than the pressure in the wellbore.

The fluids then flow into the wellbore, up the tubing string and into a stock tank.

When the formation pressure becomes insufficient to lift the fluids to the surface a lot of oil is still left behind.

Can more of this oil be recovered?

Yes, using what’s known as artificial lift.

Every oil well and many gas wells will need artificial lift at some point in their producing life.

Artificial lift refers to the use of mechanical devices, or artificial methods, to increase the flow of fluids in producing oil and gas wells.

An engineer has two common methods of artificial lift to choose from – gas lift and pumping.

The engineer will determine the optimum artificial lift method, depending on the well location, production rate and characteristics of the fluids being produced.

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Gas Lift

Under this method, gas from an outside source is injected into the wellbore. This reduces the weight of the fluids in the wellbore and reduces the pressure needed to allow the fluids to flow up to the surface.

Gas lift works for a wide range of production rates, anywhere from 50 to 50,000 barrels of oil per day.

However, gas lift is not very effective or efficient if the production rate or reservoir pressure gets too low.

Pumping

The second method for artificial lift involves pumping.

Examples are a rod pump, an electrical submersible pump and a hydraulic pump.

Rod Pump

A rod pump utilizes equipment on the surface – the big metal horsehead pumping units bobbing in a field.

Below the surface there is a pump at the bottom of the wellbore and a mechanical link, called a “sucker rod string”, connects the downhole pump to the horsehead at the surface.

A rod pump works very efficiently on wells with low production rates, anywhere from 1 to about 3,000 barrels of oil per day.

Electrical Submersible Pump – ESP

An electrical submersible pump, referred to as an ESP, involves installing a long, skinny electric motor with a protector into the wellbore.

A pump is stacked onto the top of the electric motor and the unit is screwed into the bottom of the tubing string to reach the produced fluids.

To control and power the pump, a well-protected electric cable goes from the downhole ESP to the surface.

An ESP can support a wide range of production rates, anywhere from 500 to 50,000 barrels of oil per day.

Hydraulic Pump

Like an ESP, a hydraulic pump is also placed in the wellbore.

This type of pump puts the natural energy within the well to work to raise the fluids to the surface.

Though less efficient than other methods, a hydraulic pump can be used on wells with production rates ranging from 50 to 20,000 barrels of oil per day.

Tertiary Oil and Gas Production

Tertiary production in oil and gas is known as Enhanced Oil Recovery, or EOR.

Most recently, the oil and gas production technique known as Hydraulic Fracturing, or fracking, has been one of the most impactful technological developments of the last decades.

When coupled with directional drilling techniques, this production technique has changed the ability for hydrocarbons to be produced from shale formations that were unable to be exploited previously.