Production techniques

If the drilling results are conclusive, the well is put into production

The exploitation of a field is generally spread over several decades (10 to 15 years) with the implementation of different techniques as the field ages. Oil production and associated water management is adapted to the different stages of the field’s life. There are two types of wells for this purpose : oil-producing wells and water-injecting wells.

Primary production with producing wells

At the beginning, the wells produce a fluid composed essentially of oil (petroleum) at a sustained rate (called peak production). The pressure in the oil reservoir is high: the oil can flow naturally to surface (this is called a natural flowing well). The flow rate rapidly decreases and the well no longer produces spontaneously (non-eruptive well). Pumps are then run in hole to bring the oil to the surface and continue its exploitation.

Secondary production with injectors wells

As the field is operating, the pressure inside the reservoir drops and the field produces more and more reservoir water. In order to stabilize this pressure and replace the volumes of fluid extracted, this water must be returned to the original reservoir via dedicated injector wells. The injection points are wisely choose to sweep the oil to the producing wells.

The different oil pumping devices :

If the reservoir does not have sufficient energy to produce fluids to surface, the wells are called “non-eruptive”. In this case, a pumping device adapted to production conditions of the well is run in hole to bring the fluid to the surface. The choice of pumping system is suitable to the flow rate of the well. Wells can be equipped with two main production systems:

The double-acting piston pump is run at the bottom of the well and is connected by a string of small rods (about 20 mm) to the pumping unit located at the surface, giving it a reciprocating movement. This device does not allow pumping in highly deviated wells, as it is often the case today, and is limited in flow rate (maximum 100 m3/d approximately). The surface footprint is important with an average height of 10 to 15 meters.
Electrical submersible pumps (ESP): a centrifugal pump of small diameter (120 to 130 mm) with a very large number of stages (200 to 300), is driven by a powerful electric motor (100 to 300 HP). Located at the bottom of the well, this unit is powered by a high voltage electric cable (1800V approximately) and suspended to the production string through which the fluid will be produced. This installation allows the production of highly deviated wells with flow rates that can be significant (more than 1000 m3/d). Surface footprint is limited with only a small well-head (about 2.5M height) and a power transformer station that can be offset, making this pumping method particularly discreet. For larger flows, the ESP is used, for flows below 50m3/d PUs are preferred. During the life of a well, the pumping system can change.

Production techniques