Oil Companies

The oil companies or agencies involved in the oil industry can be broadly classified into 3 groups:

1. Host Authorities
2. Operating Company or Operators
3. Service Providers

What is Streamline Simulation?

Streamline simulation technique simplifies the conventional finite difference 3D simulation (FD) into a number of 1D problems by assuming some streamlines or pipes that transport the oil molecules from high pressure zone to low pressure zone. They depict the actual flow-path of fluid molecules within the reservoir.

Source: Schlumberger

Because of its simplicity, large reservoir model can be subjected to such simulation techniques with limited computer resources. Or, large number of models or realizations can be analyzed within short period of time. The technique may not give a robust result that can be fully trusted for large scale economic investment decisions. (We have to rely on more reliable and proven techniques of FD simulation). However, it is very good tool for a number of purposes.

Pressure Transient Analysis

Pressure Transient Analysis (PTA) is simply the measurements the change of Bottom Hole Pressure (BHP) of a well as it is opened or closed. 

In a production well,  as flow-valves is opened and fluids starts to flow, BHP decreases. Measurements of pressure drop in such a well is called "Pressure Draw-Down Test". On the other hand, when the well is closed, BHP increases. Measurements of building up of pressure of such a well is called "Pressure Build-Up Test".

In an injection well, as injection starts BHP increases. Measurements of pressure building up in such a well is called "Pressure Build-Up (Injection) Test". On the other hand, when the well is closed, injection stops and BHP decreases. Measurements of pressure fall in such a well is called "Pressure/Injection Fall-Off Test".

What is 4D siesmic ?

4D seismic survey is simply a series of three dimensional (3D) seismic surveys over the same area of interest at different times. Here "time" is considered as the 4th dimension.

As a field produces oil or gas, the reservoir fluid distribution and pressure changes. This variation is reflected in seismic surveys,. The difference of surveys taken before and after production can us a clearer picture of remaining oil/gas un-swept or remained trapped and help engineers plan/redesign the depletion strategy like new infill drilling, injection optimization etc.

Recovery Factor

Recovery Factor is the amount of hydrocarbon that can be recovered or produced from a reservoir per unit volume of original in place. Mathematically, it can be written as follows:

RF = EUR / STOIIP *100 % for oil
RF = EUR / GIIP * 100 % for gas

where,
RF = Recovery Factor
EUR = Estimated Ultimate Recovery
STOIIP = Stock Tank Oil Originally in Place
GIIP = Gas Initially In Place