The pressure usually measured in pounds per square inch (psi) at the bottom of the hole. Test that is carried out by a wireline service company, that lowers a pressure recorder down the tubing to record bottom hole pressure with the well shut-in over 24 hrs (namely leaving the recorder for 24hr to stabilize the well and get a more realistic reading since over this period one can see how rapidly the reservoir pressure builds and recovers). The recorder is pulled out and downloaded into a computer. Most often downhole pressures are higher than surface pressure. The pressure from the well bore is an important element as this is essentially the energy that drives production to the surface. Another important element is the Flowing Bottom Hole Pressure; this is the pressure downhole when the well is flowing and stable