of tigure. o0' is base level. and initial oil-water intertace is aly the height Irom the base level; p is the density acceleration of gravity Figure 1-3 Reduced pressure figure the first exploration well di and gas llow, and pressure should be lesled in the beginning of each exploration well, the lesled pressure of mid-depth of reservoir is the initial formation pressure of each wel Strictly speaking, the initial equilibrium is destroyed and the initial formation pressure cannot be obtained any more as long as only once well produces. If the pressure manometer cannot be put in the mid-depth of reservoir. the initial formation pressure can be calculated from tested pressure gradient.Clearly, in order to improve the measurement accuracy. the pressure manometer should be put in the mid-depth of reservoir as far as possible 2. Current formation pressure p In the process of oil gas reservoir development, if a well is ofl production and others are sti producing stably, the bottom-hole pressure of the shut-down well will gradually increased. After a long time, the pressure will no longer increase and stabilize. The measured pressure of mid-depth of reservoir of this well is called current formation pressure, and it is also known as static prcssurc 3. Supply pressure pe When there is a fluid supply zone, the pressure of supply boundary is called supply pressure with pe stands for it 4. Bottom hole pressure p The pressure measured in the mid-depth of well bottom in the process of production is called well bottom pressure, also known as flow pressure, with p. stands fo 5. Reduced pressure pr As is known from fluid mechanics, except pressure energy, the fluid in the reservoir also has if it is in kinematical state, it is also has kinetic cnergy. As a point M in reservoir shown in figure 1-3. the total cnergy of unit mass lluid is Where: -The movement velocity of point M. Of course. as for the original state v,=o Because flow rate is very small in reservoir and the order is 10 m/s, and its square haller than hydrostatic head which should be omitted. So the total energy can be written as.'s H1=Z+