How to Calculate Downhole Hydrostatic Pressure

Decide which section of the well or borehole you want to measure. Define the upper and lower limits of the aquifer or well segment that needs to be isolated from the rest of the borehole. Open sections of bedrock wells do not require screening. Overburden wells should be screened throughout the section to be isolated and measured.

Install the lower level inflatable balloon packer by lowering the the packer to the lower limit of the borehole section to be measured, then inflating the packer with air from the air compressor. If the entire borehole or a section including the bottom of hole (BOH) is to be measured, no lower level balloon packer is needed.

Install the pressure transducer by lowering it to the approximate center of the borehole segment to be measured. Connect the transducer cable to a pressure readout meter or to an interface and laptop computer.

Install the upper level balloon packer to the depth of the top of the section to be measured. Inflate the packer with compressed air from the air compressor to seal off and isolate the borehole section below.

Record transducer pressure measurements over several hours to ensure hydrostatic pressure stability of the formation. Be sure no nearby wells are being pumped, which will decrease the accuracy and validity of your pressure readings. When pressure has stabilized, within plus or minus 5%, for one hour, take the average of that hour's readings as the hydrostatic pressure for the isolated aquifer or portion of the aquifer you are measuring.