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In subsurface hydrogeology, drawdown is the reduction in hydraulic head observed at a well in an aquifer, typically due to pumping a well as part of an aquifer test or well test. In surface water hydrology and civil engineering , drawdown refers to the lowering of the surface elevation of a body of water, the water table, the piezometric ...
The pressure gradient is described as the pressure per unit length. Often in oil well control, pressure exerted by fluid is expressed in terms of its pressure gradient. The SI unit is pascals/metre. The hydrostatic pressure gradient can be written as: Pressure gradient (psi/ft) = HSP/TVD = 0.052 × MW (ppg). [12]
Well control is the technique used in oil and gas operations such as drilling, well workover and well completion for maintaining the hydrostatic pressure and formation pressure to prevent the influx of formation fluids into the wellbore.
A well with 5,000 feet of seawater and 15,000 feet of rock could have an overburden pressures at the bottom as high as 17,220 psi (5000 * 0.444 + 15000 * 1.0). That pressure is reduced at the surface by the weight of oil and gas the riser pipe, but this is only a small percentage of the total.
Often the well efficiency is determined from this sort of test, this is a percentage indicating the fraction of total observed drawdown in a pumping well which is due to aquifer losses (as opposed to being due to flow through the well screen and inside the borehole). A perfectly efficient well, with perfect well screen and where the water flows ...
A drill stem test (DST) is a procedure for isolating and testing the pressure, permeability and productive capacity of a geological formation during the drilling of a well. The test is an important measurement of pressure behaviour at the drill stem and is a valuable way of obtaining information on the formation fluid and establishing whether a ...
Case 2 is a tank in use, with the air pressure at pressure P (gauge) and a water volume of V. Referring to the diagram on the right, a pressure tank is generally pressurized when empty with a "charging pressure" P c, which is usually about 2 psi below the turn-on pressure P lo (Case 1). The total volume of the tank is V t.
In the oil industry, waterflooding or water injection is where water is injected into the oil reservoir, to maintain the pressure (also known as voidage replacement), or to drive oil towards the wells, and thereby increase production. Water injection wells may be located on- and offshore, to increase oil recovery from an existing reservoir.