This paper presents a new, patented approach to the testing and patented approach to the testing and evaluation of a pumping oil well. For an actively pumping well, the test provides the flowing bottom-hole pressure, the flow rate at which gas is liberated up the annulus, and the pumping rate of the bottom-hole pump.
When the well is shut the technique can be used to determine the bottom-hole pressure as a function of time. This information can be used in conventional pressure-buildup analysis for damage, transmissibility, and static pressures. pressures
Knowledge of the flowing and static bottom-hole pressures in a pumping well enables the operator to optimize the surface and lifting facilities for present and future operations. The flowing bottom-hole pressure is usually determined by measuring the fluid level with a sonic device, calculating the height of the fluid column and assuming a fluid gradient. when there is doubt about the fluid level or the gradient, often the operator closes in the annulus to drive the fluid level to the pump seating nipple. Then the pressure can be accurately determined because a gas gradient exists from the surface to the pump seating nipple. The pressure data so obtained, however, may not agree with the original flow rate, in which case a new, stabilized rate must be obtained. The procedure is time-consuming, and some procedure is time-consuming, and some production loss may result because the pump production loss may result because the pump is less efficient when free gas flows through it.
This paper describes a method for determining the effective fluid level, the annular gas rate and the pumping rate without disturbing the system's equilibrium. From the effective fluid level the flowing bottom-hole pressure can be calculated by using a dead-oil gradient consistent with the pressure and temperature of the oil column. The efficiency of the pumping system can be evaluated if PVT data for the oil are available.
The theory of analyzing a pumping well is based in the gas laws. Figure 1 illustrates the method used to derive the general equation, which has many applications within the oil and gas industry. step-by-step derivation is as follows:
If we start with the familiar equation:
and replace n, the number of moles, with the weight of gas divided by the molecular weight of the gas, the equation can then be rewritten as:
where W is the mass of gas in the system in pounds. pounds. Similarly, the density of the gas in pounds per cubic foot can be written as: pounds per cubic foot can be written as:(3)