Calculation of unsteady flow in a gas well using microturbines to increase the flow rate

Stimulation of gas production is urgent to the oil and gas industry. Many large natural gas fields are in their late stage of development characterized by falling reservoir pressure and reduced flow rate up to the end of the gas supply. To resolve this problem, M.V. Kurlenya and S.V. Serdyukov suggested that intensive midrange waves excited by downhole sources should affect bottomhole zones. In this paper, we analyze the possibility of using a gas turbine drive as a source of oscillations. A mathematical model of the drive is formulated and hydraulic losses and characteristics are calculated. An experimental rig is designed to verify the calculations. The conducted experiments have shown that the values obtained by using the mathematical model are in good agreement with the corresponding experimental data, which proves the validity of the model. Numerical simulation of unsteady flow when running the well is performed and the time required to open the throttle valve as a function of the throttle area at the pipeline input is computed. It has been found that, if the relative flow area decreases to a certain value, the valve-opening time significantly decreases, while the turbine power drop is minimal. Thus, the valve opening law is evidently close to optimal. The results of study can be used to stimulate the natural gas production and recover the productivity of gas wells at late stages of field development.

References

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