A new deliverability evaluation method of gas condensate wells in gas–liquid two-phase state

Abstract

Gas well deliverability evaluation and analysis are challenging due to the frequent abnormalities of deliverability test data of gas condensate wells caused by seepage of oil and gas phases in the reservoirs. To this end, based upon the pseudo-single-phase seepage equation and the oil–gas two-phase seepage equation, a new deliverability evaluation method was established which is applicable to the following two cases when the flow of a gas well reaches the quasi-steady stage, i.e., the pseudo-single-phase stable point deliverability evaluation for the case when the formation pressure is above the dew pressure; the gas–liquid two-phase stable point deliverability evaluation for the case when the formation pressure is below the dew pressure. Using this established deliverability evaluation method, based on the basic parameters of the Yaha gas field, Tarim Basin, the IPR curves were first obtained of gas wells do not get this at the same production gas–oil ratio and at the formation pressure above and below the dew point pressure; then, according to the four condensate gas fields, such as Yaha, Tazhong I, Qianmiqiao and Dina 2, the absolute open flow (AOF) potentials of condensate gas wells under different gas–oil production ratios were calculated. Finally, through statistical analysis of the calculation results from typical wells, the following findings were obtained. This new deliverability evaluation method under the two states of condensate gas wells with quasi-single-phase and gas–liquid two-phase stable points can be used to avoid cases due to the oil–gas flow in a condensate gas well which has remained unresolved by the classical deliverability evaluation methods. Also, with the increase of gas–oil ratios in gas condensate wells, a variable discrepancy is gradually reduced in AOF potentials calculated respectively by the quasi-single-phase and gas–liquid two-phase stable point deliverability evaluation equations. For the condensate gas wells with high condensate content and low condensate gas production rates, the AOF potentials calculated by the gas–liquid two-phase stable point deliverability equation is more appropriate and reliable compared with that obtained by classical methods.