A productivity calculation method for water-locked gas wells

Abstract

The present invention analyzes the relationship between the water saturation of the core and the permeability damage rate by carrying out the gas well core water lock experiment, and fits the core water lock experiment data to establish the water lock permeability damage equation; according to the gas well water lock characteristics, the water lock permeability damage The equation is coupled with the gas well productivity equation to establish a water-locked gas well productivity model. Calculate the Darcy and non-Darcy coefficients of the productivity equation based on the data of logging, production, water lock experiment, and phase permeability experiment, etc., determine the productivity equation of the water lock gas well, and then calculate the gas well productivity as unimpeded flow. Two factors are considered in this productivity model: one is the water lock damage caused by different water saturations to reservoir permeability; the other is that gas-water two-phase flow is also considered in water-locked reservoirs. The above two factors are described by the water lock permeability damage equation and the relative permeability curve equation respectively, which are used to accurately calculate the gas well productivity of water lock and gas-water two-phase flow. Provide a more scientific calculation method for the productivity evaluation of water-locked gas wells.

Description

technical field [0001] The invention relates to the technical field of oil and gas development, in particular to a method for calculating the productivity of a water-locked gas well. Background technique [0002] Natural gas wells tend to form water locks around the wellbore due to water invasion or foreign working fluid injection, which will reduce the seepage channels and permeability of the reservoir around the wellbore. The most direct harm of water lock to gas wells is to reduce the productivity of gas wells. The productivity of gas wells is usually measured and calculated by open flow. The open flow of conventional gas wells is usually calculated based on productivity tests, stable production rates, or complete well logging and well test interpretation data. . However, for gas wells after water lock, the productivity calculation formula before water lock cannot be directly applied because the seepage conditions around the wellbore, that is, the permeability has change...

AI Technical Summary

Problems solved by technology

[0003] The technical problems solved by this patent are: 1. The production capacity calculation method of the water-locked gas well in the prior art requires on-site testing of the production capacity or unstable well test of the water-locked well, which requires a lot of manpower and material resources; 2. The production capacity calculation method of the water-locked gas well in the existing technology needs to shut down the gas well, which affects the normal production of the gas well; 3. The production capacity calculation method of the water-locked gas well in the prior art is the production capacity at a certain moment after the water lock. Continuous, that is, when the penetration rate is continuously reduced, it is impossible to track and calculate

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