Retrograde condensation damage experimental evaluation method for depletion type development near-wellbore zone of saturated condensate gas reservoir

Abstract

The invention discloses a retrograde condensation damage experimental evaluation method for a depletion type development near-wellbore zone of a saturated condensate gas reservoir; the method comprises: (1) placing a core in a core holder, and evacuating; (2) increasing oven temperature to gas reservoir formation temperature T0 for 10 hours; establishing irreducible water saturation by using dry gas displacement; (3) injecting dry gas into the core until the pressure of the entry end of the core reaches original formation pressure; (4) injecting condensate gas into the core until gas-oil ratio GOR tested at the exit end of the core is consistent to GOR0, and carrying out condensate gas test under corresponding conditions to obtain gas permeability K0; (5) starting a depletion experiment, recording core exit end pressure Pi and flow Qi, and testing gas permeability Ki of condensate gas under the corresponding pressure condition; (6) drawing a relational curve for core exit pressure and permeability decrease degree. The method has reliable principle, is simple to perform, makes up the defects of conventional retrograde condensation test methods, and has a promising market prospect.

Description

technical field [0001] The invention relates to an experimental evaluation method for retrograde condensation damage in the near-well area in the depletion type development of saturated condensate gas reservoirs in the field of petroleum and natural gas exploration and development. Background technique [0002] Condensate gas pools are a special type of gas pools. Under the original formation conditions, they are generally in a single gas phase state; when the formation pressure is lower than the dew point pressure of condensate gas, part of the heavy components in the gas phase are analyzed and attached to the rock pores. The surface occupies the gas phase seepage channel and reduces the seepage capacity of the gas phase. This phenomenon is called reverse condensation damage. The so-called saturated condensate gas reservoir, that is, the condensate gas reservoir whose formation pressure is close to the dew point pressure, once the gas reservoir is put into development near ...

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Problems solved by technology

However, this method has shortcomings in the application of saturated condensate gas reservoirs. Once the pressure of the sample container is lower than its dew point pressure, the condensate oil in the container will precipitate and settle at the bottom of the container under the influence of gravity, causing the condensate gas in the container to flow into the core. The content of condensate oil carried is reduced, thereby reducing the content of condensate oil precipitated in the core, and underestimating the reverse condensation damage near the wellbore of saturated condensate gas reservoirs

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