Case study: Numerical Simulation on Formation Damage in Low-permeability Gas Reservoir

Abstract

AbstractThe study on the formation damage mechanism in low-permeability gas reservoirs is conductive to establish reasonable and effective development policies. The effects that the threshold pressure gradient and stress sensitivity have on productivity during the development. Rock samples of PH group have gone through with threshold pressure gradient measurement and stress sensitivity test. The results show that the average threshold pressure gradient is 0.00011MPa/cm, and stress sensitivity index is 0.04 on average, belonging to low stress sensitivity. In this paper a special method of dealing with seepage law in low permeability gas reservoir is mentioned, including how to process the threshold pressure gradient and converse the experimental data to field application. The formation damages caused by threshold pressure gradient and stress sensitivity are respectively simulated in the numerical simulation software to evaluate their effects on the gas reservoir development. The results of the simulation show that: 1) when the impact of threshold pressure gradient is considered, the stable production period of the gas well is 150 days shorter than that when the impact of threshold pressure gradient is ignored, and the final recovery of stable production is 7.35% lower; 2) when the impact of stress sensitivity is considered, the stable production period of the gas well is 510 days shorter than that when the impact of stress sensitivity is ignored, and the final recovery of stable production is 12.52% lower.