Water Intrusion Identification and Regularity of Water Drive Gas Reservoir Based on Well Test Method
To avoid the reduction of gas recovery due to early water breakthrough in gas wells,the dynamic change of gas-water boundary during water intrusion is studied by the unsteady well test method,and the water intrusion regularity is analyzed by the numerical well test method.The results show that the energy is replenished and the end of the pressure derivative curve drops off after water intrusion in the gas reservoir.The fluid flows slowly and the end of the pressure derivative curve turns upward from the gas zone to the water intrusion zone.The dynamic characteristics of edge and bottom water advancing on the gas well test curve make a time difference on the pressure derivative curve,that is to say,the closer the water is to the well,the earlier the pressure derivative changes.The response characteristic of edge water for single-direction water drive is that the pressure derivative curve turns upward,and the response characteristic of edge water around water drive is that the pressure derivative curve is first concave and then up.Under the same cumu-lative production,the higher the production allocation,the smaller the distance between the gas-water bound-ary and the faster the gas-water boundary advances.The higher the gas recovery rate,the shorter the water-free gas production time.With the increase in gas recovery rate,the water-free recovery percent first increases and then decreases.Under the same recovery percent,the higher the gas recovery rate,the faster the gas-wa-ter boundary advances.The larger the permeability of the reservoir,the smaller the distance between the gas-water boundary and the faster the gas-water boundary advances.
unstable well testnumerical well testwater drive gas reservoirwater intrusionrecovery percentgas-water boundary
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