The Damage Mechanism Of The Low-permeability Gas Condensate Wells Anti-condensate And Water Lock And Disarm

During the development of the condensate gas reservoir, there will occur the liquid accumulated damage when the well flow rates is below the critical liquid-holding rates.The accumulated liquid will cause the water blocking and the retrograde condensate damage in the low permeability formation due to the well-bore backpressure and the rock wettability, microscopic capillary effects, which results in the reduction in the gas well production, especially for the low permeability and low production condensate reservoir.The tight low permeability condensate gas reservoir will be developed economically through the hydraulic fracturing, but it's proved through the numerous experiments and the fields that there will be the water base fluid leak-off during the fracturing in the reservoir, especially for the heterogeneous formations or depleted low permeability reservoirs, these drawdowns are often of the same order of magnitude as the capillary forces,which curtails well deliverability. This is the cause of that: the use of aqueous treatment fluids often results in a 'water block' due to poor recovery of the fluids that have leaked-off, and the the high water saturation zone along the fracture because of the fracturing fluid leak-off. This curtails well deliverability due to the reduced relative permeability to gas/ water in the invaded region. Meanwhile, the pressure drops drastically when the low permeability condensate gas reservoir has been fractured, the retrograde condensate is formed as the reservoir pressure drops below the dew point pressure, further, causes the contamination near the fracture, the production of the low permeability condensate reservoir is reduced much. Thus, it's of great significance to study the water block and retrograde condensate effects in the fractured and non-fractured condensate gas reservoir.This paper provides a model of water blocking removal in the non-fractured and fractured condensate gas reservoir, based on the survey of the water block damage mechanism and the water block damage removal technology in the domestic and abroad. It's emphasized on the pressure drop, temperature, formation permeability effects on the removal of the water block damage in the fractured and non-fractured condensate gas reservoir; meanwhile, a single well numerical simulation model is established to study the dry gas Huff-Puff that eliminates the the retrograde condensation damage for Qiao 69 gas condensate reservoirs by applying the GEM of CMG software.