Contamination Mechanism And Prevention And Cure Technology Research To Qiaokou Condensate Gas Reservoir

Condensate gas reservoirs developed currently in Zhongyuan oilfield are manly complex type of gas reservoir with deep level and low permeability and high temperature and anomalous pressure and wealthy condensate oil and water and near-saturated. Affected by these character, in the course of gas well production of condensate gas reservoirs, bottom liquid loading and dynamics layer damage of retrograde condensation and reverse osmosis in near wellbore formation are easily created, which lead to that the gas well productivity can not be developed effectively. The specific character includes follows:①Deep gas pay burial, long gas-bear interval section and prominent interlayer contradictory;②Most of which are condensate gas reservoirs with compaction and low porosity and low permeability and difficult to develop;③Little formation-dew pressure difference in gas well. Retrograde condensate phenomenon appears shortly after gas wells are put into production or with no long production time.④Single well controlled reserves are small and productivity of gas well are low.⑤Fluid production of gas well are general.⑥Short period of stabilized production in condensate gas reservoirs.Based on total analysis and evaluation to research of geologic characteristic and phase state characteristic and development mode of Qiaokou deep zone and low permeability condensate gas reservoir, this paper systemally implements earlier basic experimental study of slug throughput feasibility of gas condensate well gas injection and gas-alcohol (stimulator) solution, experimental study of displacement efficiency of enhancing oil recovery by gas injection and alcohol injection/gas slug alternate throughput and numerical model study to gas injection and alcohol injection/gas slug alternate throughput of condensate gas well. Water lock damage mechanism and effect factor of retrograde condensation and reverse osmosis of low permeability gas reservoir and long core displacement mechanism of gas injection and alcohol injection/gas slug alternate throughput are thoroughly studied. Aim at optimizing proration plan and reducing retrograde condensation caused by production, this paper analyze performance of low permeability condensate gas well and propose main technical measure of prevention and cure of retrograde condensation damage and study numerical model of reasonable development mode of Qiaokou gas reservoir and optimize working parameter including drawdown pressure and gas nipple diameter and reasonable productivity. The research and field application of these technology can improve individual well productivity of condensate gas well effectively and prolong period of stabilized production and have acquired preferable economic and social benefit.