Main influencing factors of non-uniform water invasion in super-thick gas reservoir

Abstract A2 gas reservoir in Tarim Basin belongs to super-thick and abnormally high pressure water-bearing gas reservoir with reservoir thickness of 200-300m. Its physical properties are mainly low porosity, medium permeability and high permeability reservoirs. There are high permeability zones and faults in the gas reservoir, the geological conditions are complex, and the water breakthrough characteristics of single well vary greatly, which seriously affects the development effect of gas reservoir. Based on the saturation test and gas production profile data of more than 60 wells, combined with structural, fracture and reservoir characteristics, water invasion law under different geological modes is studied by means of gas reservoir engineering and numerical simulation. Studies have shown that due to the influence of water body, fault and reservoir heterogeneity, the water activity, water migration channels and stress changes in different regions are the main reasons for the difference in water intrusion elevation. The southwestern flank of the structure is a fracture zone, the eastern faults are well developed, the northern high permeability zones are well developed, and the southern flank large faults block edge water migration. The stress also changes with formation pressure, especially in the sealing of faults. Through analysis, it is considered that the volume of water and the physical properties of gas-water layers determine the speed of water invasion, and that the non-uniform water invasion is affected by both geological body and production system. This paper provides a certain guiding significance for the study of water invasion law and Control Countermeasures of Kela A and similar gas reservoirs.