Research On Separate Layer Fracturing In Xushen Volcanic Gas Reservoir

The form of the Xujiaweizi rift deep volcanic reservoirs is complicate,that's interval is thick(usually 300-400m),and buryed deep (the most 4650 deepness),and the temperature is higher (geothermal gradient is usually 4℃/100m,measured temperature 178℃supreme),the rock is dence and its non-homogeneous is strong. The traditional deep well separate layer fracturing can't feet the requirement of reformed the volcanic reservoirs. The technique of separate layer fracturing with the bridge plug zonebyzone have many serious problem,like that the single well's operation time is length and the layer will be damaged by well killing frequently.For improve the per well production of deep volcanic gas well and the producing reserves degree of gas reservoir,we developed the separate layer fracturing string which is fit for the require of commercial scale fractureing in high temperature and high pressure working conditions.The separate layer fracturing string is mainly made up of the Y443-108 packer,Y344-115 packer,safety joint,hydraulic anchor,control choke,sand blaster with scale sleeve, plug-in seal section etc,and it's working index is 180℃and 100MPa resistant.The two packs are not linked together by the oil tube traditional,that can avoid the accident that the tubing sub throw off since the axial tension.When fractureing,the string immovability separated layer stimulation is fulfillment by the approach that the two intended interval is converted by throw the ball in the well head to open the scale sleeve.The string'intensity is safe and reliable which is checked by the method of finite element.The research of the overpressure thermal packer is the gordian technique in the deep well fracturing.The packer rubbers are developed though the method from such areas as preferred selection of plastic materials,formulation design,curing process,structural design and plastic tube's protection.The overpressure thermal packer is developed though the method from such areas asphysical design,material and processing technic etc.Through the wear test we research the impact that the material hardness and the erosion angle to the rate of wear,conclusion the empirical formula of the relationship in material wear and the eroding velocity,calculate the attrition value of the pipe string wall,propose the technical measure which can strengthen the wear hardness of the string.This techniques are used 3 times in field,the peak temperature is 161.4℃,maximum pressure of fracturing construction reaches 98MPa,the largest construction displacement is 6.0m3/min,the largest volume of sand in single well is 140m3.The field test import that the string immovability separated layer stimulation of two intended interval was fulfillment,the work efficiency of deep volcanic gas well is speed up and the effect of the gas deposit reformation.is improved.