The Evaluation Of The Multistage Fracturing Horizontal Wells In The Tight Glutenite Reservoir

Tight glutenite reservoir is mainly composed by the coarse clastic rock such as conglomerate and glutenite.Through the numerical simulation technology,this paper researches intensively the development law of the multistage fracturing horizontal wells in the dense glutenite reservoir in the view of its low permeability,seepage resistance and stress sensitivity based on the M well block of the K oilfield in the western China.And it basically achieves the following results:(1)According to the actual block geological characteristics and physical parameters,a static tight glutenite reservoir geological model is established.The model refines these grids which characterize horizontal well fractures by equivalent fracture flow conductivity.Optimization of the fracture grid size is done considering the model convergence and the characteristics of injection wells and production wells.(2)Through the mechanistic simulation of horizontal wells with multiple fractures,this article analyzes the influences caused by the reservoir thickness variation,reservoir permeability variation and reservoir pressure sensitive coefficient variation to the development by natural depletion through multistage fracturing horizontal wells.The result shows that cumulative production of horizontal wells and vertical wells are both increased with the increase of the reservoir thickness and reservoir permeability or the decrease of the pressure sensitive coefficient.At the same time,the non-dimensional multiple of fracturing horizontal wells reduces gradually.Hydraulic fractures are effective in the thin and low permeable reservoir.(3)A series of parameters is optimized such as the horizontal well length,direction of hydraulic fracture distribution,fracture space,fracture half length and well distance,fracture conductivity,horizontal well network,etc.Reasonable length of the horizontal well is 1600m.Fractural direction is vertical of horizontal wells.Reasonable fracture space is 80m to 100m.Reasonable fracture half length is 140m to160m.Reasonable well distance is 350m to 400m and the optimal fractural conductivity is 40?m~2·cm.Horizontal wells should be deployed in five point pattern.(4)Fracturing horizontal well water flooding can increase the single well injection to enhance the oil recovery.However water channels caused by fracture working between oil well and water well will flood out the oil well rapidly.In this situation,water flooding development of fracturing horizontal wells will lose its advantages.The risk of water breakthrough can be reduced when the fracture penetration rate of multistage fracturing horizontal wells is 0.2 to 0.4.In order to prevent the risk of flood water channeling,natural depletion through multistage fracturing horizontal wells is advised in the M wellblock.(5)7 horizontal wells in the M wellblock are developed by natural depletion.The reasonable fracture conductivity is 40?m~2·cm,reasonable fracture space is 80m,reasonable fracture half length is 140m.15 years production dynamic prediction of horizontal wells shows that the early stage of oil production is 25.3t/d to 32t/d,the average daily oil production is 3.78t/d to 6.19t/d,the cumulative oil production are2.07×10~4t to 3.39×10~4t.