Exploration On The Evaluation Method Of Fracture Network Formed By Stimulated Reservoir Volume About Chang 7 Tight Reservoir

The development of tight reservoir cannot do without a technology called stimulated reservoir volume,which can create complex network system near the wellbore.There is no clear method about evaluating the fracture network so as to effectively guide the engineering practice till now.In order to evaluate the fracture network,it is the most basic and traditional method to calculate the fracture line density.In this paper,a new method is used to calculate the fracture line density.The method described in this paper can calculate the fracture line density by construction data.Firstly,the analytical model of fracture linear density is established by the method of theoretical derivation and numerical simulation,and then programming by Excel.Next,using FracproPT2011 software based on field data and formation parameters to fit the fracture morphology.Now,fracture parameters has been obtained;Combined with the microseismic monitoring data,the calculation of fracture line density was completed,and described the effects of geological factors and construction factors on the network by this method.Taking the Chang 7 tight reservoir as an example,the calculation results show that the brittleness index of the formation is generally higher than 40%,which is propitious to the formation of multiple fractures and net fractures.When the matrix permeability increased from 0.01×10^-3?m² to 0.8×10^-3?m²,the fracture line density decreased by13.7%;As the porosity increased,the fracture line density decreased;the fracture line density increased when the thickness of stratum from 2 meters to 20 meters,the fracture line density value increased by 309.23%.In addition,the construction factors will also affect the complexity of the fracture network.The simulation results show that,with the displacement increases gradually,the fracture line density is also increased.When the displacement was increased from 8 m3/min to 12 m3/min,the fracture line density increased by 30.7%.Large displacement and volume of fracturing fluid can indeed increase the complexity of the fracture network;sand ratio's increasing will lead to reducing the fracture line density.When the sand ratio increased from 5.26%to 15.79%,the fracture line density decreased by 33.17%;pad fluid percentage has little effect on morphology and fracture linear density;there is no difference among the fractures of low viscosity of fracturing fluid in different forms.These factors can be used as an index to evaluate the fracture network,which can provide guiding significance for stimulated reservoir volume efficiently.