Research And Optimization Of Fracture Network Parameters For Horizontal Shale Gas Well Fracturing Technology

The geology of the shale gas reservoir is self-generated from the reservoir, low porosity, low permeability, and large area of continuous accumulation, the gas in the reservoir also has a variety of modes of occurrence, under normal circumstances, in the nan scale pores, or tiny cracks, the occurrence of natural gas is free (or free gas),in the porous medium and adhered to the surface of the clay minerals is adsorbed gas, and dissolved in the asphaltenes and the oil-bearing layer is dissolved gas, its content is extremely low, the three gases maintain a certain homeostasis. It’s because of these characteristics of the reservoir, the difficulty of developing shale gas increases. The success of shale gas development lies in the hydraulic fracturing technology. The key point of the hydraulic fracture is that the artificial fractures make the natural fractures expand and shear slip, make the fractures communicate with each other, and finally a large scale system of fracture network appeared, the obtained effect is the reservoir stimulation volume increased, and the production and recovery of shale gas also increased. This is the current main streaming new technology specifically for shale gas reservoir fracturing——the fracture network fracturing.The fracture network fracturing technique is mainly to get the complex "network" system, the trunk of the system is the main artificial fracture, and then the trunk expanded to form a series of branch fractures, of these branch fractures, some will extend and went back to their original position after some distance from the trunk, and some will expand, and finally form a certain angle with the trunk. Fracture network contains two points, one part of the support the trunk seam length to reach the design value, the second is the number of branches on the basis of the trunk on the seam had occurred fracture network. The technology is considered net pressure fracture extension and horizontal stress associated with the difference between this, when the critical pressure required to open natural fractures is less than the value of the former, branch joints occur, or the current person reaches a certain size when the value of a direct experience of this rock burst, branch seam will appear, this is the mechanism of fracture network initially produced.At present the following problems need to be further researched:How to effectively activate the natural fractures; How to activate the natural fractures effectively; What geological and construction conditions can meet the conditions of the appearance of the fracture network; The mechanism of the expansion of the fracture network; How to make the formed fracture network as complex as possible; The conductivity of the formed fracture network. Therefore, in order to predict the actual shape of the fracture network more accurately, make a more rational explanation for the micro seismic monitoring dates, it is necessary to research the mechanism of the formation of the fracture network, based on these, the well completion program can be further optimized, and the fracturing construction parameters can be optimized selected.Through a review of a large number of the related literatures, this paper summarized the conditions of the formation of fracture network of the shale gas reservoir, including the two aspects about the geological and the construction conditions, the geological conditions include the mineral composition and the mechanical properties of the shale, the natural fracture system and the stratification and the stress, the construction include the net pressure, the displacement of the fracturing fluid, and the fluid viscosity.About the optimization of the shale gas reservoir fracture network fracturing parameters, a comprehensive analysis about the compressibility conditions of the block is made according to the geological conditions and the rock mechanical properties about the block firstly, then according to the designed perforation results and the optimized fracture parameters, the construction scale, the displacement and the viscosity of the fracturing fluid, the ratio of the pre-liquid and the ratio of sand is optimized respectively, finally, the MShale module of the Meyer software is used for the fracturing design and simulation of the shale gas well.