Research On Hydraulic Fracturing Property Of Pickering Emulsion For Shale Gas Reservoir

In view of the problems of low carrying capacity,easy closure of fractures and large damage to the formation of slickwater fracturing fluid,a new type of fracturing fluid system based on Pickering emulsion was constructed.It is expected that through the interaction between the particles in the emulsion and the shale wall,the fracture can be stabilized and supported by solid particles in Pickering emulsion,thereby enhancing the fracture conductivity,and reducing pollution and damage to the formation.Firstly,Pickering emulsion system was prepared by screening suitable solid particles as emulsifier,the stability mechanism and influencing factors of the emulsion were explored and then the formulation of the Pickering emulsion was determined.Secondly,the performance of the fracturing fluid such as rheological properties,anti-swelling property,filtration property,and friction resistance of the Pickering emulsion was evaluated.Mechanism of interaction between the solid particles in the emulsion with shale walls was also explored.Finally,the fracturing physical simulation and other devices were used to evaluate the fracturing ability to make and support fractures of Pickering emulsion.Through above research,the modified barium sulphate particles were selected as the solid particles for preparing Pickering emulsion,the particle size was about 5 ?m,the addition amount was 1.0wt% to 5.0wt%,and biodiesel was selected as the oil phase,the oil-water ratio was 4:6~2:8.Results showed that the solid particles can form interfacial film at the oil-water interface,which stabilized the emulsion,and the emulsion has good stability and strong temperature resistance and salt resistance property.The properties evaluation results of the Pickering emulsion system,such as rheology,anti-swelling,filtration and friction resistance,indicated that the Pickering emulsion has the characteristics of plastic fluid and the viscosity can be regulated flexibly.In the low-permeability shale formation,the fluid loss was little.Pickering emulsion has a certain degree of anti-expansion performance,and can play a synergistic role with the traditional anti-swelling agent.Through experiments,it was found that solid particles can be adsorbed on the shale wall,not only in the flow process but also in the stationary process.Solid particles can accumulate on the wall of the fracture to increasethe conductivity of the fracture to some extent.Compared with slick-water fracturing fluid,Pickering emulsion had anti-swelling property,lower fluid loss and larger number of fractures.This research provided theoretical and experimental support for the optimization and application of Pickering emulsion hydraulic fracturing system.