The Study On The Rule Of Slick-water Fracturing Fluid Flow In Plugging Of Main Fracture During The Fracture Of Hydraulic Fracturing

China is rich in low permeability and ultra-low permeability oil and gas resources,and slick-water fracture technology plays an important role in its development process.At present,in order to improve the fracturing effect,temporary plugging technology is usually used.When a certain section of the main fracture is plugged,pressure will be formed in the fracture to open more secondary cracks,and slick-water is followed by sand laying.The characteristics of slick-water fracturing technology are large displacement and low sand ratio,which can eventually form a sand filling crack in the fracture,and the effect of sand filling determines the ultimate conductivity of hydraulic cracks.Therefore,the study on the sand laying rule of sliding water sand-carrying fluid under different degree of blockage of main joints has certain theoretical guiding significance for optimizing the proppant placement in joints.It is not clear how the proppant in slip water fracturing fluid enters the secondary cracks and its mechanism of sand transport is also unclear.Therefore,the study on the sand laying rule of sliding water sand-carrying fluid under different degree of blockage of main joints has certain theoretical guiding significance for optimizing the sand laying in joints.This paper fully investigates the temporary plugging technology and solid-liquid two-phase flow transport theory and its research methods at home and abroad.Based on the existing laboratory "hydraulic fracturing fracture and perforation simulation" device,the paper studies the influence of different construction parameters on the effect of sliding sand laying in the main/branch fracture when the back half of the main fracture is fully plugged,and studies the effect of displacement on sand laying in the half plugging of main fracture based on the proppant steering mechanism.Finally,the flow law of solid-liquid two-phase flow in sliding water is studied from the point of view of numerical simulation.The results show that the sand-laying law of sliding water with large displacement is similar to that of sand-laying in main fracture under the same conditions.The displacement determines the sand-carrying capacity of fluid and the radius and intensity of vortices formed at the outlet of main fracture.The larger the displacement,the less the amount of sand deposited near the outlet of main fracture.The particle size,density and sand ratio mainly affect the balance height and the corresponding balance time in the fracture.When the position of branch joint is determined,i.e.in the middle of main joint,the displacement increases,the sand carrying capacity of fluid increases,and the sand laying at the branch joint mouth depends on gravity.The greater the height difference of sand dike,the more significant the gravity effect is.The results of laboratory experiments and numerical simulation validate the accuracy and feasibility of the model,and analyze the influence of slip water viscosity on sand laying effect when the main fracture is completely blocked.It is concluded that when the main joint is fully blocked,the increase of displacement is beneficial to long-distance sand laying in the branch joint,but the overall height of the sand dike is lower;when the main joint is half blocked,it is more conducive to the settlement of proppant near the main-branch joint.