Study On The Theory Of Horizontal Well Fracturing Flowback In Sandstone Reservoir

With the development of petroleum industry,the development of the conventional reservoir mostly has entered the development stage,in order to continue the development of the petroleum industry,the focus of exploration and development and scientific research is gradually transferred to the low permeability(permeability less than 10mD)mining.For low permeability sandstone reservoirs,horizontal wells are usually used for hydraulic fracturing.The flowback of fracturing fluid is an important part of hydraulic fracturing,which has an important influence on fracturing effect.In order to determine the fracturing fracturing fluid flowback in the construction of the critical flow,the sandstone reservoir as the research object,the percolation mechanism of fracturing fluid in sandstone reservoir based on the established fracturing fluid loss equation;combined with the fracturing fluid loss equation is established,based on material balance principle and the theory of fluid mechanics is established sandstone reservoir hydraulic fracturing crack closure model,analyzes the relationship between the discharge nozzle size and crack closing time;with the related theory of dynamics and fluid mechanics of the critical flowback rate model,verify the accuracy of the model combined with the basic data of Jilin oilfield.Based on the study of the critical flowback theory of sandstone reservoir,the following conclusions are obtained.(1)based on the crack closure model,the influence factors of crack closure time are analyzed,and the conclusion is that the larger the nozzle diameter is,the shorter the closing time is.(2)through the critical discharge flow model before the crack closure,the lateral displacement of the proppant is calculated,and the displacement is compared with the crack half length.(3)based on the basic data of a certain block in Jilin oilfield,the accuracy of the critical flowback flow model is verified.It is concluded that in the actual construction,it is necessary to adopt a return flow which is slightly larger than the theoretical critical discharge.(4)critical flowback rate model to analyze the impact of proppant fracturing fluid viscosity and particle size on the fracture critical flowback rate based on the cracks in the closed condition,under the same conditions,critical flowback rate increases with the increase of the particle diameter of supporting agent,increases with the increase of the viscosity of fracturing liquid.(5)simulation experiment by hydropower,considered in different fracture number,crack spacing and crack length under the condition of the seepage field map,analysis of back interference in the process of returning the row of fracture displacement,the other conditions are the same,with the increase of the number of fractures,flowback rate will be slightly reduced a single crack,but also increase the amount of flowback,each crack on the flowback rate is the same.Based on the study of the theory of horizontal well fracturing flowback in sandstone reservoir,this paper provides some theoretical guidance for field fracturing flowback construction.