Optimization Of Fracturing Parameters For Horizontal Wells In Tight Sandstone Gas Reservoirs

The horizontal heterogeneity of tight sandstone reservoirs in block W of ordos basin is very strong,and the conventional fracturing method of horizontal Wells can not achieve the expected effect.Based on reservoir characteristics,fluid parameters and fracturing construction experience of tight sandstone gas reservoirs in this block,the following research was conducted in this paper to optimize fracturing parameters of horizontal Wells in tight sandstone gas reservoirs:(1)Combined with reservoir characteristic parameters,Eclipse reservoir numerical simulation software was used:only gas-water two-phase was considered,and orthogonal grid encryption method was adopted to establish a gas reservoir numerical model with a grid number of 29×15×11 and a volume of 1160×600×22 m~3.(2)For the grid at the location of fractures in the reservoir,the method of assigning values to the grid and adjusting the size of the grid(equivalent conductivity method)is adopted to deal with hydrofractures,and the place with relatively large pressure drop around the fracture is densified by the grid.At the same time,the production of wellbore is ignored in the production process,and only the production of fracture is considered.Thus the prediction model of horizontal well fracturing productivity is established.(3)Based on piecewise fracturing horizontal well productivity prediction model,the numerical simulation of horizontal well staged fracturing production,analyzed the different reservoir permeability under the condition of horizontal well length,fracture morphology,fracture length,fracture number,fracture spacing and the influence law of parameters such as fracture diverting capacity of production capacity,on the basis of the combination by using data,regression,formed the horizontal well staged fracturing parameters optimization chart,for a given layer fracturing purpose,through the chart can find under the different permeability and horizontal section length of the optimal fracture number,the optimal length of crack,and the optimal fracture diverting capacity,quick and easy to guide field fracturing parameters design.(4)Based on the optimization design results of horizontal well staged fracturing parameters and according to the actual geological characteristics of the reservoir,two types of horizontal well staged fracturing models of horizontal heterogeneous reservoirs are established.In addition,the optimization methods of fracture distribution,fracture length,fracture conductivity and other parameters in heterogeneous reservoirs are analyzed.At the same time,using the parameter optimization chart to carry out the optimal design of the distribution of fractures in the complex lateral heterogeneous reservoirs,and comparing with the common uniform distribution of fractures,the results show that it is necessary to carry out the optimal design of the distribution of fractures in the complex lateral heterogeneous reservoirs according to the geological characteristics.(5)Joint fracture parameter design for horizontal well section pressure as a result,based on the analysis of W block reservoir geological characteristics,main problems in the construction and the construction of the fracturing effect,on the basis of using FracproPT fracturing simulation software to fracturing operation discharge and preflush rate and amount of sand and sand size,liquid nitrogen ratio is optimized,the targeted specific fracturing operation parameters.