Study On Optimization Of Crack Parameters For Integral Fracturing In Horizontal Wells

Hydraulic fracturing is an effective technology to stimulate the production of oil wells, and it has been widely used in reservoir development at home and abroad. With the development of hydraulic fracturing techniques, fracturing a single well has gradually developed into fracturing the entire well pattern. Integral fracturing of the well pattern, not only improves the production of oil wells, but also the injected volume of injection wells have also been increased, especially in low-permeability reservoirs, and making the layer get adequate energy supplement, formation pressure can be well maintained.For this reason, numerical simulation methods and the integral fracturing development technology have been used in this text, combining with the reservoir parameters of the region of Qinghai oilfield Q16, studying production performance dynamic of five-spot pattern integral fracturing of horizontal well and vertical well, and also analyzing fracture parameters and formation parameters that impact the production of integral fracturing, and getting the following conclusion through this research:(1) According to percolation mechanism of fractured vertical well and fractured horizontal well, combining with oil-water two phase percolation of Darcy law and the principle of material balance, and also considering the effect of the existence of start-up pressure gradient, establishing a five-spot integral fracturing of oil and water two phase3D flow model of the joint vertical well and horizontal well. This model can simulate the effect of the pattern production for different injection well and horizontal production well fracture parameters, and it has a wide adaptability for the simulation of the production of integral fracturing.(2) Two kinds of different fracture of fracturing a horizontal well have been considered, one is transverse fracture and another one is longitudinal fracture. Since transverse fracture insect the horizontal well at a point, but longitudinal fracture insect horizontal well at a line, for which, based on these characteristics, using different approach to treat the two types of fracture at the wellhead.(3) According to created percolation mathematical model, using reservoir numerical simulation finite difference method and deriving the corresponding numerical model, and choosing implicit pressure explicit saturation method, solving the pressure with implicit method and dealing with the saturation by explicit solution.(4) A program which can simulate the production performance of horizontal well and vertical well joint exploitation has been created, and this program can simulate the production performance of a five-spot pattern integral fracturing when the fractured horizontal have transverse and longitudinal fracture, and provide a powerful tool for evaluating the production of integral fracturing and optimizing the fracture parameters.(5) Using the horizontal well and vertical well joint exploitation five-spot pattern integral fracturing production performance program and analyzing the number of fractures,transverse fracture of horizontal well, longitudinal fracture of horizontal well, fracture conductivity, fracture length, formation permeability isotropic, formation permeability anisotropy, start-up pressure gradient, different size of well pattern etc. which effect of production performance for the fractured reservoir, and provide a basis for the integral fracturing and exploiting of Qinghai oilfield Q16block, and also has some practical significance.