Fractured Gas Wells To Prevent Flowback Of Proppant Backflow Model And A Reasonable Capacity

Propped hydraulic fracture is an absolutely necessarily technology measure to exploitation estimation and stimulation in low penetrability gas reservoir, while flowback of fracturing fluid after fracturing treatment is an important tache in hydraulic fracturing working. At present, empirical methods are mostly adopted in the process of hydraulic fracturing flowback by controlling blow off choke to control flowback process, whereas flowback of proppant and damage of reservoir bed are resulted in because of uncertainty of blow off choke dimension. In addition, regular production of gas well is greatly affected and serious sand production problem is resulted in because of eyeless pursuing off-take potential in the production process of gas well after fracturing. In this paper, aiming at the physical problem of on-site construction, the determination of flowback process of fracturing fluid and off-take potential after fracturing are made a systematic and in-depth study in order to offer reasonable theory reference and directing scheme to flowback controlling of fracturing fluid and determination of production measure that prevents proppant flowback.Leak-off of fracturing fluid in the process of closure of fracture is firstly studied in this paper making use of the line relation between net pressure difference and net square time difference, the influence of spurt loss coefficient to fracture parameters explanation are also analyzed using the analytic solution of leak off coefficient and spurt loss coefficient of fracturing fluid.On this base, flowback model of fracturing fluid during forced fracture closure is established to explain fracture parameters in the condition of forced fracture closure as well as reflect the influence of the variation of delivery rate during the flowback process to the fracture parameters explanation.According to the theory of fluid mechanics and the principle material balance, optimizing model of blow off choke dimension during the process of flowback is established. The variation rule of wellhead pressure with time for different blow off choke size is studied, at the same time, settling distance of proppant considering particle disturbance and flowback effect of proppant is calculated, from which we can determine the optimum blow off choke size for different reservoir condition and fracturing parameters.Aiming at sand production problem in the production process after fracturing of gas well, the simple computational model of stationary off-take potential after fracturing of gas well is established. In this way, optimal off-take potential is determined contacting critical velocity model of proppant flowback.On the base of these research findings, prediction software of flowback optimizationand off-take potential of fracturing gas well is worked out, as a result controlling scheme of flowback, as well as determination reference of reasonable off-take potential are offered aiming at different reservoir condition and fracturing execution parameter, which provide dependable theory reference and indemnification to improve fracturing efficiency and keep long-term stable and high efficiency production of gas well.