Study On Backflow Control Of Drainage And Proppant After Horizontal Well Pressure

Hydraulic fracturing increases production of oil and gas wells by creating a manual fracture in the formation. Horizontal well is used to get greater production potential by expanding the production interval and reducing the percolation resistance. Currently, the combination of horizontal wells and hydraulic fracturing is necessary to evaluate the tight gas reservoir and increase the production.In this paper, the open hole fracturing horizontal wells of Xushen deep volcanic gas reservoir are the main object of study. The gas reservoir is a typical low porosity and low permeability gas reservoir. Its volcanic formation show great heterogeneity and fracture development. It is a must to expand the production interval and reduce the percolation resistance by adapting Horizontal Well Fracturing. Great production has been acquired in the Xushen by Horizontal well fracturing. But there is a problem that the Proppant backflow is serious. To address this situation, the factors of fracture closure, fluid loss, proppant transport and the fluid flow in the horizontal wellbore and hydraulic fractures have been considered to study the fracture closure model and proppant flowback model systematically and Thoroughly. On this basis of models, the materials of Fracturing construction and the construction techniques for controlling proppant flowback are optimized in this paper. The research results designed to enrich horizontal well fracturing model has certain theoretical significance for guiding horizontal well fracturing fluid flowback has some reference value to guiding the construction of fracturing fluid flowback of horizontal well. The main contents of this paper are as follows:First, the natural fracture closure is chosen for Xushen gas field according to its conditions. The model of natural fracture closure has been built on the basis of2-D leak-off model and the quasi3-D fracture model. And the calculation program of it has been written. This model can provide a theoretical basis for determining the time of flowback.Secondly, considering the stages of proppant backflow and the sands staying in the downhole after fracturing construction, the model of proppant flowback from wellholes and the model of proppant flowback from fractures has been built in this paper. Because of the two-phase flow conditions in the wellholes and fractures, the two-phase flow model in horizontal wellholes, the two-phase flow model in nozzles and proppant backflow model are coupling and the corresponding calculation program has been written. The max gas production rate and the max diameter of nozzle under different conditions can be acquired by this program.Thirdly, the materials of fracturing construction for controlling the proppant backflow have been optimized in this paper. The fracturing fluid optimized can meet the construction requirements and possesses good gel breaking property. The combination of proppants (proportional ceramics, resin coated ceramics and fibers) can avoid the proppant backflow and improve the conductivity of fractures.Finally, on this basis of analyzing the fracturing constructions of Xushen gas field, the construction parameters has been optimized to avoid proppant backflow and enhance the stimulation effect.