Low Permeability Tibet Fractured Well Productivity Studies

The gas reservoirs, which have been found middle-low or very low, are in the majority, Exploiting them has capacious foreground. Because hydraulically fracturing is an effective measure of the gas reservoirs exploited and productivity increased, this paper is based on oil and gas seeping theory, by a research object of gas well fractured, by a research target of gas well productivity fractured, which studied the seeping model, productivity forecast model and productivity influence factors of gas well fractured.(1) By the Finite-conductivity Vertically Fractured Well Model solved, we gained four of the fracture linearity flow solution, the bilinear flow solution, the formation linearity flow solution and the pseudo-radial flow solution. The character of every flow phase is analyzed. And the well-bottom pressure graphic tablets involved in the effect of wellbore storage and fracture damage have been plotted.(2) According to the well-bottom pressure solution of Finite-conductivity Vertical Fractured Well Math Model, which is transformed in Mathematics , the Binomial Ephemera Productivity Forecast Model was derived.(3) After fracture is plotted out into many puny parts on average, flux distributing equation of puny parts of Infinite-conductivity Vertical Fractured Well Model, which is related with dimensionless distance, is derived by Green Function and Line-source Function. So dimensionless flux distributing equation group of puny fracture parts is gained. By the solution of the group, the well-bottom pressure solution of Infinite-conductivity Vertical Fractured Well Model is derived, which is combined with Uniform Flux Horizontal Fracture Model.(4) By the well-bottom pressure solution of Infinite-conductivity Vertical Fractured Well Model, which is combined with the Back Pressure Well Test principle, the generic formulas of the pressure-down and pressure-back of isochronous Improved Well Test are derived. Fartherly, the form of Binomial Ephemera Productivity Equation is derived.(5) As the result of the formulas put forward of productivity forecast model. The productivity forecast models are validated by the actual example of gas field. So The productivity forecast models is chosen. And the influence factors of productivity are analyzed.Through the research of this paper, the productivity forecast models are gained. And the choice methods of the model are put forward, so for the economicappraise and optimize design of fracture, a dependable theory base is offered.