Transient Pressure Analysis Of Intermittent Well

With the continuous deepening of exploration and development, more and more low permeability reservoirs have been explored and developed. Because of the small scale of low permeability reservoir blocks,complex structure, low permeability, poor liquid capacity, the intermittent mode of production is used commonly. Due to the bottom hole pressure changes complexly under the intermittent pumping mode, if we use the porous media theory of continuous pumping oil production, ignore the increasing pressure in each cycle of stopped pumping during the interval pumping and take all flowing states as natural flowing production of oil well to process. The accuracy of interpreting results cannot be guaranteed. Therefore, the study of dynamic data of pressure interpretation under the intermittent mode of production in low permeability reservoir is an inevitable requirement for further development in oil field exploration and development.In this paper, to study Porous Media Theory under the intermittent mode of production, we carried out the following work:Analyzed the flow characteristics of underground fluid in intermitten wells, the mathematical models of unsteady flow in intermittent wells of homogeneous reservoir, double porosity medium reservoir, complex reservoir is established, and the effect of start-up pressure gradient is considered,the mathematical models are solved with finite difference method, the values of bottom-hole pressure and formation pressure is obtained.The typical transient pressure curves of homogeneous reservoir, double porosity medium reservoir, complex reservoir are drawed,and the influencing factors of tart-up pressure gradient, wellbore storage coefficient in Intermittent stage,wellbore storage coefficient in build-up stage, mobility ratio, the Interface distance and interporosity flow coefficient are analyzed in transient pressure curves.The pressure data of practical Intermittent Wells are explanated.Considering the wellbore storage effect and skin effect, the bottom hole pressure expression under intermittent mode of production in horizontal wells is provided.The transient pressure curves of horizontal wells under intermittent mode of production are plotted, and effects of horizontal well length on transient pressure curves are analyzed.With the data of production and dynamic fluid level of brought well,the principle of mechanics of flow through porous media and reservoir engineering methods, we set up ordinary differential equations about crude oil flowing from reservoir to wellbore and from wellbore to ground accouting start-up pressure gradient.solved the analytical solution of bottom hole pressure, formation pressure changes and liquid production changes.the change regularity of underground production during the recovery of oil well shut-inc is established.then formed the reservoir engineering method which calculates the present formation pressure of single well and control rerserve of single well.