Influence Of Temperature Change And Water Hammer Effect Of Transient Wellbore Pressure

Dynamic Monitoring wells are generally difficult to gauge directly down to the producing formation position,as well as to reduce the security risk,reduce monitoring costs,the general stress test wellhead or shallow segment instead of bottom hole pressure tests.Gas flows from the bottom of the formation process,by the Joule-Thomson Effect,the gas temperature will produce changes and heat exchange occurs with reservoir rocks,flowing into the bottom of the temperature is not equal to the gas reservoir temperature and constant,but the production time and production and other factors.While the opening and closing well and production systems in the process of change,wellbore temperature distribution will experience a longer period of stabilization process,and the fluid density and pressure gradients with temperature changes.In the conventional method of calculation of temperature and pressure in the wellbore,generally taken as a bottomhole temperature gas reservoir inflow temperature,under the influence of temperature changes on variable yield wellbore pressure calculation also does not consider the bottomhole pressure calculation errors will have a greater impact TEST the accuracy of interpretation and dynamic analysis.In addition,in the early wells shut,the pressure at the wellhead and shallow sections measured curve showing regular sinusoidal shape fluctuations,a phenomenon that in the ultra-deep,high-pressure gas widespread that there is pressure in the pipeline,due to the fluid flow rate sharply change,resulting in instantaneous pressure significantly,repeatedly,rapidly changing phenomenon is water hammer.For the production of smaller pressure,this water hammer pressure fluctuations even close to formation pressure recovery value,pressure build-up test interpretation.Due to the combined effect of wellbore temperature changes and water hammer,the wellhead pressure test curve and shallow sections will have a greater distortion,affect the accuracy of test data quality and interpretation of results.Based on a comprehensive analysis of domestic and foreign wellbore unsteady heat transfer,water hammer aspect of research and literature,the paper-depth study on the above issues.Fourier's law and the percolation theory,according to the energy balance equation and Duhamel's principle,the consideration of variable flow and multiphase flow well productivity layer formation temperature and pressure segment model,finite difference and converted a three-diagonal matrix equations,by Thomas solving;According to the energy conservation principle,the establishment of a unified mathematical model wellbore temperature and pressure described constant flow flowing state for open wells under constant flow conditions,and stable production shut-wellbore temperature and pressure calculation;on this basis,through the analysis of variable flow wellbore temperature change under the influence of factors,according to the relationship between the temperature of the fluid transient and steady temperature changes into the wellbore temperature decreasing type,incremental type and constant type three categories,namely the establishment of the corresponding mathematical model and calculation methods,the establishment of wells variable flow wellbore temperature and pressure unsteady heat transfer model,the model for a variety of production changes,wider range of applications,more in line with actual production;By wellbore water hammer effect mechanism analysis,according to the law of conservation of mass and Newton's second law,the establishment of well water hammer pressure gas model gas,oil,water multiphase flow conditions,by the method of characteristics of water hammer pressure mathematical model for finite difference solving,according to water hammer pressure model,establishing water hammer wave speed plate and water hammer pressure plate in a wide range of parameters,plates can quickly query by water hammer wave speed and water hammer pressure gas pressure at different temperatures,easy application.According to well productivity layer formation temperature and pressure segment model,the wellbore temperature and pressure model gas well water hammer pressure model,combined with the high pressure fluid physical parameter calculation equation solving from the wellhead to achieve coupling gas reservoir to the bottom and then to develop calculation software,to solve the gas,oil,water multiphase flow at constant flow and variable flow pressure affected by temperature calculation,gas well water hammer pressure fluctuations impact,the model can be calculated or wellhead pressure test data segments in shallow wells to wells at the end,to get the bottomhole pressure,improve interpretation accuracy purposes.The main impact of quantitative analysis by gas pressure and water temperature hit factor and variation,the results show that the production process gas downhole fluid inlet temperatures will be lower than gas reservoir temperature,the temperature of the fluid into the wellbore with the production of the dynamic changes,pressure and time.After the gas switch well,wellbore in quite a long time in a non-steady-state heat transfer stage,the more shallow wellbore temperature the greater the change,the initial switch well,rapid changes in temperature,pressure greatest impact.When the pressure recovery well testing,wellbore temperature will quickly drop fluid density and pressure gradient increases,pressure recovery curve shape,according to borehole temperature and pressure unsteady heat transfer model,causing the wellbore through the calculated temperature shut-wellbore pressure drop change,can effectively quantify and correct pressure recovery test pressure anomalies.high productivity,high pressure gas well fluid density,flow speed,shut process due to fluid inertia and elastic compression of comprehensive action,will produce significant water hammer pressure,gas well water hammer pressure model can accurately describe the relative size of the pressure gas wells hit,attenuation of water hammer.Water hammer pressure shut-size and speed,flow rate,pipe diameter,wellbore depth dependent.For high pressure,high-yield gas well,by the impact of water hammer,pressure recovery curve fitting segment early poor results.Water hammer pressure after data correction can significantly improve the effect of the pressure recovery curve fitting,more accurate explanation wellbore storage coefficient and skin factor,evaluation of reservoir acidizing effect,dimensionless recommendations for high pressure,high gas pressure build-up test interpretation water hammer pressure correction.