科研之友
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摘要
Downhole dynamic pressure is a key parameter required to determine the reservoir features or to determine the necessary conditions for production. These are of major importance in hydrodynamic calculations to find the basic parameters of reservoir rock, to determine well locations and the optimal spacing between borcholes and the optimal rate of production on the reservoir rock level. The authors made an attempt to find the downhole dynamic pressure and pressure loss in a horizontal well in the conditions of single-phase gas flow and stabilised flow in the reservoir. As density, viscosity and compressibility of gas depend on its pressure and temperature, the analytical solution for gas flows is more complicated than for flows of incompressible fluids. Furthermore, the flow of gas through a perforation in the production section of a horizontal well will interfere with the stream of flowing gas and bring about a change of the flow resistance along the we]]. Pressure in a horizontal well is governed by the energy balance equation. An analytical Solution to this equation tor the flow of gas requires that temperature-dependent gas parameters (i.e. viscosity, compressibility and resistance to flow) should be averaged, which might lead to further errors. Besides, in thus obtained solutions to the energy balance equations, the averaged parameters are related to pressure. That is why all iterative procedure was applied to obtain the static and dynamic pressure. The iterative algorithm was further utilised and an application was written in Borland Pascal that computes pressure losses in horizontal wells. This application might be employed to compute pressure losses in vertical and directional wells. Pressure loss in the well is determined for particular well sections and pressure implicitly present in the formulas is obtained by successive approximations. Resistance due to gas flow through a perforation is determined by adjusting the linear friction coefficient utilising the Quyang's correlation procedure. It is demonstrated that in the case of single-phase flows of gases the downhole pressure can be derived from well production data with sufficient accuracy. The adequacy of the proposed method is verified by a computation data for a real case.
- 出版日期2007
