A RPN Computer Solution of the James' Method of Metering Two-Phase Flow

Abstract

The initial gauging of geothermal wells producing from water dominated reservoirs is commonly performed using the method of James. This method determines a well's flow rate by an empirical relation between fluid enthalpy and critical lip discharge pressure. However, the method requires a trail and error solution of a higher order equation to relate the pressure drop across a sharp edged orifice to the critical lip pressure to determine specific stagnation enthalpy. A program written in reverse polish notation (RPN) for Hewlett-Packard programmable calculators is presented for solving the enthalpy equation. The program uses numerical approximations of James' graph for expansion factors for orifices passing steam water mixture, numerical reductions of the equation of state for geothermal water and the Newton-Raphson method for solving the roots of the higher order equation. the program allows one to quickly determine the field the flow rate of a geothermal well being tested by the James' method using only the raw data of standard recording pressure meters and the dimensions of the test equipment.