METHOD FOR MEASURING THE PRODUCTION RATE OF A GAS WELL Russian patent published in 2018 - IPC E21B47/10 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to gas industry, namely to technology of measuring the gas production rate (flow) for gas wells when conducting gas dynamic studies at the established filtration modes using a standard diaphragm critical flow meter (DCFM). Method comprises: arranging the flow of natural gas in a gas well in a critical flow regime through the diaphragm of a DCFM, measuring using an approved type of temperature and pressure measurement means for the natural gas flow in the DCFM case before the diaphragm, sampling of the natural gas stream, determination of the component composition for the selected sample of the natural gas stream. Formation of array of initial data for the determination of thermobaric, thermodynamic and gas dynamic parameters of the natural gas flow used in finding the gas production rate for a gas well, which includes the following information: material from which the diaphragm used in DCFM is made, the temperature coefficient of linear expansion of the material of the diaphragm; material from which the linear part of the case used in DCFM is made, the temperature coefficient of linear expansion of the material of the DICK case; diameter of the internal aperture of the diaphragm used in DCFM at 20 °C; inner diameter of the cylindrical part of the body used in DCFM at 20 °C; temperature and pressure of the gas flow in the linear part of DCFM case before the diaphragm; component composition of the natural gas flow passing through DCFM. Determination of thermobaric, thermodynamic and gas dynamic parameters of natural gas flow in the cylindrical part of DCFM case before the diaphragm and at the point of maximum compression of its jet beyond the diaphragm of DCFM, finding the gas production rate for a gas well with ε – the compression ratio of the gas flow jet at the point of maximum compression of its jet beyond the diaphragm of DCFM, the fraction of units; d – diameter of the aperture of the diaphragm of DCFM, m; z₁ and z₂ – gas compressibility factors before the diaphragm of DCFM and at the point of maximum compression of its jet beyond the diaphragm of DCFM, units; z_CT – gas compressibility factor under standard conditions, units; p₁ – absolute gas pressure before the diaphragm of DCFM, MPa; p_ST – pressure corresponding to the standard conditions p_ST=1.01325⋅10⁵ Pa; T_ST – temperature corresponding to the standard conditions T_ST=293.15 K; T₁ – absolute temperature of the gas in front of the diaphragm of DCFM, K; R – molar gas constant R=8.31 J/(mol⋅K); M – molar mass of the gas, kg/mol; k – adiabatic exponent of the gas, units; β – relative diameter of the aperture of the diaphragm of DCFM (β=d/D), shares of units; D – internal diameter of the cylindrical part of DCFM case before the narrowing device, compression ratio of the jet of the gas stream at the point of maximum contraction behind the DCFM diaphragm is determined taking into account the reduced gas temperature in front of the DCFM diaphragm and the reduced gas pressure in front of the DCFM diaphragm.

EFFECT: technical result consists in obtaining the measurement results with confidence in the range from minus 5 to plus 5 % without the presence of pronounced systematic errors that are typical for the known methods.

1 cl, 8 dwg, 3 tbl