Determining method of nozzle size used for concentric layered water injection

The layered water and gas injection wells in Tarim Oilfield are characterized by super depth, high temperature and high pressure. The physical properties of injected fluids change greatly along the well depth. In order to ensure calculation accuracy, the changes of physical properties of the fluids must be fully considered. The common calculation methods for water injection nozzles are not adequate, and the calculation method for gas injection nozzle are not reported yet. This paper presents a set of methods for calculation of the sizes of layered water injection nozzles determined as per the requirement for separate layer injection in Tarim Oilfield, then the pre-nozzle pressure can be found by flow in the string and the injection pressure is found by the injection index curve. Then the nozzle sizes can be calculated by nozzle flow equation using the pre-nozzle pressure and injection pressure. The difference of pipe flow and nozzle flow of injected gas and water should be considered during calculation. The changes of physical properties of the fluids with temperature and pressure should also be fully considered. And the calculation should be carried out along the well depth in small sections. The isentropic volume change exponent during gas nozzle flow calculation can be found by thermodynamic theoretical calculation. In the engineering cases of Tarim Oilfield, the sizes calculated with this calculation method are close to the actual sizes, so this method acquires very good applied effect.