Research on safe water injection pressure at wellhead on offshore oilfield

The maximum water injection pressure at wellhead of water injector is mainly related to formation fracture pressure, well depth, pressure loss along the way and pressure loss at water nozzle. Where the down-hole water injection pressure exceeds the formation fracture pressure, then micro-fractures may occur in the formation, hence affecting the safety of water injection. Based on analysis of the factors affecting separate-layer water injection pressures, the calculation method was finalized for safe water injection pressure at wellhead. Also, a software for calculating safe water injection pressure at wellhead was developed for the four forms of water injection strings often used on offshore oilfields. The promotion and application of this software is of great significance in directing offshore water injection operation and guaranteeing the safety of water injection.