Brownfield redevelopment presents challenges such as project risks, uncertain rate of return and cost optimization. A Malaysian offshore brownfield, which has been producing for more than 30 years, is redeveloped through infill drilling of new oil producer wells and water injector wells. Water injection facilities are brought into this brownfield by an MOPU. In this case study, a previous drilling rig was refurbished and converted into a mobile water injection facilities jack-up. Total duration of 12 months was taken to complete the conversion, mobilize, install, tie-in to the brownfield facilities, and commission the unit. The mobile and leased application of this water injection facilities jack-up mitigates the project risks, addresses the uncertain returns, reduces the initial capital investment, and has the flexibility to be relocated. It also contributes to the overall brownfield operations, by upgrading its philosophy from unmanned to manned concept.