Abstract
Scaling risk may be insignificant during the early stages of well life due to delayed seawater breakthrough; however, during the latter stages of production inhibitor chemical application by squeezes may be required to prevent scale deposition (Chen et al., 2013). This raises the question of what behaviour should be expected during the redevelopment of a previously seawater flooded reservoir. Should the planning and design of squeeze treatments in a brown field project be the same or different to a green field development?
This paper discusses this issue by reference to a case study in a field located in the Norwegian Sector of the North Sea. The field in question is produced by horizontal wells, and these wells will require scale inhibitor placement via bullhead squeezes deployed at appropriate pump rates to ensure effective placement to provide adequate protection. The timing and extent of seawater breakthrough have been calculated using a reservoir simulation model that accounts for the original development phase, a multi-year period during which the field was shut in - but during which fluid redistribution could still occur - and then the redevelopment phase.
These calculations have been used to identify the required timing for squeeze treatments, and to investigate what bullhead pump rates are required for adequate placement during both phases of field life. Two wells are considered during the first production period and six wells are studied during the redevelopment stage. In each case four pump rates are assessed: 2.5, 5, 7.5 and 10 barrels per minute. The main finding is that while adequate placement can be achieved using the same pump rates in both phases of field life, during the redevelopment stage the treatments will need to be deployed earlier in the redeveloped wells life, since there may not be a long time period between (formation) water breakthrough and seawater breakthrough, as there generally is during conventional green field developments.
This paper delivers a comprehensive water breakthrough and squeeze placement profile comparison between early and redevelopment stages. It presents an assessment of the scaling risk in different production wells, the timing of the first and later squeeze treatments in each production well, and the ability to mitigate that scaling risk by bullhead squeeze treatments.
