Modelling of adsorption and precipitation scale inhibitor squeeze treatments in North Sea fields

This paper presents an analysis and design study of field scale inhibitor squeeze treatments. Simulators of varying levels of complexity have been used to model squeeze data from several wells in North Sea fields. The modelling has been carried out both for simple single sandbody squeezes and for inhibitor treatments in heterogeneous systems where there is free crossflow between strata. The appropriately matched results are then used in the design of improved inhibitor squeeze strategies for the fields studied. The main results from this study relate to the field design criteria which should be applied to both adsorption/desorption and `precipitation' scale inhibitor squeeze treatments. Using quite simple models to simulate the field results, a wide range of sensitivities in adsorption/desorption squeeze treatments has been investigated (e.g. injection concentration, overflush size, shut-in time etc). A more complex model was used to simulate an adsorption squeeze carried out in a multi-layer, near-well formation. Results show the significant effect of reservoir heterogeneity on inhibitor returns and, for such cases, that the placement strategy for inhibitor slug injection should be taken into consideration. A field `precipitation' squeeze has also been modelled which highlights the effect of local formation temperature. The results demonstrate the importance of selecting appropriate preflush and overflush volumes for creating the correct thermal conditions for in-situ inhibitor `precipitation'. A number of generally applicable conclusions arise from our study and some example economic results are presented. In particular, for precipitation type processes, some field application guidelines are given for the first time in the literature.