Bean-up Guidelines for Sand-Control Completions

Abstract This paper presents a model that quantifies the production impairment caused by fines mobilization and induced by the transient gradient of pressure from the bean-up operations. Laboratory flow tests using field core samples and synthetic cores composed of different mixtures of sand and fines materials, all stressed under representative in-situ stress conditions were performed. They systematically assessed mechanisms of fines mobilization and amounts of permeability impairment as functions of different sizes of fines, amounts of fines, and flow velocities. Results of flow tests and transient gradient pressures generated by bean-up operations were combined to determine the additional production impairment or skin induced by flow velocity for the well. Application of this model allows engineers to calculate the well skin as a function of drawdown, total time of bean-up, time between choke changes, and number of steps or choke changes in the bean-up operations. Application of this method provided some general qualitative bean-up recommendations (based on production impairment caused by fines mobilization): Bean-up with smaller incremental drawdown and shorter time between choke changes is preferred to bean-up with a higher drawdown but with a longer waiting time between choke changesContinuous bean-up is better than step-wise bean-upSkin inflicted by bean-up is more sensitive to a higher drawdown than to a shorter total bean-up time.Bean-ups with the same drawdown can be performed faster for reservoirs with higher diffusivity constant The applied field example of a cased hole gravel pack well showed the bean-up inflicted skin ranged between 1 and 3 units. The effect of eliminating the transient gradient of pressure entirely only resulted in a reduction of 1 skin unit. Therefore, at least for this case, the impact of bean-up on production impairment based on fines mobilization was low. Other factors such as flow assurance; rock failures and sand production (and their impacts on sand control completion impairment and reliability) in the near well bore area may be more critical for optimizing the bean-up operations. Further studies in these areas are encouraged. Consideration of fines impairment for bean-up of sand control well is still warranted for formation sand with large amounts of "bad" fines and under low in-situ effective stress conditions. This paper should be of interest to both the completion and production engineering communities.