New formulations of potassium acetate and potassium formate polymer muds greatly improved drilling and waste disposal operations in South Italy

This paper discusses the field results of innovative K-Acetate or K-Formate mud formulations that have been used by ENI S.p.A./Agip Division to drill several wells through very plastic shales in South Italy. Field muds have b een carefully designed and evaluated as far as drilling and waste disposal activities an concerned. While drilling, the integration between field obse rvations, standard laboratory tests, and nonconventional rheological approa ches provided the assessment of useful correlations between rheological pro perties, performance, and formulations of field muds. These findings permit ted a gradual improvement of the mud effectiveness with a large reduction i n dilution rates, bit balling, and hole cleaning problems. At the rig, the strict cooperation between all the people involved in field operations repr esented a key factor for the successful application of the know-how acquire d. With respect to the previous wells drilled in the field with traditional dispersed muds, the optimization and careful management of the new muds co ntributed, in spite of the increased ROP, to a considerable reduction both in time spent to remove bit balling or reaming and in tons of wastes produc ed per hole volume. These improvements led to great savings in drilling and disposal costs that largely compensated the 8.4% increase in the mud mixin g costs per hole volume due to the presence of potassium salts.