Drilling cuttings and associated process fluids re-injection underground into geological formations is a complex process. In order to inject drilled-out rock back into the formation, cuttings must follow through a long preparation chain. Firstly, rock is grained at several stages to obtain desired size granules. Then slurry pulp is prepared by mixing the slurry with the liquid. The rheology of the slurry pulp must maintain the solid phase in suspension (until them displaced in the formation). Next, the slurry pulp is injected into geological domain at pressure exceeding formation hydraulic fracturing pressure. Of all the existing drilling waste disposal methods the cuttings re-injection is considered the most appropriate technique for shelf projects due to environmentally sensitive marine ecosystem. This technology allows safely dispose all necessary drilling waste and at the same time allows to meet strict "zero discharge" requirements. Cuttings re-injection technology especially relevant for technical projects where it is not possible to dispose drilling waste using traditional methods (thermal desorption, annealing, dehydration, drying of drill cuttings, encapsulation and burial in sludge pits) due to severe climatic conditions, complexity of production processes. This article describes the basic principles of cuttings re-injection process and reviews the reasons for geological object capacity decrease while drilling waste disposal. The article also describes measures aimed at restoring fractured domain capacity probed at cuttings re-injection well drilled at offshore Piltun-Astokhskoye oilfield, the Sea of Okhotsk.
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