Subsurface Management of Drill Cuttings Reinjection in a Challenging Offshore Environment, Sakhalin, Russia

Smits, Wouter.G.¹, Dave Buller² (1) Sakhalin Energy Investment Company, The Hague, Netherlands (2) Gidatec Limited, North Petherwin, United Kingdom

SEIC operates in an environmentally sensitive area offshore Sakhalin, eastern Russia, in the sea of Okhotsk. Down-hole disposal of drilling generated waste in hydraulic induced fractures is the preferred disposal option. No other infrastructure currently is in place for disposal or waste storage options.

During the 2003-2005 period Sakhalin Energy is executing a drilling campaign in the Astokh oil field. The large out-step wells require high deviation drilling (ERD) using oil base mud (OBM) as drilling fluid. OBM cuttings and completion fluids are injected in a dedicated cuttings re-injection (CRI) well. The drilling waste is slurrified and disposed in the dedicat­ed CRI well in a shaly interval, well above the producing reservoir, into hydraulically induced fractures. In order to monitor and control the development of these fractures subsurface models (structural, stratigraphical and geomechanical) were generated. The models allowed the prediction, monitoring and evaluation of the development of the subsurface disposal domain, key to: · assure continuous drilling operation · assure safe operating conditions · comply with the stringent Russian injection license requirements The active subsurface planning, modeling and monitoring of the disposal domain together with active management of the surface operations have contributed to a successful CRI operation.

This presentation describes the modeling, the operation (management) and results of the SEIC 2004 waste disposal operation.