Managing Risks and Uncertainties in Drill Cuttings Re-Injection in ChallengingEnvironments – Field Experience from Sakhalin Island

摘要

Drilling waste disposal using hydraulic fracturing is often thepreferred waste management option because it can achievetrue zero discharge without being limited by the drillinglocation. This is particularly true for drilling operations inremote and challenging areas such as offshore Sakhalin Islandas there is no established infrastructure for drilling wastemanagement.This paper presents a case history of managinguncertainties and risks related to a drill cuttings re-injection(CRI) project offshore Sakhalin Island. Although there areuncertainties and risks with the CRI project in this case,regulatory requirements and the operator’s commitment tozero discharge made it the preferred option for drilling wastemanagement. Complicating the decision was a previousinjection well where cuttings settling made it inoperative.Thus, the only option was to inject the oily cuttings into adeviated well intended for future use as a development well,which posed a number of risks related to the proposed CRIoperation.Since this is the only option for drilling waste managementand loss of this well would have delayed the drilling programand field development for at least a year, managing the risksand uncertainties related to this CRI project and assurance of atrouble-free CRI operation were critical.This paper presents monitoring and diagnostic analysesthat were used for slurry design and optimization, pumpingprocedure design and optimization considerations, as well assolids transport modeling and planning length of shut-inintervals between batches. These quality assurance andoptimization measures were proven to be effective inmanaging the risks and uncertainties associated with thiscritical cuttings injection well off Sakhalin Island. At the time of this writing, more than 100,000 bbl of slurry and fluid hadbeen injected into this well without incident.