Scale Squeeze Fractured Reservoirs in the Bakken, North Dakota

Abstract

AbstractScale inhibitor squeezes are common for scale prevention in conventional reservoirs, but similar applications into fractured reservoirs are unusual and the mechanism of inhibitor transport and retention is not fully understood. This paper discusses the selection and field application of a scale inhibitor for the Bakken, North Dakota fractured reservoirs. The Bakken development is a hydraulically fractured reservoir where calcium carbonate and iron carbonate scaling pose a threat to productivity, necessitating the deployment of preventative scale inhibitor treatments. The results of a comprehensive inhibitor testing program, including compatibility, formation damage studies, dynamic tube blocking and static adsorption testing are presented, providing an overview of the product selection criteria for the fractured reservoir. This paper demonstrates how production-, completion- and laboratory-derived data were used with treatment modeling software to enable the successful application of a scale squeeze into the Bakken formation. Complex Bakken completion orientations made the use of conventional modeling programs a challenge and a number of assumptions that were made are discussed in the paper. The final part of the paper reviews the squeezes performed on three Bakken wells, and discusses relative performance against the modeled treatment predictions. The scale inhibitor retention in the reservoir is documented, and possible mechanisms are discussed.