Controlling Cement Circulation Loss to Both High-Permeability and Fractured Formations

Abstract

ABSTRACT A polymeric material is described which has been developed for controlling lost circulation during cementing. The morphology of the material permits sufficient particle deformation to optimize plugging of high permeability matrices, while the particle size of the material is precisely sized so as to optimize sealing of fractures. This optimization of morphology and particle size distribution enables the material to effectively control cement circulation loss to both high permeability and fractured formations. Laboratory data are presented comparing the relative effectiveness of the new material, gilsonite, gilsonite plus cellophane flakes, crushed coal and a graded plastic material in controlling cement slurry loss to simulated high permeability and fractured formations. In simulated high permeability formations the new material outperforms gilsonite and gilsonite plus cellophane flakes, and is slightly better than crushed coal. In simulated fractured formations this material outperforms a graded plastic material. It is shown that the new material does not appreciably affect thickening time or compressive strength of the cement slurries. Free water data for the cement systems tested with this material are satisfactory, but gel should be added to some systems to optimize this slurry property. Wyoming Overthrust, Williston Basin and Powder River Basin case histories are presented which demonstrate the effectiveness of this new material in areas where severe lost circulation problems have been encountered. It has been used to control cement circulation loss in wells with both high permeability and fractured formations, in wells with high bottomhole static temperatures and in applications requiring flow through downhole tools.