NOVEL WEIGHT MATERIALS FOR USE IN CEMENT, SPACER AND DRILLING FLUIDS

摘要

A drilling fluid, spacer fluid and cementing compositions for use in subterranean wells are disclosed along with methods for making using same, where the compositions include a weighting system having an effective amount of a metal silicon alloy, mixtures of metal silicon alloys, or mixtures of metal silicon alloys and conventional weighting agents, to produce compositions having a desired high density, while retaining other fluid properties such as pumpability, gas tight sealing, low tendency to segregate, and reduced high temperature cement strength retrogression.

主权项

1. A method of cementing in an annulus between a well casing and a borehole comprising:
placing in the annulus a cementitious composition comprising:
water;a hydraulic cement; andfrom 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm3, where the wt. % is based on the weight of the hydraulic cement in the absence of the primary weighting agent, and where the primary weighting agent increases the density of the downhole cement composition, while maintaining other properties including at least pumpability, gas tight sealing, reduced tendency to segregate, and/or reduced high temperature cement strength retrogression, and where the composition has (1) a plastic viscosity at least 10% lower than a composition including an equivalent amount of hematite as the primary weighting agent, (2) a yield point at least about 15% lower than a composition including an equivalent amount of hematite as the primary weighting agent, (3) a cure rate at least 10% faster than a composition including an equivalent amount of hematite as the primary weighting agent, and (4) a cure strength after 6 hours of curing and a final cure strength at least 10% higher than a composition including an equivalent amount of hematite as the primary weighting agent.