Novel weight materials for use in cement, spacer and drilling fluids

Abstract

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.

We claim: 
     
         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; and 
 from 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm 3 , 
   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.   
     
     
         2 . The method of  claim 1 , wherein the cementitious composition further comprises:
 a gelling agent including oxides of antimony, zinc oxide, barium oxide, barium sulfate, other irons ores or mixtures and combinations thereof;   a secondary weighting agent including iron, steel, barite, hematite, other iron ores, tungsten, tin, manganese, manganese tetraoxide, calcium carbonate, illmenite, sand or mixtures thereof;   a dispersing agent;   a fluid loss control additive; and   mixtures or combinations thereof.   
     
     
         3 . The method of  claim 2 , wherein the primary weighting agent and the secondary weighting agent are in the form of a powder, a shot, or mixtures and combinations thereof. 
     
     
         4 . A drilling fluid composition comprising:
 from 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm 3 ,   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 increase the density of the composition while maintaining other properties including at least pumpability, gas tight sealing, low tendency to segregate, and/or reduced high temperature cement strength retrogression.   
     
     
         5 . The composition of  claim 4 , wherein the cementitious composition further comprises:
 a gelling agent including oxides of antimony, zinc oxide, barium oxide, barium sulfate, other irons ores or mixtures and combinations thereof;   a secondary weighting agent including iron, steel, barite, hematite, other iron ores, tungsten, tin, manganese, manganese tetraoxide, calcium carbonate, illmenite, sand or mixtures thereof;   a dispersing agent;   a fluid loss control additive; and   mixtures or combinations thereof.   
     
     
         6 . The composition of  claim 5 , wherein the primary weighting agent and the secondary weighting agent are in the form of a powder, a shot, or mixtures and combinations thereof. 
     
     
         7 . A method for drilling a subterranean well comprising:
 circulating a drilling fluid, while drilling a borehole,   where the drilling fluid includes:
 from 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm 3 , 
   where the wt. % is based on the weight of the drilling fluid in the absence of the primary weighting agent, and   where the primary weighting agent to increase the column weight of the fluid to a desired pressure and where the drilling fluid has improved properties relative to a drilling fluid having a weight equivalent amount of a hematite weighting agent.   
     
     
         8 . The method of  claim 7 , wherein the cementitious composition further comprises:
 a gelling agent including oxides of antimony, zinc oxide, barium oxide, barium sulfate, other irons ores or mixtures and combinations thereof;   a secondary weighting agent including iron, steel, barite, hematite, other iron ores, tungsten, tin, manganese, manganese tetraoxide, calcium carbonate, illmenite, sand or mixtures thereof;   a dispersing agent;   a fluid loss control additive; and   mixtures or combinations thereof.   
     
     
         9 . The method of  claim 7 , wherein the primary weighting agent and the secondary weighting agent are in the form of a powder, a shot, or mixtures and combinations thereof. 
     
     
         10 . A spacer fluid composition comprising:
 water, and   from 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm 3 ,   where the amount is sufficient to impart a desired high bulk density to the spacer fluid composition, the spacer fluid composition has a pseudo-plastic fluid with near constant shear stress profile having a 300/3 ratio between about 2 and about 6, and the spacer fluid composition has a density of the spacer fluid is between about 9 pounds per gallon and about 24 pounds per gallon.   
     
     
         11 . The composition of  claim 10 , further comprising:
 1) 10 wt. % to 50 wt. % by weight of SMA as a dispersant;   2) 40 wt. % to 90 wt. % by weight of bentonite as a suspending agent;   3) 1 wt. % to 20 wt. % a viscosifier;   4) 0.01 gal per bbl to 10.0 gal per bbl of aqueous base spacer of an ethoxylated nonylphenol surfactant having a mole ratio of ethylene oxide to nonylphenol ranging from 1.5 to 15; and   5) 20 wt. % to 110 wt. % of the weighting system.   
     
     
         12 . The composition of  claim 11 , further comprising:
 a secondary weighting agent including iron, steel, barite, hematite, other iron ores, tungsten, tin, manganese, manganese tetraoxide, calcium carbonate, illmenite, sand or mixtures thereof;   
     
     
         13 . The composition of  claim 12 , wherein the primary weighting agent and the secondary weighting agent are in the form of a powder, a shot, or mixtures and combinations thereof. 
     
     
         14 . A method for changing fluids in a subterranean well comprising:
 displacing a first fluid in the well with a spacer fluid, and   displacing the spacer fluid in the well with a second fluid,   where the first fluid and spacer fluid are incapable and the spacer fluid and the second fluid are incompatible and the spacer fluid includes from 25 wt. % to 110 wt. % of a primary weighting agent including a ferrosilicon having a density of at least 6.0 g/cm 3 .   
     
     
         15 . The method of  claim 14 , wherein the cementitious composition further comprises:
 a gelling agent including oxides of antimony, zinc oxide, barium oxide, barium sulfate, other irons ores or mixtures and combinations thereof;   a secondary weighting agent including iron, steel, barite, hematite, other iron ores, tungsten, tin, manganese, manganese tetraoxide, calcium carbonate, illmenite, sand or mixtures thereof;   a dispersing agent;   a fluid loss control additive; and   mixtures or combinations thereof.   
     
     
         16 . The method of  claim 15 , wherein the primary weighting agent and the secondary weighting agent are in the form of a powder, a shot, or mixtures and combinations thereof.