Composition for and process of recovering oil from an oil-bearing formation

Abstract

A composition for forming a foam, a foam composition, and a process for using the foam composition to recover oil from an oil-bearing formation are provided. The composition includes water, a surfactant mixed with the water, and fly-ash particles suspended in the mixture of water and surfactant, where the fly-ash particles have a particle size distribution with an average particle size of less than 200 nm, and where the suspension has an absolute zeta potential of from 10 mV to 40 mV. The composition may be mixed with a gas to produce a foam composition, and the foam composition may be contacted with oil in an oil-bearing formation in a process to recover oil from the formation.

What is claimed: 
     
         1 . A composition comprising,
 water;   a surfactant mixed with the water; and   fly-ash particles suspended in the mixture of water and surfactant,   wherein the fly-ash particles have a particle size distribution with an average particle size of less than 200 nm, and wherein the suspension of fly-ash particles in the mixture of water and surfactant has an absolute zeta potential of from 10 mV to 40 mV.   
     
     
         2 . The composition of  claim 1  wherein the suspension has a pH of from 4.0 to 12.0. 
     
     
         3 . The composition of  claim 1  further comprising an inorganic acid or an inorganic base mixed in the suspension. 
     
     
         4 . The composition of  claim 3  wherein the inorganic acid is hydrochloric acid. 
     
     
         5 . The composition of  claim 3  wherein the inorganic base is sodium hydroxide. 
     
     
         6 . The composition of  claim 1  wherein the surfactant is an anionic surfactant. 
     
     
         7 . The composition of  claim 6  wherein the anionic surfactant is an alpha-olefin sulfonate. 
     
     
         8 . The composition of  claim 1  wherein the surfactant is a cationic surfactant, an amphoteric surfactant, or a non-ionic surfactant. 
     
     
         9 . The composition of  claim 1  wherein the fly-ash particles are free of a surface modifying compound attached to the surface of the fly-ash particles. 
     
     
         10 . The composition of  claim 1  wherein the fly-ash particles are comprised of silica. 
     
     
         11 . The composition of  claim 1  wherein the suspension comprises from 0.01 wt. % to 0.5 wt. % of the surfactant and from 0.1 mg/ml to 3 mg/ml of the fly-ash particles. 
     
     
         12 . The composition of  claim 1  further comprising a gas dispersed within the suspension, wherein the composition is a foam. 
     
     
         13 . The composition of  claim 1  wherein the fly-ash particles have a particle size distribution with an average particle size of from 100 nm to 200 nm. 
     
     
         14 . The composition of  claim 1  wherein the suspension has a zeta potential of from 25 mV to 35 mV 
     
     
         15 . A process for recovering oil from an oil-bearing formation comprising:
 contacting a foam with oil in the oil-bearing formation, where the foam is comprised of a gas dispersed in a suspension comprised of fly-ash particles dispersed in a fluid comprised of water and a surfactant, wherein the fly-ash particles have a particle size distribution having an average particle size of at most 200 nm, and wherein the suspension has an absolute zeta potential of from 10 mV to 40 mV; and   producing oil from the oil-bearing formation after contacting the foam with the oil in the oil-bearing formation.   
     
     
         16 . The process of  claim 15 , further comprising displacing oil in the formation with the foam. 
     
     
         17 . The process of  claim 15  wherein the surfactant is an anionic surfactant. 
     
     
         18 . The process of  claim 15  wherein the fly-ash particles are free of a surface modifying compound attached to the surface of the fly-ash particles. 
     
     
         19 . The process of  claim 15  wherein the fly-ash particles are comprised of silica. 
     
     
         20 . The process of  claims 15 , wherein the foam further comprises an inorganic acid or an inorganic base or ionic components thereof. 
     
     
         21 . The process of  claim 15 , wherein the fly-ash particles have a particle size distribution having an average particle size of from 100 nm to 200 nm. 
     
     
         22 . The process of  claim 15  wherein the suspension has a pH of from 4.0 to 8.5. 
     
     
         23 . The process of  claim 22  further comprising the step of adding an inorganic acid or an inorganic base to the suspension to adjust the pH of the suspension to a pH of from 4.0 to 12.0. 
     
     
         24 . The process of  claim 15  further comprising adding an inorganic acid or an inorganic base to the suspension to adjust the absolute zeta potential of the suspension to 10 mV to 40 mV. 
     
     
         25 . The process of  claim 15  wherein the gas is carbon dioxide, nitrogen, or a mixture thereof. 
     
     
         26 . The process of  claim 15  further comprising the steps of:
 introducing the suspension into the oil-bearing formation; 
 introducing the gas into the formation and contacting the gas with the suspension in the formation to form the foam in the formation. 
 
     
     
         27 . The process of  claim 26  further comprising the step of co-injecting at least a portion of the suspension and at least a portion of the gas into the formation to introduce the suspension and the gas into the formation. 
     
     
         28 . The process of  claim 26  further comprising the steps of:
 injecting at least a portion of the suspension into the formation to introduce the suspension into the formation; 
 injecting at least a portion of the gas into the formation after injecting at least a portion of the suspension into the formation to introduce the gas into the formation. 
 
     
     
         29 . The process of  claim 28  further comprising the steps of alternately injecting at least two portions of the suspension and at least two portions of the gas into the formation. 
     
     
         30 . The process of  claim 15 , further comprising:
 separating the fly-ash particles from a fly-ash feedstream having a particle size distribution with an average particle size of greater than 200 nm;   dispersing the separated fly-ash particles in the fluid comprised of water and surfactant to form the suspension.