Controlling Coal Fines in Coal Bed Operations

Abstract

The migration of coal fines within a bed is reduced, inhibited or constrained by contacting the fines with nanoparticles, such as magnesium oxide crystals having an average particle size of about 30 nm. These nanoparticles may coat a proppant during the fracturing of a subterranean formation to produce methane from a coal bed therein. The nanoparticles may also treat a proppant pack in a fractured coal bed. The nanoparticles cause the coal fines to thus bind to or associate with the proppants. Thus, most of the coal fines entering fractures away from the near-wellbore region will be restrained or controlled near their origin or source and the production of methane at a desired level will be maintained much longer than a similar situation than where the nanoparticles are not used.

1 . A coal-fines containing fluid comprising:
 a base fluid selected from aqueous fluids, hydrocarbon fluids, alcohols, glycols, and mixtures thereof;   coal fines; and   a particulate additive, where the particulate additive:
 has a mean particle size of 100 nm or less, and 
 is selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, transition metal hydroxides, post-transition metal oxides, post-transition metal hydroxides, piezoelectric crystals, pyroelectric crystals, and mixtures thereof. 
   
     
     
         2 . The fluid of  claim 1  where the amount of the particulate additive within the fluid is sufficient to inhibit the ability of the coal fines to move within the fluid as compared to an identical fluid absent the particulate additive. 
     
     
         3 . The fluid of  claim 1  where:
 the alkaline earth metal is selected from the group consisting of magnesium, calcium, strontium, and barium; 
 the alkali metal is selected from the group consisting of lithium, sodium, potassium; 
 the transition metal is selected from the group consisting of titanium and zinc; and 
 the post-transition metal is aluminum, and mixtures thereof. 
 
     
     
         4 . The fluid of  claim 1  where the amount of the particulate additive ranges from about 2 to about 300 pptg (about 0.24 to about 36 kg/1000 liters) based on the fluid. 
     
     
         5 . The fluid of  claim 1  where the mean particle size of the particulate additive is 90 nm or less. 
     
     
         6 . The fluid of  claim 1  further comprising a proppant, where the particulate additive at least partially coats the proppant. 
     
     
         7 . The method of  claim 6  where the proppant at least partially coated by the particulate additive further comprises a non-aqueous coating agent. 
     
     
         8 . The method of  claim 6  where the proppant at least partially coated by the particulate additive further comprises a dry particulate additive. 
     
     
         9 . A coal-fines containing fluid comprising:
 a base fluid selected from aqueous fluids, hydrocarbon fluids, alcohols, glycols, and mixtures thereof;   coal fines; and   about 2 to about 300 pptg (about 0.24 to about 36 kg/1000 liters) based on the fluid, of a particulate additive, where the particulate additive:
 has a mean particle size of 100 nm or less, and 
 is selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, transition metal hydroxides, post-transition metal oxides, post-transition metal hydroxides, piezoelectric crystals, pyroelectric crystals, and mixtures thereof; 
   
       where the amount of the particulate additive within the fluid is sufficient to inhibit the ability of the coal fines to move within the fluid as compared to an identical fluid absent the particulate additive. 
     
     
         10 . The fluid of  claim 9  where:
 the alkaline earth metal is selected from the group consisting of magnesium, calcium, strontium, and barium; 
 the alkali metal is selected from the group consisting of lithium, sodium, potassium; 
 the transition metal is selected from the group consisting of titanium and zinc; and 
 the post-transition metal is aluminum, and mixtures thereof. 
 
     
     
         11 . The fluid of  claim 9  where the mean particle size of the particulate additive is 90 nm or less. 
     
     
         12 . The fluid of  claim 9  further comprising a proppant, where the particulate additive at least partially coats the proppant. 
     
     
         13 . The method of  claim 12  where the proppant at least partially coated by the particulate additive further comprises a non-aqueous coating agent. 
     
     
         14 . The method of  claim 12  where the proppant at least partially coated by the particulate additive further comprises a dry particulate additive.