Controlling the release of chemical additives in well treating fluids

A method of controlling the rate of release of a liquid chemical additive in a treating fluid introduced into a well comprising the steps of:

• (a) causing said liquid chemical additive to be absorbed into a porous solid material whereby said liquid chemical additive is encapsulated thereby and when the resulting encapsulated liquid chemical additive is combined with said treating fluid said liquid chemical additive is slowly released into said treating fluid, said porous solid material being precipitated silica which remains dry and free flowing after absorbing a liquid chemical additive therein;
• (b) combining said encapsulated liquid chemical additive with said treating fluid;
• and
• (c) introducing said treating fluid containing said encapsulated liquid chemical additive into said well.

A method of controlling the rate of release of a liquid chemical additive in a treating fluid selected from the group of cement slurries, polymeric compositions, viscous aqueous liquids, viscous non-aqueous liquids and well drilling fluids introduced into a well comprising the steps of:

• (a) causing said liquid chemical additive to be absorbed into a particulate porous solid material which remains dry and free flowing after absorbing said liquid chemical additive whereby said liquid chemical additive is encapsulated by said porous solid material and when the resulting encapsulated liquid chemical additive is combined with said treating fluid said liquid chemical additive is slowly released into said treating fluid, said particulate porous solid material being selected from the group consisting of precipitated silica, alumina, zeolites, clays, hydrotalcite, styrene-divinylbenzene based materials, cross-linked polyalkylacrylate esters and cross-linked modified starch;
• (b) combining said encapsulated liquid chemical additive with said treating fluid;
• and
• (c) introducing said treating fluid containing said encapsulated liquid chemical additive into said well.

A method of controlling the rate of release of a liquid chemical additive in a cement slurry introduced into a well comprising the steps of:

• (a) causing said liquid chemical additive to be absorbed into particulate porous silica whereby said liquid chemical additive is encapsulated thereby and when the resulting encapsulated liquid chemical additive is combined with said cement slurry, said liquid chemical additive is slowly released into said cement slurry;
• (b) combining said encapsulated liquid chemical additive with said cement slurry;
• and
• (c) introducing said cement slurry containing said encapsulated liquid chemical additive into said well.