Agip S.p.a.

Eniricerche S.p.a.

Eniricherche S.p.a.

Eniricerche S.p.a. and Agip S.p.a.

Giovanni Burrafato

Thomas Paul Lockhart

Stefano Carminati

Fausto Miano

Antonello Pittalis

Thomas P Lockart

Pretreated clays, their preparation and use in formulation drilling muds

Aqueous drilling muds are disclosed which contain, as fluidifier agent, one or more complexes, which may be either pre-formed or produced in situ, selected from: tetravalent zirconium and one or more organic acids, or their salts, having the general formula (I) ##STR1## wherein R.sub.1 and R.sub.2, which may be the same or different from each other, represent --H, --COOH, --CH.sub.3, --CH.sub.2 COOH, --CH(OH)COOH; aluminum citrate.

Aqueous drilling muds fluidified by means of zirconium and aluminum

Aqueous drilling muds effective at high temperature containing complexes, preformed or formed in situ, of tetravalent zirconium with one or more organic acids, or relative salts, of general formula (I) ##STR1## where R.sub.1 and R.sub.2, which can be the same or different, represent --H, --COOH, --CH.sub.3, --CH.sub.2 COOH or --CH(OH)COOH, or R.sub.1 and R.sub.2 jointly represent an oxo group (.dbd.O).

Drilling muds effective at high temperature

The permeability of high-permeability zones in a oil reservoir can be reduced by using a gellable aqueous composition with delayed gelation. The composition comprises:

Gellable aqueous composition and its use in enhanced petroleum recovery

Gellable aqueous composition and its use in enhanced petroleum

A gellable aqueous compositions able to reduce the permeability of high-permeability zones in an oil reservoir is a aqueous solution containing metered quantities of:

Gellable aqueous compositions and its use in enhanced petroleum recovery

A method for reducing the permeability of a high-permeability zone in a high-temperature oil reservoir comprises: preparing a gellable polymeric aqueous solution, operating on the surface under controlled conditions; injecting said gellable solution into the oil reservoir through a well; moving the solution through the reservoir until it reaches and substantially fills the high-permeability zone to be treated; and gelling the solution in situ with consequent lowering of the permeability in said high-permeability zone, and is essentially characterized in that the gellable solution is an aqueous solution containing a Cr(III) ion cross-linking agent and a water-soluble organic polymer cross-linkable by the effect of said cross-linking agent, said solution being free or substantially free of ligands for the cross-linking agent and having a pH adjusted to a value within the range of 1.5 to 5.5, depending on the desired gelling time.

Method and composition for reducing the permeability of a

A gellable aqueous composition particularly suitable for reducing the permeability of high-permeability zones in an oil reservoir is an aqueous solution comprising:

Gellable buffered aqueous composition and its use in enhanced petroleum

When used as occlusion agents or to cause fractures in a petroleum reservoir, polymer gels crosslinked with polyvalent metal ions can be removed by the use of special complexing agents.

Growing community of inventors

Tavazzano, Italy

Giovanni Burrafato