Abstract: The invention concerns a water-based additive for well fluid, comprising an acrylamide and branched styrene sulphonate copolymer. It also concerns a water-based fluid comprising an acrylamide and branched styrene sulphonate copolymer. The additive is useful for controlling the filtering of a well fluid through the wall. The invention is advantageously applicable to drilling and/or completion of oil wells having a temperature higher than 120° C.

Abstract: For controlling filtration loss during the installation of climber cement in a well, the procedure entails the addition of a specific quantity of at least one derivative of galactomannan, hydrophilically and hydrophobically modified, a hydrophobically modified hydroxy propyl guar (HMHPG).

Abstract: Hydrosoluble copolymers made of hydrophilic monomers, e.g., acrylamide, and of silane or siloxane derivative-based hydrophobic monomers, e.g., a silane or or siloxane acrylate, is obtained by micellar or heterogeneous radical copolymerization, and such copolymers can be used as rheology control agents in, e.g., a well bore.

Abstract: The invention concerns a water based foaming composition and the method of making it. The composition is optimized in that it contains a surfactant specifically selected according to the polymer also present in the composition. The surfactant and the polymer are selected so that they are oppositely charged. The invention is very useful in drilling or treating wells.

Abstract: The invention concerns a method for underground mining comprising the following steps: circulating in a well a foaming composition containing surfactants with cloud point higher than the temperature of the underground formation, heating the composition returning from the bottom to a temperature higher than the cloud point. The invention also concerns a system and a foaming composition based on water for implementing the method. The invention is useful for drilling and oil well completion operations requiring the use of a low-density fluid.

Abstract: The present invention relates to a process used in a well for controlling the filtration of a drilling, a completion or a workover fluid set in a well. The process comprises adding a predetermined amount of at least one hydrophobically modified cellulose derivative. In a variant of the invention, the cellulose derivative is a hydrophobically modified hydroxyethylcellulose. The invention further relates to a drilling, a completion or a workover fluid including at least one hydrophobically modified cellulose derivative, for example hydrophobically modified hydroxyethylcellulose and notably viscosifiers such as polymers or reactive clay.

Abstract: The present invention relates to a method of stabilizing argillaceous rocks containing reactive clays in the presence of water, wherein said argillaceous rocks are placed in contact with an aqueous solution containing a polymer with hydrophilic groups and hydrophobic groups.

Abstract: The present invention relates to a method of stabilizing argillaceous rocks containing reactive clays in the presence of water, wherein said argillaceous rocks are placed in contact with an aqueous solution containing a polymer with hydrophilic groups and hydrophobic groups.

Abstract: The present invention relates to a method of stabilizing argillaceous rocks containing reactive clays in the presence of water, wherein said argillaceous rocks are placed in contact with an aqueous solution containing a polymer with hydrophilic groups and hydrophobic groups.

Abstract: In a drilling well, well completion, or well workover, the permeability of the walls is controlled by adding a predetermined amount of at least one hydrophobically modified guar gum derivative, e.g., a hydrophobically modified hydroxypropyl guar (HMPG), so as to reduce the amount of filtrate lost through the walls. The fluid may also include viscosifiers such as polymers or reactive clay.

Abstract: The present invention relates to a method of stabilizing argillaceous rocks containing reactive clays in the presence of water, wherein said argillaceous rocks are placed in contact with an aqueous solution containing a polymer with hydrophilic groups and hydrophobic groups.

Abstract: The present invention relates to a process used in a well for controlling the filtration of a drilling, a completion or a workover fluid set in a well. The process comprises adding a predetermined amount of at least one hydrophobically modified cellulose derivative. In a variant of the invention, the cellulose derivative is a hydrophobically modified hydroxyethylcellulose. The invention further relates to a drilling, a completion or a workover fluid including at least one hydrophobically modified cellulose derivative, for example hydrophobically modified hydroxyethylcellulose and notably viscosifiers such as polymers or reactive clay.

Abstract: For controlling the dispersion of solids, e.g., cuttings, in water-based fluid used during operations such as drilling, completion or workover operations in a well crossing at least one permeable geologic formation, there is added to the fluid an optimized amount of a water soluble polymer HM PAM based on acrylamide and hydrophobic units. In a variant, a useful amount of hydrophobically modified cellulose derivative, e.g., modified hydroxyethylcellulose, HMHEC, is also added, thus forming a fluid containing HM PAM and HM HEC. The process has particular application to slim-hole and/or strongly deviated drilling.

Abstract: The present invention relates to an optimized lubricating composition including, in useful amount, an ester and a fatty acid, and optionally, the invention also relates to a well fluid including the lubricating composition according to the invention and the use of the composition for controlling the lubricity of a water-base fluid.

Abstract: A water-base fluid of optimized composition for solving problems encountered during operations such as drilling, completion or workover operations in a well crossing at least one permeable geologic formation contains (i) a hydrophilic/hydrophobic polymer, (ii) an acrylamide-base polymer of hydrophobic unit, (iii) a hydrophobically modified cellulose derivative, and (iv) a polysaccharide type polymer.The fluid can be used in a process implemented in a well drilled through at least one formation having a given permeability and is for particular application to slim-hole and/or deviated drilling.