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 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: 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.

Abstract: The stabilization of selected photochromic compounds, selected from certain fulgides and fulgimides, is made possible by associating with such compounds a clay mineral having an expanding crystal lattice, which can stabilize a selected photochromic compound in a higher-energy colored form. The stabilized photochromic compound may be one included in a coating composition, such as a paper coating composition, or may constitute or be incorporated in a filler for a papermaking furnish or for a plastics material. The stabilizer serves to maintain the photochromic compound in its higher-energy colored state or one of its higher-energy colored states, thereby tending to prevent deterioration of color as the photochromic compound converts to an uncolored or weakly colored lower-energy state.