Abstract: The invention concerns a method and a system for predicting the apparent flow conductivity of a heterogeneous medium. According to the invention, the following steps are implemented:—choosing a flow conductivity element type with a given set of characteristic parameters;—determining equations for said flow in said element type;—determining a network statistics for said given set of characteristic parameters; and—performing a stochastic homogenisation of said equations, for said network statistics. The invention applies more particularly to the predicting of the apparent viscosity of non-Newtonian fluids in a heterogeneous porous medium.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: A water-based drilling fluid (WBM) comprises as additive a reaction product of a polyhydroxyalkane and alkylene oxide. The polyhydroxyalkane is desirably based on a monosacchoride, and is preferably sorbitol. The alkylene oxide may comprise ethylene oxide (EO), propylene oxide (PO) and/or butylene oxide (BO). Good results have been obtained with additives including Sorbitol+18EO, Sorbitol+9PO, Sorbitol+4EO+6BO, Sorbitol+6EO+6BO, or Sorbitol+6BO. Drilling fluids in accordance with the invention have been found in laboratory tests to exhibit improved shale inhibition properties as compared with known polyol containing WBM, particularly in the absence of added potassium ions. This is environmentally advantageous.

Abstract: An emulsion with flow-initiated gelling properties is described, comprising at least two discontinuous phases with a polymer and cross-linking agent separated by two phase boundaries. The novel emulsion is preferably used for remedial operations in a subterranean formation or wellbore.

Abstract: A method for placing a plug at a predetermined location in a wellbore, the method being based on utilising a supporting fluid solidifying after being subjected to shear forces. After placing the supporting fluid and allowing it to develop sufficient strength, the plug material is injected. A preferred example of the fluid is an emulsion comprising polymer material and crosslinking agent separated by phase boundaries prior to the shearing process.