Abstract: A method for continuously mixing a borehole fluid such as cement includes using a measurement of the solid fraction of a cement slurry as it is being mixed to determine the ratio of the solid and liquid components to be added to the slurry. A system for mixing the includes a liquid material (water) supply including a flow meter; a solid material (cement) supply; a mixer which receives the liquid and solid materials and includes an output for delivering materials from the mixer to a delivery system; a device for measuring the amount of material in the mixer; and a flow meter in the output; wherein measurements from the flow meters and the device for measuring the amount of material in the mixer are used to control the amount of solid and/or liquid material added to the mixer.

Abstract: The improved recovery of hydrocarbons from subterranean formations by hydraulically fracturing a subterranean formation is accomplished. Fracturing fluids using a viscosifying surfactant fluid containing viscosifying micelles, for example, wormlike micelles, are useful to improve recovery of hydrocarbons and limit the loss of fracturing fluid into the formation fracture face. The invention further relates to novel fracturing and acidizing methods useful for increasing hydrocarbon production, limiting water production, resisting fracturing fluid loss into the subterranean formation, and reducing the equipment requirements in mixing and pumping fracturing fluid. The action of viscosifying micelles of surfactant in aqueous zones of the subterranean formation diverts fracturing fluid or acid from the aqueous zones to the hydrocarbon-bearing zones and also facilitates the flowback of increased amounts of hydrocarbons once a fractured well is placed back on production.

Abstract: An improved method for transport of particulate matter in a wellbore fluid, and particularly the transport of particulate matter in subterranean wells, such as hydrocarbon wells, is disclosed, the method being characterized by utilization of specified fibers to aid in transport of the particulate matter. Additional embodiments include the removal of particulate matter (particles) and particle deposits, such as from drill cuttings, during the drilling of wells, and the removal of particulate matter deposits in cleanout operations.

Abstract: An acidic fluid that is useful in stimulation and workover operations, and in particular, in matrix acidizing treatments, comprises an acid, such as hydrochloric acid; water; an aliphatic aldehyde having 1-10 carbon atoms; and an aromatic aldehyde having 7-20 carbon atoms. The aliphatic aldehyde preferably has 1-6 carbon atoms. Glyoxylic acid and glyoxal are especially preferred aliphatic aldehydes. The aromatic aldehyde preferably has 7-10 carbon atoms. Cinnamaldehyde is especially preferred.

Abstract: Methods of treating wells for cementing operations and for improving placement of cement in wells containing water swelling clays include treatment of the well with a fluid containing clay precipitating agents capable of coagulating clays in the well. The coagulating fluid can contain quaternary ammonium salts, aqueous salts of potassium or cesium, or silicates as the clay coagulating agent. The coagulating fluids can be applied to convert soft mud cake into hard mud cake prior to placement of cement.

Abstract: The invention provides a method of isolating an open hole fitted with a slotted liner, the method consisting in pumping a cement or a resin to the level of the slotted liner by means of injection apparatus provided with lips for scrapping the slotted liner downstream from the injection point so that the cement or resin fills the entire borehole upstream from the injection apparatus and also fills the space behind the slotted liner while the apparatus is being raised towards the surface. The invention also provides injection apparatus particularly adapted to implement the method, which apparatus can advantageously be displaced by means of coiled tubing.

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.