A method of monitoring conditions in a wellbore by disposing capsules with a signaling agent downhole, and monitoring the presence of the signaling agent released from the capsules that escape the wellbore. The capsules are formed by combining immiscible liquids, where one of the liquids contains the signaling substance, and each of the liquids contains a reagent. When combined, the liquids segregate into a dispersed phase and a continuous phase, with the dispersed phase having the signaling agent. The reagents react at the interfaces between dispersed and continuous phases and form polymer layers encapsulating the signaling agent to form the capsules. When disposed downhole, such as in casing cement, the capsule membranes can burst under pressure or temperature to release the signaling agent. Adjusting relative concentrations of the reagents varies membrane strength and permeability.

A method of monitoring conditions in a wellbore by disposing capsules with a signaling agent downhole, and monitoring the presence of the signaling agent released from the capsules that escape the wellbore. The capsules are formed by combining immiscible liquids, where one of the liquids contains the signaling substance, and each of the liquids contains a reagent. When combined, the liquids segregate into a dispersed phase and a continuous phase, with the dispersed phase having the signaling agent. The reagents react at the interfaces between dispersed and continuous phases and form polymer layers encapsulating the signaling agent to form the capsules. When disposed downhole, such as in casing cement, the capsule membranes can burst under pressure or temperature to release the signaling agent. Adjusting relative concentrations of the reagents varies membrane strength and permeability.

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

The invention provides methods and compositions for treating wash water from concrete production with carbon dioxide. The treated wash water can be reused as mix water in fresh batches of concrete.

The present invention provides a rapid-hardening admixture for accelerating hardening of a cement composition and a method for producing the same. The rapid-hardening admixture includes calcium aluminate, inorganic sulfate, and a setting modifier, in which the calcium aluminate has an average particle diameter in a range of 8 m to 100 m, and the setting modifier has an average particle diameter of 5 m or less.

Class C fly ash-based cementitious materials, concretes, and related techniques are disclosed. In accordance with some embodiments, an activated class C fly ash-based cementitious material may be produced by intergrinding class C fly ash (e.g., classified to remove quartz and/or other contaminants and, thus, increase the reactive materials present), an activator, sodium citrate, borax, and a polycarboxylate material. The class C fly ash may have an amorphous glass content of about 60 wt % or more, a calcium oxide (CaO.sub.2) content of about 20 wt % or more, and a quartz content of about 10 wt % or less. The activator may be a chemical which reacts with class C fly ash to form str?tlingite structures therein when introduced with water. In some cases, the cementitious material may be provided as an all-in-one powder blend. In some cases, techniques disclosed herein may be utilized in providing a fast-setting flowable fill material.