Abstract: Methods to separate or recover brine that is present in an invert emulsion are described. The brine is present as an internal phase in the invert emulsion. The brine can be a valuable component, such as an alkali metal formate, and separation and recovering of the brine from the invert emulsion permits the brine to be reused.

Abstract: A well fluid has a particle stabilized emulsion that has a first phase containing hydrocarbon fluid, a second phase containing brine, such as an aqueous alkali metal brine, and solid particles, wherein at least a portion of the solid particles are arranged at an interface between the first phase and the second phase to stabilize the emulsion. The well fluids can be used for drilling, completion, and/or workover fluids. A method of preparing the well fluid, which can be done in the absence of a surfactant, is also described.

Abstract: A hydrocarbon-based or ester-based drilling fluid or mud is described wherein the drilling fluid contains cesium phosphate. The hydrocarbon-based or ester-based drilling fluid or mud can have, for example, an external phase that contains hydrocarbon fluid and an internal phase that contains cesium phosphate. The hydrocarbon-based drilling fluid or mud can further contain at least one emulsifier or surfactant, and optionally other ingredients. The present invention can permit hydrocarbon-based drilling fluids to be essentially solids-free and may be used without corrosion and/or formation damage problems, for example, due to the use of the cesium phosphate in an internal phase of the hydrocarbon-based or ester-based drilling fluid. The present invention also relates to hydrocarbon-based or ester-based fluids for completion, workover, suspension and packer operations which contain cesium phosphate.

Abstract: Methods to separate or recover brine that is present in an invert emulsion are described. The brine is present as an internal phase in the invert emulsion. The brine can be a valuable component, such as an alkali metal formate, and separation and recovering of the brine from the invert emulsion permits the brine to be reused.

Abstract: A hydrocarbon-based or ester-based drilling fluid or mud is described wherein the drilling fluid contains cesium phosphate. The hydrocarbon-based or ester-based drilling fluid or mud can have, for example, an external phase that contains hydrocarbon fluid and an internal phase that contains cesium phosphate. The hydrocarbon-based drilling fluid or mud can further contain at least one emulsifier or surfactant, and optionally other ingredients. The present invention can permit hydrocarbon-based drilling fluids to be essentially solids-free and may be used without corrosion and/or formation damage problems, for example, due to the use of the cesium phosphate in an internal phase of the hydrocarbon-based or ester-based drilling fluid. The present invention also relates to hydrocarbon-based or ester-based fluids for completion, workover, suspension and packer operations which contain cesium phosphate.