Fully Soluble Solid Surfactant Package for Reactive Spacer Fluid Systems

Abstract A new solid surfactant formulation based entirely on organic materials is presented. It is fully water soluble with a fast dissolution rate, can be used in high or low salinity environments, it has good wetting properties, and it provides clean separation of the oil-water interface. In order to address an existing demand from operators that utilize solids addition equipment, a new formulation was designed, consisting of non-ionic surfactants entrained into a soluble organic matrix such that the final product is a solid. The active content of the surfactant is in the range of 40%-70% and the product meets a few important performance criteria, such as: fast dissolution rate of under 2 minutes in room temperature water, excellent water wetting properties, fast emulsion inversion and good melting/softening temperature, of 130°F or higher. The surfactants used in these formulations were selected following a performance screening, where non-ionic surfactants (NIS) with various hydrophobes – linear, semi-branched, branched – and different carbon numbers were tested by monitoring emulsion inversion rates with a conductivity meter. The mud utilized was provided by an operator, it was an almost fully spent drilling fluid, with high fines content. The spacer fluid was generated following a typical recipe using pumice as main component and having a density of about 0.5 ppg higher than the mud. The performance and optimization testing were done on a Grace viscometer with spacer loadings between 3-10 gpt in the temperature range of 80-140°F. The new solid surfactant system for reactive spacer fluid brings a number of advantages, such as: fast dissolution rate, great wetting ability, absence of insoluble particulates, high active content, good performance over a range of temperatures, and high melting/softening point of over 130°F, with good flowability of the pellets. These features are important for the operators helping them to utilize the solids addition equipment while the use of a solid NIS, fast dissolution rate and rapid mud inversion allows for a truly dry on the fly spacer fluid to be formulated.