Knowledge Gaps and Outstanding Issues

Abstract

Despite substantial progress made in research and development of cement formulations, preflush engineering, cementing technologies, and numerical modelling over the past decades, several knowledge gaps and unresolved problems still exist. These problems are likely to persist in the future as more complicated cementing conditions are encountered, e.g. in deepwater wells, HPHT wells, geothermal wells, and during underground CO₂ storage. New challenges are due either to harsh downhole conditions (e.g. HPHT) or more stringent environmental and safety regulations (e.g. geothermal and CO₂ wells). Challenges are found in the design, where perfect mud displacement and cement placement are still rare. Numerical models used to design cementing jobs are still often either too complicated (i.e. too slow) or inaccurate. Uncertainties about the formation properties (permeability, temperature, etc) and about the behavior of cement at downhole conditions reduce the practical value of even the most promising models. Despite these knowledge gaps, continuous progress over the past decades suggests that, in the years to come, the technology of primary cementing will continue to improve, based on our steadily improving knowledge of its physics and mechanics.