The chemical and mechanical performance of cement solutions is adjusted by blending in materials, chemicals and additives to address the specific challenges of each individual well. As downhole environments have become increasingly challenging, the selection of Halliburton additives has grown from a dozen in the mid-fifties to several hundred today. This wide selection of chemicals and additives enables the customization of any given slurry so that it is engineered for the demands of each well. Options include accelerators, dispersants, fluid loss agents, gas migration additives, latexes, retarders and weighting agents.
Materials, chemicals and additives blended into slurries at engineered concentrations can help achieve reliable zonal isolation by altering slurry performance properties such as:
- Controlling thickening time for anticipated temperature and pressure conditions so that the slurry remains pump-able throughout the time required to place the cement and achieve top of cement as planned.
- Achieving optimum compressive strength so that the cement sheath can resiliently stand up to the highest anticipated axial forces or crush loading exerted against it.
- Affect the rheology of the slurry: (a) the resistance to flow (plastic viscosity measured in centipoise) and (b) a decrease in the resistance to flow under pressure (yield point measured in force per unit of contact area).
- Preventing fluid loss so that the cement slurry retains cement filtrate (the mix water plus dissolved ions from dissolution of the aqueous phase of cement) rather than losing it to the permeable formation in downhole temperature conditions.
- Reducing free fluid or minimizing the volume of fluid that separates from suspended particles/solids and collects at the vertical surface on the top of a slurry column or on the high side of a horizontal or highly deviated wellbore.
- Producing slurry stability through the uniform and consistent distribution of solids throughout the slurry.
- The density of the slurry required to resist the flow pressure from the formation without exceeding the fracture gradient of the same; density is measure in lb/gal according to the Principle of Archimedes.
All of Halliburton’s chemical and additive advancements were made with one goal in mind: to help operators benefit from a long-term tight annular seal and cement-sheath resilience for superior zonal isolation, even in technically demanding wells or environmentally sensitive areas.