ZoneSeal® Isolation Process
The ZoneSeal® Isolation Process is a fully engineered zonal isolation process with automated controls to deliver the benefits of light-weight (foam) cement for the life of the well. The ZoneSeal process begins with pre-job evaluation and continues through to operations at the wellsite and to post-job follow up.
OptiCem™ Cement Job Design and Simulation System, along with specialized laboratory testing (standardized within Halliburton globally), provides an engineered solution to specific challenges of each well. This engineered approach helps optimize the annular seal not only for a good bond log, but also for years of withstanding temperature and pressure changes in the wellbore. This integrated solution includes a pumping/displacement plan and a customized slurry blend designed with appropriate chemical and mechanical properties tailored to the unique attributes of each reservoir and well, taking into account all aspects of the formation throughout the annulus. The goal is an optimized annular seal to enhance well economics by helping to minimize the need for remediation and maximize ultimate recovery.
The field process is achieved by full automation of the blending, pumping and injection actions for greater control. Additionally, the equipment (cement pumping unit, nitrogen unit and injection unit) is integrated, providing precision in shearing the slurry to create a stable foam.
Post-job Follow Up
Process-certified specialists monitor the job throughout the design and field operations and then provide a post-job report.
The Advantages of Foam Cement
Foam cement provides particular benefits in geothermal wells due to its lower thermal conductivity and other enhanced mechanical properties. A low thermal conductivity cement sheath allows for less and slower heat transfer/heat loss in the wellbore. This benefit will allow for more productive steam-generating wells in geothermal projects. These enhanced mechanical properties will allow more flexibility for the cement sheath to respond to the effects of excessive temperatures in the wellbore, therefore maintaining cement sheath integrity and providing zonal isolation/casing protection.
Enhanced and highly-engineered mechanical properties of the cement sheath allow it to move with the wellbore and also absorb stresses resulting from the mechanical shocks from pipe tripping to expansion and contraction of the casing during pressure and well testing, injection and production cycling.
Importantly, foam cement establishes a tight bond for a reliable annular seal because the nitrogen bubbles help to prevent shrinkage while the cement slurry goes through the hydration stage. A foamed system, due to its expansion properties, also accommodates challenging wellbore geometries such as wash-outs.
It is important to note that foam cement has historically been used primarily for reduction of slurry density. Halliburton has delivered foam cement systems much lighter than water, yet without compromising essential mechanical properties to establish life-of-the-well zonal isolation.