Non-productive time (NPT) has been documented to account for nearly 20% of total well construction costs. Whole mud losses, differential sticking and other equally costly consequences of wellbore instability cost the global industry hundreds of millions of dollars each year.
Wellbore instability is an increasing priority that poses tremendous challenges for operators faced with drilling and cementing high-profile deepwater wells, mechanically weak formations and high overbalance and depleted zones. The low fracture gradients and narrow mud weight windows common to these weak formations generate the wellbore instability issues that usually are exacerbated during drilling and cementing operations.
Approaches to tackling the profit-draining ramifications of wellbore instability run the gamut, from pumping wellbore strengthening material (WSM) with the drilling fluid to “stress caging,” where fractures are created and subsequently sealed with precise concentrations of bridging or sealing agents. For the most part, these widely differing approaches to maintaining wellbore stability are reactive, and each requires additional rig time and costs.
A New Approach
Wellbore Shielding® offers a field-proven alternative to these more conventional approaches, in that the objective is preventing wellbore destabilization through a preventative, technology-based shielding process. Unlike traditional wellbore strengthening techniques, the shielding technology essentially stabilizes troublesome zones by minimizing fluid and pressure invasion into matrix pores and microfractures. Importantly, Wellbore Shielding also minimizes the formation damage that is all too common with conventional stabilizing additives.
Our Wellbore Shielding products comprise a proprietary blend of modified polymers and solids, manufactured to form small, deformable aggregates in the fluid system. The “shields,” or aggregates, in these products produce an extremely low-permeability barrier at the fluid-rock interface, delivering ultra-low invasion across a broad range of permeability and microfractures. In most circumstances, the low flow initiation pressure of the deposited barrier is easily removed by simply flowing the well.
In challenging applications worldwide, the unique Wellbore Shielding approach has demonstrated its capacity to eliminate or considerably reduce mud losses and reservoir impairment, effectively improve wellbore stability and minimize the risk of differential sticking. Our wellbore shielding products consistently have been shown to enhance the performance of drilling fluids in overcoming the myriad wellbore instability issues that can arise when encountering induced or natural fractures, the natural heterogeneity of the geology and chemical reactivity of swelling shales. By preventing fluid and pressure from penetrating either microfractures or between bedding planes, Wellbore Shielding additives clear the way for trouble-free drilling in some of the world’s most unstable and mechanically-weak formations.