Impact Fluid Solutions demonstrated how Star Shield was able to eliminate wellbore instability and water influx in the Bakken due to nearby salt water disposal wells.
Wellbore instability and fluid loss to downhole formations are frequent and costly drilling issues. Stress caging and pumping of lost circulation material are two methods used to lessen the impact of these events; this paper presents another solution. To address the issue of wellbore instability within challenging shale and sand formations, several operators in North Dakota have adopted drilling fluid technologies that have significantly improved their drilling programs. The operators drilled nearly 60 wells without incident in a region characterized by catastrophic hole instability.
Offset wells typically address wellbore instability after the fact. The operators of the wells discussed in this paper proactively utilized a unique drilling fluid technology to prevent instability. When drilling, this technology forms a barrier over mechanically weak, depleted, and fragile formations. As a result, the operator avoids drilling fluid losses, stuck pipe, and other wellbore instability issues that typically increase NPT and add unplanned costs associated with lost circulation.
In this region, new operational drilling practices were adopted by multiple operators to eliminate wellbore instability, lost circulation, and water influx from nearby saltwater injection wells while extending mud weights in mechanically weak formations. In the wells documented in this paper, the results demonstrated minimal whole mud losses with extended mud weights in the 17½-in. surface hole section and 12¼-in. intermediate section.
By limiting fluid and pressure invasion into matrix pores and microfractures, this drilling fluid technology can stabilize difficult zones and prevent loss-inducing fracture propagation. When applied properly in the field, this drilling fluid technology can help to reduce wellbore instability and operational costs, while ensuring safe and cost-effective performance when drilling near saltwater disposal wells.
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