New water-based fluid system helps operators save time and reduce costs
Challenge – With its unconventional field developments, the outstanding success of the Permian Basin as a global oil and gas swing producer has been sustained by operators and service companies using innovative technologies and cost-efficient operational practices.
Overlying much of the hydrocarbon-rich Delaware Basin – the western province of the Permian Basin – is a thick evaporite sequence posing a significant challenge for wellbore integrity. Commonly used water-based drilling fluids suffer substantially from wellbore washout and from high dump and dilution rates due to salt leaching when drilling through the evaporites. A further drilling hazard has been the frequent occurrence of lost circulation below the evaporite formation because of a reduced formation fracture gradient. Poor hole quality has impacted cementing operations where drilling permits have demanded cement to surface as proof of satisfactory zonal isolation Moreover, environmental regulations have required waste haul-offs to designated disposal sites where long-distance transportation costs become aggravated by the high dilution volumes.
Solution – In the pervading low-cost oil environment, Baroid and its customers identified an opportunity to mitigate challenging operating conditions and costs. In introducing the new BaraShale™ Lite water-based fluid system, Baroid was able to actively demonstrate significant improvements in hole quality, along with a dramatic reduction in lost circulation events and fluid waste volumes. The new direct emulsion drilling fluid system prevented leaching of the evaporitic salt layers, thus maintaining near-gauged hole conditions and removing the need for continuous fluid dilution and dumping. Furthermore, the direct emulsion system facilitated easy management of low fluid densities, enabling successful drilling of formations with very low fracture gradients.
With BaraShale Lite fluid in the hole, Baroid’s customers were able to realize substantial improvements in the efficiency and integrity of cementing operations. Improved hole conditions were demonstrated by caliper logs and by reduced cement volumes and pumping schedules in multiple wells where BaraShale Lite fluid was used. Improved wellbore integrity and the prevention of lost circulation from lower fluid densities allowed the customers to set casing points deeper, thus enabling them to remove a casing string and to substantially improve costs and operational efficiency. Greater rates of penetration (ROPs) with the new direct emulsion system relative to offset wells were also experienced, significantly reducing time to total depth. Further operational gains at the rigsite were realized from a greater efficiency of solids control equipment, as well as from improved cuttings integrity. Salt cuttings were observed for the first time relative to offset operations using conventional water-based drilling fluid systems. The BaraShale Lite fluid provided substantially lower haul-off volumes by preventing salt dissolution.
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