When M-I SWACO, a Schlumberger company, introduced its I-BOSS wellbore strengthening-while-drilling solution suite, the oil and gas industry sought a way to restore well stability and prevent lost circulation due to induced fractures. “The industry issue was essentially [being able to] successfully drill through depleted zones [sands] to access reservoirs that were previously inaccessible,” said Jim Friedheim, Ph.D. and corporate director for fluids research at M-I SWACO.

The technology works to seal drilling-induced fractures and isolate fracture tips from further elongation and reopening using continuous application of bridging particles, according to the company’s website. As a result, operators see a reduction in fluid losses and a strengthened wellbore, enabling construction with low fracture gradients and a decrease in costs.

In 2009 the I-BOSS suite of solutions won the drilling fluids category of Hart Energy’s Meritorious Awards for Engineering Innovation. Since its introduction the technology has experienced much success in the industry.

While drilling offset wells in the Mississippi Canyon block of the deepwater Gulf of Mexico, an operator identified mud losses and wellbore stability as challenges to drilling a section above the salt, the salt layer itself, the zone below the salt, and deeper zones, according to an M-I SWACO case study. The operator used the I-BOSS suite to strengthen the wellbore in intervals above, within, and below the salt layer.

“The technique of choice in all five intervals was circumferential stress enhancement, or stress caging, which is attained by inducing shallow fractures in a formation using elevated wellbore pressure and simultaneously forcing wellbore strengthening materials into the fractures to keep them propped and in a stressed state,” according to the case study.

Using wet sieve analysis, the correct concentration and sizes of the wellbore strengthening materials were maintained, with each of the five intervals targeted requiring a different wellbore strengthening materials blend. As a result of applying this technology, “there were zero mud losses in the well while drilling the permeable zones of interest using the continuous application of wellbore strengthening materials,” according to the case study. The use of the I-BOSS suite also enabled the operator to reduce cost in materials and rig time.

Since the technology’s introduction, M-I SWACO has added OPTISTRESS software, built a new fracture tester, developed several new additives for fracture sealing, and developed a new theory for wellbore strengthening known as fracture propagation resistance.

Friedheim noted that the technology has been continually improved, adjusted, and updated with new findings, techniques, and products. “The industry is even more interested in wellbore strengthening since the issue of depleted zone drilling has increased with a greater depletion factor,” he said.

The company is currently conducting Phase III of its research cooperative agreement on fracture sealing and wellbore strengthening. “We are looking at larger fractures, fractured shale, and the use of fibers as possible additives to the current product mix,” Friedheim said.

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