The fracturing technique is generally used in deeper, lower quality and under-pressured reservoirs, which continue to represent a larger portion of reservoirs requiring stimulation as fields mature and higher quality reservoirs become less abundant.

"Long effective fracture half-length is key to maximising return on investment (ROI) in tight gas fracturing operations," said Ian Bryant, business development manager, Well Production Services, Schlumberger.

"ClearFRAC CO2 accomplishes this with its robust, stable nature and the superior clean-up characteristic of solids-free VES fracturing fluids. It also reduces the propensity for height growth, thus increasing fracture length in the pay zone."

According to Schlumberger, ClearFRAC CO2 enabled an Oklahoma-based independent oil and gas exploration company to sand fracture with CO2 down 2-3/8" tubing with the confidence of job placement. This treatment increased fracture half-length and conductivity to maximize production.

Additionally, it reduced tubing installation costs by eliminating snubbing operations and packer lubrication, and there was no need to kill the well. This allows a fresh look at old wells with casing problems or previously skipped over sands that require fracture stimulation down tubing for commercial flow rates.

An extension of the Schlumberger ClearFRAC family of VES fracturing fluids, the ClearFRAC CO2 formulation embodies all of the associated attributes, but incorporates a fit-for-purpose surfactant package that addresses the complexities of stabilising the supercritical CO2.