Published: 06/12/2007
Published: 06/12/2007
An operator wanted to improve production from an aging field in the Texas Panhandle. The reservoir depth and pressure depletion made CO2-base fracturing fluids the system of choice for the field. The problem was achieving an effective fracture half-length with CO2 that would maximize financial returns.
Normal treatments were polymer-base CO2 systems pumped down 41.2-in casing. High friction pressure would not allow pumping this system down smaller diameter tubing. Conventional polymer-base fluids used in CO2 foam fracturing operations do not clean up well in tight gas sands. If sufficient fluid is not recovered, the polymer left behind shortens the effective fracture half-length. Flowing the well back up tubing increases the flowback velocity, which aids cleanup by increasing the liquid-carrying capacity.
To improve cleanup by stimulating downtubing and not introducing polymers that could damage the proppant pack, the operator used robust ClearFRAC CO2 fracturing fluid. Low-friction ClearFRAC CO2 treatment was successfully performed down 23.8-in tubing, which both reduced rig time and improved cleanup. Operations were further simplified because the ClearFRAC CO2 system used only 1 liquid additive and an encapsulated breaker mixed on the fly, whereas the polymer fluid required 7 additives.
ClearFRAC CO2 treatment increased fracture half-lengths by 41% and conductivity by 197%. As a result, production was increased by 29% in comparison with polymer treatment of the same formation in a nearby well. Normalized by net foot of pay, the production increase was 164%.
Significant reductions in the cost of operations were realized by using the ClearFRAC CO2 system over conventional polymer treatments. The treatment fluid volume was 18% less and the flush volume was 25% less. Tubing installation costs were reduced because snubbing operations, packer lubrication, and killing the fractured zone were no longer necessary.
The operator is planning more ClearFRAC CO2 treatments in the field to improve production in additional wells.
The innovative ClearFRAC CO2 system is specifically formulated to address the unique problems associated with creating robust fracturing fluids with high-pressured supercritical CO2. The result is an entirely new approach that can be used in all low-pressure, low-permeability, and brownfield applications, including dry gas reservoirs.
With a recommended foam quality of 60% or higher, ClearFRAC CO2 fluids perform better than conventional polymers, are not time-dependent at normal fracturing conditions, and also reduce the load to be recovered.
Challenge: An operator wanted to improve production from an aging field in the Texas Panhandle. The problem was achieving an effective fracture half-length with CO2 that would maximize financial returns.
Solution: Low-friction ClearFRAC CO2 treatment was successfully performed down 23.8-in tubing, which both reduced rig time and improved cleanup. Operations were further simplified because the ClearFRAC CO2 system used only 1 liquid additive and an encapsulated breaker mixed on the fly, whereas the polymer fluid required 7 additives.
Results: ClearFRAC CO2 treatment increased fracture half-lengths by 41% and conductivity by 197%. Resulting production was increased by 29% in comparison with polymer treatment of the same formation in a nearby well. Normalized by net foot of pay, the production increase was 164%.
