DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

Technical Report · Fri Jul 01 04:00:00 EDT 2005

DOI:https://doi.org/10.2172/842205· OSTI ID:842205

Mohanty, Kishore K

There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory imbibition tests show that imbibition rate is not very sensitive to the surfactant concentration (in the range of 0.05-0.2 wt%) and small amounts of trapped gas saturation. It is however very sensitive to oil permeability and water-oil-ratio. Less than 0.5 M Na2CO3 is needed for in situ soap generation and low adsorption; NaCl can be added to reach the necessary total salinity. The simulation result matches the laboratory imbibition experimental data. Small fracture spacing and high permeability would be needed for high rate of recovery.

• Research Organization: University of Houston
• DOE Contract Number: FC26-02NT15322
• OSTI ID: 842205
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ADSORPTION
CARBONATES
ENHANCED RECOVERY
FRACTURED RESERVOIRS
FRACTURES
GAS SATURATION
PERMEABILITY
SALINITY
SANDSTONES
SIMULATION
SOAPS
SOLUBILITY
SURFACTANTS
WATERFLOODING