Dilute Surfactant Methods for Carbonate Formations

Mohanty, Kishore K.

University of Houston

关键词: Fractures;    Wettability;    Waterflooding;    Sandstones;    Progress Report;   

DOI  :  10.2172/890025
RP-ID  :  None
RP-ID  :  FC26-02NT15322
RP-ID  :  890025

美国|英语

来源: UNT Digital Library

【 摘 要 】

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 best 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-scale surfactant brine imbibition experiments give high oil recovery (35-62% OOIP) for initially oil-wet cores through wettability alteration and IFT reduction. Core-scale simulation results match those of the experiments. Initial capillarity-driven imbibition gives way to a final gravity-driven process. As the matrix block height increases, surfactant alters wettability to a lesser degree, or permeability decreases, oil production rate decreases. The scale-up to field scale will be further studied in the next quarter.