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Abstract A multi-phase effort that involved geological, geophysical, and petroleum engineering studies yielded an improved understanding of naturally fractured reservoirs and potential manners to improve the inddence of oil production from such reservoirs. Maps of fracture traces on bedding planes in the Austin Chalk outcrops showed organized trends of the fracture development and a hierarchical nature within the complete fracture system. Vertical Seismic Profile, VSP data has been used to estimate fracture orientation from shear-wave splitting. Well log responses in Austin Chalk wells have shown to be a reliable indicator of organic maturity. Well logs have also been used to calculate average resistivity of producing zones and to correlate resistivity with oil saturation and therefore with producing potential. Additionally, the use of carbonated water imbibition displacement processes has shown encouraging results of accelerating and increasing oil recovery of oil which do not have appredable asphaltene contents. Introduction A multi-disciplinary investigation to develop innovative methods to characterize and to enhance oil recovery from dual porosity, naturally fractured, low permeability oil reservoirs was conducted for several years. The Austin Chalk, a naturally fractured, oil producing horizon trending through Texas was the subject of the present study. Two major technological problems characteristic of the Austin Chalk as well as to other dual porosity reservoirs were present: Reservoir Description Commercial oil production from this type of reservoirs is dependent on the wellbore encountering a significant number of essentially vertical trending natural fractures. P. 97^ |
