PART6-GEOLOGICAL METHODS B zone A and c zones absent combined 8-12 0-2 Zone B 10 000 feet Figure 6. Poroslty thickness(oh) maps for the b and c zones from the San Andres Formation reservoir, Jordan fleld, Ector and Crane Counties, Texas. Contours in PV fraction-feet. (After Major and Holtz, 1989 Water Cut example of cumulative production that was concluded to be only poorly correlated to storage capacity(Figure 6)in Water cut is the fraction of a liquid production stream that individual and summed zones of a carbonate reservoir(Major is water, where oil cut=1-water cut. Like GOR, water cut and Holtz, 1989). In this case, porosity did not necessarily will change during the life of a reservoir, and periodic indicate effective porosity mapping can serve as a performance indicator for reservoir management. A variety of performance features can be indicated by water cut maps, including water coning, OTHER MAPS directional permeability or channeling, and formation damat A variety of other maps can come into play during the development of a specific reservoir. Maps of facies, facies Cumulative production architecture, paleoenvironment, and isolithology might be particularly important in selecting stepout well locations and Cumulative oil or gas production is a parameter useful for planning reservoir development strategy. Other reservoir ultimate reserves forecasts. Cumulative production can also properties such as temperature can have value for specific be mapped periodically as a performance indicator signaling reservoir engineering applications, particularly where areas of the reservoir that may be responding in a manner potentially temperature-sensitive chemical stimulation, seemingly unrelated production, or recovery technology might be involved298 PART 6—GEOLOGICAL METHODS B zone absent A and C zones A combined 10,000 feet Figure 6. Porosity thickness (4>H) maps for the B and C zones from the San Andres Formation reservoir, Jordan field, Ector and Crane Counties, Texas. Contours in PV fraction-feet. (After Major and Holtz, 1989.) Water Cut Water cut is the fraction of a liquid production stream that is water, where oil cut = 1 - water cut. Like GOR, water cut will change during the life of a reservoir, and periodic mapping can serve as a performance indicator for reservoir management. A variety of performance features can be indicated by water cut maps, including water coning, directional permeability or channeling, and formation damage. Cumulative Production Cumulative oil or gas production is a parameter useful for ultimate reserves forecasts. Cumulative production can also be mapped periodically as a performance indicator signaling areas of the reservoir that may be responding in a manner seemingly unrelated to initial potential. Figure 7 shows an example of cumulative production that was concluded to be only poorly correlated to storage capacity (Figure 6) in individual and summed zones of a carbonate reservoir (Major and Holtz, 1989). In this case, porosity did not necessarily indicate effective porosity. OTHER MAPS A variety of other maps can come into play during the development of a specific reservoir. Maps of fades, facies architecture, paleoenvironment, and isolithology might be particularly important in selecting stepout well locations and planning reservoir development strategy. Other reservoir properties such as temperature can have value for specific reservoir engineering applications, particularly where potentially temperature-sensitive chemical stimulation, production, or recovery technology might be involved