Changes

Channel complex connectivity will depend upon whether the individual channels show extensive sand-sand contacts with each other or not. It is not always easy to assess this with limited well control. This is a particular problem when it comes to the costly appraisal of deep-marine sandstone reservoirs offshore.<ref>Steffens, G. S., R. C. Shipp, B. E. Prather, A. Nott, J. L. Gibson, and C. D. Winker, 2004, The use of near-sea floor 3D seismic data in deep-water exploration and production, in R. J. Davies, J. A. Cartwright, S. A. Stewart, S. A. Lappin, and J. R. Underhill, eds., 3D seismic technology, applications to the exploration of sedimentary basins: Geological Society (London) Memoir 29, p. 35–43.</ref>

Channel complex connectivity will depend upon whether the individual channels show extensive sand-sand contacts with each other or not. It is not always easy to assess this with limited well control. This is a particular problem when it comes to the costly appraisal of deep-marine sandstone reservoirs offshore.<ref>Steffens, G. S., R. C. Shipp, B. E. Prather, A. Nott, J. L. Gibson, and C. D. Winker, 2004, The use of near-sea floor 3D seismic data in deep-water exploration and production, in R. J. Davies, J. A. Cartwright, S. A. Stewart, S. A. Lappin, and J. R. Underhill, eds., 3D seismic technology, applications to the exploration of sedimentary basins: Geological Society (London) Memoir 29, p. 35–43.</ref>

Weimer and Slatt<ref name=WeimerandSlatt /> gave guidelines on how to differentiate between sheet and channelized deep-marine sandstones. If the log patterns and net-to-gross ratios vary considerably over short distances between wells, then the chances are that this is a channelized system (Chapin et al., 1994). A typical pattern is for channels to have high net-to-gross values and a blocky log response in the channel axis, with lower net-to-gross values and a serrated log response toward the margins ([[:File:M91FG193.JPG|Figure 1]]). In core, channel-fill sandstones can show erosional features such as erosional bases, shale clasts, and an abundance of chaotic looking sediments.

Weimer and Slatt<ref name=WeimerandSlatt /> gave guidelines on how to differentiate between sheet and channelized deep-marine sandstones. If the log patterns and net-to-gross ratios vary considerably over short distances between wells, then the chances are that this is a channelized system.<ref>Chapin, M. A., P. Davies, J. L. Gibson, and H. S. Pettingill, 1994, Reservoir architecture of turbidite sheet sandstones in laterally extensive outcrops, Ross Formation, western Ireland, in P. Weimer, A. H. Bouma, and B. F. Perkins, eds., Submarine fans and turbidite systems: Gulf Coast Section SEPM Foundation 15th Annual Research Conference, v. 15, p. 53–68.</ref> A typical pattern is for channels to have high net-to-gross values and a blocky log response in the channel axis, with lower net-to-gross values and a serrated log response toward the margins ([[:File:M91FG193.JPG|Figure 1]]). In core, channel-fill sandstones can show erosional features such as erosional bases, shale clasts, and an abundance of chaotic looking sediments.

Sheet sandstones and their associated shale interbeds are more layered and massive both at the core and interwell scale. Erosive features are relatively rare with few or no shale rip-up clasts. Post-production formation tester data can help to recognize the high degree of lateral continuity likely to be present here.

Sheet sandstones and their associated shale interbeds are more layered and massive both at the core and interwell scale. Erosive features are relatively rare with few or no shale rip-up clasts. Post-production formation tester data can help to recognize the high degree of lateral continuity likely to be present here.