Changes

Determining the connectivity of the sand bodies in a meander belt system is critical to evaluating the commerciality of types of reservoirs. Individual point bars are relatively small reservoir bodies likely to contain only a few million barrels of recoverable oil at best. They may be successfully drilled onshore where wells are relatively cheap, but they are less likely to make much profit as a primary target offshore. However, if several of these sand bodies overlap with each other, then they can combine to form a larger connected sand volume.

Determining the connectivity of the sand bodies in a meander belt system is critical to evaluating the commerciality of types of reservoirs. Individual point bars are relatively small reservoir bodies likely to contain only a few million barrels of recoverable oil at best. They may be successfully drilled onshore where wells are relatively cheap, but they are less likely to make much profit as a primary target offshore. However, if several of these sand bodies overlap with each other, then they can combine to form a larger connected sand volume.

[[file:M91FG179.JPG|thumb|300px|{{figure number|8}}Net sand isochore map of the Q reservoir in the Little Creek field in Mississippi. The reservoir comprises three connected point bar sandstones in a background of floodplain mudstones and siltstones. Just to the north is the Sweetwater field, which produces from a depositionally isolated point bar in the same meander belt system (from Werren et al., 1990). Reprinted with permission from, and © by, Springer Ltd.]]

[[file:M91FG179.JPG|thumb|300px|{{figure number|8}}Net sand isochore map of the Q reservoir in the Little Creek field in Mississippi. The reservoir comprises three connected point bar sandstones in a background of floodplain [[mudstones]] and siltstones. Just to the north is the Sweetwater field, which produces from a depositionally isolated point bar in the same meander belt system (from Werren et al., 1990). Reprinted with permission from, and © by, Springer Ltd.]]

Technical papers indicate that connectivity in meander belt sediments can be highly variable and prone to chance factors. An example of this is the Little Creek field in Mississippi.<ref name=Werrenetal_1990 /> The lower reservoir unit comprises three connected point bar sandstones ([[:file:M91FG179.JPG|Figure 8]]). The Sweetwater field immediately to the north is believed to form part of the same fluvial system and produces from a fourth point bar sand body along the same trend. Nevertheless, the Sweetwater field is isolated from the Little Creek field on the evidence of a 24-m (79-ft) higher oil-water contact. The two fields are thought to be separated by a shale plug or an area with relatively high capillary [[displacement pressure]]. A similar observation was made by Carter<ref name=Carter_2003 /> for a meander belt reservoir in the Widuri field in the Java Sea. Following the depletion of a well on the updip side of a 100-m (328-ft)-wide abandoned channel, a second well was drilled on the opposite site of the clay plug. A full oil column was found in the new well, unaffected by production from the previous well. In the Saddle Lake area of Alberta, Canada, oil and gas pools are restricted to point bars completely surrounded by clay plugs.<ref name=Edieandandrichuk_2003>Edie, R. W., and J. M. Andrichuk, 2003, [http://bcpg.geoscienceworld.org/content/51/3/253.short Meander belt entrapment of hydrocarbons at Saddle Lake, Alberta and an untested in situ combustion scheme for recovery of heavy oil]: Bulletin of Canadian Petroleum Geology, v. 51, no. 3, p. 253–274.</ref>

Technical papers indicate that connectivity in meander belt sediments can be highly variable and prone to chance factors. An example of this is the Little Creek field in Mississippi.<ref name=Werrenetal_1990 /> The lower reservoir unit comprises three connected point bar sandstones ([[:file:M91FG179.JPG|Figure 8]]). The Sweetwater field immediately to the north is believed to form part of the same fluvial system and produces from a fourth point bar sand body along the same trend. Nevertheless, the Sweetwater field is isolated from the Little Creek field on the evidence of a 24-m (79-ft) higher oil-water contact. The two fields are thought to be separated by a shale plug or an area with relatively high capillary [[displacement pressure]]. A similar observation was made by Carter<ref name=Carter_2003 /> for a meander belt reservoir in the Widuri field in the Java Sea. Following the depletion of a well on the updip side of a 100-m (328-ft)-wide abandoned channel, a second well was drilled on the opposite site of the clay plug. A full oil column was found in the new well, unaffected by production from the previous well. In the Saddle Lake area of Alberta, Canada, oil and gas pools are restricted to point bars completely surrounded by clay plugs.<ref name=Edieandandrichuk_2003>Edie, R. W., and J. M. Andrichuk, 2003, [http://bcpg.geoscienceworld.org/content/51/3/253.short Meander belt entrapment of hydrocarbons at Saddle Lake, Alberta and an untested in situ combustion scheme for recovery of heavy oil]: Bulletin of Canadian Petroleum Geology, v. 51, no. 3, p. 253–274.</ref>