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The global distribution of basin-centered gas accumulations (BCGAs) is poorly known, and knowledge of the stratigraphic distribution of BCGAs is incomplete. Even in North America, where most of the exploration activity for BCGAs has occurred, the geographic distribution is not well known. [[:file:BasinCenteredGasFig13.jpg|Figure 1]] shows the locations of known and suspected BCGAs in the United States. A tabulation of these areas, as well as areas outside North America, is shown in Table 1. The geographic distribution of BCGAs is probably best known in the Rocky Mountain region, where a considerable amount of research has occurred.

The global distribution of basin-centered gas accumulations (BCGAs) is poorly known, and knowledge of the stratigraphic distribution of BCGAs is incomplete. Even in North America, where most of the exploration activity for BCGAs has occurred, the geographic distribution is not well known. [[:file:BasinCenteredGasFig13.jpg|Figure 1]] shows the locations of known and suspected BCGAs in the United States. A tabulation of these areas, as well as areas outside North America, is shown in Table 1. The geographic distribution of BCGAs is probably best known in the Rocky Mountain region, where a considerable amount of research has occurred.

| Benue trough, Nigeria || Moderate/High || Cretaceous || Direct || Obaje and Abaa<ref name=Obajeandabaa_1996>Obaje, N. G., and S. I. Abaa, 1996, Potential for col-derived gaseous hydrocarbons in the middle Benue Trough of Nigeria: Journal of Petroleum Geology, v. 19, p. 77-94.</ref>

| Benue trough, Nigeria || Moderate/High || Cretaceous || Direct || Obaje and Abaa<ref name=Obajeandabaa_1996>Obaje, N. G., and S. I. Abaa, 1996, Potential for col-derived gaseous hydrocarbons in the middle Benue Trough of Nigeria: Journal of Petroleum Geology, v. 19, p. 77-94.</ref>

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The stratigraphic distribution of BCGAs extends from the Cambrian through the Eocene (Table 1). However, there appear to be some differences in the stratigraphic distribution of direct and indirect BCGAs. For example, the preponderance of direct BCGAs occur in Cretaceous through Eocene rocks (Table 1), whereas indirect BCGAs more commonly occur in pre-Cretaceous rocks. Although some of the apparent difference in stratigraphic distribution may be attributable to the disproportionate number of studies in Cretaceous and younger rocks compared to numbers of studies in pre-Cretaceous rocks, the question of seal integrity in direct systems arises. As previously discussed, the effective life of [[capillary pressure]] seals in direct systems is not known; therefore, because of the perceptions of a leaky seal in direct systems, the occurrence of direct systems in pre-Cretaceous rocks may be less common than in Cretaceous and younger rocks. Some examples, however, of pre-Cretaceous direct BCGAs include Permian rocks in the Timan-Pechora basin, Russia<ref name=Lawetal_1996 /> and the Sichuan basin, China;<ref name=Dajunandyunho_1994 /> Pennsylvanian rocks in the Arkoma basin;<ref name=Meckeletal_1992 /> and Carboniferous rocks in the Dnieper-Donets basin, Ukraine<ref name=Lawetal_1998b /> (Table 1).

The stratigraphic distribution of BCGAs extends from the Cambrian through the Eocene (Table 1). However, there appear to be some differences in the stratigraphic distribution of direct and indirect BCGAs. For example, the preponderance of direct BCGAs occur in Cretaceous through Eocene rocks (Table 1), whereas indirect BCGAs more commonly occur in pre-Cretaceous rocks. Although some of the apparent difference in stratigraphic distribution may be attributable to the disproportionate number of studies in Cretaceous and younger rocks compared to numbers of studies in pre-Cretaceous rocks, the question of seal integrity in direct systems arises. As previously discussed, the effective life of [[capillary pressure]] seals in direct systems is not known; therefore, because of the perceptions of a leaky seal in direct systems, the occurrence of direct systems in pre-Cretaceous rocks may be less common than in Cretaceous and younger rocks. Some examples, however, of pre-Cretaceous direct BCGAs include Permian rocks in the Timan-Pechora basin, Russia<ref name=Lawetal_1996 /> and the Sichuan basin, China;<ref name=Dajunandyunho_1994 /> Pennsylvanian rocks in the Arkoma basin;<ref name=Meckeletal_1992 /> and Carboniferous rocks in the Dnieper-Donets basin, Ukraine<ref name=Lawetal_1998b /> (Table 1).