Bedded limestones and reefs are normally parts of a gradational sedimentary series with the reefs concentrated in the seaward areas. Many major oil fields produce from bedded limestone reservoirs. Bedded limestones are composed of clastic particles which, when coarse-grained and cleanly washed, resemble clean sharp sands. If porous, permeable accumulations of clastic carbonates are connected with source beds and sealed with an impervious cap, primary reservoirs result. Lime muds may be excellent source rocks. Dolomitization and secondary solution may improve but do not initiate limestone reservoirs. Fracturing is the main agent for secondary reservoir development.

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