Noodle Creek limestone reservoirs of Rough Draw field represent tabular biostromes that contain the same biota found in phylloid algal mounds. The Noodle Creek contains three carbonate intervals, separated by shales, which range in thickness from 25 to 30 ft. Production occurs from the lower two carbonates. In ascending order, Noodle Creek limestones exhibit a vertical sequence of four subtidal deposition facies: (1) algal-plate-boundstone, (2) algal-intraclast-boundstone, (3) peloid-foraminiferal-boundstone/grainstone, and (4) foraminiferal grainstone facies. The principal binder-encruster, which formed the boundstone fabric, is an enigmatic, tubular, branched, nonseptate foram or alga. Other binder-encrusters include tubiphytes and several encrusting forams. Relatively soon after deposition, each Noodle Creek carbonate interval was exposed subaerially and subjected to freshwater diagenesis. Dissolution of aragonitic phylloid algae created much secondary porosity in the lower intervals. Vadose cements, consisting of scalenohedral crusts and meniscoid patterns, were followed by phreatic cements consisting of blocky equant calcite, ferroan calcite, and ferroan dolomite, which occluded most porosity in many intervals. Most oil is produced from grainstones and phylloid algal-rich facies wherein residual primary and secondary porosity was enhanced by late-stage dissolution that occurred during burial diagenesis.
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