Tertiary Lacustrine Algal Limestone Mixed Carbonate Reservoir, Qaidam Basin, China
Compared with the global distribution of marine carbonate rocks, lacustrine carbonate rocks are relatively scarce, Research on these rocks is far less common than on marine carbonate rocks, yet lacustrine carbonate rocks under certain conditions are important source rocks, and may also be important oil and gas reservoir rocks. A recently found example Qaidam Basin in China is the Tertiary Youshashan Formation lacustrine microorganism limestone. These mixed reservoirs demonstrate that large and potentially valuable exploration targets exist in lacustrine carbonate rocks, The Qaidam is a large salted lake basin found in a high on the Tibetan Plateau, displaying the double deposition of marine and lacustrine deposits. Within these mixed deposition conditions, algal, gray, dolomite carbonate rocks are formed. Logging data is used to determine lacustrine microorganism limestone reservoir sedimentary facies distribution of the Youshashan Formation in Tertiary in the Dafengshan area. Detailed drill cuttings and core data are used to describe the sedimentary structures and sedimentary bedding, and to recognise the sedimentary environment and microfacies. This paper makes full use of microscopic analysis and FMI methods in the investigation of this limestone reservoir, and to study sediment characteristics, rock type, reservoir characteristics, the type of reservoir pore, the reservoir cause analysis. Understanding the characteristics of the Dafengshan area Youshashan Formation lacustrine microorganism limestone reservoirs and combining with oil and gas flow data obtained by industry would suggest exploring this layer in Qaidam Basin. It is expected to expand further the scope of their exploration and to become an important field of exploration in Qaidam Basin. For other regions of exploration the development of the lake facies carbonate reservoirs may also be significant.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013