The Lower Cambrian Xiaoerbulake Formation in the Tarim Basin as a potential carbonate source rock

Abstract

The oil and gas exploration of the Middle and Lower Cambrian in the Tarim Basin reveals widely distributed source rocks with the Yuertusi Formation being recognized as high-quality source rocks that are distributed in a rather small range. The Xiaoerbulake Formation that is right under the Yuertusi Formation has also been eyed as potential high-quality source rocks and is studied through analyses focusing on the stratigraphic development, the abundance, type, and maturity of organic matter, and the paleoproductivity of a dark-colored algae dolomite within the formation. The results show that the dolomite is rich in organic matter of mainly types I and II kerogens. Although reached the high mature to over-mature stage, the dolomite was deposited in an anoxic sedimentary environment featuring a high paleoproductivity level and a high organic carbon burial efficiency, quite favorable for the development of high-quality source rocks. The study provides material evidence to the Middle-Lower Cambrian subsalt source rock-reservoir-caprock combination model for the Tarim Basin.