Quartz cement and its origin in tight sandstone reservoirs of the Cretaceous Quantou formation in the southern Songliao basin,China |
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| Institution: | 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong, 266580, China;2. Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, 0316, Oslo, Norway;3. Research Institute of Petroleum Exploration & Development, Beijing, 100083, China;4. College of Earth Sciences, Northeast Petroleum University, Daqing, Hei Longjiang, 163318, China;1. School of Geoscience, China University of Petroleum, Qingdao 266580, China;2. Department of Earth Sciences, Durham University, Durham DH1 3LE, UK;1. School of Geoscience, China University of Petroleum, Qingdao, 266580, China;2. Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK;3. 41 Oaken Lane, Claygate, Esher, Surrey, KT10 0RG, UK;1. Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK;2. Department of Physics, Durham University, Durham, DH1 3LE, UK;3. WiscSIMS Lab, Department of Geoscience, University of Wisconsin, Madison, WI, 53706-1692, USA;1. Department of Geosciences, University of Oslo, Norway;2. Petroleum Exploration Private Limited, Islamabad, Pakistan;3. Department of Meteorology, COMSATS University Islamabad, Pakistan;1. School of Geosciences, China University of Petroleum, Qingdao 266580, China;2. Department of Geosciences, University of Oslo, Oslo 0316, Norway;3. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;4. Xinchun Oil Production Plant of Shengli Oilfield, Sinopec, Dongying 257015, China |
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| Abstract: | The tight sandstones of the Cretaceous Quantou formation are the main exploration target for hydrocarbons in the southern Songliao basin. Authigenic quartz is a significant cementing material in these sandstones, significantly reducing porosity and permeability. For efficient predicting and extrapolating the petrophysical properties within these tight sandstones, the quartz cement and its origin need to be better understood. The tight sandstones have been examined by a variety of methods. The sandstones are mostly lithic arkoses and feldspathic litharenites, compositionally immature with an average framework composition of Q43F26L31, which are characterized by abundant volcanic rock fragments. Mixed-layer illite/smectite (I/S) ordered interstratified with R = 1 and R = 3 is the dominating clay mineral in the studied sandstone reservoirs. Two different types of quartz cementation modes, namely quartz grain overgrowth and pore-filling authigenic quartz, have been identified through petrographic observations, CL and SEM analysis. Homogenization temperatures of the aqueous fluid inclusions indicate that both quartz overgrowths and pore-filling authigenic quartz formed with a continuous process from about 70 °C to 130 °C. Sources for quartz cement produced are the conversion of volcanic fragments, smectite to illite reaction and pressure solution at micro stylolites. Potassium for the illitization of smectite has been sourced from K-feldspar dissolution and albitization. Silica sourced from K-feldspars dissolution and kaolinite to illite conversion is probably only minor amount and volumetrically insignificant. The internal supplied silica precipitate within a closed system where the transport mechanism is diffusion. The quartz cementation can destroy both porosity and permeability, but strengthen the rock framework and increase the rock brittleness effectively at the same time. |
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| Keywords: | Quartz cement Silica sources Smectite to illite reaction Pressure solution Quantou formation Songliao basin |
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