Wenbiao Huang

Pore characteristics of lacustrine mudstones from the Cretaceous Qingshankou Formation, Songliao Basin

AbstractCretaceous Qingshankou (K2qn) mudstone of lacustrine origin is the major source rock for conventional hydrocarbon currently being produced in the Daqing and Jilin oilfields of the Songliao Basin, which is one of the largest continental basins in the world. Therefore, elucidating the geochemical and petrological characteristics of the K2qn mudstone is important to help determine its quality as an economically viable source for shale oil production. In our study, eight dark mudstone core samples from the K2qn formation were subjected to total organic carbon (TOC), Rock-Eval pyrolysis, X-ray diffraction, scanning electron microscopy (SEM), field emission SEM (FE-SEM), and low-pressure N2 gas adsorption (LPGA-N2) experiments. Geochemical and petrological analysis results indicated the presence of a high TOC content, which originated mainly from alginate and some plant-derived organic matter, whereas bitumen was frequently present in mudstones with thermal maturity in the oil-generation stage. The K2qn...

Controlling Function of Overlying High-Quality Source Rock on Above-Generation and Below-Storage Tight Oil Reservoirs

continent faulted lake basin of China,the theory that“high-quality source rocks controls hydrocarbon accumulation”has been accepted by many scholars at home and abroad (Jin et al., 2008; Lu et al., 2012). Especially,the formation of tight oil reservoirs must be rely on high-quality source rocks. For instance,Bakken formation in north America develops two sets of highquality source rocks,which have large thickness,wide distribution,high abundance,excellent types and high hydrocarbon potential and other features (Webster, 1984). What’s more,the formation of tight oil in Yanchang group of Ordos basin and Lower Ganchaigou formation of Qaidm Basin in China are all based on the widely distributed high-quality source rocks (Bai et al., 2013; Fu et al., 2013). But,there is no unified understanding at what’s high-quality source rocks so far. For example,Wang Li (2009)think source rocks whose TOC>1.0% is highquality source rocks (Wang et al., 2009). However,Zheng Hongju(2007)and Lu Shuangfang(2012) pointed out that TOC=2.0% is the minimum of high-quality source rocks. In comparison to this,Hou Dujie(2008) hold that its TOC lower limit must greater than 3.0%. And more importantly,the above mentioned evaluation standards are built rely on experience and lack scientific evidence. Aimed at the weak link,this paper establishes the evaluation standard of high-quality source rocks in abundance and maturity of organic matter through the point of hydrocarbon expulsion from source rocks. Then,on this basis,we profoundly analyzed its controlling action on above-generation and below-storage tight oil reservoirs from the distribution range and overpressure of source rocks in K2qn formation. 1 Geologic Aspects